Download PART – B - E

NEHRU ARTS AND SCIENCE COLLEGE
DEPARTMENT OF MICROBIOLOGY WITH NANOTECHNOLOGY
E-LEARNING
CLASS
: III B.Sc.
SUBJECT : ENVIRONMENTAL AND AGRICULTURAL MICROBIOLOGY
_________________________________________________________________________
UNIT-I
UNIT -I
Distribution of microorganisms in nature – Microbial communities in soil- factors
Influencing the microbial density in soil- zymogenous and autochthonous flora in SoilMicrobial associations – symbiotic proto cooperation, ammensalism, Commensalism,
syntropism, parasitism and predation with suitable examples.
UNIT 1
PART – A
1. An increase in the atmospheric level of automobile exhaust gases does not lead to(a) Pb Pollution
(b) O2 Pollution
(c) Particulate air pollution
(d) O3 Pollution
Ans: (d) O3 Pollution
2. UV radiations is injurious to plants because it(a) Break phosphate bonds
(b) Increases respiration
(c) Causes dehydration
(d) Causes genetic changes
Ans: (d) Causes genetic changes
3. The most stable ecosystem could be(a) Ponds
(b) Oceans
(c) Desert
(d) Forest
Ans: (b) Oceans
5. Pollution of big cities can be controlled to large extent by(a) Wide roads and factories away from city
(b) Cleanliness drive and proper use of pesticides
(c) Proper sewage and proper exit of chemicals from factories
(d) All of the above
Ans: (d) All of the above
5. Mention the main cause of smog.
Answer: Some of the main causes and sources of smog are gasoline and diesel power
vehicles, factories, oil based paints, solvents and cleaners, pesticides and coal fired generating
stations.
PART – B
1. Given an account of sources of air pollution
Most of the sources of air pollution are related to man's activities as a result of the
modern lifestyle. Added to this are also natural causes like the volcanoes, anaerobic
decomposition of organic matter, atmospheric reactions, etc.
Burning of Fossil Fuels
Fossil fuels include petroleum and coal. Burning of coal produces a lot of smoke and
dust whereas burning of petrol mainly produces sulphur dioxide. In addition to these, the
pollutants include carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides,
hydrocarbons, particulate matter and traces of metals.
Automobiles
Petrol on combustion produces carbon monoxide, hydrocarbons, nitrogen oxides,
aldehydes, sulphur compounds, organic acids and ammonia and carbon particles. Incomplete
combustion of petrol produces a hydrocarbon, 3,4 benzpyrene. There is more pollution during
acceleration and deceleration than during constant speed.
Industries
Fertiliser Plants
They produce oxides, sulphur, nitrogen, hydrocarbons, particulate matter and fluorine.
Thermal Plants
Since they are coal based the pollutants are fly ash, soot and sulphur dioxide.
Textile Industries
They produce cotton dust, nitrogen oxides, chlorine, naphtha vapours, smoke and
sulphur dioxide.
Steel Plants

They produce carbon monoxide, carbon dioxide, sulphur dioxide, phenol, fluorine,
cyanide, particulate matter, etc.

Volcanic eruptions release oxides of nitrogen that pollute the atmosphere.

Decomposition of organic matter under anaerobic conditions produces methane which on
being oxidised in the atmosphere produces carbon monoxide. Decomposition of these
matter also produces foul smelling gases.

Photochemical oxidation of marine organic matter and biological oxidation by marine
organisms produce lot of carbon monoxide on the surface of the oceans which enters the
atmosphere.
Major Pollutants
There are six main categories of air pollutants:

