Département Technologie des procédés

Water Hub au NEST

Daniel Röttele, infografik.ch

Water Hub au NEST - assainissement décentralisé orienté vers la valorisation

Le Water Hub fait partie du bâtiment NEST, un laboratoire vivant de l'Empa et de l'Eawag. Ce bâtiment modulaire se compose d'unités remplaçables, qui fournissent des appartements fonctionnels et habités, des bureaux, des salles de réunion et une unité de fitness et de bien-être. Le NEST est en constante évolution. Des solutions de construction innovantes et durables sont développées, construites, testées et présentées dans des conditions réelles. Cette approche de laboratoire vivant permet de combler le fossé entre la recherche et l'industrie et accélère ainsi l'entrée sur le marché de technologies innovantes.

Au sous-sol du NEST, les chercheurs de l'Eawag gèrent le Water Hub. Les eaux usées du NEST sont collectées ici pour être traitées comme une ressource plutôt que comme un déchet : nous traitons les eaux usées pour récupérer les nutriments, l'eau propre et l'énergie. Cela permet de réduire la pression sur l'environnement et ses ressources.

Notre approche est décentralisée : nous séparons les eaux usées à la source et les traitons au sein du bâtiment, ce qui augmente l'efficacité du traitement et de la récupération. Le traitement décentralisé peut être particulièrement utile lorsque les réseaux d'égouts et les stations d'épuration ne peuvent être construits ou pour réduire la pression sur ces infrastructures, notamment dans les zones à forte croissance urbaine. La décentralisation permet également d'adopter une approche systémique lors de la conception de solutions d'assainissement pour différents contextes, en tirant le meilleur parti des ressources rendues disponibles localement par le traitement des eaux usées.

Dans le cadre du NEST, des toilettes spéciales séparent l'urine non diluée des eaux de la chasse d’eau, des fèces et du papier toilette, qui constituent ensemble les eaux noires. Les autres flux d'eaux usées sont séparés par des réseaux de canalisations distincts. Ces réseaux transportent vers le Water Hub les eaux grises légères, provenant des machines à laver et des canalisations des salles de bains, et les eaux grises lourdes, provenant des cuisines. L'eau de pluie est également collectée, stockée et réutilisée pour alimenter les toilettes du NEST.

Le Water Hub est également une plateforme de collaboration entre les chercheurs et les partenaires de l'industrie et de la pratique. Les technologies permettant un assainissement décentralisé axé sur la valorisation des ressources peuvent être installées dans les unités du NEST ou testées dans le Water Hub. Le Water Hub est ouvert à la collaboration avec l'industrie et met à disposition des fonds de démarrage (seed funding) pour lancer de petits projets afin d'évaluer le potentiel de nouveaux concepts et technologies.

En outre, le Water Hub est intéressé par des échanges avec des acteurs des secteurs de l'assainissement, de la construction, de l'énergie et de l'agriculture, afin de discuter de l'influence de l'assainissement décentralisé axé sur la valorisation des ressources dans leurs domaines et de son intégration dans leurs projets.

Vous pouvez visiter le Water Hub et le NEST dans le cadre de visites guidées publiques!

Le Water Hub se concentre sur les projets suivants, en cours ou terminés :

Toilettes NoMix

Grâce aux toilettes NoMix, il est possible de séparer l'urine et les matières fécales pour les traiter séparément. L'urine est produite en petits volumes et présente des concentrations relativement faibles en agents pathogènes. Les humains excrètent la plupart des nutriments, antibiotiques et micropolluants par l'urine.

Contact

Les fèces, évacuées avec les eaux de chasse d’eau, sont principalement constituées de matières organiques et ont une teneur en agents pathogènes beaucoup plus élevée. Il est avantageux de traiter les deux flux séparément.

Pendant 20 ans, l'Eawag a testé en conditions réelles différents prototypes de toilettes NoMix, avec des mécanismes de séparation allant de la mécanique au capteur. Ces tests ont mis en évidence la nécessité d'un mécanisme de séparation plus robuste et des toilettes plus conviviale.

Le designer autrichien Harald Gründl, d'EOOS next, a mis au point des toilettes NoMix dotées d'un mécanisme de séparation innovant, invisible pour l'utilisateur et fonctionnant sans pièce mécanique ni capteur.

