Removal of pharmaceuticals by conventional wastewater treatment plants

The chapter details the occurrence of 74 selected pharmaceuticals from 15 therapeutic classes in raw wastewater and in secondary effluent and treated sludge from municipal treatment plants. The ability of the treatment most commonly adopted worldwide, conventional activated sludge system, in removing such compounds from the influent wastewater is discussed. The influence of the main chemical - physical properties of the selected compounds in predicting and explaining their observed removal is analysed, as well as the effect of the main design parameters and operational conditions of the bioreactors. In addition, the risk posed by the pharmaceuticals persisting in the final effluent and sludge is evaluated by calculating their risk quotients. These figures, along with their mass loads, are then used to identify the most critical compounds present in domestic wastewaters. Finally, a brief discussion on the treatment of the effluent from the pharmaceutical industry, generally activated sludge systems, is included, and a critical analysis regarding the ability and reliability of this system in removing pharmaceuticals is made

A framework for the assessment of the environmental risk posed by pharmaceuticals originating from hospital effluents

The consumption of pharmaceuticals is increasing in both hospitals and households. After administration, many compounds enter the water cycle as parent compounds or their metabolites via excretion. Conventional municipal wastewater treatment plants are unable to efficiently remove all the different compounds found in sewage and, consequently, treated effluents are one of the main sources of persistent micropollutants in the environment. Hospital patients are administered relatively high quantities of drugs and therefore hospital wastewaters can consistently contribute to treatment plant influent loads, with the magnitude of environmental risk posed by pharmaceuticals originating from hospital effluents largely unknown. This study has therefore developed a framework to enable authorities responsible for hospital management and environmental health to evaluate such risk, considering site-specific information such as the contribution of human population and hospital sizes, wastewater treatment removal efficiency, and potential dilution in the receiving water body. The framework was applied to three case studies, that are representative of frequent situations in many countries, and findings demonstrated that the degree of risk posed by any compound was site-specific and depended on a combination of several factors: compound concentration and toxicity, compound removal efficiency in the wastewater treatment plant and dilution factor. Oflaxacin, 17α-ethinylestradiol, erythromycin and sulfamethoxazole were identified as compounds of concern and might require management in order to reduce ris

What have we learned from worldwide experiences on the management and treatment of hospital effluent?– An overview and a discussion on perspectives.

This study overviews lessons learned from experimental investigations on dedicated treatment systems of hospital effluent carried out worldwide in the last twenty years. It includes 48 peer reviewed papers from 1995 to 2015 assessing the efficacy of different treatment levels (preliminary, primary, secondary and polishing) of hospital wastewater in removing a wide spectrum of pharmaceutical compounds as well as conventional contaminants. Moreover, it highlights the rationale and the reasons for each study: reducing the discharge of micropollutants in surface water, improving existing wastewater treatment technologies, reducing the risk of spread of pathogens causing endemic diseases and finally, it offers a critical analysis of the conclusions and suggestions of each study. The most investigated technologies are membrane bioreactors equipped with ultrafiltration membranes in the secondary step, ozonation followed by activated carbon filtration (in powder and in granules) in the polishing step. Interesting research projects deal with photo-Fenton processes acting as primary treatments to enhance biodegradation before biological treatment, and as a polishing step, thus further reducing micro-contaminant occurrence. Investment and operational costs are also presented and discussed for the different treatment technologies tested worldwide, in particular membrane bioreactors and various advanced oxidation processes. This study also discusses the need for further research to evaluate toxicity resulting from advanced oxidation processes as well as the need to develop an accurate feasibility study that encompasses technical, ecotoxicological and economic aspects to identify the best available treatment in the different situations from a global view point

How efficient are constructed wetlands in removing pharmaceuticals from wastewater? - A review

