This study aims to assess the effect of different urban configuration regarding the choice of wastewater management of the district with source separation systems. Understanding this link can guide researchers, and also urban actors, in order to choose the best source separation solution to implement in a specific urban configuration. For this purpose, an integrated modelling approach was used to model the district with different types of urban planning, the water resources recovery facility (WRRF) and create a life cycle inventory to carry out a life cycle assessment (LCA). Six different urban configurations were tested with three different source separation scenarios and compared with an advanced WRRF with high level of nutrients and organic matter recovery. This study concludes that urine source separation is beneficial compared to advanced WWRF for all the urban configurations. Sewer construction was identified as the main contributor to environmental impact for the low-density configuration (pavilions), limiting the benefits of source separation in this urban settlement. Blackwater separation with a decentralised treatment is only beneficial for high densely populated area. Treatment of blackwater and greywater for reuse, has greater impact than reference scenario, in all urban configurations, due to high energy consumption for greywater treatment. Future research should therefore explore technical solutions for limiting the energy consumption.

As part of the move towards a circular economy and the transition to a more sustainable society, it is necessary to reduce the quantity of municipal solid waste and improve the overall management of its organic fraction, i.e. bio-waste. Proper management of this bio-waste is essential to avoid numerous nuisances, limit its environmental impact and promote its agronomic recovery, while contributing to the production of renewable energy. Arguing that bio-waste is not biomass waste like any other, the authors, drawing on their own experience of the subject as well as on the results of the literature, highlight the challenges associated with optimising the management of bio-waste and food waste in particular: reducing its production, sorting it at source, collecting it efficiently, treating it and recovering it. The paper explains how the specific characteristics and multiple territorial contexts of bio-waste management need to be taken into greater account in order to improve the performance of each stage of the management system. Beyond the challenges associated with improving the technical stages of bio-waste management, the paper highlights the need for a systemic approach to the design of bio-waste management systems. The multiple factors influencing system design as well as modelling tools and the need for co-construction with all stakeholders to support the design of the management system are discussed. Throughout the discussion, recommendations are made on the issues that research should address to help improve the management and recovery of bio-waste.

Stringent discharge regulations are encouraging researchers to create innovative and sustainable wastewater treatment solutions. Urine source separation (USS) is among the potent approaches that may reduce nutrient peak loads in the influent wastewater and improve nutrient recovery. A phenomenological model was used to simulate dynamic influent properties and predict the advantages gained from implementing USS in an urban water basin. Several scenarios were investigated assuming different levels of deployment: at the entire city, or specifically in office buildings for men's urine only, or for both men and women employees. The results confirmed that all scenarios of urine source separation offered benefits at the treatment plant in terms of reducing nitrogen influent load. The economic benefits in terms of reducing energy consumption for nitrification and decreasing methanol addition for denitrification were quantified, and results confirmed environmental advantages gained from different USS scenarios. Despite larger advantages gained from a global USS rate in an entire city, implementation of a specific USS in office buildings would remain more feasible from a logistical perspective. A significant benefit in terms of reducing greenhouse gas emissions is demonstrated and this was especially due to the high level of N2O emissions avoided in nitrifying biological aerated filter.

