Environmental risk of pharmaceuticals in waters: Investigation on their occurrence and removal in conventional treatment plants

At present, approximately 15000 different pharmaceutical compounds are used in the European Union, including analgesics/anti-inflammatories. antibiotics, beta-blockers, lipid regulators, antidepressants and many more, for human consumptions (therapeutic or diagnostic purposes). One important emission source of pharmaceuticals in the water cycle is via human metabolism: in fact, once administered, these compounds are only partially metabolized by the human body, and therefore enter the water cycle either as parent (unchanged) compounds, or as a mixture of metabolites and/or conjugated compounds. Unfortunately, municipal wastewater treatment plants (WWTPs) are generally unable to effectively remove either unaltered or metabolized forms of pharmaceutical compounds (PhCs) from wastewaters, and as a results their occurrence in surface water has been documented. While the presence of pharmaceuticals in the environment is established, sources of these compounds in the environment, the pathways by which they reach sensitive receptors and their effects on these receptors are less characterized, moreover the latter must be determined before the effectiveness of risk mitigation measures can be assessed. Hospital wastewater (HWWs) represent an important source of PhCs, but has only slightly been investigated. In this work, an experimental investigation was conducted in the area of Ferrara, Italy, on the effluent of two different sized hospitals and the influent and effluent of the receiving municipal treatment plant of one of the examined hospitals. The aim was to investigate 73 selected pharmaceuticals, belonging to twelve different classes, comparing their occurrence in the effluent directly exiting the hospital with that, mixed with the local urban effluent, at the points of its entry and exit from the treatment plant. Consistent differences were found in the concentrations of some antibiotics, analgesics and lipid regulators in the two wastewaters, confirming that hospital effluents should not be considered as possessing the same pollutant nature as urban wastewater. Furthermore, analysis of percentage contributions of the hospital to the treatment plant influent evidences that hospitals represent one of the main sources of pollutants, in particular antibiotics, receptor antagonists and lipid regulators. Hence, an environmental risk assessment, performed on the effluent from the hospital and the influent and effluent from the treatment plant, revealed a high risk for 9 pharmaceuticals in hospital effluent and for 4 of the 9 substances in the treatment plant influent and effluent, with antibiotics being the most critical compounds in terms of contribution and potential environmental risk for the hospital. Moreover, the occurrence of 27 pharmaceutical compounds, belonging to different classes, in the effluent from two full-scale wastewater treatment plants (WWTPs) and their receiving water bodies in the sensitive area of the Po Valley (northern Italy) has been investigated. The receiving water bodies were monitored upstream and downstream of the effluent discharge points in order to evaluate the effluent impact on the quality of surface waters, commonly used for irrigation. Consequently, an environmental risk assessment was also conducted by calculating the risk quotient, i.e. the ratio between measured concentration and predicted no effect concentration. Collected data show that, although average values of the selected compounds were in general higher in the effluent than in the surface waters, some compounds not detected in the WWTP effluent were detected in the receiving water (upstream as well as downstream), indicating that sources other than treated effluents are present as contaminations during extraction and analysis have to be excluded. The most critical compounds for the environment were found to be the antibiotics sulfamethoxazole, clarithromycin and azithromycin. The study shows that the potential toxicological effects of persistent micropollutants can be mitigated to some extent by a high dilution capacity, i.e. a high average flow rate in the receiving water body with respect to the effluent. The results obtained from the conducted experimental investigations have been compared with those calculated by prediction models that represent the base for the environmental risk assessment. The results showed that there are differences between predicted and measured concentration, and these differences varied among the selected compounds and the sampling points investigated (influent, effluent and surface water), both predicted and measured concentrations are plagued by uncertainty and indicate that calculation models still need considerable refinement to increase model reliability and discriminative power. Finally, a tool to estimate the level of environmental risk posed by PhCs originated from HWWs at site specific catchment area to aid the authorities and decision makers in the management of HWWs and the reducing of PhCs discharged into the environment has been developed. The results suggest that due to the presence of PhCs, HWWs could pose a risk for the receiving environment and their risk is relevant to many factors. Erythromycin and sulfamethoxazole are potentially compounds of concern in the HWWs and they required a management, whilst other compounds may not required any management due to their low risk. The risk posed by HWWS due to the presence of PhCs could be reduced with various degree, and it is relevant to the characteristics of each catchment area where the hospital is situated. In some cases, the pathway of HWWs contribute significantly to the risk in the influent of a site-specific WWTP, and their contribution is correlated to the bed density. Nevertheless the limitations that the proposed tool experienced, it is provide a useful information about the management options that should be adopted to reduce the risk of HWWs

Environmental risk of pharmaceuticals in waters: Investigation on their occurrence and removal in conventional treatment plants