oxides of carbon

sulphur dioxide

oxides of nitrogen

hydrocarbon

inorganic particulate matter and aerosols

organic particulate matter
Microbes Found in Air
In addition to gases, dust particles and water vapour, air also contains microorganism. There are
vegetative cells and spores of bacteria, fungi and algae, viruses and protozoan cysts. Since air is often
exposed to sunlight, it has a higher temperature and less moisture. So, if not protected from desiccation,
most of these microbial forms will die. Air is mainly it transport or dispersal medium for
microorganisms. They occur in relatively small numbers in air when compared with soil or water. The
microflora of air can be studied under two headings outdoor and indoor microflora.
Outdoor microflora: The air in the atmosphere, which is found outside the buildings, is
referred to as outside air. The dominant microflora of outside air are fungi. The two common genera
of fungi are Cladosporium and Sporobolomyces. Besides these two genera, other genera found in air
are Aspergillus, Alternaria, Phytophthora and Erysiphe. The outdoor air also contains basidispores,
ascopores of yeast, fragments of mycelium and conidia of molds. Among the bacterial genera
Bacillus and Clostridium, Sarcina, Micrococcus, Corynebacterium and chromobacter are widely
found in the outside air. The number and kind of microorganisms may vary from place to
place, depending upon the human population densities.
Indoor microflora: The air found inside the building is referred to as Indoor air. The
commonest genera of fungi in indoor air are Penicillum, Aspergillus. The commonest genera of
bacteria found in indoor air are Staphyloccocci, Bacillus and Clostridium. In case of occupants
being infected, The composition shows slight variations with latitude and to a lesser extent with
altitude. The ozone owes its existence in the atmosphere to photosynthesis from oxygen under
the influence of solar ultraviolet radiations.
Sources of Microorganisms in Air
Although a number of microorganisms are present in air, it doesn't have an indigenous flora.
Air is not a natural environment for microorganisms as it doesn't contain enough moisture and
nutrients to support their growth and reproduction. Quite a number of sources have been studied in
this connection and almost all of them have been found to be responsible for the air microflora.
One of the most common source of air microflora is the soil. Soil microorganisms when disturbed
by the wind blow, liberated into the air and remain suspended there for a long period of time. Man
made actions like digging or ploughing the soil may also release soilborne microbes into the air.
Similarly microorganisms found in water may also be released into the air in the form of water
droplets or aerosols. Splashing of water by wind action or tidal action may also produce droplets
or aerosols.
Air currents may bring the microorganisms from plant or animal surfaces into air. These
organisms may be either commen or plant or animal pathogens. Studies show that plant
pathogenic microorganisms are spread over very long distances through air . For example, spores
of Puccinia graminis travel over a thousand kilometers. However, the transmission of animal
diseases is not usually important in outside air
The main source of airborne microorganisms is human beings. Their surface flora may
be shed at times and may be disseminated into the air. Similarly, the commen as well as
pathogenic flora of the upper respiratory tract and the mouth are constantly discharged into
the air by activities like coughing, sneezing, talking and laughing. The microorganisms are
discharged out in three different forms which are grouped on the basis of their relative size
and moisture content. They are droplets, droplet nuclei and infectious dust. It was Wells, who
described the formation of droplet nuclei. This initiated the studies on the significance of
airborne transmission.
Droplet: Droplets are usually formed by sneezing, coughing or talking. Each consists of saliva
and mucus. Droplets may also contain hundreds of microorganisms which may be pathogenic if
discharged from diseased persons. Pathogens will be mostly of respiratory tract origin. The size of
the droplet determines the time period during which they can remain suspended.
Most droplets are relatively large, and they tend to settle rapidly in still air. When inhaled
these droplets are trapped on the moist surfaces of the respiratory tract. Thus, the droplets
containing pathogenic microorganisms may be a source of infectious disease.
Droplet Nuclei Small droplets in a warm, dry atmosphere tend to evaporate rapidly and
become droplet nuclei. Thus, the residue of solid material left after drying up of a droplet is
known as droplet nuclei. These are small, 1-4µm, and light. They can remain suspended in air
for hour s or days, traveling long distances. They may serve as a continuing source of infection
if the bacteria remain viable when dry. Viability is determined by a set of complex factors
including, the atmospheric conditions like humidity, sunlight and temperature, the size of the
particles bearing the organisms, and the degree of susceptibility or resistance of the particular
microbial species to the new physical environment. If inhaled droplet nuclei tend to escape the
mechanical traps of the upper respiratory tract and enter the lungs. Thus, droplet nuclei may act
as more potential agents of infectious diseases than droplets.
Droplets are usually for med by sneezing, coughing and talking. Each droplet consists of
saliva and mucus and each may contain thousands of microbes. It has been estimated that the
number of bacteria in a single sneeze may be between 10,000 and 100,000. Small droplets in a
warm, dry atmosphere are dry before they reach the floor and thus quickly become droplet nuclei.
Infectious Dust - Large aerosol droplets settle out rapidly from air on to various surfaces and
get dried. Nasal and throat discharges from a patient can also contaminate surfaces and become dry.
Disturbance of this dried material by bed making, handling a handker chief having dried secretions or
sweeping floors in the patient's room can generate dust particles which add microorganisms to
the circulating air.
Most dust particles laden with microorganisms are relatively large and tend to settle rapidly.
Droplets expelled during coughing, sneezing, etc consist of sativa and mucus, and each of them
may contain thousands of microorganisms. Most droplets are large, and, like dust, tend to settle
rapidly. Some droplets are of such size that complete evaporation occurs in a warm, dry climate,
and before they reach the floor quickly become droplet nuclei. These are small and light, and
may float about for a relatively long period. Air borne diseases are transmitted by two types
of droplets, depending upon their size.
(1) Droplet infection proper applies to, droplets larger than 100 µm in diameter.
(2) The other type may be called airborne infection, and applies to dried residues of
droplets. Droplet infection remains localized and concentrated, whereas air borne
infection may be carried long distances arid is dilute.
Microorganisms can survive for relatively longer periods in dust. This creates a significant
hazard, especially in hospital areas. Infective dust can also be produced during laboratory practices
like opening the containers of freeze dried cultures or withdrawal of cotton plugs that have dried
after being wetted by culture fluids. These pose a threat to the people working in laboratories.
2. Illustrate the techniques for microbiological analysis of air
There are several methods, which require special devices, designed for the enumeration of
microorganisms in air. The most important ones are solid and liquid impingement devices, filtration,
sedimentation, centrifugation, electrostatic precipitation, etc. However, none of these devices collects
and counts all the microorganisms in the air sample tested. Some microbial cells are destoyed and
some entirely pass through in all the processes.
Impingement in liquids: In this methods, the air drawn is through a very small opening or a
capillary tube and bubbled through the liquid. The organisms get trapped in the liquid
medium. Aliquots of the liquid are then plated to determine its microbial content. Aliquots
of the broth are then plated to determine microbial content.
Impingement on solids: In this method, the microorganisms are collected, or impinged
directly on the solid surface of agar medium. Colonies develop on the medium where the organism
impinges. Sever al devices are used, of which the settling-plate technique is the simplest, In this
method the cover of the pertridish containing an. agar medium is removed, and the agar surface is
exposed to the air for sever al minutes. A cer tain number of colonies develop on incubation of the
petridish. Each colony represents particle carrying micro organisms. Since the technique does not
record the volume of air actually sampled, it gives only a rough estimate. However, it does give
information about the kind of microorganisms in a particular area. Techniques where in a
measured volume of air is sampled have al so been developed. These are sieve slit type devices. A
seive device has a large number of small holes in a metal cover, under which is located a petridish
containing an agar medium.
A measured volume of air is drawn, through these small holes. Airborne particles
impinge upon the agar surface. The plates are incubated and the colonies counted. In a slit
device the air is drawn through a very narrow slit onto a petridish containing agar medium. The
slit is approximately the length of the petridish. The petridish is rotated at a particular speed
under the slit One complete turn is made during the sampling operation.
Filtration: The membrane filter devices are adaptable to direct collection of
microorganisms by filtration of air. The method is similar in principle to that d escribed
for water sampling.
PART – C
1. Write down the significance of Air Microflora
Although, when compared with the microorganisms of other environments, air
microflora are very low in number, they playa very significant role. This is due to the fact
that the air is in contact with almost all animate and inanimate objects.
The significance of air flora has been studied since 1799, in which year Lazaro Spallanzani
attempted to disprove spontaneous generation. In t 837, Theodor e Schwann, in his experiment to
support the view of Spallanzani, introduced fresh heated air into a sterilized meat broth and
demonstrated that microbial growth couldn't occur. This formed the basis of modern day forced
aeration fermentations. It was Pasteur in 1861, which first showed t hat microorganisms could
occur as air borne contaminant s. He used special cot t on in his air sampler onto which the
microorganisms were deposited. He microscopically demonstrated the presence of
microorganisms in the cotton. In his famous swan necked flask experiment, he showed that growth
could not occur in sterile media unless airborne contamination had occur r ed.
Air Microflora Significance in Human Health
The significance of air microflora in human health relies on the fact that air acts as a
medium for the transmission of infectious agents. An adult man inhales about '5m3 of air per day.
Although most of the microorganism present in air are harmless saprophytes and commensals, less
than1 % of the airborne bacteria are pathogens. Eventhough the contamination level is very low, the
probability of a person becoming infected will be greatest if he is exposed to a high concentration of
airborne pathogens. Carriers, either with the manifestation of corresponding symptoms or without
any apparent symptoms, may continuously release respiratory pathogens in the exhaled air.
Staphylococcus aureus is the most commonly found pathogen in air since the carriers are
commonly present. The number of S. aureus in air may vary between 0-l/ m3 and 50/ m3.
Practically speaking, outdoor air doesn't contain disease causing pathogen in a significant
number to cause any infection. The purity of outdoor air, however, is an essential part of man's
environment. Dispersion and dilution by large volume of air is an inherent mechanism of air
sanitation in outside air. In the case of indoor air chance for the spread of infectious disease is more,
especially in areas where people gather in large number s.
Air Microflora Significance in Hospitals
Although hospitals are the war fields for combating against diseases, there are certain
occasions in which additional new infectious diseases can be acquired during hospitalization. Air
within the hospital may act as a reservoir of pathogenic microorganisms which are transmitted
by the patients.
Infection acquired during the hospitalization is called nosocomial infections and the
pathogens involved are called as nosocomial pathogens. Infections, manifested by the
corresponding symptoms, after three days of hospitalization can be regarded as nosocomial
infection. Nosocomial infection may arise in a hospital unit or may be brought in by the staff or
patients admitted to the hospital. The common microorganisms associated with hospital infection
are Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, Pseudomonas
aeruginosa, members of Enterobacteriaceae and respiratory viruses. Development of high
antibiotic resistance is a potential problem among nosocomial pathogens.
For example, Methicillin Resistant Staphylococcus aureus (MRSA) and gentamicin
resistant Gram-negative bacilli are of common occurrence. Even antiseptic liquids used would
contain bacteria, for example Pseudomon as, due to their natural resistance to certain disinfectants
and antiseptics and to many antibiotics.
Nosocomial pathogens may cause or spread hospital outbreaks. Nosocomial pneumonia is
becoming a serious problem nowadays and a number of pathogens have been associated with it. Frequent
agents are Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Enterobacter,
Klebsiella, Escherichia coli and Haemophilus influenzae. Other less frequent agents are enterococci,
streptococci other than S. pneumoniae, Serratia marcescens, Citrobacter freundii, Acinetobacter sp. and
Xanthomonas sp.
In addition Legionella, Chlamydia pneumoniae and Mycobacterium tuberculosis have also
been repoted. Nosocomial transmissions of tuberculosis from patients to patients and from
patients to health care workers have also been well documented. There are two main routes of
transmission for nosocomial pathogens, contact (either direct or indirect) and airborne spread.
Airborne spread is less common than the spread by direct or indirect contact. It occur s by the
following mechanisms. The source may be either from per sons or from inanimate objects.
In case of spread from per sons the droplets from mouth, skin scales from nose, skin exudates
and infected lesion transmit diseases such as measles, tuberculosis, pneumonia, staphylococcal sepsis
and streptococcal sepsis. Talking, coughing and sneezing produce droplets. Skin scales are shed during
wound dressing or bed making. In case of inanimate sources particles from respiratory equipment and
air-conditioning plant may transmit diseases. These include Gram-negative respiratory infection,
Legionnaire's disease and fungal infections.
2.Analyze the process of air Sanitation
Air Sanitation - Sanitation of air is essential in enclosed places like hospital wards,
operation theatres and burns unit to prevent infection. Food processing and packaging
industries, pharmaceutical industries and rooms where sterile materials or products are stored
require aseptic atmosphere to prevent contamination and to ensure safe handling.
Sterilization of large volumes of air has also become essential for aerobic industrial
fermentations. As a result of these, air sanitation has become an important area in airmicrobiology. Sanitation of air can be effected in a number of ways each having its own
applications
1.Use of chemicals,
2. Mechanical methods,
3. Ultraviolet light,
4. Electrostatic precipitation and
5. Heating methods
Air Sanitation By Chemical Agent - Air sanitation can be done by the use of certain
gaseous chemical agents. These agents are mostly used to sterilize air in an enclosed space.
Limitations with chemical agents are
(1) it is difficult to maintain a desired concentration because of the deposition of the
agents on surfaces and
(2) large volumes of agents are required to maintain the final concentration.Although no
chemical agent has been found to be successful, the following are of some use.
Hypochlorous acid: Hypochlorous acid or a hypochlorite like sodium hypochlorite in a final
concentration of 1:2 million can be used to sanitize air. This concentration is sufficient to
cause a reduction of bacteria as well as viruses like influenza virus.
As with other gaseous agents, the effectiveness of hypochlorous acid or hypochlorite
against airborne microorganisms depends upon the moisture content of air. Slightly increased
relative humidity has a profound action. For example, rapid killing of streptococci and
staphylococci occurs at a relative humidity of 90%.
Quaternary ammonium surface active disinfectant: This is a commercially available
disinfectant and can be used as an air sanitizing agent. There occurs a reduction in the
number of airborne and surface bacteria in hospital rooms when this compound is sprayfogged.
Fogging procedures are effectively used to decontaminate the rooms vacated by
patients infected with staphylococci, streptococci, pseudomonads and Salmonella.
Glycols: Propylene glycol and triethylene glycol are active against streptococci,
staphylococci, pneumococci, H. influenzae and influenza virus at a concentration 1:4 million.
Their microbicidal activity is maximum at a temperature of about 27°C and a relative
humidity of 45 - 70%.
The bactericidal activity of glycols are due to their hygroscopicity. When glycol
molecules are atomized into the air they dissolve in the film of moisture surrounding each
microorganism. At a particular concentration of glycol, the moisture inside the bacterial cell
is drawn out of the cell and this leads to the death of the microbe
Air Sanitation By Mechanical Methods
Mechanical methods are aimed at the removal reduction of microorganisms.
Suppression of dust: Dust particles act as a substratum for microorganisms to adhere
Microorganisms can remain viable for quite long period in these dust particles. Depending
upon the factors such as air current and weight of the particle, bacteria carrying dust particles
can either remain suspended in air or they may settle down on various objects.
Thus dust particles play an important role in the dispersion of microorganisms in air. So any
procedure that suppresses the emergence or distribution of dust will in turn affect the
microflora of air.
Applying oil emulsion to floors, bed cloths and other textiles will provide an effective
control over dust and dust borne bacteria. Oil mechanically inhibits the spread of dust by
binding to them. Oiling methods are simple in procedure and are practicable.
Even cost wise also, they are economical. Various studies have shown that oiling
floors and bed cloths in hospitals have considerably reduced the incidence of respiratory tract
infections.Removal of dust using vacuum pump followed by application of disinfectant
solution has also been recommended.
Filters: Filtration can also be used as a method of air sanitation. Most of the airborne
microorganisms are present in dust particles of size larger than 5/lm. Hence the
microorganisms can be removed from air by passage through simple filters, which can retain
particles of this size. If the smaller particles are also important then high efficiency filters can
be used.
The various types of filter materials used in air sterilization are
1. granular - activated charcoal;
2. fibrous pads - cotton wool, slag wool, and glass wool; and
3. filter papers - cellulose - asbestos and glass fibre.
3. Briefly describe the airborne diseases
There are two main sources of microorganisms in air. These are saprophytic soil
organisms raised as dust, and organisms from body tissues introduced into the air during
coughing, sneezing talking, and singing. Most dust particles laden with micro organisms are
relatively large and tend to settle rapidly. Droplets expelled during coughing, sneezing, etc
consist of sativa and mucus, and each of them may contain thousands of micro organisms.
Air Borne Bacterial Diseases

Brucellosis: Brucellasuis It is mainly an occupational disease among veternaian, butcher and
slaughter house workers.

Pulmonary Anthrax: Bacillus anthracis is the causative agent. Transmission is mainly by
inhaling the dust contaminated by animal pr oducts.

Diseases Caused by Streptococcus Pyogenes: A number of diseases are caused by Streptococcus
pyogenes which is mainly transmitted through air. Diseases Caused by Streptococcus
pyogenes occur in the throat, skin.

Rheumatic Fever: This is upper respiratory tract infection by S. pyogenes characterized by
inflammation and degeneration of hear t valves.

Streptococcal Pneumonia: It is of major occurrence among the bacterial pneumonia.
Causative agent is Streptococcus pneumonia.

Meningitis: Haemophilus influenzae causes meningitis in children between 6 weeks and
2years of age.

Diptheria: Diphtheria is mainly contracted by children. Infection of the tonsils,
throat and nose and gener alized toxemia ar e the symptoms. The causative agent is
Corynebacterium diphtheria.

Tuberculosis: Pulmonary tuberculosis is a severe respiratory disease. Loss of appetite, fatigue,
weight loss, night sweats and persistent cough are some of the symptoms. Causative agent is
Mycobacterium tuberculosis.

Legionellosis: It is a type of branchopneumonia. Legionella pneumophila is the causative
agent. It occurs in natural water. At times it enters and proliferates in cooling tower, air
cooler and shower bath. Spr aying and splashing of water containing pathogen may pr
oduce aerosols which are disseminated in air.
Air Borne Fungal Diseases
It consists of man y types. They are following,

Cryptococcosis: Leads to mild pneumonitis. Causative agent is the yeast Cryptococcusneofor
mans. It is a soil saprophyte. Infection is acquired by inhalation of soil particles
containing the causative agent.

Blastomycosis: Formation of suppurative and granulomatous lesions in any part of the
body. Blastomyces dermatitis is the causative agent. It is a soil borne fungus and hence
inhalation of soil particles containing the fungus produces the infection.

Coccidiodomycosis: Infection may not be apparent but in sever e cases it is fatal. Usually
infection leads to self-limited influenza fever known as valley fever or desert rheumatism.
Causative agent of the disease is a soil fungus, Coccidioidesimmitis. Inhalation of dust
containing arthrospores of the fungus leads to infection.

Aspergillosis: It is an opportunistic disease of human. Causative agent is Aspergillus
fumigatus. Infection occur s through inhalation of spores.
Air Borne Viral Diseases:
Air borne viral diseases are of different types. They are following,

Common Cold: It is the most frequent of all human infections. Characteristic symptom
includes running noses. Rhinovirus is the causative agent. Droplets with nose and throat
discharges from infected per sons are the source.

Influenza: Symptoms of influenza are nasal discharge, head ache, muscle pains, sore throat
and general weakness.

Measles: Measles is the most common communicable human disease mainly affecting
children. Symptoms are fever, cough, cold and red, blotchy skin rash. Causative virus is
morbillivirus. Source of infection is respiratory tract secretions in the form of
droplets.

Mumps: It is a communicable disease and common child hood disease. It is characterized by
painful swelling of parotid glands and salivary glands. Mumps vi r us causes the disease.
Droplets containing infected saliva are the main source.