Les toilettes utilisent la tension superficielle et la vitesse différente à laquelle l'urine et l'eau de la chasse s'écoulent dans la cuvette pour séparer les deux flux. La géométrie a été optimisée en collaboration avec Laufen et l'ETH Zurich. Ces nouvelles toilettes sont maintenant installées et testées dans le NEST.

Ce système, plus robuste et plus efficace que les solutions précédentes, promet de révolutionner la séparation de l'urine.

Plus d'informations

Valorisation des nutriments dans l'urine

Les humains excrètent la plus grande partie des nutriments dans l'urine.  Dans le Water Hub, les nutriments de l'urine sont récupérés dans l'engrais "Aurin" en utilisant le procédé VUNA : après le stockage, la volatilisation de l'ammoniac de l'urine est empêchée à l'aide de bactéries nitrifiantes. Ensuite, les produits pharmaceutiques sont éliminés dans un filtre à charbon actif. Enfin, l'urine traitée est concentrée et les agents pathogènes sont tués lors de la distillation.

Contact

Prof. Dr. Kai Udert Tel. +41 58 765 5360 Envoyez un message

Les chercheurs travaillent actuellement sur :

  • le développement de variantes du procédé VUNA, par exemple en soutenant les bactéries par l'électrochimie
  • l’optimisation de l'élimination des produits pharmaceutiques avec du charbon actif
  • l'utilisation des données de l'installation pour optimiser la consommation énergétique, les coûts, la maintenance et augmenter la fiabilité du procédé

Pour le traitement de l'urine, les chercheurs du Water Hub collaborent étroitement avec la Spin-off Vuna de l'Eawag.

Plus d'informations

 

Source: Vuna Sàrl

Traitement et réutilisation des eaux grises

Procédés de traitement

Les eaux usées domestiques se composent des eaux grises ainsi que des flux de déchets provenant des toilettes. Au lieu de mélanger ces flux et de les rejeter à l'égout, il est possible de traiter et de réutiliser les eaux grises à l'intérieur du bâtiment pour des applications telles que la chasse d'eau des toilettes et l'irrigation, la douche et le lavage des mains. La réutilisation prévue dicte la qualité requise des eaux grises traitées. Elle dicte également les niveaux nécéssaires de robustesse, fiabilité et surveillance des procédés de traitement.

Procédés de traitement

Contact

Prof. Dr. Eberhard Morgenroth Tel. +41 58 765 5539 Envoyez un message

Au Water Hub, les chercheurs de l'Eawag comparent les performances de différents systèmes de traitement des eaux grises. Cela permet de concevoir des systèmes de traitement flexibles qui produisent différentes qualités d'eau en fonction de l'utilisation finale prévue. Cela permet également à nos chercheurs d'adapter le système à la question de recherche à laquelle ils veulent répondre. Les priorités actuelles sont les suivantes :

  • Le traitement avancé incluant un bioréacteur à membrane et une filtration au charbon actif, suivi d'une désinfection (UV ou chlore) et potentiellement d'une nanofiltration (pour une réutilisation avancée).
  • Prévision de la salubrité de l’eau à l'aide de capteurs simples

Durant l'essai des nouveaux procédés de traitement, l'eau traitée est rejetée à l’égout. Toutefois le but ultime est de réutiliser l'eau traitée à l'intérieur du bâtiment.

Graphique: Peter Penicka, Eawag

Qualité microbienne des eaux grises

Pathogènes entériques

Les eaux grises peuvent également contenir des concentrations importantes d'agents pathogènes entériques. Elles doivent donc être traitées pour réduire les risques pour la santé humaine à un niveau acceptable. Les chercheurs de l'Eawag valident actuellement la capacité des procédés de traitement (individuels et combinés) à réduire les microorganismes pathogènes selon diverses conditions d'opération. Cette procédure de validation du traitement guidera la conception de filières de traitement complètes afin de garantir que les eaux grises puissent être réutilisées en toute sécurité pour différentes applications.

