Making Waves: Why water reuse frameworks need to co-evolve with emerging small-scale technologies

Abstract

Novel technologies allow to reuse or recycle water for on-site applications such as toilet flushing, showering, or hand washing at the household- or building-scale. Many of these technologies have now reached technology readiness levels that require for verification and validation testing in the field. Results from such field tests of decentralized water reuse systems have been published over the past few years, and observed performance is often compared to quality targets from water reuse frameworks (WRFs). An inspection of ten recent journal publications reveals that targets from WRFs are often misinterpreted, and the emphasis of these publications is too often on demonstrating successful aspects of the technologies rather than critically evaluating the quality of the produced water. We hypothesize that some of these misinterpretations are due to ambiguous definition of scopes of WRFs (e.g., “unrestricted urban reuse”) and unclear applicability for novel recycling systems that treat the water for applications that go beyond the reuse scopes defined in current WRFs. Additional challenges are linked to the verification of WRF quality targets in small-scale and decentralized systems under economic and organizational constraints. Current WRFs are not suitable for all possible reuse cases, and there is need for a critical discussion of quality targets and associated monitoring methods. As the scope of water reuse has expanded greatly over the past years, WRFs need to address new applications and advances in technology, including in monitoring capacities.

Financial Viability and Environmental Sustainability of Fecal Sludge Treatment with Pyrolysis Omni Processors

“…While this study provides insights into the financial viability and environmental implications of fecal sludge management via OP technology, it has several limitations. In particular, the two deployment scenarios of the OP technology were compared to one benchmark system (i.e., pit latrines, transport, and anaerobic treatment); however, multiple pathways exist to provide safely managed sanitation (e.g., centralized versus decentralized) and should be considered before deployment of any system. , Also, our analysis assumes that a maintenance network is in place to provide the necessary support to the OP. In accordance with ISO 31800 and ISO 30500, the routine maintenance of non-sewered sanitation systems and fecal sludge treatment units needs to be outlined, which can provide guidance on the development of this network. , Furthermore, our technical assumptions use both laboratory-based experiments and field deployment of the Biogenic Refinery.…”

“…Additionally, further studies on biochar quality may introduce greater opportunities to lower costs, especially for the treatment of mixed excreta and when supplementing additional feedstocks. Costs may also be offset from the sale of briquettes (produced from biochar) for cooking; however, emissions and health risks to users should be also considered for these practices . Contextual parameters such as diet (i.e., calorie intake) can impact the GHG emissions from the treatment of mixed excreta.…”

“…Costs may also be offset from the sale of briquettes (produced from biochar) for cooking; however, emissions and health risks to users should be also considered for these practices. 85 Contextual parameters such as diet (i.e., calorie intake) can impact the GHG emissions from the treatment of mixed excreta. Conversely, the protein intake of different populations provides distinctive opportunities for nutrient recovery from the treatment of source-separated excreta.…”

Integration of silicate minerals for ammonium and phosphate removal with an on-site wastewater treatment prototype

“…Despite the clear need for a multiplicity of approaches in providing on-site and non-sewered sanitation systems, recent regulatory standards have been somewhat narrow in addressing different water reuse contexts [83], particularly when it comes to nutrients. For example, the ISO 30500 standard for pre-fabricated non-sewered sanitation systems briefly mentions recovery of nutrients, and states that the nutrient concentration in the effluent "can be used to determine the reasonable reuse" of the effluent [18].…”

An assessment of technological development and applications of decentralized water reuse: A critical review and conceptual framework

“…There are various technologies for water reclamation and reuse throughout the world, especially centralized systems that follow existing international, national, and local guidelines and regulations. However, recent advancement in water recycling technologies such as decentralized systems and green technology together with the emergence of complicated situations due to urbanization like heavy pollution of freshwater sources and an increasing number of informal settlements in huge metropolitan cities, shift the research priorities toward the need to review the technological development and applications of water reuse to update water reclamation guidelines for small‐scale technologies and form a conceptual framework for proper applications in urban areas (Angelakis et al, 2018; Reynaert et al, 2021).…”