Adeno Viral Diseases: Adenovirses cause acute self -limiting rasporatory and eye infections.
Adenoviruses are trasmitted by air mode. Diseases include acute febrile pharyngitis, acute
respiatory disease and adenovirus pneumonia.
UNIT II
Microbial decomposition; cellulose, Hemi cellulose, lignin, pectin and chitin. –Factors
influencing degradation- acetate utilization -bioconversion of organicwastes- sugarcane
wastes- coir pith composition- composting, principles and Applications- conversion process
___________________________________________________________________________
PART – A
1. Define soil
Soil is the thin layer on the surface of the Earth on which the living beings of the earth
survive since it is the layer of materials in which plants have their roots.
2. Define weathering
Weathering is the process of the breaking down rocks.
3. List of soil pollutants

Discharge of industrial waste into the soil

Percolation of contaminated water into the soil

Rupture of underground storage tanks

Excess application of pesticides, herbicides or fertilizer
PART – B
1. Write a note on Sulphur and phosphorus cycle
Facts

Component of protein

Cycles in both a gas and sedimentary cycle

The source of Sulfur is the lithosphere (earth'scrust).

Sulfur (S) enters the atmosphere as hydrogen sulfide (H2S) during fossil fuel
combustion, volcanic eruprtions, gas exchange at ocean surfaces, and decomposition.

H2S is immediately oxidized to sulfur dioxide (SO2)

SO2 and water vapor makes H2SO4 ( a weak sulfuric acid), which is then carried to
Earth in rainfall.
Sulfur
in
incorporated
travels
soluble
into
through
form
amino
the
food
is
taken
acids
chain
up
such
and
by
as
is
plant
roots
and
cysteine.
It
then
eventually
released
throughdecomposition.
Phosphorus cycle
Facts

Component of DNA, RNA, ATP, proteins and enzymes

Cycles in a sedimentary cycle

A good example of how a mineral element becomes part of an organism.

The source of Phosphorus (P) is rock.

It is released into the cylce through erosion or mining.

It is soluble in H2O as phosphate (PO4)

It is taken up by plant roots, then travels through food chains.

It is returned to sediment
2. Discuss about Weathering formation
Weathering:
Weathering is the process of the breaking down rocks. There are two different types of
weathering.
Physical
weathering
and
chemical
weathering.
In physical weathering it breaks down the rocks, but what it's made of stays the same. In
chemical weathering it still breaks down the rocks, but it may change what it's made of. For
instance, a hard material may change to a soft material after chemical weathering.
Stages in the Formation of Soil
stage
stage 3
1
stage
stage 4
2
PART – C
1.Write a note on -Structure, Types, Physical and Chemical properties of soil
Soil structure
Soil structure refers to the gross arrangement of the soil particles into aggregates. A
soil may have either a simple or a compound structure. Sands and gravels, examples of soils
with a simple structure, have very little cohesion, plasticity, and consistency (the resistance
of the particles in the soil to separation. Simple-structured soils are usually composed of
materials that are relatively resistant to weathering, such as quartz sand. They, are also said to
have a single-grain structure.
Most agricultural soils have a compound structure; their particles aggregate, or stick
together. Several distinct sizes of compound structures are recognized.
Structural type
Aggregate diameter (millimeters)
Columnar
Blocky
Granular
Crumbly
Massive
>250
5-25
3-5
1-3
Completely puddled or compacted
Soil structure develops when small colloidal soil particles clump together or
flocculate into granules. Granulation is promoted by freezing and thawing, the disruptive
action of plant roots, the mixing effects of soil fauna, the expansion and contraction of water
films, and the presence of a network of fungal hyphae. However, unless the granules are
stabilized by coatings of organic matter or by their own electrochemical properties, they will
coalesce into clods. Good soil structure is very important for agricultural soils. Highly
granulated soils are well aerated and have a high water holding capacity because of the
increased volume of the soil pore space. The pore space of soil is occupied by water and air
in varying proportions, the soil acting as a huge sponge. The total pore space of soil, which is
typically about 50% of the total volume, is not as important as the size of the individual
pores. Clay soils have more total pore space than sandy soils, but because of the small size of
the pores in clay soils, air and water move through them slowly. When the small pores of clay
soils become filled with water, aeration is greatly limited. Large pore spaces become filled
and are drained by gravity, whereas small pores absorb and retain water by capillary action.
Capillary water is of the utmost importance to the plant: it is the soil solution most used by
plants.
The crumbly nature of good agricultural soils depends on soil texture and on the
percentage of humus (decomposed, stable organic matter). Clay soils low in organic matter
typically have poor structure. In order to maintain good compound structure in clay soils,
they must be carefully managed. If worked when too wet, the structure may be damaged.
When clods are exposed they become dry hard, and difficult to work back into the soil. In
heavy soils it is necessary to add organic matter to maintain good structure. In sandy soils,
where structure is not as critical, it is necessary to add organic matter to increase its water and
nutrient-holding capacities.
Definition:
Soil is the thin layer on the surface of the Earth on which the living beings of the earth
survive since it is the layer of materials in which plants have their roots.
Soil Types
Therefore depending on the size of the particles in the soil, it can be classified into
these following types:

Sandy soil

Silty soil

Clay soil

Loamy Soil

Peaty Soil

Chalky Soil
Sandy Soil - This type has the biggest particles and the size of the particles does determine
the degree of aeration and drainage that the soil allows. It is granular and consists of rock and
mineral particles that are very small. Therefore the texture is gritty and sandy soil is formed
by the disintegration and weathering of rocks such as limestone, granite, quartz and shale.
Sandy soil is easier to cultivate if it is rich in organic material but then it allows drainage
more than is needed, thus resulting in over-drainage and dehydration of the plants in summer.
It warms very fast in the spring season. So if you want to grow your plant in sandy soil it is
imperative that you water it regularly in the summers and give a break in the winters and
rainy season, sandy soil retains moisture and nutrients. In a way sandy soil is good for plants
since it lets the water go off so that it does not remain near the roots and lead them to decay.
Silty Soil-Silty soil is considered to be one of the most fertile of soils. It can occur in nature
as soil or as suspended sediment in water column of a water body on the surface of the earth.
It is composed of minerals like Quartz and fine organic particles. It is granular like sandy soil
but it has more nutrients than sandy soil and it also offers better drainage. In case silty soil is
dry it has a smoother texture and looks like dark sand. This type of soil can hold more
moisture and at times becomes compact. It offers better drainage and is much easier to work
with when it has moisture.
Clay Soil - Clay is a kind of material that occurs naturally and consists of very fine grained
material with very less air spaces, that is the reason it is difficult to work with since the
drainage in this soil is low, most of the time there is a chance of water logging and harm to
the roots of the plant. Clay soil becomes very heavy when wet and if cultivation has to be
done, organic fertilizers have to be added. Clay soil is formed after years of rock
disintegration and weathering. It is also formed as sedimentary deposits after the rock is
weathered, eroded and transported.
Loamy Soil - This soil consists of sand, silt and clay to some extent. It is considered to be the
perfect soil. The texture is gritty and retains water very easily, yet the drainage is well. There
are various kinds of loamy soil ranging from fertile to very muddy and thick sod. Yet out of
all the different kinds of soil loamy soil is the ideal for cultivation.
Peaty Soil - This kind of soil is basically formed by the accumulation of dead and decayed
organic matter, it naturally contains much more organic matter than most of the soils. It is
generally found in marshy areas. Now the decomposition of the organic matter in Peaty soil is
blocked by the acidity of the soil. This kind of soil is formed in wet climate. Though the soil
is rich in organic matter, nutrients present are fewer in this soil type than any other type.
Peaty soil is prone to water logging but if the soil is fertilized well and the drainage of the soil
is looked after, it can be the ideal for growing plants.
Chalky Soil - Unlike Peaty soil, Chalky soil is very alkaline in nature and consists of a large
number of stones. The fertility of this kind of soil depends on the depth of the soil that is on
the bed of chalk. This kind of soil is prone to dryness and in summers it is a poor choice for
plantation, as the plants would need much more watering and fertilizing than on any other
type of soil. Chalky Soil, apart from being dry also blocks the nutritional elements for the
plants like Iron and Magnesium.
Physical Properties of Soil
Permeability (the rate at which water moves through the soil) and Water-Holding Capacity
(WHC; the ability of a soils micropores to hold water for plant use) are affected by

The amount, size and arrangement of pores

Macropores control a soil’s permeability and aeration.

Micropores are responsible for a soil’s WHC
Porosity is in turn affected by

Soil texture

Soil structure

Compaction

Organic matter
Soil texture (the relative proportions of sand,
silt, and clay) is important in determining the
water-holding capacity of soil:
1. Fine-textured soils hold more water
than coarse-textured soils but may not
be ideal
2. Medium-textured soils (loam family) are most suitable for plant growth
- Sands are the largest particles and feel gritty
- Silts are medium-sized and feel soft, silky, or floury
- Clays are the smallest sized particles and feel sticky and are hard to squeeze.
- Relative size perspective: Sand (house) > Silt > Clay (penny)
Four main types of soil structure (the arrangement of aggregates in a soil):

Platy - common with puddling or ponding of soils

Prismatic (columnar) – common in subsoils in arid and semi-arid regions

Blocky – common in subsoils especially in humid regions

Granular (crumb) – common in surface soils with high organic matter content
Properties of soil particle size
Sand
Silt
Clay
Porosity
mostly large
pores
small pores
predominate
small pores
predominate
Permeability
rapid
low to moderate
slow
Water holding
capacity
limited
medium
very large
Soil particle
surface
small
medium
very large
Soil Compaction destroys the quality of the soil because it restricts rooting depth and
decreases pore size. The effects are more water-filled pores less able to absorb water,
increasing runoff and erosion, and lower soil temperatures. To reduce compaction:

Add organic matter

Make fewer trips across area

Practice reduced-till or no-till systems

Harvest when soils are not wet
Chemical Properties of Soil
1. pH
2. Salinity (EC)
3. Cation exchange capacity (CEC)
4. Organic matter
5. C:N ratio (Carbon to Nitrogen)
Soil pH

A measure of the acidity or alkalinity of a soil.

Neutral = 7.0

Acidic < 7.0

Alkaline > 7.0

Logarithmic scale which means that a 1-unit drop in pH is a 10-fold increase in
acidity.
Soil pH and plant growth

Affects availability of plant nutrients (in general, optimal pH is between 5.5-7.5)

Low pH soils (<6.0) results in an increase in Al. Aluminum is toxic to plants

Affects availability of toxic metals (in general, more available in acidic soils)

Affects the activity of soil microorganisms, thus affecting nutrient cycling and disease
risk
Nutrient Availability
Increasing soil pH: Liming materials (pure calcium carbonate or dolomitic lime) will
increase soil pH.
1. Lime is a certified organic product
2. Slow-release product. Do not add every year.
3. 15-25 lbs lime per 1000 sq ft is recommended
Wood ashes are another product to raise soil pH. They also are a source of K, Ca, and Mg.
Some composts also can increase soil pH.
Gypsum is calcium sulfate. It is not a substitute for lime, and has little effect on soil pH.
Gypsum only improves structure in soils that have extremely high sodium contents (rare in
the NW).
Decreasing soil pH: Some plants thrive under acidic conditions (ex. rhododendrons,
blueberries, and azaleas). Elemental sulfur is often recommended (50 lb S per 1000 sq. ft).
Ammonium and ammonium-forming N fertilizers will also result in a decrease in soil pH.
Soil salinity

Potential problem in irrigated soils due to high evaporation rates and low annual
rainfall leaving salts to accumulate.

Salts can come from irrigation water, fertilizers, composts, and manure.