Pathogènes entériques

Contact

Dr. Tim Julian Tel. +41 58 765 5632 Envoyez un message
Dr. Frederik Hammes Tel. +41 58 765 5372 Envoyez un message

Pathogènes opportunistes (croissance pendant le stockage)

La réutilisation des eaux grises à l'échelle d'un bâtiment nécessitera un traitement, un stockage et une redistribution. Au cours de ces étapes, l'eau doit rester salubre pour la réutilisation, tant du point de vue de la santé humaine que de la performance du système. Au sein du Water Hub, les chercheurs de l'Eawag surveillent et évaluent l'impact du traitement des eaux grises sur la qualité microbienne et chimique pendant le stockage et la distribution. En particulier, nous voulons :

  • surveiller les caractéristiques physico-chimiques des eaux traitées pendant le stockage et le traitement,
  • surveiller la croissance et/ou la stabilité microbiologique,
  • identifier des méthodes pour surveiller, prévoir et prévenir la dégradation microbienne de l'eau,
  • étudier les facteurs influençant la croissance et les changements potentiels au sein de la communauté microbienne.

 

Plus d'informations

Pathogènes opportunistes (croissance pendant le stockage)

Récupération des ressources contenues dans les eaux noires

Les eaux noires se composent de matières fécales, d'urine, de papier toilette et d’eau de chasse. La forte teneur en nutriments et en énergie des fèces offre un grand potentiel de récupération des ressources. En outre, les eaux usées peuvent être traitées et réutilisées. Afin de récupérer en toute sécurité les nutriments, l'énergie et l'eau des eaux noires, une séparation solide-liquide (déshydratation) est nécessaire.

Des recherches approfondies ont été menées sur la déshydratation des boues issues du traitement des eaux usées municipales. Cependant, il s'est avéré difficile d'adapter les technologies existantes aux systèmes autonomes (non connectés au réseau d’égout), en raison de la grande variabilité des caractéristiques des eaux noires.

Contact

Michael Vogel Tel. +41 58 765 5944 Envoyez un message
Dr. Linda Strande Tel. +41 58 765 5553 Envoyez un message
  • Au sein du Water Hub, les eaux noires sont utilisées à la fois pour la recherche fondamentale et pour le développement de technologies pratiques. La recherche actuelle se concentre sur la compréhension des mécanismes de déshydratation afin de développer une meilleure surveillance et un meilleur contrôle pendant le traitement.
  • Les eaux noires collectées dans le Water Hub sont utilisées pour tester et développer diverses technologies de déshydratation, qui conviennent au traitement et à la récupération des ressources dans NEST et à l'échelle mondiale.

Entre les ressources qui est possible récupérer après la séparation de l’eau des eaux noires il y a de l'énergie, des nutriments et de la matière organique, du substrat pour des larves dédiées au nourrissage des animaux et de l'eau.

Plus d’informatons

L’eau et l’énergie: des ressources interconnectées – Projet terminé

Les installations fournissant de l’eau chaude pour l’usage domestique sont très énergivores. Heureusement, de nouvelles technologies permettent de réduire cette consommation. Certaines de ces technologies sont testées dans le NEST. Dans l’unité DFAB House, des douches à recyclage valorisent l’énergie thermique contenue dans les effluents. De plus, l’innovant système de distribution de l’eau chaude permet de réduire les pertes d’énergie et d’eau en vidant les tuyaux entre deux épisodes de consommation.

Contact

Si ces technologies sont prometteuses, leur intégration dans des systèmes complexes d'eau chaude sanitaire nécessite une attention particulière. En effet, les interactions entre les différentes technologies peuvent amoindrir leur potentiel énergétique et économique respectif. En cause, les relations complexes entre l'énergie et la consommation d'eau, appelé le nexus eau-énergie.

Les scientifiques de l’Eawag ont développé un modèle pour optimiser l’intégration de ces technologies dans les systèmes sanitaires. Le modèle a été utilisé à plusieurs échelles pour évaluer l’influence de ces technologies sur le cycle urbain de l’eau dans son ensemble : du bâtiment à la station d’épuration en aval, en passant par les canalisations publiques. Dans le cadre de ce projet, par exemple, une étude a conclu qu’il est souvent plus intéressant de récupérer (et de réutiliser) l’énergie thermique des eaux usées directement dans l’enceinte du bâtiment plutôt que dans les canalisations publiques, en raison de l’impact thermique moindre sur le traitement biologique des eaux usées dans la station d’épuration.