Current trends show that wastewater treatment plants (WWTPs) will intend to shift towards water resources recovery facility (WRRF), however nutrients recovery in WRRF is limited by the need of highly concentrated stream for the process. Source separation can help to increase this potential, but assessment is necessary to evaluate the whole system at district scale. In this study three scenarios based respectively on urine diversion, blackwater and greywater separation were compared to the conventional end-of-pipe strategy with adjunction of treatment at the centralized WRRF for producing renewable fertilizers and energy. Life cycle assessment was used to compare environmental impacts. The study was performed to represent the implementation of a new district in an urban context. Treatments have been chosen among the best technologies available for resource recovery. Results show that for maximizing nutrients recovery and limiting the greenhouse gas emissions, urine and blackwater separation are better scenarios than conventional mixing option and centralized WRRF. Indeed it allows to mitigate by at least 60% the nitrous oxide (N2O) emissions and to avoid nitrogen fertilizer production which emits large amount of greenhouse gases (8.6 kg CO2-Eq/kgN). Urine source separation is particularly beneficial by recovering nitrogen at a low environmental footprint: impact on climate change decreases by 45% compared to the Reference. The separation of blackwater treated at decentralized scale shows a decrease of 34% of impact on climate change compared to Reference, thus a little worse than Urine due to a higher external energy demand at decentralized scale for nitrogen recovery. Phosphorus can be recovered in all the source separation system without additional climate change impact. If the priority is given at water reclamation the treatment of blackwater and greywater separately is a valuable option. However energy balance and greenhouse gases emissions analysis do not support this scenario if highly energy consuming technology is used for greywater treatment (more than 0.56 kWh/m3 treated). It would become acceptable in case of decarbonized energy or if tap water production is a high greenhouse gases emitter. (c) 2021 Published by Elsevier Ltd.

The simulation of wastewater treatment plants allows obtaining predictive results when one needs to understand, evaluate, optimize, or design a plant. However, one of the bottlenecks of simulation feasibility is to obtain reliable and dynamic influent data. This difficulty is even more important when alternative scenarios are considered, such as source-separated streams. The present paper offers an influent generator to simulate scenarios where urine is separated at the source and at a user-specified level of retention. The proposed tool contains several blocks to include different contributions (household and industrial wastewater) and, due to its flexibility, allows the user to easily modify the parameters to fit other case studies. The tool allowed generating dynamic, long-term, and predictive data for both urine and wastewater streams. Also, the extensive set of state variables ensured the generation of influents for different modeling platforms.

Les eaux usees ne sont plus vues uniquement comme une pollution mais aussi comme des ressources a valoriser. La mise en place de nouvelles filieres de gestion et traitement, dont la separation a la source, doit permettre une amelioration de l'empreinte environnementale du systeme de gestion des eaux usees. Il convient de bien evaluer ces nouveaux scenarios sur la base d'une analyse integree.

Innovative treatment technologies and management methods are necessary to valorise the constituents of wastewater, in particular nutrients from urine (highly concentrated and can have significant impacts related to artificial fertilizer production). The FP7 project, ValuefromUrine, proposed a new two-step process (called VFU) based on struvite precipitation and microbial electrolysis cell (MEC) to recover ammonia, which is further transformed into ammonium sulphate. The environmental and economic impacts of its prospective implementation in the Netherlands were evaluated based on life cycle assessment (LCA) methodology and operational costs. In order to tackle the lack of stable data from the pilot plant and the complex effects on wastewater treatment plant (WWTP), process simulation was coupled with LCA and costs assessment using the Python programming language. Additionally, particular attention was given to the propagation and analysis of inputs uncertainties. Five scenarios of VFU implementation were compared to the conventional treatment of 1 m3 of wastewater. Inventory data were obtained from SUMO software for the WWTP operation. LCA was based on Brightway2 software (using ecoinvent database and ReCiPe method). The results, based on 500 iterations sampled from inputs distributions (foreground parameters, ecoinvent background data and market prices), showed a significant advantage of VFU technology, both at a small and decentralized scale and at a large and centralized scale (95% confidence intervals not including zero values). The benefits mainly concern the production of fertilizers, the decreased efforts at the WWTP, the water savings from toilets flushing, as well as the lower infrastructure volumes if the WWTP is redesigned (in case of significant reduction of nutrients load in wastewater). The modelling approach, which could be applied to other case studies, improves the representativeness and the interpretation of results (e.g. complex relationships, global sensitivity analysis) but requires additional efforts (computing and engineering knowledge, longer calculation time). Finally, the sustainability assessment should be refined in the future with the development of the technology at larger scale to update these preliminary conclusions before its commercialization.