Salts can be leached by slowly applying excess water.
o
Three inches removes about 50% of the soluble salts.
o
Five inches removes about 90%.
Soil Salinity and Interpretation
Conductivity (mmho/cm) Interpretation
4 or above
Severe accumulation of salts. May restrict
growth of many vegetables and ornamentals.
2 to 4
Moderatre accumulation of salts. Will not
restrict plant growth, but may require more
frequent irrigation.
less than 2
Low salt accumulation. Will not affect plants.
Soil microbes
Soil organisms play an important part in soil development. In addition to the roots of
higher plants, the soil is inhabited by a wide variety of plant and animal life (Fig.5). In fact, a
soil does not usually develop until the inorganic material is "invaded" by various kinds of
organisms. The total weight of soil organisms (excluding higher plants) in the upper 30
centimeters (about 1 foot) of fertile agricultural soils is impressive, as much as 7000
kilograms per hectare (about 6250 pounds per acre), which is equivalent to the weight of 20
to 30 marketable hogs. This is, however, only about 0.1 percent of the weight of the soil that
the organisms occupy.
Average weight of organisms in the upper
centimeters of soil (in kilograms/hectare).
Organism Bacteria
Fungi 1680 2240
Actinomycetes
Protozoa
Algae
Nematodes
Low
High
560
1680
895
225
225
28
1120
2240
1680
450
335
55
Other worms and insects
Total
895 1120
4508 7000
2.Write briefly on source, types and causes of Soil pollution
There are many different ways that soil can become polluted, such as:
• Seepage from a landfill
• Discharge of industrial waste into the soil
• Percolation of contaminated water into the soil
• Rupture of underground storage tanks
• Excess application of pesticides, herbicides or fertilizer
• Solid waste seepage
The most common chemicals involved in causing soil pollution are:
• Petroleum hydrocarbons
• Heavy metals
• Pesticides
• Solvents
Types of Soil Pollution
a. Agricultural Soil Pollution
i) pollution of surface soil
ii) pollution of underground soil
b. Soil pollution by industrial effluents and solid wastes
iii) pollution of surface soil
iv) disturbances in soil profile
c. Pollution due to urban activities
v) pollution of surface soil
vi) pollution of underground soil
Causes of Soil Pollution
Soil pollution is caused by the presence of man-made chemicals or other alteration in
the natural soil environment. This type of contamination typically arises from the rupture of
underground storage links, application of pesticides, percolation of contaminated surface
water to subsurface strata, oil and fuel dumping, leaching of wastes from landfills or direct
discharge of industrial wastes to the soil. The most common chemicals involved are
petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. This occurrence
of this phenomenon is correlated with the degree of industrialization and intensities of
chemical usage. A soil pollutant is any factor which deteriorates the quality, texture and
mineral content of the soil or which disturbs the biological balance of the organisms in the
soil. Pollution in soil has adverse effect on plant growth.
Pollution in soil is associated with
• Indiscriminate use of fertilizers
• Indiscriminate use of pesticides, insecticides and herbicides
• Dumping of large quantities of solid waste
• Deforestation and soil erosion
Sources
Pesticides
The pesticides used in agriculture have chemicals that last long in the environment. In
addition to killing the pests, they also effect some beneficial organisms like the earthworm in
the soil. Organisms like earthworm are vital to the decomposition of materials and formation
of soil.
Acid Rains
The acid rains can change the pH of the soil making it unsuitable for cultivation.
Garbage
The household and other city garbage lies scattered in the soil in the absence of a
proper disposal system. Materials like polythene can block the passage of water into the soil
and affect its water-holding capacity.
Industrial Wastes
Many industries produce harmful chemicals which are disposed of without being
treated.
Radioactive Substances
Improper disposal of nuclear wastes can cause radioactive substances to remain in the
soil for a long time. These substances cause mutations.
Night Soil
Human excreta mixed with soil is called night soil. Open latrines in the villages and
some parts of cities are the source of this pollution. These contain disease-causing germs
which can spread the disease. It is estimated that millions of children worldwide die before
they reach the age of five due to lack of sanitary facilities.
3.Briefly describe the nitrogen and carbon cycle.
Nitrogen cycle
Nitrogen (N) is an essential component of DNA, RNA, and proteins, the building
blocks of life. All organisms require nitrogen to live and grow. Although the majority of the
air we breathe is N2, most of the nitrogen in the atmosphere is unavailable for use by
organisms. This is because the strong triple bond between the N atoms in N2 molecules
makes it relatively inert. In fact, in order for plants and animals to be able to use nitrogen, N 2
gas must first be converted to more a chemically available form such as ammonium (NH4+),
nitrate (NO3-), or organic nitrogen (e.g. urea - (NH2)2CO). The inert nature of N2 means that
biologically available nitrogen is often in short supply in natural ecosystems, limiting plant
growth and biomass accumulation.
Five main processes cycle nitrogen through the biosphere, atmosphere, and
geosphere:
1. nitrogen fixation,
2. nitrogen uptake (organismal growth),
3. nitrogen mineralization (decay),
4. nitrification,
5. denitrification.
Nitrogen fixation
N2
NH4+ Nitrogen fixation is the process wherein N2 is converted to ammonium,
essential because it is the only way that organisms can attain nitrogen directly from the
atmosphere. Certain bacteria, for example those among the genus Rhizobium, are the only
organisms that fix nitrogen through metabolic processes. This symbiosis is well-known to
occur in the legume family of plants (e.g. beans, peas, and clover). There are also nitrogen
fixing bacteria that exist without plant hosts, known as free-living nitrogen fixers. In aquatic
environments, blue-green algae (really a bacteria called cyanobacteria) is an important freeliving nitrogen fixer.
Nitrogen uptake
NH4+
Organic N The ammonia produced by nitrogen fixing bacteria is usually
quickly incorporated into protein and other organic nitrogen compounds, either by a host
plant, the bacteria itself, or another soil organism.
Nitrogen mineralization
Organic N
NH4+ After nitrogen is incorporated into organic matter, it is often
converted back into inorganic nitrogen by a process called nitrogen mineralization, otherwise
known as decay. When organisms die, decomposers (such as bacteria and fungi) consume the
organic matter and lead to the process of decomposition. During this process, a significant
amount of the nitrogen contained within the dead organism is converted to ammonium. Once
in the form of ammonium, nitrogen is available for use by plants or for further transformation
into nitrate (NO3-) through the process called nitrification.
Nitrification
NH4+
NO3- Some of the ammonium produced by decomposition is converted to
nitrate via a process called nitrification. The bacteria that carry out this reaction gain energy
from it. Nitrification requires the presence of oxygen, so nitrification can happen only in
oxygen-rich environments like circulating or flowing waters and the very surface layers of
soils and sediments. The process of nitrification has some important consequences.
Ammonium ions are positively charged and therefore stick (are sorbed) to negatively charged
clay particles and soil organic matter. The positive charge prevents ammonium nitrogen from
being washed out of the soil (or leached) by rainfall. In contrast, the negatively charged
nitrate ion is not held by soil particles and so can be washed down the soil profile, leading to
decreased soil fertility and nitrate enrichment of downstream surface and groundwaters.
Denitrification
NO3-
N2+ N2O Through denitrification, oxidized forms of nitrogen such as nitrate
and nitrite (NO2-) are converted to dinitrogen (N2) and, to a lesser extent, nitrous oxide gas.
Denitrification is an anaerobic process that is carried out by denitrifying bacteria, which
convert
nitrate
to
NO3-
dinitrogen
NO2-
in
the
following
NO
sequence:
N2O
N2.
Nitric oxide and nitrous oxide are both environmentally important gases. Nitric oxide (NO)
contributes to smog, and nitrous oxide (N2O) is an important greenhouse gas, thereby
contributing to global climate change.
Once converted to dinitrogen, nitrogen is unlikely to be reconverted to a biologically
available form because it is a gas and is rapidly lost to the atmosphere. Denitrification is the
only nitrogen transformation that removes nitrogen from ecosystems (essentially
irreversibly), and it roughly balances the amount of nitrogen fixed by the nitrogen fixers
described above.
4.Write a brief note on Carbon cycle
Fact

Carbon
(C)
enters
the
biosphere
during
photosynthesis:
CO2 + H2O ---> C6H12O6 + O2 + H2O

Carbon
is
returned
to
the
biosphere
in
cellular
respiration:
O2 +H2O + C6H12O6 ---> CO2 +H2O + energy
Amount of CO2 during the year

Every
year
there
concentration
For
of
example,
is
a
atmospheric
in
winter
measurable
difference
CO2
in
phase
with
there
is
almost
no
a
measurable
in
the
the
seasons.
photosynthesis
therefore there is a high concentration of CO2.

During
the
growing
concentration
of
example,
sunrise
by
at
afternoon
season
there
atmospheric
plant
is
CO2 over
photosynthesis
begins
respiration
increases,
parts
with
at
of
each
the
uptake
sunset
stops so the concentration of CO2 in the atmosphere increases.
Human induced changes in the global carbon cycle

The Earth is getting warmer.

The 20th century has been the warmest in the last 600 years.
differnece
in
day.
of
the
For
CO2,
photosynthesis

This
century
is
about
of
evidence
1
degree
Fahrenheit
warmer
than
last
fossil
fuel
century.

The
(eg.
balance
coal,
oil,
natural
gas),
suggests
which
that
emits
burning
CO2
as
of
a
waste,
is
the
cause.

