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Principals of Hospital Wastewater Management. 18Jan . 2012. Introduction. Emerging pollutants Unregulated pollutants Potential health effects
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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.
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.
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 nuclearmedicine 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)