At present, approximately 15000 different pharmaceutical compounds are used in the European Union, including analgesics/anti-inflammatories. antibiotics, beta-blockers, lipid regulators, antidepressants and many more, for human consumptions (therapeutic or diagnostic purposes). One important emission source of pharmaceuticals in the water cycle is via human metabolism: in fact, once administered, these compounds are only partially metabolized by the human body, and therefore enter the water cycle either as parent (unchanged) compounds, or as a mixture of metabolites and/or conjugated compounds. Unfortunately, municipal wastewater treatment plants (WWTPs) are generally unable to effectively remove either unaltered or metabolized forms of pharmaceutical compounds (PhCs) from wastewaters, and as a results their occurrence in surface water has been documented. While the presence of pharmaceuticals in the environment is established, sources of these compounds in the environment, the pathways by which they reach sensitive receptors and their effects on these receptors are less characterized, moreover the latter must be determined before the effectiveness of risk mitigation measures can be assessed. Hospital wastewater (HWWs) represent an important source of PhCs, but has only slightly been investigated. In this work, an experimental investigation was conducted in the area of Ferrara, Italy, on the effluent of two different sized hospitals and the influent and effluent of the receiving municipal treatment plant of one of the examined hospitals. The aim was to investigate 73 selected pharmaceuticals, belonging to twelve different classes, comparing their occurrence in the effluent directly exiting the hospital with that, mixed with the local urban effluent, at the points of its entry and exit from the treatment plant. Consistent differences were found in the concentrations of some antibiotics, analgesics and lipid regulators in the two wastewaters, confirming that hospital effluents should not be considered as possessing the same pollutant nature as urban wastewater. Furthermore, analysis of percentage contributions of the hospital to the treatment plant influent evidences that hospitals represent one of the main sources of pollutants, in particular antibiotics, receptor antagonists and lipid regulators. Hence, an environmental risk assessment, performed on the effluent from the hospital and the influent and effluent from the treatment plant, revealed a high risk for 9 pharmaceuticals in hospital effluent and for 4 of the 9 substances in the treatment plant influent and effluent, with antibiotics being the most critical compounds in terms of contribution and potential environmental risk for the hospital. Moreover, the occurrence of 27 pharmaceutical compounds, belonging to different classes, in the effluent from two full-scale wastewater treatment plants (WWTPs) and their receiving water bodies in the sensitive area of the Po Valley (northern Italy) has been investigated. The receiving water bodies were monitored upstream and downstream of the effluent discharge points in order to evaluate the effluent impact on the quality of surface waters, commonly used for irrigation. Consequently, an environmental risk assessment was also conducted by calculating the risk quotient, i.e. the ratio between measured concentration and predicted no effect concentration. Collected data show that, although average values of the selected compounds were in general higher in the effluent than in the surface waters, some compounds not detected in the WWTP effluent were detected in the receiving water (upstream as well as downstream), indicating that sources other than treated effluents are present as contaminations during extraction and analysis have to be excluded. The most critical compounds for the environment were found to be the antibiotics sulfamethoxazole, clarithromycin and azithromycin. The study shows that the potential toxicological effects of persistent micropollutants can be mitigated to some extent by a high dilution capacity, i.e. a high average flow rate in the receiving water body with respect to the effluent. The results obtained from the conducted experimental investigations have been compared with those calculated by prediction models that represent the base for the environmental risk assessment. The results showed that there are differences between predicted and measured concentration, and these differences varied among the selected compounds and the sampling points investigated (influent, effluent and surface water), both predicted and measured concentrations are plagued by uncertainty and indicate that calculation models still need considerable refinement to increase model reliability and discriminative power. Finally, a tool to estimate the level of environmental risk posed by PhCs originated from HWWs at site specific catchment area to aid the authorities and decision makers in the management of HWWs and the reducing of PhCs discharged into the environment has been developed. The results suggest that due to the presence of PhCs, HWWs could pose a risk for the receiving environment and their risk is relevant to many factors. Erythromycin and sulfamethoxazole are potentially compounds of concern in the HWWs and they required a management, whilst other compounds may not required any management due to their low risk. The risk posed by HWWS due to the presence of PhCs could be reduced with various degree, and it is relevant to the characteristics of each catchment area where the hospital is situated. In some cases, the pathway of HWWs contribute significantly to the risk in the influent of a site-specific WWTP, and their contribution is correlated to the bed density. Nevertheless the limitations that the proposed tool experienced, it is provide a useful information about the management options that should be adopted to reduce the risk of HWWs

Electrochemical disinfection of groundwater for civil use – An example of an effective endogenous advanced oxidation process