CO2 is a "Green House" gas - it traps heat at the Earth's surface.
(H2O vapor and methane are also examples of green house gases)
UNIT III
Microorganisms in the decomposition of organic matter- carbon cycle – nitrogen Cycle
nitrogen
fixing microorganisms- root nodule bacteria – non symbiotic Nitrogen fixers – biofertilizers
in agriculture- Rhizobium and phosphate solubilisers- Mycorrhizial association –
phosphorous cycle.
___________________________________________________________________________
PART – A
1. Eutrophication of water bodies resulting to killing of fishes is mainly due to(a) Non-availability of food
(b) Non-availability of light
(c) Non-availability of oxygen (d) Non-availability of essential minerals
Ans: (c) Non-availability of oxygen
2. A high BOD value in aquatic environment is indicative of(a) A pollution free system
(b) A highly polluted system due to excess of nutrients
(c) A highly polluted system due to abundant heterotrophs
(d) A highly pure water with abundance of autotrophs
Ans: (b) A highly polluted system due to excess of nutrients
3. In which of the following the maximum plant diversity is found(a) Tropical evergreen forests
(b) Tropical moist deciduous forests
(c) Sub tropical mountain forests (d) Temperate moist forests10.
Ans: (a) Tropical evergreen forests
4. Carbon enters a long-term cycle in the ecosystem when it is converted into carbonates,
which make up hard parts of bones and shells
a. true
b. false
Ans: (a) true
PART – B
1.Discuss on source of water pollution
Sewage that includes organic matter, animal and human excreta-one of the major
pollutants of water in the urban and rural areas is the sewage. The sewage most often contains
the organic matter that encourages the growth of microorganisms. These organisms besides
spreading diseases also consume the oxygen present in water. This is called oxygen
depletion. The aquatic organisms like the fish cannot then survive in such waters. This creates
an imbalance in the aquatic ecosystems.
Industries
The industries are mostly situated along the riverbanks for easy availability of water
and also disposal of the wastes. But these wastes include various acids, alkalis, dyes and other
chemicals. They change the pH of water. There are also detergents that create a mass of white
foam in the river waters. All these chemicals are quite harmful or even fatally toxic to fish
and other aquatic populations.
The industrial wastes include toxic metals like lead, mercury, cadmium, etc, and other
chemicals like the fluorides, ammonia, etc.
Certain industries such as power plants, refineries, nuclear reactors release a lot of hot
water from their cooling plants. This hot water is let into the water bodies without the
temperature being reduced. This results in heating up of the water and thereby killing the
aquatic life. The oxygen content of water also becomes less due to increase in the
temperature. This is called thermal pollution.
Agriculture
Modern methods of agriculture have resulted in use of fertilisers and pesticides to
increase the yield of the crops. Most of them are synthetic and chemicals-based. They are
collectively called agro-chemicals. These chemicals enter into the water bodies with the rain
water flow and the ground water by seepage. The chemicals remain in the environment for a
long time and can enter the food chain. They cause a number of problems in the animals.
Oil
Oil spill is a major problem in the oceans and seas. The oil tankers and offshore
petroleum refineries cause oil leakage into the waters. This pollutes the waters. Oil floats on
the water surface and prevents the atmospheric oxygen from mixing in the water. The oil
enters the body of the organisms. It also coats the body of the aquatic animals and birds
which may also kill them.
Pollutant
Source/Cause
Effect
Sewage that
Sewarage of rural Oxygen depletion Spread of diseases/ epidemics
includes domestic
and urban areas.
wastes, hospital
wastes, excreta, etc.
Metals-Mercury
Industnal wastes
Minamata disease (resulted from the contaminated waters
of the Minamata bay in Japan in 1953) - causes numbness
of limbs, lips and tongue, blurred vision, deafness and
mental derangement.
Lead
Industrial wastes
Absorbed into blood and affects PBCs, liver, kidney,
bone, brain and the penpheral nervous system. Lead
poisoning can even lead to coma.
Cadmium
Cadmium
industnes,
fertilisers
Deposited in organs like the kidney, pancreas, liver,
intestinal mucosa, etc. Cadmium poisoning causes
headache, vomiting, bronchial pneumonia, kidney
Pollutant
Source/Cause
Effect
necrosis, etc.
Arsenic
Fertilisers
Arsenic poisoning causes renal failure and death, It can
cause nerve disorder, kidney and liver disorders, muscular
atrophy, etc.
Agrochemicals like
DDT
Pesticides
Accumulates in the bodies of fishes, birds, mammals
including man. Adversely affects the nervous system,
fertility. Causes thinning of egg shells in birds.
2.Describe the test involved in assessment of water quality
•
Water quality is the physical, chemical and biological characteristics of water.
•
The parameters for water quality are determined by the intended use. Work in the area
of water quality tends to be focused on water that is treated for human consumption or
in the environment.
Drinking water
Physical assessment
•
pH
•
Temperature
•
Total suspended solids (TSS)
•
Total dissolved solids (TDS)
•
Turbidity
•
Alkalinity
•
Color of water
•
Taste and odor (geosmin, 2-methylisoborneol (MIB)
Biological assessment
•
Microorganisms such as fecal coliform bacteria (E.coli), Cryptosporidium, and
Giardia lamblia
Chemical assessment
•
Conductivity (also see salinity)
•
Dissolved Oxygen (DO)
•
nitrate-N
•
orthophosphates
•
Chemical oxygen demand (COD)
•
Biochemical oxygen demand (BOD)
•
Pesticides
•
Dissolved metals and salts (sodium, chloride, potassium, calcium, manganese,
magnesium)
•
Dissolved metals and metalloids (lead, mercury, arsenic, etc.)
•
Dissolved organics: colored dissolved organic matter (CDOM), dissolved organic
carbon (DOC)
•
Radon
•
Heavy metals
•
Pharmaceuticals; Hormone analogs
3.Write a note on Indicator organisms which determine the quality of water
Microbial indicator’, the following three groups are now recognised:
•
General (process) microbial indicators,
•
Faecal indicators (such as E. coli)
•
Index organisms and model organisms.
Definitions for indicator
Process indicator - A group of organisms that demonstrates the efficacy of a process, such as
total heterotrophic bacteria or total coliforms for chlorine disinfection.
Faecal indicator - A group of organisms that indicates the presence of faecal contamination,
such as coliforms or E. coli. Hence, they only infer that pathogens may be
present.
Index and model organisms - A group/or species indicative of pathogen presence and
behaviour respectively, such as E. coli as an index for Salmonella and
F-RNA coliphages as models of human enteric viruses.
Total and fecal coliforms, and the enterocci - fecal streptocci are the indicator organisms
currently used in the public health arena. Coliform bacteria include all aerobic and facultative
anaerobic, gram-negative, nonspore-forming, rod-shaped bacteria that ferment lactose with
gas formation.
There are three groupings of coliform bacteria used as standards:
•
total coliforms (TC)
•
fecal coliforms (FC) and
•
•
E. coli.
Total coliforms - Escherichia, Enterobacter, Klebsiella, and Citrobacter. found in
the soil, as well as in feces.
•
Fecal coliforms - which includes bacteria commonly found in the human intestinal
tract. Usually between 60% and 90% of total coliforms are fecal coliforms.
•
E. coli - are a particular species of bacteria that may or may not be pathogenic but are
ubiquitous in the human intestinal tract. Generally more than 90% of the fecal
coliform are Escherichia (usually written as E. coli)
PART - C
1.Analyze the sources of water pollution and pathogen spread through water.
Wastewater, by its nature, is teaming with microbes. Many of these microbes are
necessary for the degradation and stabilization of organic matter and thus are beneficial. On
the other hand, wastewater may also contain pathogenic or potentially pathogenic
microorganisms, which pose a threat to public health.
Definition: A pathogen is an organism capable of inflicting damage on its host.
Waterborne and water-related diseases caused by pathogenic microbes are among the
most serious threats to public health today. Waterborne diseases whose pathogens are spread
by the fecal-oral route (with water as the intermediate medium) can be caused by bacteria,
viruses, and parasites (including protozoa, worms, and rotifers).
Protozoa Found in Surface Water
Parasites are defined as organisms that grow, feed, and live on or in another organism
to whose survival it contributes nothing. The three most important protozoal pathogens in
temperate zone countries are:
Microrganism Disease
Symptoms
Amoeba
Amoebic dysentery Severe diarrhea, headache, abdominal pain, chills,
fever; if not treated can cause liver abscess, bowel
perforation and death
Cryptosporidium Cryptosporidiosis
Feeling of sickness, watery diarrhea, vomiting,
parvum
lack of appetite
Giardia
Giardiasis
Diarrhea, abdominal cramps, flatulence, belching,
fatigue
Toxoplasm
Toxoplasmosis
Flu, swelling of lymph glands
gondii
With pregnant women subtle abortion and brain
infections
Bacteria
Bacteria are defined as any of the one-celled prokaryotic organisms, which vary in
morphology and nutritional requirements and may be free-living, saprophytic, or pathogenic.
The major bacterial pathogens and their associated diseases are:
Bacteria
Aeromonas
Disease/ infection
Enteritis
Symptoms
Very thin, blood- and mucus-containing
diarrhea
Flue, diarrhea, head- and stomachaches,
Campylobacter Campilobacteriose
fever, cramps and nausea
jejuni
Escherichia coli Urinary tract infections, Watery diarrhea, headaches, fever, homiletic
neonatal meningitis,
uremia, kidney damage
intestinal disease
Plesiomonas-infection Nausea, stomachaches and watery diarrhea,
Plesiomonas
sometimes fevers, headaches and vomiting
shigelloides
Typhus
Typhoid fever
Salmonellosis
Salmonella
Streptococcus
Vibrio El Tor
(freshwater)
Fevers
Sickness, intestinal cramps, vomiting,
diarrhea and sometimes light fevers
(Gastro) intestinal
Stomach aches, diarrhea and fevers,
disease
sometimes vomiting
(Light form of) Cholera Heavy diarrhea
Viral Sources of Waterborne Disease
Viruses are defined as genetic elements, containing either DNA or RNA and a protein
capsid membrane, which are able to alternate between intracellular and extracellular states,
the latter being the infectious state. Over 100,000 different viral types have been identified in
human feces, and therefore, there is a direct correlation between contact with improperly
disposed of treated waste and diarrheal disease. Among the viral pathogens listed below are
over 120 enteric viruses, all pathogenic to humans requiring low infectious doses. The major
viral pathogens include:
•
Viral Pathogens
Related Disease
Hepatitis A
Hepatitis
Norwalk-like agents
Gastroenteritis
Virus-like 27 nanometer particles Gastroenteritis
Rotavirus
Gastroenteritis and polio
Hepatitis A: inflammation and necrosis of liver
•
Norwalk-type virus: acute gastroenteritis
•
Rotaviruses: acute gastroenteritis, especially in children
•
Enteroviruses: many types affect intestines and upper respiratory tract
•
Reoviruses: infects intestines and upper respiratory tract
2.Illustrate the steps involved in Waste water treatment
Sewage or wastewater is composed waste coming from:
–
Domestic used water and toilet wastes
–
Rainwater
–
Industrial effluent (Toxic industrial water is pretreated)
–
Livestock wastes
Sources of organic matter
•
Natural inputs-- bogs, swamps, leaf fall, and vegetation aligning waterways.
•
Human inputs-- pulp and paper mills, meat-packing plants, food processing industries,
and wastewater treatment plants.
•
Nonpoint inputs-- runoff from urban areas, agricultural areas, and feedlots.
Wastewater treatment systems take human and industrial liquid wastes and make
them safe enough (from the public health perspective) to return to the aquatic or terrestrial
environment.
Effects of waste water
•
Causes a demand for dissolved oxygen (lower DO levels of streams)
BOD: Oxygen is removed from water when organic matter is consumed by bacteria.
Low oxygen conditions may kill fish and other organisms
•
Adds nutrients (nitrate and phosphate) to cause excessive growth
•
Increases suspended solids or sediments in streams (turbidity increase)
Sewage Treatment
Wastewater or sewage treatment is a multistep process:
1. Primary (Physical process)

Raw sewage is passed through series of screens for removal of grit and large objects
(material to landfill for disposal) by physical separation. The sewage is allowed to
settle in the “sedimentation.tank” yielding sludge.

This process typically removes 50% of the solids and 25% of the BOD.

flocculating chemicals are added to enhance sedimentation
2. Secondary (Microbial process)
Supernatant or primary effluent contains high levels of dissolved organic load.
Naturally occurring and inoculated microbes oxidize organic material into CO2. Aerobic
conditions must be maintained via mixing in an “aerator”.
organic matter + O2  CO2 + NH3 + H2O
NH3  NO3
This process can remove as much as 95% of the BOD