Plus d’informations

Documentation

Pour plus d'information sur le Water Hub, vous trouverez des articles et publications si-dessous.

Médias & articles

Double usage pour l'eau de la douche, Eawag News (09.09.2021)

Ressourcen aus Abwasser direkt im Gebäude zurückgewinnen, Wohnen (September 2021)

Visitez virtuellement le Water Hub, Eawag News (11.06.2021)

Mise au point - Toilettes: Merci de ne pas tirer la chassse, RTS (06.06.2021)

Projekt Sanitärwende - Wenn Kot zu Kompost auf dem Acker wird, Zeitfragen Deutschlandfunk Kultur (01.06.2021)

Podcast NEST avec Tove Larsen, Eawag News (25.03.2021)

Water Hub Phase II, WINGS-Newsletter (17.03.2021)

Le traitement des eaux grises - oui, mais comment?, Eawag News (23.02.2021)

Toilettes et durabilité (2/5) – Des ressources dans les eaux usées ?, RTS on va vers le beau (12.01.2021)

Les eaux usées sont une source de nutriments, d’énergie et d’eau, Eawag News (29.09.2020)

Abwasser - von der Giftbrühe zur Goldgrube, NZZ Format (03.09.2020)

Water Hub im NEST-Gebäude. Eine Plattform zum Testen von innovativen ressourcenorientierten Sanitärsystemen, Aqua & Gas, 100(2), 52-57 (Février 2020)

"Des toilettes qui séparent", SRF News (19.11.2019)

Réutilisation d'eau, Haustech (Octobre 2019)

Tove Larsen explique la révolution des toilettes, Eawag News (11.03.2019)

Reportage sur le Water Hub "Il giardino di Albert", RSI (08.01.2017)

"The toilet of the future", Empa Quarterly (Anglais, May 2016)

Reportage sur l'inauguration du NEST, SRF Tagesschau (23.5.2016)

Article sur l'inauguration du NEST, NZZ (23.5.2016)

Conférences

Publications

Mainstreaming decentralized urban water management solutions for sustainable cities

Climate change, rapid urbanization and other grand challenges increasingly force cities to rethink their urban (water) infrastructure. In particular, decentralized urban water management solutions, which can recover valuable resources close to the source are increasingly applied to remediate water scarcity, sanitation or environmental pollution challenges. Yet, although interesting demonstration projects with decentralized solutions (from here on labeled ‘decentralized UWM solutions’) are underway in several world regions, actors developing and implementing this transformative innovation are not effectively coordinating their efforts and sharing the latest knowledge. While effective technologies, business models, or regulative frameworks increasingly exist that could inform, inspire and improve similar activities elsewhere, details of local successes and failures are still (too) rarely shared or transferred across space. Drawing from experience on the mainstreaming of other transformative infrastructure solutions (like renewable energies, electric mobility or circular waste management), we posit that the global diffusion of decentralized UWM solutions has been significantly slowed down by this lack of interaction among key stakeholders, and the resulting lack of an effective innovation ecosystem.
Binz, C.; Sedlak, D.; O’Callaghan, P.; Truffer, B.; Nesi, M.; Morgenroth, E.; Lesch, D.; Miörner, J.; Maurer, M.; Narayan, A.; Schelbert, V.; Lüthi, C.; Aalbu, S.; Wellauer, S. (2024) Mainstreaming decentralized urban water management solutions for sustainable cities, 27 p, doi:10.55408/eawag:33039, Institutional Repository

Integrating recent scientific advances to enhance non-sewered sanitation in urban areas

Half of the world’s population is now served by non-sewered sanitation, yet the field remains fragmented, with a focus on individual research agendas, and prevalence of imprecise terminology that hinders scientific learnings and leads to misconceptions. The field is at a decisive juncture, with scientific knowledge taking off that holds the potential to fulfil the urgent need for inclusive sanitation in a rapidly urbanizing world. In this critical Review, relevant and diverse research results are assembled with findings translated to one consistent terminology, to provide scientific evidence to draw out interlinkages and learnings, debunk common misconceptions and identify key research needs. Properties of non-sewered wastewater are highly variable, and degradation during storage has a direct impact on greenhouse gas emissions and downstream treatment processes, which facilitate different resource recovery. New technologies and wastewater-based epidemiology can help to address the lack of monitoring. The findings are presented by wastewater properties, biological processes during storage, treatment processes and monitoring.
Strande, L. (2024) Integrating recent scientific advances to enhance non-sewered sanitation in urban areas, Nature Water, 2(5), 405-418, doi:10.1038/s44221-024-00240-7, Institutional Repository

Urban sanitation: new terminology for globally relevant solutions?

