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Abstract This opinion paper focuses on the role of eco-toxicological tools in the assessment of possible impacts of emerging contaminants on the aquatic ecosystem, hence, on human health. Indeed, organic trace pollutants present in raw and treated wastewater are the pivot targets: a multidisciplinary approach allows defining the basic principles for managing this issue, from setting a proper monitoring campaign up to evaluating the optimal process treatment. Giving hints on trace pollutants fate and behaviour, attention is focused on the choice of the bioassay(s), by analysing the meaning of possible biological answers. Data interpretation and exploitation are detailed with the final goal of providing criteria in order to be able to select the best targeted treatment options. The manuscript deals with conventional and innovative analytical approaches for assessing toxicity, by reviewing laboratory and field assays; illustrative real scale and laboratory applications integrate and exemplify the proposed approach. Graphical abstract Unlabelled Image Highlights • Bioassays must be chosen by taking into account the meaning of biological responses. • Lab and in situ bioassays must be integrated, based on reliability and applicability. • Trace pollutants can cause unpredictable and non-linear biological responses. • Wastewater composition and flowrate variability affects any toxicity assessment. • Environmental and socio-economic aspects underpin sewage treatment scheme choice. [ABSTRACT FROM AUTHOR]

The wastewater treatment process is based on complex chemical, physical and biological mechanisms that are closely interconnected. The efficiency of the system (which depends on compliance with national regulations on wastewater quality) can be achieved through the use of tools such as monitoring, that is the detection of parameters that allow the continuous interpretation of the current situation, and experimental tests, which allow the measurement of real performance (of a sector, a single treatment or equipment) and comparison with the following ones. Experimental tests have a particular relevance in the case of municipal wastewater treatment plants fed with a strong industrial component and especially in the case of plants authorized to treat aqueous waste. In this paper a case study is presented where the application of management tools such as careful monitoring and experimental tests led to the technical and economic optimization of the plant: the main results obtained were the reduction of sludge production (from 4,000 t/year w.w. (wet weight) to about 2,200 t/year w.w.) and operating costs (e.g. from 600,000 €/year down to about 350,000 €/year for reagents), the increase of resource recovery and the improvement of the overall process performance. [ABSTRACT FROM AUTHOR]

Wastewater treatment facilities are increasingly being considered as centralized installations where various resources can be recovered from the sewage. Novel technological solutions are already available for achieving this goal. However, their application to upgrade existing plants can be far more challenging than building new dedicated plants. While the scientific literature is generally focused on testing and comparing the recovery options, this work was aimed at giving a holistic evaluation of the actual impacts of upgrading existing facilities. Commercially available systems were considered for retrofitting two plants of different size (50,000 and 500,000 population equivalents) and achieving either energy self-sufficiency or material recovery. Based on mass and energy balances, a detailed evaluation of technical, social, economic, and administrative aspects was carried out. Environmental aspects were also included, adopting a simplified approach. It turned out that energy self-sufficiency (external energy supply reduced down to about 10% of the total need) is not far away to be achieved, with moderate techno-economic implications, especially when the plant is already equipped with primary sedimentation and anaerobic digestion. Integral recovery of treated effluent, sludge and nitrogen can also be pursued in large facilities, while several potential criticalities arise for medium-sized plants. The adopted procedure evidenced critical aspects that are often disregarded in the decision process: this may suggest where to address efforts in evaluating real situations. [ABSTRACT FROM AUTHOR]

The legislative framework in force in Europe entails restrictive effluent standards for sensitive areas, and quite severe restrictions on the properties of residual sewage sludge, both for landfill disposal and for agricultural use. Several technologies and management strategies have been proposed and applied in wastewater treatment plants to minimise sludge production and contamination. However, their techno-economic and environmental performance has to be carefully evaluated. The ROUTES project, funded within the EU Seventh Framework programme, aims to find new routes for wastewater treatment and sludge management and thereby guide EU members in their future choices. Within this project, the authors have developed and applied a procedure for technoeconomic- environmental assessment of new wastewater and sludge processing lines in comparison to reference plants. The reference plants are model conventional plants that experience different types of problems and the new plants are modified plants in which different innovative technologies have been added to solve these problems. The procedure involves a rating of selected technical issues, estimates of operating costs and an assessment of environmental impacts from a life cycle perspective. This paper reports on the procedure and shows examples of results. [ABSTRACT FROM AUTHOR]

Abstract: A key issue in biological Waste Water Treatment Plants (WWTPs) operation is represented by the sludge management. Mechanical dewatering is a crucial stage for sludge volume reduction; though, being a costly operation, its optimization is required. We developed an original experimental methodology to evaluate the technical (dewatering efficiency) and financial (total treatment costs) performance of dewatering devices, which might be used as a DSS (Decision Support System) for WWTP managers. This tool was then applied to two real case studies for comparing, respectively, three industrial size centrifuges, and two different operation modes of the same machine (fixed installation vs. outsourcing service). In both the cases, the best option was identified, based jointly on economic and (site-specific) technical evaluations. [Copyright &y& Elsevier]