lowers suspended solids content (into sludge)
3. Tertiary treatment of Effluent
Nitrates removed by denitrification via microorganisms.
2NO3- + 5H2 + 2H  N2+ 6H2O + Energy
• Phosphates removed either chemically or microbially, but both result in precipitation of
phosphates out of solution
PO4-3 + Al+3  AlPO4 (s) (into sludge)
Final treatment
Effluent back to stream after
–
a final carbon filtration and
–
chlorination/dechlorination
Treated water is discharged to waterways
•
Used for irrigation
•
Recycled into drinking water
Anaerobic Digestion of Sludge
Sludges from the primary and secondary treatment settling tanks are pumped into an
anaerobic digester. Sludges contain cellulose, proteins, lipid and other insoluble polymers
•
Anaerobic bacteria digest the sludge to methane and carbon dioxide
organic compounds  organic acids + CO2 + H2
organic acids  acetate + CO2 + H2
acetate + CO2 + H2  CH4
The result is a nutrient-rich product called stabilized sludge. Sludge – very nutrient
rich It can be
–
applied directly to land as fertilizer
–
incinerated (good fuel after drying)
–
used as landfills
2. Enlist the importance of Biological Oxygen Demand (BOD)
Biochemical Oxygen Demand (BOD) refers to the amount of oxygen that would be
consumed if all the organics in one litre of water were oxidised by bacteria and protozoa. The
first step in measureing BOD is to obtain equal volumes of water from the area to be tested
and dilute each specimen with a known volume of distilled water which has been thoroughly
shaken to insure oxygen saturation. After this, an oxygen meter is used to determine the
concentration of oxygen within one of the vials. The remaining vial is than sealed and placed
in darkness and tested five days later. BOD is then determined by subtracting the second
meter reading from the first. The range of possible readings can vary considerably: water
from an exceptionally clear lake might show a BOD of less than 2 ml/L of water. Raw
sewage may give readings in the hundreds and food processing wastes may be in the
thousands.
Generally, when BOD levels are high, there is a decline in DO (Disolved Oxygen)
levels. This is because the demand for oxygen by the bacteria is high and they are taking that
oxygen from the oxygen dissolved in the water. If there is no organic waste present in the
water, there would not be as many bacteria present to decompose it and thus the BOD will
tend to be lower and the dissolve oxygen level will tend to be higher.
BOD (in ppm)
Water Quality
1-2
Very Good: There will not be much organic
waste present in the water supply.
3–5
Fair: Moderately Clean
6–9
Poor: Somewhat Polluted Usually indicates
organic matter is present and bacteria are
decomposing this waste.
100 or greater
Very Poor: Highly Polluted Contains organic
waste.
CHEMICAL OXYGEN DEMAND (COD)
The COD test will give a good estimate of the first stage oxygen demand for most
wastewaters. An advantage of the COD test over the biochemical oxygen demand (BOD) test
is 2 to 3 hours versus 5 days. The COD test also is used to measure the strength of wastes that
are too toxic for the BOD test. The COD test should be considered an independent
measurement and not a quick substitute for the BOD test. The COD is usually higher than the
BOD, but the amount will vary from waste to waste. The COD test should be considered an
independent measurement of organic matter in a sample rather than a substitute for the BOD
test.
Chemical Oxygen Demand measures the ability of hot chromic acid solution to
oxidize organic matter. This analyzes both biodegradable and non-biodegradable (refractory)
organic matter. Expressed as O2. The results of the COD (chemical oxygen demand) tests are
usually higher that the corresponding BOD test for several reasons. Many organic compounds
which are dichromate oxidizable are not biochemically oxidizable; Certain inorganic
substances, such as sulphides,sulphates, thiosulphates, nitrites and ferrous iron are oxidized
by dichromate, creating an inorganic COD, which is misleading when estimating the organic
content of the wastewater. If this is true, a BOD value for a glucose/glutamic acid standard
should be 60-70% of the COD value for the same sample.
The BOD to COD ratio is nothing more than the BOD concentration divided by the
COD concentration for the same sample (e.g., if BOD is 60 mg/L, and COD is 100 mg/L for
a sample, the ratio is 60/100, or 0.60). There are three fairly reliable ‘rules of thumb’
correlations between COD/BOD. 1. Ratios for COD to BOD of 0.5 to 2 are usually found in
potable water or exceptionally clean surface or groundwater. 2. Ratios of COD to BOD of 2
to 4 are usually seen in routine domestic/municipal sewage wastes. 3. Ratios of COD to BOD
of 4 to 6 are usually indicative of industrial type wastes. Of course, each specific treatment
system may be checked for its own particular ratios. In some industrial effluents
(pretreatment program), BODs can be higher than CODs (for example, some effluents which
are high in sugars, as can be found in the bakery industry, or soda bottling. Some industrial
effluents will have higher demand because of the higher quantities of chemicals that demand
oxygen.
Most applications of COD determine the amount of organic pollutants found in
surface water (e.g. lakes and rivers), making COD a useful measure of water quality. It is
expressed in milligrams per liter (mg/ L), which indicates the mass of oxygen consumed per
liter of solution. Older references may express the units as parts per million (ppm).
UNIT IV
Water microbiology, algae, phytoplankton- eutrophication- water treatment - Primary,
secondary
and
tertiary.
Drinking
waterPortabilityMPN
technique
___________________________________________________________________________
PART – A
1. Effect of chlorofluorocarbon is ozone depletion
2. List of the chemical factors used to determine the water quality.
Acidity, alkalinity, Cl, Na
3. Wilt disease caused by Fusarium Oxysporum
4. The Importance of nitrogen cycle is fixing atmospheric nitrogen
5. Methane is responsible for green house effect
PART – B
1.Discuss in brief the greenhouse effect.
The greenhouse gases in the lower levels of the atmosphere, like glass are transparent
to the near infra-red rays of shorter wavelength but are opaque to the heat radiated by the
heated earth (longer wavelength heat ray) and trap them. By not letting the solar rays to
escape into the outer space, greenhouse gases add to the heat that is already present on the
earth surface. This results in increase in temperature and is commonly known as Greenhouse
effect. The major sources of greenhouse gases are: carbon dioxide, methane,
chlorofluorocarbons, nitrous oxide etc.
PART – C
1.Discuss in detail about Bacterial, Fungal, Viral diseases (Wilt, Blight, Canker, Mosaic)
in plants
Tobacco Mosaic Virus
The first plant virus discovered, tobacco mosaic virus (TMV), attacks members of the
nightshade, or solanaceae, family. These include tobacco, pepper, potato, tomato, eggplant,
cucumber and petunia. The virus spreads through entry into breaks of cell walls caused by
insects or other physical damage.
Cucumber Mosaic Virus
Cucumber mosaic virus infects cucumber, tomato, peppers, melons, squash, spinach,
celery, beet and other plants. Aphids spread it, and they cause physical damage to the plant,
which allows entry of the virus via wind, splashing or dripping sap. The virus causes twisting
in young leaves. That stunts growth of the entire plant and causes poor fruit or leaf
production.
Barley Yellow Dwarf
The barley yellow dwarf virus infects several grains and staple crops, including
wheat. Aphids primarily spread the virus. The virus causes discoloration of leaves and the
tips of the plants, which reduces photosynthesis, stunts growth and decreases production of
seed grains.
Bud Blight
The bud blight virus infects soybeans, a staple crop. It causes the stem to bend at the
top and the buds to turn brown and drop off the plant. Nematodes spread this virus.
Sugarcane Mosaic Virus
The sugarcane mosaic virus discolors leaves of the sugarcane plant, restricting its
ability to feed itself through photosynthesis and grow. It stunts the growth of young plants.
Aphids and infected seed spread the virus.
Cauliflower Mosaic Virus
The cauliflower mosaic virus infects members of the brassica, or mustard, family,
which includes cabbage, brussels sprouts, cauliflower, broccoli and rape seed. It causes a
mosaic or mottle on the leaves, which stunts growth. Aphids and mechanical exposure spread
the virus.
Lettuce Mosaic Virus
The lettuce mosaic virus mottles the leaves of almost all types of lettuce, stunting its
growth and eliminating its market appeal. Aphids and infected seeds spread the virus.
Maise Mosaic Virus
The maise mosaic virus causes yellow spots and stripes on the leaves of corn,
stunting its growth. Leafhoppers spread the virus.
Peanut Stunt Virus
The peanut stunt virus causes discoloration and distortion of the leaves of peanuts and
some other rhizomes, stunting their growth. Aphids and sap spread the virus.
Blossom End Rot
Blossom end rot affects tomatoes, peppers and eggplants, beginning as a small, wetlooking spot opposite of the stem that enlarges until as much as half of the fruit is affected.
Blossom end rot causes yield reductions of 50 percent or more in affected crops. Because the
disease is physiological in nature, there is no treatment. Cornell University recommends
growing young plants in moist soil that is high in calcium.
Early Blight
Early blight causes spotting and fruit rot in potatoes and tomatoes. The disease is
caused by a fungus and results in significant yield losses. Early blight directly affects the
fruits, as well as reducing plant productivity due to leaf loss. The loss of leaves also makes
fruits more susceptible to sun scald, leading to further losses.
Powdery Mildew
Powdery mildew affects cucurbit vegetables, particularly squash. Cucumber and
melons appear to be fairly resistant. Powdery mildew is a fungal infection that both destroys
and damages fruits, causing severe losses. Yields are directly reduced due to fewer and
smaller fruits. Additionally, powdery mildew damages fruits, causing sunburn, discoloration
and poor flavor. Plants affected by powdery mildew also become more susceptible to other
diseases that further reduce yields.
Corn Smut
Corn smut is an airborne fungal disease that tends to affect sweet corn more than field
corn. The disease causes the corn to become gnarled and blackened. Corn smut does not tend
to result in crop failures, however. The University of Ohio Extension Office states that losses
rarely surpass 20 percent.
Bacterial Spot
Bacterial spot is one of the most destructive pepper diseases and may also affect tomatoes.
The disease first manifests as brown spots on the leaves that cause them to yellow and fall
off. Fruits are also affected and become unmarketable. Cornell University reports that
bacterial spot may cause complete crop failures due to reduced plant productivity, marred
fruit
and
sunscald
due
to
the
loss
2.Effect of air pollution in plants and humans is harmful – justify.
Common effects
•
Interferes with photosynthesis, carbohydrate production
•
Damage to leaf tissue, needles and fruit
•
Reduction in growth rate or suppression of growth
•
Increased susceptibility to disease, pests, and adverse
weather
•
It reduces crop yields and makes fruit smaller, lighter
and less nutritious
Nitrous oxide Effects on Plants
•
Seriously injure vegetation at certain concentrations. Effects include:
of
leaves.
–
Bleaching or killing plant tissue.
–
Causing leaves to fall.
–
Reducing growth rate.
–
lesions on leaves
•
Corrode metals (due to nitrate salts formed from nitrogen oxides).
•
Reduce visibility.
•
Oxides of nitrogen, in the presence of sunlight, can also react with hydrocarbons,
forming photochemical oxidants or smog.
Sulfur oxides Effects on Plants
•
Sulfur dioxide easily injures many plant
•
Positive benefits from low levels, in a very few species growing on sulfur deficient
soils.
•
Dust pollution - from screening out sunlight, dust on leaves blocks stomata, lowers
their conductance to CO2, simultaneously interfering with photosystem II.
•
Polluting gases such as SO2 and NOx enter leaves through stomata, NOx dissolves in
cells and gives rise to nitrite ions (NO2–, which are toxic at high concentrations)
•
SO2 - stomatal closure, which protects the leaf against further entry of the pollutant
but also curtails photosynthesis.
Ozone effect on Plants
•
Ozone is presently considered to be the most damaging phytotoxic air pollutant yields of soybean, maize, winter wheat, and cotton would be decreased
•
Ozone is highly reactive: It binds to plasma membranes and it alters metabolism. As a
result, stomatal apertures are poorly regulated, chloroplast thylakoid membranes are
damaged, rubisco is degraded, and photosynthesis is inhibited.
•
Ozone reacts with O2 and produces reactive oxygen species - denature proteins and
damage nucleic acids (thereby giving rise to mutations), and cause lipid peroxidation,
which breaks down lipids in membranes.
•
Polluting Gases, Dissolved in Rainwater, Fall as "Acid Rain"
SO2 and NOx react with H2O and O2 to produce acidic rain (sulfuric, nitric acids)
•
the added acid can result in the release of aluminum ions from soil minerals, causing
aluminum toxicity.
Effect of air pollution in humans
UNIT V
Aero microbiology- aerosol, droplet nuclei, air pollution- sources (Microbiological) – air
quality
analysisair
sampling
devices
___________________________________________________________________________
PART – A
1. Differentiate between degradable and non- degradable pollutants.
Answer: Degradable pollutants can be decomposed, removed or reduced to acceptable level
either by natural or artificial means e.g. human sewage, animal and crop waste etc.
Non-degradable pollutants cannot be degraded by natural or artificial means. They are not
recycled in the aqueous system naturally.
e.g. radioactive materials, heavy metals and plastics.
2. Define bioremediation
Bioremediation is defined as the process whereby organic wastes are biologically
degraded under controlled conditions to an innocuous state, or to levels below concentration
limits established by regulatory authorities.
3.Bioleaching is the extraction of specific metals from their ores through the use of bacteria.
4. List out Bio-degradable waste
paper, wood, fruits and others
5. List out Non-biodegradable
plastics, bottles, old machines, cans, styrofoam containers and others
6. Incineration is a disposal method that involves combustion of waste material.
7.Define Compost
Compost is composed of organic materials derived from plant and animal matter that
has been decomposed largely through aerobic decomposition.
PART – B
1.Write a note on biodegradation
Biodegradation is the chemical breakdown of materials by a physiological
environment. Organic material can be degraded aerobically with oxygen, or anaerobically,
without oxygen. A term related to biodegradation is biomineralisation, in which organic
matter is converted into minerals. Biosurfactant, an extracellular surfactant secreted by
microorganisms, enhances the biodegradation process.
Biodegradable matter is generally organic material such as plant and animal matter
and other substances originating from living organisms, or artificial materials that are similar
enough to plant and animal matter to be put to use by microorganisms.
Microorganisms have a naturally occurring, microbial catabolic diversity to degrade,
transform or accumulate a huge range of compounds including
a) Hydrocarbons (e.g. oil),
b) Polychlorinated biphenyls (PCBs),
c) Polyaromatic hydrocarbons (PAHs),
d) Pharmaceutical substances,
e) Radionuclides and metals.
2.Write a note on bioremediation
Bioremediation is defined as the process whereby organic wastes are biologically degraded
under controlled conditions to an innocuous state, or to levels below concentration limits
established by regulatory authorities.
Bioremediation is cheaper than the chemical and physical options, and can deal with lower
concentrations of contaminants more effectively, although the process may take longer
 The strategies for bioremediation in both soil and water can be as follows.
 Use the indigenous microbial population.
 Encourage the indigenous population.
 Bioaugmentation; the addition of adapted or designed inoculants.
 Addition of genetically modified micro-organisms.
 Phytoremediation.
Types of bioremediation
Two types:
a) Engineered bioremediation- intentional changes
b) intrinsic bioremediation- allows biodegradation to occur under natural conditions.
Advantages of bioremediation
1.Bioremediation is a natural process and is therefore perceived by the public as an
acceptablewaste treatment process for contaminated material such as soil.
2. Microbes able to degrade the con-taminant increase in numbers when the contaminant is
present;when the contaminant is degrad-ed,the biodegradative population declines.The
residues for the treatment are usually harmless products and include carbon dioxide,water,and
cell biomass.
3. bioremediation is useful for the complete destruction of a wide variety of contaminants.Many compounds that are legally considered to be hazardous can be transformed to
harm-less products. This eliminates the chance of future liability associated with treatment
and dispos-al of contaminated material.
4.Instead of transferring contaminants from one environmental medium to another,for
example,from land to water or air,the complete destruction of target pollutants is possible.
5.Bioremediation can often be carried out on site,often without causing a major disruption of
nor-mal activities.This also eliminates the need to transport quantities of waste off site and
the poten-tial threats to human health and the environment that can arise during
transportation.
6.Bioremediation can prove less expensive than other technologies that are used for clean-up
of hazardous waste.
3.Give and account on bioleaching
Bioleaching is the extraction of specific metals from their ores through the use of
bacteria. This is much cleaner than the traditional heap leaching using cyanide.[1] Bioleaching
is one of several applications within biohydrometallurgy and several methods are used to
recover copper, zinc, lead, arsenic, antimony, nickel, molybdenum, gold, and cobalt.
Traditional extractions involve many expensive steps such as roasting and smelting, which
require sufficient concentrations of elements in ores and are environmentally unfriendly. Low
concentrations are not a problem for bacteria because they simply ignore the waste which
surrounds the metals, attaining extraction yields of over 90% in some cases. These
microorganisms actually gain energy by breaking down minerals into their constituent
elements. The company simply collects the ions out of the solution after the bacteria have
finished.
Some advantages associated with bioleaching are:

