Download “GEM” Mini Sewage Treatment Plant

African Environmental Development
Portion 129 of the farm
Sterkfontein 173 IQ
Mogale City
Republic of South Africa
African Environmental Development
PO Box 1588
Rant-en-Dal
1751
Tel & Fax: - (+27) 11 956 6537 or 083 657 0560
E-mail: - [email protected]
http://www.aed.co.za
African
Environmental
Development
THE "GEM" MINI SEWAGE TREATMENT PLANT
Direction of flow
Introduction:
For many centuries, a septic tank coupled to a French drain soak-away has
been the only choice of sewage and wastewater treatment and disposal in
areas not connected to a municipal sewerage system. This has worked fine in
many areas for many years. However, an increase in the incidence of
groundwater contamination and restrictions on the use of French drains within
certain municipal areas and in regions located on certain rock types prone to
the development of sinkholes (such as dolomite) and in certain other
environmentally sensitive areas, has prompted us to look at more modern
alternatives to the conventional septic tank / French drain combination.
Furthermore, the shortage of water in many regions in Africa has made it
necessary to re-use water as far as practical.
We are therefore proud to announce a modern-day alternative to the septic
tank / French drain, the “GEM” Mini Sewage Treatment Plant manufactured
by Ballam-Waterslot (Pty) Ltd.
The “GEM” Mini Sewage Treatment Plant is an on-site sewage treatment
plant capable of producing an effluent, which complies with the General
Effluent Standard (as promulgated in Government Notice 991/9225 of
18/05/1984), the current standard for sewage effluent for most areas in South
Africa.
In essence, the “GEM” Mini Sewage Treatment Plant is a compact sewage
treatment plant employing principles of anaerobic and aerobic (activated
sludge) biological sewage treatment used by all municipal sewage treatment
plants in South Africa. The “GEM” Mini Sewage Treatment Plant is merely a
miniature version of a municipal sewage treatment plant.
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African Environmental Development
Portion 129 of the farm
Sterkfontein 173 IQ
Mogale City
Republic of South Africa
African Environmental Development
PO Box 1588
Rant-en-Dal
1751
Tel & Fax: - (+27) 11 956 6537 or 083 657 0560
E-mail: - [email protected]
http://www.aed.co.za
African
Environmental
Development
Advantages of the “GEM” Mini Sewage Treatment Plant

The biological processes used have been proven and have been used
in all types of sewage treatment plants for many years.

Low cost, low maintenance, hygienic solution.

Prevents groundwater pollution, as there is no need for a French drain
soak-away.

Prevents the spread of waterborne diseases.

Installation and commissioning is relatively simple.

It produces an effluent free of odours and can be installed close to
dwellings/buildings.

No need for a 2-pipe system as is the case with septic tanks. The unit
treats all wastewater from toilets, baths, wash-hand basins, washing
machines and dishwashers.

The unit is designed for a normal household of up to 6 people
(calculated at 200 litres per person per day).

The ultimate solution in replacing pit latrines and/or bucket systems,
subject to a water supply and a 220V power supply being made
available.

The effluent water produced by the unit is safe to use for irrigation
under controlled conditions.

Ideally suited for single households, caravan parks, clinics, schools,
game reserves, lodges, offices, coastal chalets, public toilets, ablution
blocks, etc. where a municipal sewer connection is not available. Any
application where the General Effluent Standard for sewage effluent is
applicable and a compact unit is required.