Abstract: A major source of the wide presence of EDCs (Endocrine Disrupting Compounds) in water bodies is represented by direct/indirect discharge of sewage. Recent scientific literature reports data about their trace concentration in water, sediments and aquatic organisms, as well as removal efficiencies of different wastewater treatment schemes. Despite the availability of a huge amount of data, some doubts still persist due to the difficulty in evaluating synergistic effects of trace pollutants in complex matrices. In this paper, an integrated assessment procedure was used, based on chemical and biological analyses, in order to compare the performance of two full scale biological wastewater treatment plants (either equipped with conventional settling tanks or with an ultrafiltration membrane unit) and tertiary ozonation (pilot scale). Nonylphenol and bisphenol A were chosen as model EDCs, together with the parent compounds mono- and di-ethoxylated nonylphenol (quantified by means of GC–MS). Water estrogenic activity was evaluated by applying the human breast cancer MCF-7 based reporter gene assay. Process parameters (e.g., sludge age, temperature) and conventional pollutants (e.g., COD, suspended solids) were also measured during monitoring campaigns. Conventional activated sludge achieved satisfactory removal of both analytes and estrogenicity. A further reduction of biological activity was exerted by MBR (Membrane Biological Reactor) as well as ozonation; the latter contributed also to decrease EDC concentrations. [Copyright &y& Elsevier]

This work is aimed at assessing the effects of pretreated aqueous wastes stream-fed to a biological nutrient removal (BNR)- activated sludge plant. Aqueous wastes (mainly landfill leachate and liquid residues from chemical and pharmaceutical factories) are pretreated by means of a traditional coagulation-flocculation stage and subsequently sent to the BNR stage together with municipal wastewater. Pretreated aqueous wastes contribute up to about 75% of the influent load, in terms of chemical oxygen demand (COD; average concentration 23,000 mg=L). The resilience of the system, that is, the capacity to maintain high and stable performances despite sudden perturbations of the input conditions, was evaluated by interrupting the aqueous waste dosage and then progressively restoring the initial condition. The consequent variation of the influent load and composition caused a reduction of the biomass activity, which led to a decrease of the nitrogen removal efficiency (from 89% down to 73%). More than 30 days were required for restoring typical working conditions (in terms of influent load, process performance, and biomass activity), the sludge retention time (SRT) being 23 days. [ABSTRACT FROM AUTHOR]

A chemical and bio-analytical protocol is proposed as a holistic monitoring framework for the assessment of WWTPs (Wastewater Treatment Plants) performance. This combination of tests consists of: i) an analysis of emerging contaminants, to be added to the established physico–chemical parameters in order to understand the causes of (new) pollution phenomena and ii) some of the bio-analytical tools most widely applied in the field of wastewater research, which provide information on groups of chemicals with a common mode of toxic action (baseline toxicity, estrogenicity and mutagenicity/genotoxicity, selected as the most representative for human health). The negative effects of the discharge can thus be highlighted directly and used to assess the global environmental impact of WWTPs. As a validation, this multi-tiered approach was applied to a full-scale WWTP (150,000 p.e.), where different measurements were carried out: EDCs (Endocrine Disrupting Compounds) detection; algal growth inhibition, bioluminescence inhibition and acute toxicity test (for baseline toxicity); an E-Screen-like assay (for estrogenic activity); Ames, Allium cepa and Comet tests (for mutagenic/genotoxic activity). As a result, the WWTP showed good performance for all these issues, displaying its ability to enhance effluent quality, except for residual mutagenic behaviour, probably due to the by-products generated by the tertiary ozonation. [ABSTRACT FROM AUTHOR]

Several decision support systems have been developed in recent years, aimed at judging environmental technologies under the lens of a multi-criteria analysis. This has also been applied in the field of wastewater treatment, where different factors (techno-economic-environmental) are inherent to the process and have to be balanced. The aim of this work is to calculate the damage on human health as a key factor for the evaluation of different wastewater treatment processes. The damage due to emissions into both water and air was taken into account. Indeed, the benefits related to the improved effluent quality after treatment could be counteracted by the negative effects when computing atmospheric emissions related to energy requirement. While a set of specific cost factors was applied for air pollution, a highly innovative perspective was adopted in the case of water pollution: several biological assays were used to weight waterborne diseases. Their application in the framework of a decision making process represents a novel approach in the wastewater domain. In short, we found that the economic equivalent of the impact on human health is remarkably affected by the selected treatment train, ranging from ≈2 €/PE/y for advanced systems up to ≈3 €/PE/y for conventional activated sludge plants. In particular, the most advisable schemes consist of an activated sludge plant integrated with either i) activated carbon and sand filtration or ii) sand filtration and ozonation. Finally, the applicability of the proposed procedure is also discussed and compared with the conventional life cycle assessment (LCA) approach, and the main difference is pointed out: for the former, biological assays and related diseases are used for endpoint calculation while the latter is based on the effect of each single compound. [ABSTRACT FROM AUTHOR]