economical: bioleaching is generally simpler and therefore cheaper to operate and
maintain than traditional processes, since fewer specialists are needed to operate
complex chemical plants.

environmental: The process is more environmentally friendly than traditional
extraction methods. For the company this can translate into profit, since the necessary
limiting of sulfur dioxide emissions during smelting is expensive. Less landscape
damage occurs, since the bacteria involved grow naturally, and the mine and
surrounding area can be left relatively untouched. As the bacteria breed in the
conditions of the mine, they are easily cultivated and recycled.
Some disadvantages associated with bioleaching are:

economical: the bacterial leaching process is very slow compared to smelting. This
brings in less profit as well as introducing a significant delay in cash flow for new
plants.

environmental: Toxic chemicals are sometimes produced in the process. Sulfuric acid
and H+ ions which have been formed can leak into the ground and surface water
turning it acidic, causing environmental damage. Heavy ions such as iron, zinc, and
arsenic leak during acid mine drainage. When the pH of this solution rises, as a result
of dilution by fresh water, these ions precipitate, forming "Yellow Boy" pollution. For
these reasons, a setup of bioleaching must be carefully planned, since the process can
lead to a biosafety failure.
Currently it is more economical to smelt copper ore rather than to use bioleaching, since the
concentration of copper in its ore is generally quite high. The profit obtained from the speed
and yield of smelting justifies its cost. However, the concentration of gold in its ore is
generally very low. The lower cost of bacterial leaching in this case outweighs the time it
takes to extract the metal.
PART – C
1. Write down the steps involved in recycling of liquid and solid wastes
Waste is unwanted or unusable materials. Litter is waste which has been disposed of
improperly, particularly waste which has been carelessly disposed of in plain sight, as
opposed to waste which has been dumped to avoid paying for waste disposal fees
There are many waste types defined by modern systems of waste management

municipal solid waste (MSW)

construction waste and demolition waste (C&D)

institutional waste, commercial waste, and industrial waste (IC&I)

medical waste (also known as clinical waste)

hazardous waste, radioactive waste, and electronic waste

biodegradable waste .
Classification of waste :
a) Solid wastes:
These waste includes domestic, commercial and industrial wastes especially
common as co-disposal of wastes
Examples: plastics, styrofoam containers, bottles, cans, papers, scrap iron, and other
trash
b) Liquid Wastes:
The wastes in liquid form

Examples: domestic washings, chemicals, oils, waste water from ponds,
manufacturing industries and other sources
c) Bio-degradable waste
These waste includes that can be degraded .Example :paper, wood, fruits and others
d) Non-biodegradable
These includes the waste that cannot be degraded
.Example plastics, bottles, old machines, cans, styrofoam containers and others
Methods of Waste Disposal .
There are following methods use in waste disposal management
a) Integrated waste management
Integrated waste management using LCA (life cycle analysis) attempts to offer the most
benign options for waste management. For mixed MSW (Municipal Solid Waste) a number
of broad studies have indicated that waste administration, then source separation and
collection followed by reuse and recycling of the non-organic fraction and energy and
compost/fertilizer production of the organic waste fraction via anaerobic digestion to be the
favored path. Non-metallic waste resources are not destroyed as with incineration, and can be
reused/ recycled in a future resource depleted society.
b) Plasma gasification
Plasma is a highly ionized or electrically charged gas. An example in nature is lightning,
capable of producing temperatures exceeding 12,600 °F (6,980 °C). A gasifier vessel utilizes
proprietary plasma torches operating at +10,000 °F (5,540 °C) (the surface temperature of the
Sun) in order to create a gasification zone of up to 3,000 °F (1,650 °C) to convert solid or
liquid wastes into a syngas. When municipal solid waste is subjected to this intense heat
within the vessel, the waste’s molecular bonds break down into elemental components. The
process results in elemental destruction of waste and hazardous materials.
According to the U.S. Environmental Protection Agency, the U.S. generated 250 million tons
of waste in 2008 alone, and this number continues to rise. About 54% of this trash
(135,000,000 short tons (122,000,000 t)) ends up in landfills and is consuming land at a rate
of nearly 3,500 acres (1,400 ha) per year. In fact, landfilling is currently the number one
method of waste disposal in the US. Some states no longer have capacity at permitted
landfills and export their waste to other states. Plasma gasification offers states new
opportunities for waste disposal, and more importantly for renewable power generation in an
environmentally sustainable manner.
c) Landfill
Disposing of waste in a landfill involves burying the waste, and this remains a
common practice in most countries. Landfills were often established in abandoned or
unused quarries, mining voids or borrow pits. A properly designed and well-managed landfill
can be a hygienic and relatively inexpensive method of disposing of waste materials. Older,
poorly designed or poorly managed landfills can create a number of adverse environmental
impacts such as wind-blown litter, attraction of vermin, and generation of liquid leachate.
Another common byproduct of landfills is gas (mostly composed of methane and carbon
dioxide), which is produced as organic waste breaks down anaerobically. This gas can create
odour problems, kill surface vegetation, and is a greenhouse gas.
Designing a modern landfill include methods to contain leachate such as clay or
plastic lining material. Deposited waste is normally compacted to increase its density and
stability, and covered to prevent attracting vermin (such as mice or rats). Many landfills also
have landfill gas extraction systems installed to extract the landfill gas. Gas is pumped out of
the landfill using perforated pipes and flared off or burnt in a gas engine to generate
electricity.
d) incineration
Incineration is a disposal method that involves combustion of waste material.
Incineration and other high temperature waste treatment systems are sometimes described as
"thermal treatment". Incinerators convert waste materials into heat, gas, steam and ash.
Incineration is carried out both on a small scale by individuals and on a large scale by
industry. It is used to dispose of solid, liquid and gaseous waste. It is recognized as a practical
method of disposing of certain hazardous waste materials (such as biological medical waste).
Incineration is a controversial method of waste disposal, due to issues such as emission of
gaseous pollutants.
Incineration is common in countries such as Japan where land is more scarce, as these
facilities generally do not require as much area as landfills. Waste-to-energy (WtE) or
energy-from-waste (EfW) are broad terms for facilities that burn waste in a furnace or boiler
to generate heat, steam and/or electricity. Combustion in an incinerator is not always perfect
and there have been concerns about micro-pollutants in gaseous emissions from incinerator
stacks. Particular concern has focused on some very persistent organics such as dioxins,
furans, PAHs, molasses which may be created within the incinerator and afterwards in the
incinerator plume which may have serious environmental consequences in the area
immediately around the incinerator. On the other hand this method or the more benign
anaerobic digestion produces heat that can be used as energy.
2.Write a note on composting
Compost is composed of organic materials derived from plant and animal matter that
has been decomposed largely through aerobic decomposition. The process of composting is
simple and practiced by individuals in their homes, farmers on their land, and industrially by
cities and factories.
Composting, often described as nature’s way of recycling, is the biological process of
breaking up of organic waste such as food waste, manure, leaves, grass trimmings, paper,
worms, and coffee grounds, etc., into an extremely useful humus-like substance by various
micro-organisms including bacteria, fungi and actinomycetes in the presence of oxygen.
Actinomycetes are similar to fungus in the way they grow and spread, but its
distinguishing elements are that the types of materials they are efficient at decomposing. The
active nature in this microscopic bacteria and the sheer number present (about 10 million per
1 gram of soil), make them highly effective at breaking down materials like tree bark,
newspaper, and other hard organic material.
Today, the use of composting to turn organic wastes into a valuable resource is
expanding rapidly in many countries, as landfill space becomes scarce and expensive, and as
people become more aware of the impact they have on the environment
Composting organisms require four equally important things to work effectively

Carbon — for energy; the microbial oxidation of carbon produces the heat
o

High carbon materials tend to be brown and dry.
Nitrogen — to grow and reproduce more organisms to oxidize the carbon.
o
High nitrogen materials tend to be green (or colorful, such as fruits and
vegetables) and wet.