Lab-scale experiments using real groundwater were carried out using the CabECO® reactor system in order to evaluate its suitability for producing safe water, acceptable for civil purposes. Trials were carried out in discontinuous and in continuous mode, analyzing the influence of electrical and hydraulic process parameters on the quality of treated water. The use of highly boron-doped diamond electrodes in the reactor allowed the electrosynthesis of considerable amounts of ozone. Because of the relatively high amount of chloride in the groundwater samples, a mixture of HOCl/ClO- was also synthesized. Somewhat unexpectedly, the increase in the current density in the explored range 100 -1000 A m-2 was accompanied by an increase in the faradaic yield of the electrosynthesis of oxidants, which was more pronounced for ozone than for free chlorine. As reported in literature, the main radical intermediate in the relevant reactions is ●OH, which can lead to different oxidation products, namely ozone and HOCl/ClO-. The electrolytic treatment also caused a decrease in the concentration of minor components, including NH4+ and Br-. Other byproducts were ClO3- and ClO4-, although their concentration levels were low. Moreover, due to alkali formation at the cathode surface, the precipitation of calcium and magnesium carbonates was also observed. In addition, the experimental investigation showed that even Pseudomonas aeruginosa and Legionella could be completely removed in the treated stream, due to the unique capacity of the reactor to synthesize biocidal agents like ozone, HOCl/ClO-, and chloramines. These effects were particularly evident during batch experiments.Lab-scale experiments using real groundwater were carried out using the CabECO® reactor system in order to evaluate its suitability for producing safe water, acceptable for civil purposes. Trials were carried out in discontinuous and in continuous mode, analyzing the influence of electrical and hydraulic process parameters on the quality of treated water. The use of highly boron-doped diamond electrodes in the reactor allowed the electrosynthesis of considerable amounts of ozone. Because of the relatively high amount of chloride in the groundwater samples, a mixture of HOCl/ClO− was also synthesized. Somewhat unexpectedly, the increase in the current density in the explored range 100–1000 A m−2 was accompanied by an increase in the faradaic yield of the electrosynthesis of oxidants, which was more pronounced for ozone than for free chlorine. As reported in literature, the main radical intermediate in the relevant reactions is [rad]OH, which can lead to different oxidation products, namely ozone and HOCl/ClO−. The electrolytic treatment also caused a decrease in the concentration of minor components, including NH4+ and Br−. Other byproducts were ClO3− and ClO4−, although their concentration levels were low. Moreover, due to alkali formation at the cathode surface, the precipitation of calcium and magnesium carbonates was also observed. In addition, the experimental investigation showed that even Pseudomonas aeruginosa and Legionella could be completely removed in the treated stream, due to the unique capacity of the reactor to synthesize biocidal agents like ozone, HOCl/ClO−, and chloramines. These effects were particularly evident during batch experiments

Contributions of combined sewer overflows and treated effluents to the bacterial load released into a coastal area

The impact of combined sewer overflow (CSO) on the receiving water body is an issue of increasing concern, as it may lead to restrictions in the use and destination of the receiving body, such as bathing or recreational area closures, fish and shellfish consumption restrictions, and contamination of drinking water resources. Recent investigations have mainly referred to the occurrence and loads of suspended solids, organic compounds and, in some cases, micropollutants. Attempts have been made to find correlations between the discharged load and the size and characteristics of the catchment area, climate conditions, rainfall duration and intensity. This study refers to a touristic coastal area in the north-east of Italy, which is characterized by a combined sewer network including 5 CSO outfalls which, in the case of heavy rain events, directly discharge the exceeding water flow rate into channels which, after a short distance, reach the Adriatic Sea. The study analyzed: i) rainfall events during the summer period in 2014 which led to overflow in the different outfalls, ii) the inter- and intra-event variability with regard to E. coli, Enterococci and conductivity, and iii) the hydraulic and pollutant (E. coli and Enterococci) loads discharged by the local wastewater treatment plant and by all the CSO outfalls. Finally, it estimated the contribution of each source to the released hydraulic and pollutant loads into the receiving water body. Moreover, it was also found that the modest water volume discharged by all CSO outfalls (only 8 % of the total volume discharged by the area) contains more than 90 % of the microbial load

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

Hospital wastewater treatments adopted in Asia, Africa, and Australia

This chapter provides an overview of the current management and treatment of hospital wastewater in Asia, Africa, and Australia. Twenty peer reviewed papers from different countries have been analyzed, highlighting the rationale behind each study and the efficacy of the investigated treatment in terms of macro- and micro-pollutants. Hospital wastewaters are subjected to different treatment scenarios in the studied countries (specific treatment, co-treatment, and direct disposal into the environment). Different technologies have been adopted acting as primary, secondary, and tertiary steps, the most widely applied technology being conventional activated sludge (CAS), followed by membrane bioreactor (MBR). Other types of technology were also investigated. Referring to the removal efficiency of macro- and micro-pollutants, the collected data demonstrates good removal efficiency of macro-pollutants using the current adopted technologies, while the removal of micro-pollutants (pharmaceutical substances) varies from low to high removal and release of some compounds was also observed. In general, there is no single practice which could be considered a solution to the problem of managing HWWs â\u80\u93 in many cases a number of sequences are used in combination

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