This study deals with the ability of constructed wetlands (CWs) in removing 138 pharmaceutical compounds (PhCs) belonging to 20 therapeutic classes from wastewater. It reviews 50 peer-reviewed journal articles, referring to experimental investigations carried out in about 100 plants including surface flow systems (SF), horizontal and vertical subsurface flow beds (H-SSF, V-SSF) (pilot or full scale) acting as primary, secondary or tertiary treatment. Occurrence of the selected PhCs in the CW influent and effluent, as well as in sediments and gravel is presented and discussed; removal mechanisms and efficiencies for the different compounds are presented, discussed and correlated to the main chemical properties of the compounds themselves (pKa, LogKd, LogKow…), the design parameters and the operational and environmental conditions of the corresponding treatment system; average pharmaceutical mass load for the effluents of a CW is evaluated. Finally an environmental risk assessment, based on the risk quotient RQ, is carried out for treated effluents providing to a ranking of the most critical compounds that can be present in the final effluent. This is compared with that found for activated sludge effluents (Verlicchi et al., 2012). The study completes with a discussion of the perspectives in the adoption of CWs in removing such persistent organic compounds

Removal of Personal Care Products in Constructed Wetlands

This chapter is an overview of the occurrence of common personal care products in the influent and effluent of different types of constructed wetlands fed with domestic wastewaters, acting as primary, secondary or tertiary steps and the corresponding removal efficiency achieved by these treatments. The reviewed personal care products belong to 9 different classes: 3 antioxidants, 2 antiseptics, 1 deodorant, 1 flame retardant, 1 insect repellant, 1 plasticizer, 3 sun screen products, 5 synthetic musks and 16 surfactants (7 anionic and 9 nonionic). Data are collated from 36 peer review papers, referring to investigations carried out in Europe (64 %), America (28 %) and Asia (8 %). Of the 88 treatment lines reviewed, the most common constructed wetland type was the horizontal subsurface flow (49 %) followed by the surface flow (39 %) and, in a few cases, the vertical subsurface flow. Removal was mainly influenced by redox potential, temperature, hydraulic retention time and influent concentration of the compound. The highest values of removal were found for fragrances in secondary systems and fragrances and triclosan in polishing systems. Due to the different and simultaneous removal mechanisms occurring within these systems and their buffer capacity, they might represent a reliable and feasible treatment which is able to control and reduce the spread of personal care products in the aquatic environment

Environmental Risk Assessment of Pharmaceutical Compounds as a Tool for the Management of Hospital Effluents

The study deals with the proposal of a new tool called called THEMT (Tool for Hospital Effluent Management and Treatment), able to estimate the potential environmental impact posed by selected PhCs in hospital effluent in terms of their risk quotient (RQ) range. It takes into consideration the characteristics of: (i) the hospital in question (number of beds, wards, water consumption), (ii) its catchment area (inhabitant equivalent, water needs), (iii) the treatment train the hospital effluent is subjected to and the corresponding removal efficiencies of the selected compounds, and (iv) the characteristics of the receiving water body (dilution and hydrodynamic features). As it can simulate different scenarios featuring different catchment area, treatment train and surface receiving body characteristics, THEMT can be used in both the design and verification phases of hospital construction. This makes this tool a valuable aid to informed decision-making regarding the best treatment train for a particular hospital effluent, i.e., one that will reduce the environmental risk in surface water to desired (acceptable) levels

BEST PRACTISES IN THE MANAGEMENT OF HOSPITAL EFFLUENTS

In the last decade, greater attention has been paid to the presence in the water of emerging contaminants (including pharmaceutical and personal care products, pesticides, flame retardants…), that are quite often unregulated compounds. Hospitals are one of the most important sources of pharmaceutical compounds (PhCs) in a concentrated area and, together with households and industries, can be seen as significant urban area hotspots for discharging these contaminants into the sewer network and surface waters, with a potential impact on ecosystem. Hospital wastewaters (HWWs) are composed of the effluents of different services: kitchen, internal laundry, heating and cooling systems, laboratories, radiology departments, outpatients departments, transfusion centres and wards. By law, HWWs are often considered to be of the same pollutant nature as urban wastewaters (UWWs), and so they are generally discharged into sewage networks, collected at a wastewater treatment plant (WWTP) and treated along with UWWs. WWTPs were originally built, and more recently upgraded, with the aim of removing C, N and P compounds: the pollutants regularly arriving at the WWTP in concentrations to the order of mg/L. This paper analyses the differences between the wastewater from a hospital and an urban settlement in terms of hydraulic load as well as pollutants load and concentration on the basis of experimental investigations and literature data. Then it discusses if is correct to consider these two effluents of the same pollutant nature and if/when HWWs could be conveyed to a municipal WWTP for cotreatment with UWWs. Moreover it discusses the strategies in treating hospital flow rate (on site or off site, dedicated treatment or cotreatment at a municipal WWTP) on the basis of the hospital pollutant and hydraulic loads and finally it presents the most adequate treatment for HWWs on the basis of the recent results of the researches on the removal of PhCs. Furthermore a case study of the management of the effluent from a large hospital in a small town is also provided and discussed

