Download 18JAN. 2012 Principals of Hospital Wastewater Management

Principals of
Hospital Wastewater Management
18JAN. 2012
Introduction
 Emerging pollutants
 Unregulated pollutants
 Potential health effects
 They include surfactants, pharmaceuticals and
personal care products (PPCPs), endocrine
disruptors, drugs, gasoline additives and many
other groups of compounds.
Hospitals are important sources of these
compounds: a great variety of microcontaminants
result from diagnostic, laboratory and research
activities on one side and medicine excretion by
patients on the other.
They include active principles of
 drugs and their metabolites
 chemicals
 heavy metals
 disinfectants and sterilizants
 specific detergents for instruments
 radioactive markers and iodinated contrast media.
Water consumption in hospital structures
 Hospitals require a significant quantity of water
per day for the different purposes and services
depending on the activities which take place within
the structure.
 There is not a clear correlation between specific
hospital consumptions and hospital size (that is
bed numbers)
 Water consumption keeps around 0.2–0.4 m3 per
bed and day
The quantity of WWs produced in a hospital
depends on different factors:
 bed numbers
 hospital age
 accessibility to water
 general services present inside the structure
(kitchen, laundry and air conditioning)
 number and type of wards and units
 institution management policies and awareness in
managing the structure in safeguarding the
environment
 climate and cultural and geographical factors
Chemical and microbiological characteristics of
HWWs and UWWs
 Despite their specific nature, quite often hospital
effluents are considered to be of the same pollutant
load as urban wastewaters (UWWs) and are
discharged into public sewer networks, collected to
a WWTP and co-treated with UWWs.
 Before entering into the municipal sewer, a
chlorination is sometimes required for the whole
hospital wastewater flow rate, sometimes only for
the effluent from infectious disease wards.
average values for BOD5, COD and SS
in HWWs
 Referring to these three parameters, and by
considering their usual concentrations in the
influents to municipal WWTPs, it can be observed
that in HWWs BOD5, COD and SS keep 2–3 times
higher than in UWWs.
 The resulting specific contributions for each
patient are:
 As for other common macropollutants, typical
ranges of variability as well as average
concentrations in HWWs and UWWs as derived
from an analysis of the literature data are reported
 Adsorbable organic compounds (AOX) are the
compounds which are the most persistent in the
environment and which tend to accumulate in the
food chain; often they are toxic to humans and
aquatic organisms.
 Some pharmaceuticals and their metabolites may
contain organic bound halogens and therefore
contribute to AOX emissions.
Analgesics and antibiotics in HWWs
Other emerging contaminants in HWWs
Average concentrations for the main classes of
micropollutants in HWWs and UWWs
Overview of treatment options
 HWWs are generally co-treated with domestic
wastewaters in conventional WWTPs and are then
released into the environment.
 However, many pharmaceuticals are resistant to
conventional treatments.
 Source controls could be an effective precautionary
measure and an alternative to end-of-pipe
upgrading of treatment plants.
 A correct management of hospital effluents
requires that discharges from toilets used by
patients undergoing nuclear medicine therapy
must be collected into separated tanks and treated
in the required way, thus avoiding emission of
radioactive compounds into the hospital sewage
and from there into the public sewage.
Wastewater Treatment Methods
 Physico-chemical treatments
A coagulation-flocculation process was generally found to be unable to remove
personal care products
- Adsorption by activated carbons has great potential for the removal of trace
emerging contaminants
-
 Biological treatments
Activated sludge processes
- membrane biological reactors (MBR)
-
 Reverse osmosis (RO)
 Nanofiltration (NF)
 Ozonation and advanced oxidation processes (AOPs)
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