Progress toward Sustainable Development Goals for global access to safe sanitation is lagging significantly. In this Feature, we propose that misleading terminology leads to errors of categorization and hinders progress toward sanitation service provision in urban areas. Binary classifications such as "offsite/onsite" and "sewered/nonsewered" do not capture the need for "transport to treatment" or the complexity of urban sanitation and should be discarded. "Fecal sludge management" is used only in the development context of low- or middle-income countries, implying separate solutions for "poor" or "southern" contexts, which is unhelpful. Terminology alone does not solve problems, but rather than using outdated or "special" terminology, we argue that a robust terminology that is globally relevant across low-, middle-, and upper-income contexts is required to overcome increasingly unhelpful assumptions and stereotypes. The use of accurate, technically robust vocabulary and definitions can improve decisions about management and selection of treatment, promote a circular economy, provide a basis for evidence-based science and technology research, and lead to critical shifts and transformations to set policy goals around truly safely managed sanitation. In this Feature, the three current modes of sanitation are defined, examples of misconceptions based on existing terminology are presented, and a new terminology for collection and conveyance is proposed: (I) fully road transported, (II) source-separated mixed transport, (III) mixed transport, and (IV) fully pipe transported.
Strande, L.; Evans, B.; von Sperling, M.; Bartram, J.; Harada, H.; Nakagiri, A.; Nguyen, V.-A. (2023) Urban sanitation: new terminology for globally relevant solutions?, Environmental Science and Technology, 57(42), 15771-15779, doi:10.1021/acs.est.3c04431, Institutional Repository

High content of low molecular weight organics does not always affect pharmaceutical adsorption on activated carbon: the case of acetate, propionate and ethanol in source-separated urine

Adsorption on activated carbon is a common process to remove pharmaceuticals in wastewater treatment. Activated carbon adsorption is usually applied to wastewater with a low content of biological degradable organics, i.e. after biological treatment. Especially low molecular weight (LMW) compounds are known to compete with pharmaceuticals for adsorption sites. The goal of this study was to test the hypothesis that biological treatment is necessary for efficient pharmaceutical removal. Source-separated urine after anaerobic storage (anaerobically stored urine) and after aerobic biological removal of organics without nitrification (organics-depleted urine) were used in this study. In anaerobically stored urine 60% of the organic compounds were LMW organics, of which about 40% were acetate and propionate. 74% of the DOC and 100% of acetate and propionate were removed during aerobic biological treatment. To investigate the effect of the organic compounds on pharmaceutical removal, sorption experiments with 19 spiked pharmaceuticals and one artificial sweetener were conducted with powdered activated carbon. Ethanol, another LMW organic, was included in the study, as it is regularly used for pharmaceutical spiking thereby strongly increasing the DOC content. The experiments showed that the adsorption of the pharmaceuticals and the sweetener were hardly affected by the easily biodegradable LMW organics or ethanol. Therefore, it was concluded that biological pre-treatment is not necessary for efficient pharmaceutical adsorption. Since acetate, propionate and ethanol contribute substantially to the DOC content but do not absorb UV light, the latter is recommended as indicator for pharmaceutical removal in solutions with high contents of biodegradable LMW organics.
Heusser, A.; Dax, A.; McArdell, C. S.; Udert, K. M. (2023) High content of low molecular weight organics does not always affect pharmaceutical adsorption on activated carbon: the case of acetate, propionate and ethanol in source-separated urine, Water Research X, 21, 100199 (10 pp.), doi:10.1016/j.wroa.2023.100199, Institutional Repository

