Practical implementation of true on-site water recycling systems for hand washing and toilet flushing

Reynaert, Eva; Greenwood, Esther E.; Ndwandwe, Bonginkosi; Riechmann, Michel E.; Sindall, Rebecca; Udert, Kai M.; Morgenroth, Eberhard

doi:10.1016/j.wroa.2020.100051

Cited by 19 publications

(17 citation statements)

References 23 publications

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“…In a recent field study, we tested a handwashing water recycling system in Durban, South Africa, with a similar setup as presented in this study but with a design flow of 500 L/day and including an electrolysis post-treatment for the production of chlorine ( Reynaert et al., 2020 ). In spite of highly variable nitrogen concentrations in the greywater input (between 14 and 260 mg total N/L), the treated water always contained residual chlorine under normal operation and ammonia concentrations were mostly below the detection limit of 0.05 mg N/L.…”

Section: Discussionmentioning

confidence: 99%

Disruptions in loading and aeration impact effluent chlorine demand during biological greywater recycling

et al. 2021

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Greywater recycling systems designed for high-quality applications, such as hand washing, must deliver microbially safe and aesthetically acceptable water under the challenging operating conditions present where such systems are needed most urgently. As chlorination is the most popular strategy for reducing bacterial concentrations in greywater, understanding chlorination in the context of disruptive and challenging operation is essential to designing robust treatment. In this study, we have examined how disruptions through overall increased loading, interrupted aeration and increased ammonia loading have impacted the chlorine demand of the water produced by a greywater recycling system. We also presented concentrations of significant chemicals that contributed to this chlorine demand. The results indicate that a 1 d period with 8 times (8x) the normal design loading produced a peak chlorine demand of 0.74 mg Cl 2 /L, which is approximately double the baseline value. While this chlorine demand can be overcome by adding more chlorine, tests involving disruptions in aeration or feeding additional ammonia into the bioreactor produced much greater increases (>30x). The risks of increased chlorine demand on microbial safety can be overcome by limiting ammonia inputs to the system, providing backup systems to ensure sufficient aeration, or through additional anti-bacterial measures that do not depend on maintaining residual chlorine.

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Section: Discussionmentioning

confidence: 99%

Disruptions in loading and aeration impact effluent chlorine demand during biological greywater recycling

et al. 2021

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“…We investigated ten recent publications (including our own) on field tests of water reuse systems that compare their monitoring results to quality targets from WRFs ( Reynaert et al., 2020 ; Sahondo et al., 2020 ; Varigala et al., 2020 ; Welling et al., 2020 ; Cid et al., 2018 ; Hawkins et al., 2018 ; Rogers et al., 2018 ; Fountoulakis et al., 2016 ; Santasmasas et al., 2013 ; Knerr et al., 2011 ). The criteria for including a publication were: (i) water reuse system with the aim for unrestricted urban reuse (e.g., toilet flushing); (ii) field test or full-scale test with real wastewater input; and (iii) comparison of reclaimed water quality to targets from WRF.…”

Section: Common Misinterpretations Of Water Reuse Framework Applied To Novel Small-scale Water Reuse Technologiesmentioning

confidence: 99%

“…In our own work ( Reynaert et al., 2020 ), we faced all of these challenges when field-testing prototypes recycling handwashing water in Switzerland and South Africa: (1) It was not clear to what extent categories such as “unrestricted urban reuse” or “supply to sanitation appliances” were intended to cover high-quality (and thus high-risk) applications such as handwashing. Only one of the applicable WRFs explicitly mentioned handwashing (ISO 30500, 2018) , however, without providing explicit quality targets.…”

Section: On the Difficulty Of Applying Water Reuse Framework For Small-scale Water Reuse Applicationsmentioning

confidence: 99%

“…Recent technological developments – especially the rapid development and wide acceptance of membrane technologies – have multiplied the potential applications of reclaimed water far beyond traditional reuse in agriculture ( Angelakis et al., 2018 ; Chen et al., 2013 ). Novel small-scale technologies allow to reuse or recycle (i.e., reuse for the same application) water for on-site residential uses such as toilet flushing ( Bair et al., 2015 , Cid et al., 2018 , Rogers et al., 2018 , Sahondo et al., 2020 ), showering ( Gassie and Engelhardt, 2017 ) or hand washing ( Reynaert et al., 2020 ). Here, we use the term “small-scale” for technologies that operate at the household- or building-scale and are thus, by definition, decentralized.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, the International Organization for Standardization has developed a standard for non-sewered sanitation systems, including performance requirements for unrestricted urban reuse (ISO 30500, ISO 2018). Sanz and Gawlik (2014) present an overview of WRFs around the globe and Reynaert et al. (2020) summarize requirements from 18 WRFs that are applicable to toilet flushing and handwashing reuse applications, including WRFs for the USA ( US EPA, 2012 ), Western Australia ( Government of Western Autralia, 2010 ), Canada ( Health Canada, 2010 ) and Spain ( Ministry of the Presidency Spain, 2007 ).…”

Section: Introductionmentioning

confidence: 99%

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

2021

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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.

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Technologies for pollutant removal and resource recovery from blackwater: a review

Zhang

Chu

Yang

et al. 2023

Front. Environ. Sci. Eng.

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Blackwater (BW), consisting of feces, urine, flushing water and toilet paper, makes up an important portion of domestic wastewater. The improper disposal of BW may lead to environmental pollution and disease transmission, threatening the sustainable development of the world. Rich in nutrients and organic matter, BW could be treated for resource recovery and reuse through various approaches. Aimed at providing guidance for the future development of BW treatment and resource recovery, this paper presented a literature review of BWs produced in different countries and types of toilets, including their physiochemical characteristics, and current treatment and resource recovery strategies. The degradation and utilization of carbon (C), nitrogen (N) and phosphorus (P) within BW are underlined. The performance of different systems was classified and summarized. Among all the treating systems, biological and ecological systems have been long and widely applied for BW treatment, showing their universality and operability in nutrients and energy recovery, but they are either slow or ineffective in removal of some refractory pollutants. Novel processes, especially advanced oxidation processes (AOPs), are becoming increasingly extensively studied in BW treatment because of their high efficiency, especially for the removal of micropollutants and pathogens. This review could serve as an instructive guidance for the design and optimization of BW treatment technologies, aiming to help in the fulfilment of sustainable human excreta management.

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Practical implementation of true on-site water recycling systems for hand washing and toilet flushing

Cited by 19 publications

References 23 publications

Disruptions in loading and aeration impact effluent chlorine demand during biological greywater recycling

Disruptions in loading and aeration impact effluent chlorine demand during biological greywater recycling

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

Technologies for pollutant removal and resource recovery from blackwater: a review

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