Oxygen — for oxidizing the carbon, the decomposition process.

Water — in the right amounts to maintain activity without causing anaerobic
conditions.
Micro-organisms
With the proper mixture of water, oxygen, carbon, and nitrogen, micro-organisms are allowed
to break down organic matter to produce compost. The composting process is dependent on
micro-organisms to break down organic matter into compost. There are many types of
microorganisms found in active compost of which the most common are:

Bacteria- The most numerous of all the microorganisms found in compost.

Actinomycetes- Necessary for breaking down paper products such as newspaper,
bark, etc.

Fungi- Molds and yeast help break down materials that bacteria cannot, especially
lignin in woody material.

Protozoa- Help consume bacteria, fungi and micro organic particulates.

Rotifers- Rotifers help control populations of bacteria and small protozoans.
In addition, earthworms not only ingest partly composted material, but also continually recreate aeration and drainage tunnels as they move through the compost.
A lack of a healthy micro-organisms community is the main reason why composting
processes are slow in landfills with environmental factors such as lack of oxygen, nutrients or
water being the cause of the depleted biological community
Types of Composting / According To Its Nature
Aerobic composting: This means to compost with air. High nitrogen waste (like grass
clippings or other green material) will grow bacteria that will create high temperatures (up
to 160 degrees). Organic waste will break down quickly and is not prone to smell.
This type of composting is high maintenance, since it will need to be turned
every couple days to keep air in the system and your temperatures up. It is also likely to
require accurate moisture monitoring. This type of compost is good for large volumes of
compost.
Anaerobic composting: This is composting without air. Anaerobic composting is low
maintenance since you simply throw it in a pile and wait a couple years. If you just stack your
debris in a pile it will generally compact to the point where there is no available air for
beneficial organisms to live.
Instead you will get a very slow working bacteria growing that does not require air.
Your compost may take years to break down (this is what happens when you throw your food
waste in the garbage that goes to the landfill). Anaerobic composts create the awful smell
most people associate with composting. The bacteria break down the organic materials into
harmful compounds like ammonia and methane.
Vermicomposting: This is most beneficial for composting food waste. Along with red
worms, this includes composting with bacteria, fungi, insects, and other bugs.
Some of these guests break down the organic materials for the others to eat. Red worms eat
the bacteria, fungi, and the food waste, and then deposit their castings. Oxygen and moisture
are required to keep this compost healthy mixture of straw and some spoiled latex paint,
combined with waste blood-albumin glue
Types of Composting / According To Its Use
Industrial systems: - Industrial composting systems are increasingly being installed as a waste
management alternative to landfills, along with other advanced waste processing systems.
Mechanical sorting of mixed waste streams combined with anaerobic digestion or in-vessel
composting, is called mechanical biological treatment.
Treating biodegradable waste before it enters a landfill reduces global warming from fugitive
methane; untreated waste breaks down anaerobically in a landfill, producing landfill gas that
contains methane, a potent greenhouse gas.
Agriculture: - In agriculture, windrow composting is used. It is the production of compost by
piling organic matter or biodegradable waste, such as animal manure and crop residues, in
long rows (windrows). This method is suited to producing large volumes of compost.
These rows are generally turned to improve porosity and oxygen content, mix in or remove
moisture, and redistribute cooler and hotter portions of the pile. Windrow composting is a
commonly used farm scale composting method.
Home: - Home composting is the simplest way to compost. At home, composting is generally
done by using composting bins or in the form of pile composting. Other methods include
trench composting and sheet composting. It is a small scale process and requires less outlay
of capital and labor.
Composting of Organic Waste
Composting organic waste is simple, here's what you can easily compost and how:Dried Leaves: This is the most common material available to home gardeners. It is valuable
as a source of humus, but don't take seriously the "richness" of this material often mentioned
by uninformed individuals. Before trees and shrubs drop their leaves in autumn, they
withdraw starches, sugars and other food elements from the leaves. Leaves are largely
cellulose, so additional starches as well as nitrogen are needed to rot them. Leaves are best if
mixed in the compost heap with such materials as stale bread, spoiled flour or meal, and so
on.
Table Wastes: Richness of this source depends on how extravagant you are. The higher the
percentage of meat scraps in table waste, the more valuable it is when composting organic
waste.
Sawdust: If you have a home workshop, or if sawdust and shavings are available from a
local source, wood wastes make excellent compost. If wanted as a source of humus, use
plenty of nitrogen with these wastes, but if you want compost that is less completely
converted to humus, add more starchy material and less nitrogen to the pile.
Chicken Manure and Poultry Wastes: Local broiler plants often throw away offal, feathers,
etc. Many poultry raisers find chicken manure a nuisance and are glad to give it away; it is
sufficiently high in nitrogen but not in phosphorus and potash. These two elements plus
starch should be added to speed up chicken waste breakdown.
Brewery Wastes: The spent hops from breweries are about on a par with leaves and require
about the same composting attention. One difference: hops are usually wet when received.
Seaweed and Kelp: If you live near the sea, don't scorn the sea's free gift of kelp and
seaweed. These are high in potash as well as many minor elements. Additional nitrogen helps
speed breakdown.
Nut Shells: Pecan shells, peanut husks, cocoanut fiber and other nut wastes make excellent
compost. One precaution: avoid shells of walnuts. They contain a chemical that inhibits plant
growth and works like an antiseptic to kill off bacteria.
Tobacco Stems and Wastes: An excellent source of humus and a good soil conditioner
when composted.
Fish Wastes: When cleaning fish, always save the offal for the compost pile. Salt-water fish
in particular contribute all the minor elements as well as the three major elements in their
skin, bones and offal.
Wool Clippings: Worn-out wool clothing should be buried in the compost pile. It will take
about two years to decompose. Dark colors rot more slowly than light tones.
Corn Cobs: Although rather high in silica, corn cobs do contain considerable potash and thus
are useful in the compost heap. Both nitrogen and phosphorus (at least a sprinkling of the
latter) will improve the compost produced by corn cobs.
Sewerage Sludge: If it can be had for the hauling, air-dried sewerage sludge is worth
composting. However, be sure it goes through at least a full year's decay before it is used.
Amoeba can survive in sewerage sludge and cause infection in human beings. A full year's
composting, if the pile is turned, should eliminate them.
Lawn Clippings: They should be added to the compost heap rather than allowed to lie on the
surface of the lawn, where they build up a duff that fosters fungus diseases. Allow the fungi
in the compost pile to work on them instead.
Straw, Hay, Cattails: These are low in nitrogen. A compost "food" is needed to rot them.
The finished product closely resembles barnyard manure.
Weeds and Discarded Plants from the Garden: Use these only if not visibly infected with
plant diseases. If weeds have formed seed, be sure to place them deep in the pile so the heat
of composting will kill the seed.
Tanbark: Not easy to find nowadays, but if available it can be composted with the "food"
mixture recommended for straw.
Cotton Nolls and Wastes: Difficult to start a compost with this type of material, but it yields
a high percentage of humus. Allow about a year for breakdown.
Paper Scraps: Mentioned here only because paper is often a subject of doubt. Almost pure
cellulose, it requires both nitrogen and starches or sugar in order to break down. A small
percentage of paper in the compost pile won't hurt.
Actually, for composting organic waste, practically anything of organic origin can be
composted in time. I once made some excellent compost with a mixture of straw and some
spoiled latex paint, combined with waste blood-albumin glue.
3. Biogas production and utilization is environmental friendly – justify.
Biogas typically refers to a gas produced by the biological breakdown of organic
matter in the absence of oxygen. Biogas originates from biogenic material and is a type
of biofuel. Biogas is produced by anaerobic digestion or fermentation of biodegradable
materials
such
as biomass, manure, sewage, municipal
waste, green
waste, plant
material and energy crops. This type of biogas comprises primarily methane and carbon
dioxide. Other types of gas generated by use of biomass is wood gas, which is created
by gasification of wood or other biomass. This type of gas consist primarily
of nitrogen, hydrogen, and carbon monoxide, with trace amounts of methane.
Biogas is practically produced as landfill gas (LFG) or digester gas.A biogas plant is
the name often given to an anaerobic digester that treats farm wastes or energy crops.
Biogas can be produced utilizing anaerobic digesters. These plants can be fed with
energy crops such as maize silage or biodegradable wastes including sewage sludge and food
waste. During the process, an air-tight tank transforms biomass waste into methane producing
renewable energy that can be used for heating, electricity, and many other operations that use
any variation of an internal combustion engine, such as GE Jenbacher gas engines. There are
two key processes: Mesophilic and Thermophilic digestion.
Stages in biogas production
Composition and properties of biogas
Biogas is a mixture of gases that is composed chiefly of:
· methane (CH4): 40-70 vol.%
· carbon dioxide (CO2): 30-60 vol.%
· other gases: 1-5 vol.% including · hydrogen (H2): 0-1 vol.% · hydrogen sulfide (H2S): 0-3
vol.%
Like those of any pure gas, the characteristic properties of biogas are pressure and
temperature-dependent. They are also affected by the moisture content. The factors of main
interest are:

change in volume as a function of temperature and pressure,

change in calorific value as a function of temperature, pressure and water-vapor

content, and

changes in vapour content and as a function of temperature and pressure.
Biogas Appliances
Biogas is a lean gas that can, in principle, be used like other fuel gas for household and
industrial purposes, especially for
· Gas cookers/stoves
· Biogas lamps
· Radiant heaters
· Incubators
· Refrigerators
· Engines
4. Discuss the types and Xenobiotic Degradation .
Xenobiotics or xenobiotic compounds are man made chemicals that are present in the
environment and pollute the environment when present in high concentrations. The
word “xeno” means foreign. A compound that is normal to one organism may be a
xenobiotic to another. For example, antibiotics can be referred as xenobiotics in a human
body because human body does not contain them or produce them naturally. Organs
transplanted in foreign bodies of different species are termed as xeno transplantation.
Types
There are two types of xenobiotic compounds. They may be biodegradable or non degradable
(recalcitrant). Biodegradable xenobiotic compounds are those that get degraded by the action
of microbes or other reactions while recalcitrant compounds are resistant to degradation by
any reactions. The recalcitrant xenobiotic compounds can be grouped into various groups like
halocarbons, polychlorinated biphenyls, oil mixtures, synthetic polymers, alkyl benzyl
sulphonates,etc.
Xenobiotics and Environment
Xenobiotics pose threat to the environment. They pollute the environment as some of them
are recalcitrant. Synthetic polymers such as plastics and nylon are insoluble in water. Oil is
also a pollutant; many of its compounds are biodegradable and are degraded at different rates.
Oil is recalcitrant mainly because of its insolubility in water and due to the toxicity of some
of its compounds.
Hazards from Xenobiotics
•
Many xenobiotics are recalcitrant and persist in the environment and increase in
concentration with time.
•
•
At low concentration they can cause various skin problems.
They tend to accumulate in the environment and lead to bioaccumulation and
biomagnifications.
•
Many of them are toxic to bacteria and lower eukaryotes.
•
Carbon halogenated compounds have proven to be carcinogenic in nature.
Use of Microbes to Treat Xenobiotics
Two different microbes can together be used to degrade xenobiotic compounds completely.
Use of mix cultures of microorganisms produce different enzymes that act on recalcitrant
compounds and degrade them to simpler form.
The microorganisms that contain a variety of mono and di oxygenase enzymes are capable of
degrading xenobiotic compounds into smaller compounds that are again taken up by other
series of microbes and degraded wholly.
Thus microorganisms can be employed for treating and degrading these compounds to make
our environment free of any solid pollutants if handled carefully.