Occurrence of Pharmaceutical Compounds in Urban Wastewater: Removal, Mass Load and Environmental Risk after a Secondary Treatment – A Review

This review focuses on 118 pharmaceuticals, belonging to seventeen different therapeutic classes, detected in raw urban wastewater and effluent from an activated sludge system, an usual treatment adopted for urban wastewaters worldwide prior to final discharge into surface water bodies. Data pertaining to 244 conventional activated sludge systems and 20 membrane biological reactors are analysed and the observed ranges of variability of each selected compound in their influent and effluent reported, with particular reference to the substances detected most frequently and in higher concentrations. A snapshot of the ability of these systems to remove such compounds is provided by comparing their global removal efficiencies for each substance. Where possible, the study then evaluates the average daily mass load of the majority of detected pharmaceuticals exiting the secondary treatment step. The final part of the review provides an assessment of the environmental risk posed by their presence in the secondary effluent by means of the risk quotient, that is the ratio between the average pharmaceutical concentration measured in the secondary effluent and the predicted no-effect concentration. Finally, mass load rankings of the compounds under review are compared with those based on their risk level. This analysis shows that the highest amounts discharged through secondary effluent pertain to one antihypertensive, and several beta-blockers and analgesics/anti-inflammatories, while the highest risk is posed by antibiotics and several psychiatric drugs and analgesics/anti-inflammatories. These results are reported with a view to aiding scientists and administrators in planning measures aiming to reduce the impact of treated urban wastewater discharge into surface water bodies

Hospital Wastewaters: Quali-quantitative Characterization and Strategies for Their Treatment and Disposal

Hospital wastewaters comprise the effluents of various services: general (kitchen, internal laundry, heating and cooling systems), diagnostic (laboratories, radiology departments, outpatients’ departments, transfusion centres) and wards (general medicine, surgery, specialities, haemodialysis, etc.). Due to the nature and quantity of the micropollutants they harbour, such as active substances of medicines and their metabolites, chemicals, heavy metals, disinfectants, sterilizers and radioactive markers, which are typically present at concentrations of μg/L, they should be earmarked for special consideration. By law, however, hospital effluents are often considered to be in the same pollutant class as urban wastewaters, and so are generally discharged into (municipal) sewage networks, collected at a wastewater treatment plant and co-treated along with them. However, although dilution of hospital effluents with urban wastewaters usu-ally results in a reduction of the pharmaceutical compound content in the final ef-fluent (from μg/L to ng/L), it does not affect the total load, that is, the quantity re-leased daily into the receiving water body. This chapter analyses the differences between the effluent of hospitals and urban settlements in terms of hydraulic and pollutant load, and discusses whether distinction should be made between these two types of wastewaters and evaluates potential strategies for management of hospital effluents (co-treatment or dedi-cated strategies). Finally it presents and discusses the most appropriate treatment for hospital wastewaters, based on the results of the recent research into the re-moval of pharmaceutical compounds from wastewaters

Monitoring and Risk Assessment of Pharmaceutical Compounds in Two WWTP Effluents and Their Receiving Rivers in the Po Valley, Italy.

This study was devised to monitor the concentrations of 27 common pharmaceutical compounds both in the effluents of two wastewater treatment plants (WWTPs), situated near Ferrara (Po Valley, Northern Italy), and in their respective receiving water bodies. These rivers were monitored both upstream and downstream of the effluent discharge point in order to determine the impact of the effluents on the quality of surface water, generally used for irrigation, and risk quotients were calculated for each compound. In general, the data collected reveal higher average values of the selected compounds in WWTP effluents than in surface waters, although some compounds not detected in the effluents but were present in the receiving water (upstream as well as downstream), highlighting the existence of other, untreated, sources of effluent. Risk assessment showed that the most environmentally critical compounds at both locations are the antibiotics sulphamethoxazole and clarithromycin. The average flow rate of the receiving water body with respect to the incoming effluent was found to be an important factor mitigating the negative effect of micro-pollutants