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• Potential recovery of toilet paper in wastewater was studied and optimized by rotating belt filtration. • Cellulosic material recovery was predicted and linked with conventional operative parameters of waste water treatment plants. • Recovered fibres characterization were carried out in terms of chemical and physical proprieties. • Possible application in binder-based materials was studied. • Simplified economic assessment for application of recovered cellulose in mortars was proposed. The recovery of cellulose in toilet paper from municipal wastewater is one of the most innovative actions in the circular economy context. In fact, fibres could address possible new uses in the building sector as reinforcing components in binder-based materials. In this paper, rotating belt filters were tested to enhance the recovery of sludge rich in cellulose fibres for possible valorisation in construction applications. Recovered cellulosic material reached value up to 26.6 gm−3 with maximum solids removal of 74%. Content of cellulose, hemicellulose and lignin was found averagely equal to 87% of the total composition. Predictive equation of cellulosic material was further obtained. The addition of recovered cellulose fibres in mortars bring benefits in terms of lightness, microstructure and moisture buffering value (0.17 g/m2%UR). Concerning mechanical properties, flexural strength was improved with the addition of 20% of recovered cellulose fibres. In addition, a simplified economic assessment was reported for two possible pre-mixed blends with 5% and 20% of recovered fibres content. [ABSTRACT FROM AUTHOR]

In the framework of minimum liquid discharge (MLD) or zero liquid discharge (ZLD), sustainable brine management can be achieved via appropriate hybrid treatment technologies that provide water reuse, resource recovery, energy recovery and even freshwater production. This paper reviews the state of the art brine treatment technologies targeting MLD/ZLD and resource recovery and highlights their advantages and limitations. The right combination of treatment processes can add a high value to the brine management and shift the focus from removal to recovery and reuse point and help to adopt a more circular economy approach. ZLD technologies targets 100% water recovery using both membrane- and thermal-based technologies, while they are often hindered by high cost and intensive energy requirement. Meanwhile, the recovery of salts and other resources can partially compensate the operation cost of ZLD processes. MLD is a promising option that achieves up to 95% water recovery by using mainly membrane-based technologies. At this point, feasibility assessment is important to assess the environmental and economic sound of technologies. In the second part, we provide a techno-economic assessment of the most common technologies to provide possible benefits on a desalination plant. In the latter sections, innovative brine treatment schemes are discussed aiming MLD/ZLD, while resource recovery from brine and possible valorization routes of the recovered materials are highlighted to help to reduce the overall costs of the plants and to reach the targets of circular economy. • Commercial/emerging treatment technologies for brine management are reviewed. • Sustainable brine management can shift the focus from removal to recovery/reuse. • A techno-economic assessment is done on thermal and membrane-based treatment. • Data on brine treatment processes are still incomplete and not contextualized. • Membrane-based technologies can lead to significant environmental benefits. [ABSTRACT FROM AUTHOR]

Water supply and reuse through non-conventional water resources can significantly decrease the stress on natural water resources. Decentralized systems can help not only to alleviate issues of water security in arid areas, but also to create a sustainable framework within a circular economy. Although these small-scale innovative technologies are able to achieve ready-to-use, high quality of recovered/treated water on-site, the loop cannot be closed in most cases due to legislative barriers. Similarly, the end-use of sewage sludge after treatment in decentralized systems still lacks specific regulations that limit its valorization. This work analyzes the current policy and legislations related to water supply, wastewater treatment, water reuse and resource valorization within the context of decentralized state-of-the-art technologies applied in rural areas. The drawbacks in the current EU legislation that set barriers to close water-related loops in European countries are highlighted. A regulatory fitness check was applied to each type of loop to identify the key factors to accomplish the legislative compliance, and financing pathways were further evaluated at the EU level. As a possible solution, further development of an innovation deal approach is recommended to address the environmental, regulatory and financial gaps in water management through an integrated framework, providing ad-hoc policies and prescriptions for sustainable reuse of all water resources. • Regulatory fitness check was applied to closed water loops to identify legislative and financing barriers. • Current EU legislatives do not provide ad-hoc guidelines to decentralized systems. • No general barriers were detected for the reuse of reclaimed water in the EU legislation. • Serious limitations exist on drinking water production from non-conventional water resources. • Major constraints were determined for EC-marked compost for organic farming. [ABSTRACT FROM AUTHOR]