Ideally suited in areas where the soil and/or geological formations
exclude the use of French drains due to the potential risk of
groundwater contamination or sinkhole formation or in environmentally
sensitive areas such as the Cradle of Humankind World Heritage Site,
located almost exclusively on dolomitic limestone.
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African Environmental Development
Portion 129 of the farm
Sterkfontein 173 IQ
Mogale City
Republic of South Africa
African Environmental Development
PO Box 1588
Rant-en-Dal
1751
Tel & Fax: - (+27) 11 956 6537 or 083 657 0560
E-mail: - [email protected]
http://www.aed.co.za
African
Environmental
Development
Technical Data and Operating Principles
The “GEM” Mini Sewage Treatment Plant makes use of natural biological
processes to purify the sewage water and it does this in three stages.
The First Stage (Anaerobic Digestion)
The first stage of the plant makes use of anaerobic bacteria to break
down the complex organic material in the sewage to simpler organic
molecules. This phase is similar to a septic tank where anaerobic
bacteria (bacteria that live in the absence of oxygen) are used to break
down the complex organic molecules. The by-products produced by
these bacteria are mostly gases such as methane, hydrogen sulphide
and carbon dioxide. These gases are vented off through the normal
ventilation system of a building’s sewage pipe system. Using anaerobic
digestion, around 40% of the organic substances found in sewage can
be broken down. To remove the rest of the organic substances to a
concentration that complies with the General Effluent Standards, a
further aerobic process is required.
The Second Stage (Aerobic or Activated Sludge Section)
The second stage of the “GEM” Mini Sewage Treatment Plant is the
aerobic treatment section. Here a different type of bacteria is grown,
aerobic bacteria (bacteria that requires oxygen to break down organic
substances found in sewage). Aerobic bacteria are much more efficient
than anaerobic bacteria in the
breakdown of organic matter found in
sewage,
but
require
excessive
amounts of oxygen. For this reason,
the “GEM” Mini Sewage Treatment
Plant is fitted with a small compressor,
which uses only 180W of power.
The compressed air is diffused into
very small bubbles through a stainless
steel diffuser at the bottom of the
aerobic section of the “GEM” Mini Sewage Treatment Plant and
apart from keeping the bacteria in suspension, also provides oxygen for
the bacteria.
The type of aerobic bacteria grown in the second stage of the “GEM”
Mini Sewage Treatment Plant tends to group together in the form of
“flocks”. The second part of the aerobic section of the “GEM” Mini
Sewage Treatment Plant is used to separate the aerobic bacterial
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African Environmental Development
Portion 129 of the farm
Sterkfontein 173 IQ
Mogale City
Republic of South Africa
African Environmental Development
PO Box 1588
Rant-en-Dal
1751
Tel & Fax: - (+27) 11 956 6537 or 083 657 0560
E-mail: - [email protected]
http://www.aed.co.za
African
Environmental
Development
flocks from the purified water. The clean water then flows to the third
stage of the “GEM” Mini Sewage Treatment Plant, while the bacterial
flocks are re-circulated to the aerated section of the plant so that they
can continue to perform their water purifying work. In order to recirculate the bacterial flocks, an airlift pump is used. The airlift pump is
powered by compressed air from the same compressor that provides
air for the aerobic bacteria in the second (aerobic) section of the plant.
After a while, the population of bacteria in the second section of the
“GEM” Mini Sewage Treatment Plant will become too large.
Provision has therefore been made to continuously “waste” small
amounts of these bacteria to the first (anaerobic) section of the plant.
Here the anaerobic bacteria consume the “wasted” aerobic bacteria in
a similar manner as the way they “consume” organic matter in the raw
sewage entering the system.
The Third Section – Disinfection
By the time the treated water (effluent) leaves the second (aerobic)
stage of the plant, the organic load in the sewage that entered the
“GEM” Mini Sewage Treatment Plant has been brought down to
acceptable levels. There may, however, still be pathogenic bacteria left
in the effluent water from the second aerobic stage of the plant. For this
reason a disinfection section is provided as the final stage of the
sewage water treatment process.
The disinfection section of the “GEM” Mini Sewage Treatment Plant
comprises of a chlorinator that uses a
cartridge of chlorine tablets. The type
of chlorinator used on the “GEM”
Mini Sewage Treatment Plant is
simple to use and to adjust. The grey
top of the chlorinator is simply
removed; the old chlorine cartridge is
removed and replaced with a new
one. To adjust the amount of chlorine
dosed, the grey cap is merely screwed in deeper. Calibration marks on
the side of the chlorinator indicates the dosage. One cartridge of
chlorine tablets should last between 6 and 12 months, depending on
the number of people occupying the house/premises.
What to do with the effluent?
Although the effluent is not purified to a drinking standard, it is nevertheless
safe and may be used in a variety of applications. There are many ways the
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Created on 11/06/2004 08:38:00
African Environmental Development
Portion 129 of the farm
Sterkfontein 173 IQ
Mogale City
Republic of South Africa
African Environmental Development
PO Box 1588
Rant-en-Dal
1751
Tel & Fax: - (+27) 11 956 6537 or 083 657 0560
E-mail: - [email protected]
http://www.aed.co.za
African
Environmental
Development
final effluent produced by the “GEM” Mini Sewage Treatment Plant may be
utilised.
The most useful application of the effluent is to irrigate it onto lawns, gardens
or crops. In this case, effluent will
have to be stored in some form of
reservoir until enough effluent has
accumulated for irrigation. Please
also adhere to the safety principles
discussed hereunder.
In general, a plastic lined reservoir
is the simplest method of storing
effluent water produced by the
“GEM” Mini Sewage Treatment
Plant. It can also be turned into an
attractive water feature by installing
a water fountain in the reservoir. When sufficient water has been
accumulated, a centrifugal pump may be employed to spray the effluent onto
gardens, etc. If enough of a slope is present, the water could be gravitated
onto the crops intended for irrigation.
A second alternative to storage is to direct the effluent into an artificial
wetland. This wetland could ultimately discharge into a pond or it could be
constructed in such a manner that it would use all the water within the wetland
through evapotranspiration. Please always keep the environmental
considerations, discussed hereunder, in mind when designing and
constructing such a wetland.
There are many other industrial and domestic uses for sewage effluent not
discussed in this pamphlet.
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African Environmental Development
Portion 129 of the farm
Sterkfontein 173 IQ
Mogale City
Republic of South Africa
African Environmental Development
PO Box 1588
Rant-en-Dal
1751
Tel & Fax: - (+27) 11 956 6537 or 083 657 0560
E-mail: - [email protected]
http://www.aed.co.za
African
Environmental
Development
Product Specifications
From the outside, both of the units look identical. Internally, however, they
differ considerably. The unit specifications of the housings are as follows:
Construction
continuous injection moulding
Height:
1.4 m (base to manhole lid)
Diameter:
1.2 m
Length:
1.5 m per unit
Approximate dimensions of excavation for installation:
1.5m deep x 1.5m wide x 4.5m length
Construction
cylindrical ribbed with dome ends
Weight
40 Kg
Chambers
2 (both units)
Total capacity
1200 litres
Fluid working capacity
1000 litres
Wall thickness
5 mm
Inlet and outlet diameter
standard 110 mm, both fitted with
screw-in inspection eyes
Manhole diameter
450 mm
Manhole lid design
provision for filling with concrete
ballast
Manhole access extension
500 mm
No metallic components used in tank construction
Stainless steel aeration diffusers used in aeration tank
Manufacturer of compressor
Becker
Manufacturer of chlorinator
Klorman
Time between de-sludging
5 to 10 years, depending on the
amount of inorganic matter, such as
sand, allowed into the sewer ahead
of the plant.
Environmental Management and Safety Considerations
Although the “GEM” Mini Sewage Treatment Plant is intended to replace
the septic tank / French drain entirely in all areas not serviced by a municipal
sewer, it was primarily designed to be used in environmentally sensitive areas
or in areas where the geology is such that septic tanks / French drains are not
permitted, i.e. where groundwater contamination or sinkhole formation may
result from French drains. As described above, an anaerobic septic tank does
not purify sewage water to nearly the same quality as an aerobic process.
The following items are therefore listed as an environmental/safety guide
when installing or operating the “GEM” Mini Sewage Treatment Plant.
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Created on 11/06/2004 08:38:00
African Environmental Development
Portion 129 of the farm
Sterkfontein 173 IQ
Mogale City
Republic of South Africa
African Environmental Development
PO Box 1588
Rant-en-Dal
1751
Tel & Fax: - (+27) 11 956 6537 or 083 657 0560
E-mail: - [email protected]
http://www.aed.co.za
African
Environmental
Development
Safety Considerations