Performance and dynamics of active greywater heat recovery in buildings

In the effort to de-carbonize the building stock, heat pumps are increasingly utilized in Switzerland, with 70% of the fast-growing heat pump market using ambient air as heat source. Inexpensive and easy to implement, these heat pumps are, however, less efficient than their ground- or water-source counterparts. In this modeling study, we aim at increasing the efficiency of air-source heat pumps using domestic greywater-contained heat. We assess the performance improvement relative to standard heat pump configurations across various climates, seasons, building envelopes, and domestic hot water consumption patterns. The results show that the annually-averaged coefficient of performance improves by 4.1% on average - ranging from 0.6% to 7.5%. This efficiency gain translates on average to 1.8 kWh/week of compressor electricity savings. Although attractive due to its simplicity, the proposed open-loop configuration - preheating of an external heat source - only leads to moderate performance improvement of air-source heat pumps. Based on these results, we extensively discuss and compare alternative system configurations and identify several fundamental differences in the heat recovery dynamics of each configuration. We show that closed-loop systems - using greywater as direct heat source - show the largest performance improvement potential, although being more expensive and complex to implement.
Hadengue, B.; Morgenroth, E.; Larsen, T. A.; Baldini, L. (2022) Performance and dynamics of active greywater heat recovery in buildings, Applied Energy, 305, 117677 (13 pp.), doi:10.1016/j.apenergy.2021.117677, Institutional Repository

State of the art of urine treatment technologies: a critical review.

Over the last 15 years, urine treatment technologies have developed from lab studies of a few pioneers to an interesting innovation, attracting attention from a growing number of process engineers. In this broad review, we present literature from more than a decade on biological, physical-chemical and electrochemical urine treatment processes. Like in the first review on urine treatment from 2006, we categorize the technologies according to the following objectives: stabilization, volume reduction, targeted N-recovery, targeted P-recovery, nutrient removal, sanitization, and handling of organic micropollutants. We add energy recovery as a new objective, because extensive work has been done on electrochemical energy harvesting, especially with bio-electrochemical systems. Our review reveals that biological processes are a good choice for urine stabilization. They have the advantage of little demand for chemicals and energy. Due to instabilities, however, they are not suited for bathroom applications and they cannot provide the desired volume reduction on their own. A number of physical-chemical treatment technologies are applicable at bathroom scale and can provide the necessary volume reduction, but only with a steady supply of chemicals and often with high demand for energy and maintenance. Electrochemical processes is a recent, but rapidly growing field, which could give rise to exciting technologies at bathroom scale, although energy production might only be interesting for niche applications. The review includes a qualitative assessment of all unit processes. A quantitative comparison of treatment performance was not the goal of the study and could anyway only be done for complete treatment trains. An important next step in urine technology research and development will be the combination of unit processes to set up and test robust treatment trains. We hope that the present review will help guide these efforts to accelerate the development towards a mature technology with pilot scale and eventually full-scale implementations.
Larsen, T. A.; Riechmann, M. E.; Udert, K. M. (2021) State of the art of urine treatment technologies: a critical review., Water Research X, 13, 100114 (20 pp.), doi:10.1016/j.wroa.2021.100114, Institutional Repository

Predictive models using "cheap and easy" field measurements: can they fill a gap in planning, monitoring, and implementing fecal sludge management solutions?

The characteristics of fecal sludge delivered to treatment plants are highly variable. Adapting treatment process operations accordingly is challenging due to a lack of analytical capacity for characterization and monitoring at many treatment plants. Cost-efficient and simple field measurements such as photographs and probe readings could be proxies for process control parameters that normally require laboratory analysis. To investigate this, we evaluated questionnaire data, expert assessments, and simple analytical measurements for fecal sludge collected from 421 onsite containments. This data served as inputs to models of varying complexity. Random forest and linear regression models were able to predict physical-chemical characteristics including total solids (TS) and ammonium (NH4+-N) concentrations, and solid-liquid separation performance including settling efficiency and filtration time (R2 from 0.51-0.66) based on image analysis of photographs (sludge color, supernatant color, and texture) and probe readings (conductivity (EC) and pH). Supernatant color was the best predictor of settling efficiency and filtration time, EC was the best predictor of NH4+-N, and texture was the best predictor of TS. Predictive models have the potential to be applied for real-time monitoring and process control if a database of measurements is developed and models are validated in other cities. Simple decision tree models based on the single classifier of containment type can also be used to make predictions about citywide planning, where a lower degree of accuracy is required.
Ward, B. J.; Andriessen, N.; Tembo, J. M.; Kabika, J.; Grau, M.; Scheidegger, A.; Morgenroth, E.; Strande, L. (2021) Predictive models using "cheap and easy" field measurements: can they fill a gap in planning, monitoring, and implementing fecal sludge management solutions?, Water Research, 196, 116997 (12 pp.), doi:10.1016/j.watres.2021.116997, Institutional Repository

Stagnation leads to short-term fluctuations in the effluent water quality of biofilters: a problem for greywater reuse?