A novel approach is investigated, based on an integrated solution aiming at exploiting the energy harvestable from both drinking water reaching a municipality (or district) and wastewater flowing out from households. Global costs are also analyzed under several macroeconomic scenarios. A first experimental set was carried out using a supply system, where the mechanical power was generated using a pump as turbine (PAT). The biogas production, especially from black water discharged in a separated sewage system, was analyzed during a second set, to evaluate the anaerobic valorization of carbon sources. Several scenarios were built for small-scale urban applications, varying parameters like population and macroeconomic conditions. The produced energy changes among the scenarios: the PAT is optimized when hydraulic regulation is used, while the anaerobic digestion is optimized for decentralized system coupled to toilet operation without urine separation. Differences in energy production and costs exist between the analyzed technologies, the PAT requiring small investments for a small production, the anaerobic digestion requiring high costs for a large production. Hence, the application to urban contexts depends on the local means/needs and the size of the exploitable territory. The work also draws a potential methodology for urban planning in developing or developed countries. [ABSTRACT FROM AUTHOR]

Cost benefit analysis (CBA) and social impact assessment are well established methodologies to systematically estimate the viability of investments on technologies as well as the benefits for the society. However, there is a limited application of these assessment methods in the wastewater sector especially for resource recovery to deliver circularity objectives within urban water cycle management. In this regard, the Horizon 2020 SMART-Plant Innovation Action aimed to evaluate holistic impacts of wastewater-based resource recovery by applying and adapting cost benefit and social analysis on innovative technologies (SMARTechs). The SMARTechs were implemented and validated in real wastewater treatment plants (WWTPs) across Europe and Mediterranean basin where potential impacts in terms of carbon, material and energy efficiency, recovery and safe reuse were defined. Sixteen bottom-up SMARTech scenarios were analysed for the estimation of technical, economic and social impacts using CBA, social life cycle assessment (S-LCA) and social readiness level (SRL) methods. Overall, the SMARTechs created benefits both from an environmental and social point of view, with a maximum relative total economic value up to +23% compared to baseline scenario (without any SMARTech implementation). In terms of social benefits, the S-LCA highlighted a global positive impact of all the SMARTechs in terms of technical characteristics and social acceptance. Specifically, SMARTech 1 (cellulose recovery) was the most socially accepted solution thanks to its high performance and simplicity. Finally, based on the SRL assessment, most of the SMARTechs were positioned within the SRL range of 6–7, which implies a good societal acceptance and adaptation potential. • Socio-economic impacts of wastewater-based resource recovery were determined. • Nine different technologies were evaluated in sixteen bottom-up scenarios. • CBA and S-LCA were carried out leading to TEV and SRL. • Cellulose recovery scored the highest relative TEV and social acceptance. • Most of the technologies fell within a SRL range of 6–7. [ABSTRACT FROM AUTHOR]

Reuse of treated wastewater for irrigation purposes is a measure to reduce water stress and overexploitation of freshwater resources. This study aims to investigate the environmental and economic impacts of a current conventional wastewater treatment plant (WWTP) in Peschiera Borromeo (Milan, Italy), and compare possible scenarios to enable reclaimed water reuse for agriculture. Accordingly, we propose alternative disinfection methods (i.e. enhanced UV, peracetic acid) and replace conventional activated sludge (CAS) with upflow anaerobic sludge blanket (UASB) for biological treatment and use anaerobic membrane bioreactor (AnMBR) as the tertiary treatment. Life cycle assessment (LCA) and life cycle costing (LCC) were implemented on the existing full-scale wastewater treatment line and the hypothetical scenarios. In most cases, the impact categories are primarily influenced by fertilizer application and direct emissions to water (i.e. nutrients and heavy metals). The baseline scenario appears to have the largest environmental impact, except for freshwater eutrophication, human ecotoxicity and terrestrial ecotoxicity. As expected, water depletion is the most apparent impact category between the baseline and proposed scenarios. The UASB + AnMBR scenario gives relatively higher environmental benefits than the other proposed scenarios in climate change (−28%), fossil fuel depletion (−31%), mineral resource depletion (−52%), and terrestrial ecotoxicity compared to the baseline. On the other hand, the highest impact on freshwater eutrophication is also obtained by this scenario since the effluent from the anaerobic processes is rich in nutrients. Moreover, investment and operational costs vary remarkably between the scenarios, and the highest overall costs are obtained for the UASB + AnMBR line mostly due to the replacement of membrane modules (24% of the total cost). The results highlighted the importance of the life cycle approach to support decision making when considering possible upgrading scenarios in WWTPs for water reuse. • Different technologies for tertiary wastewater treatment are compared using LCA and LCC. • The proposed scenarios with water reuse provide benefits in most impact categories. • There were no significant differences observed between the disinfection by PAA or UV. • Higher environmental benefits are obtained by the UASB + AnMBR, except freshwater eutrophication. • The highest overall costs are obtained for the AnMBR process. [ABSTRACT FROM AUTHOR]