Never drink the treated effluent. It has not been treated to a drinking
water standard. Mark any taps with effluent water with a clear “nondrinking water” sign.
Always treat raw sewage water with respect. It may contain pathogenic
bacteria (bacteria that could transmit diseases to people coming into
contact with the water). Always wear protective clothing and gloves and
wash your hands with disinfectant soap immediately after handling any
untreated sewage or sanitary fittings.
Although chlorine is one of the most efficient disinfectants used in the
water treatment industry, do not assume that the effluent is safe. The
chlorinator may not be adjusted correctly. Always treat effluent as if it
may contain pathogenic bacteria.
When irrigating the effluent, never allow it to be sprayed directly onto
people or animals.
Do not irrigate treated effluent onto vegetables or fruit that are normally
eaten raw.
When irrigated onto the lawns of sports fields, always allow for at least
two days of drying in the sun before any sports activities are allowed on
the field, especially in the case of sports where people may fall and
come into direct contact with the lawn.
Adhere to open dam safety principles, especially when there are
children around that cannot swim. Always protect all open dams with
some type of barrier similar to that used around swimming pools.
When there are children around, ensure that concrete ballast is cast in
the lids of the two manholes to prevent them from opening the
manholes. If a person falls into one of the units drowning could result.
Environmental Considerations



Never allow effluent to be discharged directly onto ground near a
drinking water borehole. This is of particular importance if the
underlying geology is dolomite. As a rule of thumb, provide for a
distance of at least 100m from any borehole. In dolomite, however,
there may be preferential access routes directly into the groundwater
from much further distances. Also keep the distance from your
neighbours’ boreholes in mind!
If effluent water is discharged into an artificial wetland, always ensure
that the wetland is constructed on impermeable soil or alternatively,
construct such a wetland using an impermeable lining.
Never allow water to stand in a permanent un-lined pond in areas
underlain with dolomite. This practice may lead to the formation of
sinkholes and could also contaminate the groundwater.
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African Environmental Development
Portion 129 of the farm
Sterkfontein 173 IQ
Mogale City
Republic of South Africa



African Environmental Development
PO Box 1588
Rant-en-Dal
1751
Tel & Fax: - (+27) 11 956 6537 or 083 657 0560
E-mail: - [email protected]
http://www.aed.co.za
African
Environmental
Development
Ensure that there are no leaking pipes/couplings, especially pipes
containing raw sewage en route to the sewage treatment plant. This
may lead to groundwater contamination.
Do not discharge the effluent produced by any sewage treatment plant
directly into any public stream without a water license from the
Department of Water Affairs and Forestry.
Under normal circumstances, a sand trap or grease trap is not fitted
ahead of the plant. Under conditions where there may be excessive
grease or sand/gravel entering the plant, it is recommended to install
these in order to protect the plant from premature siltation.
African Environmental Development is the distributor for the “GEM” Mini
Sewage Treatment Plant in East, Central and West Rand and, more
importantly, in the Cradle of Humankind World Heritage Site. One of the very
first units installed in South Africa was installed at our offices in the World
Heritage site in an environmentally sensitive area, with dolomitic caves,
including the world-famous Sterkfontein Caves, within a stone’s throw from
our premises. Customers are welcome to visit us to view the unit at our offices
first hand.
We also install units in whichever configuration most suits your location,
environment, effluent application and budget. Please contact us at any time
for more information relating to the product and its installation.
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