An increasing world population is projected to increase water, energy and food requirements, three vital resources for humankind. Projected climate change impacts will aggravate water availability, as well as flood risks, especially in urban areas. Nature-based solutions (NBS) have been identified as key concepts to defuse the expected tensions within the Water-Energy-Food (W-E-F) nexus due to their multiple benefits. In this paper, the authors outlined the theories and concepts, analyzed real-life case studies, and discussed the potential of NBS to address the future W-E-F nexus. For this purpose, we performed a systematic literature review on the theories of NBS that address the W-E-F nexus, and we summarized 19 representative real-life case studies to identify the current knowledge gaps and challenges. The quantitative and qualitative data was used to differentiate and discuss the direct and indirect potential benefits of NBS to the W-E-F nexus. The study further expanded on the challenges for the implementation of NBS and highlighted the growing possibilities in the context of circularity and the implementation of NBS in urban planning. It was concluded that the potential impacts of NBS on the W-E-F nexus have been identified, but the quantitative effects have not been analyzed in-depth. Moreover, indicators are mostly single-purpose and not multipurpose, as required to fully characterize the W-E-F nexus and circularity holistically. Overall, there is a need to adopt systemic thinking and promote the multipurpose design of NBS. [Display omitted] • This work combines a systematic literature review and the analysis of case studies. • The aim was to understand the link between urban NBS and the W-E-F nexus. • The literature review provides some examples of specific NBS addressing specific nexus. • Potential benefits are demonstrated for several case studies, but quantification is scarce. • Challenges were identified covering technical, sustainability, and governance issues. [ABSTRACT FROM AUTHOR]

The occurrence, fate and removal of microplastics (MPs) in a wastewater treatment plant (WWTP) in Central Italy were investigated together with their potential adverse effects on anaerobic processes. In the influent of the WWTP, 3.6 MPs.L−1 were detected that mostly comprised polyester fibers and particles in the shape of films, ranging 0.1–0.5 mm and made of polyethylene and polypropylene (PP). The full-scale conventional activated sludge scheme removed 86% of MPs, with the main reduction in the primary and secondary settling. MPs particles bigger than 1 mm were not detected in the final effluent and some loss of polymers types were observed. In comparison, the pilot-scale upflow granular anaerobic sludge blanket (UASB) + anaerobic membrane bioreactor (AnMBR) configuration achieved 94% MPs removal with the abatement of 87% of fibers and 100% of particles. The results highlighted an accumulation phenomenon of MPs in the sludge and suggested the need to further investigate the effects of MPs on anaerobic processes. Accordingly, PP-MPs at concentrations from 5 PP-MPs.gTS−1 to 50 PP-MPs.gTS−1 were spiked in the pilot-scale UASB reactor that was fed with real municipal wastewater, where up to 58% decrease in methanogenic activity was observed at the exposure of 50 PP-MPs.gTS−1. To the best of our knowledge, the presented results are the first to report of PP-MPs inhibition on anaerobic processes. • Characterization of MPs in full-scale CAS and pilot-scale UASB + AnMBR configurations. • Overall greater removal of MPs by UASB + AnMBR (94%) compared to CAS (86%). • MPs retain and accumulate in the sludge line, mainly PE and PP. • PP-MPs inhibition on anaerobic processes is reported for the first time. • UASB tolerated up to 18 PP-MPs.gTS−1 but was inhibited by 58% at 50 PP-MPs.gTS−1. [ABSTRACT FROM AUTHOR]