A key characteristic of decentralized greywater treatment and reuse is high variability in both nutrient concentrations and flow. This variability in flow leads to stagnant water in the system and causes short-term fluctuations in the effluent water quality. Automated monitoring tools provide data to understand the mechanisms underlying the dynamics and to adapt control strategies accordingly. We investigated the fluctuations in a building-scale greywater treatment system comprising a membrane bioreactor followed by a biological activated carbon filter. Short-term dynamics in the effluent of the biological activated carbon filter were monitored with automated flow cytometry and turbidity, and the impact of these fluctuations on various hygiene-relevant parameters in the reuse water was evaluated. Continuous biofilm detachment into the stagnant water in the biological activated carbon filter led to temporarily increased turbidity and cell concentrations in the effluent after periods of stagnation. The fluctuations in cell concentrations were consistent with a model assuming higher detachment rates during flow than during times with stagnant water. For this system, total cell concentration and turbidity were strongly correlated. We also showed that the observed increase in cell concentration was not related to either an increase of organic carbon concentration or the concentration of two opportunistic pathogens, P. aeruginosa and L. pneumophila. Our findings demonstrate that turbidity measurements are sensitive to changes in the effluent water quality and can be used to monitor the fluctuations caused by intermittent flow. Intermittent flow did not lead to an increase in opportunistic pathogens, and this study provides no indications that stagnant water in biological activated carbon filters need be prevented.
Hess, A.; Baum, C.; Schiessl, K.; Besmer, M. D.; Hammes, F.; Morgenroth, E. (2021) Stagnation leads to short-term fluctuations in the effluent water quality of biofilters: a problem for greywater reuse?, Water Research X, 13, 100120 (9 pp.), doi:10.1016/j.wroa.2021.100120, Institutional Repository

Biological activated carbon filter for greywater post-treatment: Long-term TOC removal with adsorption and biodegradation

Biological activated carbon (BAC) filters can be used to remove residual total organic carbon (TOC) from greywater after a membrane bioreactor. The two main TOC removal processes are adsorption to the granular activated carbon (GAC) and biological degradation. Biodegradation leads to the growth of microorganisms in the filter bed, which can lead to increased pressure loss over the filter bed. However, the roles of sorption and biodegradation in long-term TOC removal and how they complement each other are unclear. We monitored TOC removal from greywater in a BAC filter installed following a membrane bioreactor over more than 900 days. Removal performance depended on the operational time of the BAC filter, the influent TOC concentration, and in the upper part of the filter on the empty bed contact time (EBCT). Across the overall filter, the EBCT did not significantly influence TOC removal, showing that the filter was sufficiently large for the range of flow rates observed. Analysis of the long-term data revealed the equal importance of sorption and biodegradation over the whole operation period and the whole filter bed. Most of the TOC was removed in the upper part of the filter, where biodegradation was the dominant mechanism. In the lower part of the filter, sorption capacity remained and allowed high influent TOC concentrations to be buffered. The generous filter design with low average filtration rates ensured long-term TOC removal. The only maintenance needed was backwashing, which was required only after more than 800 days of operation. Backwashing effectively reduced the pressure loss but had no significant influence on the effluent water quality. Our study shows that BAC filters are a suitable post-treatment step for the treatment of greywater with highly variable flow and TOC concentrations.
Hess, A.; Morgenroth, E. (2021) Biological activated carbon filter for greywater post-treatment: Long-term TOC removal with adsorption and biodegradation, Water Research X, 13, 100113 (9 pp.), doi:10.1016/j.wroa.2021.100113, Institutional Repository

In-building heat recovery mitigates adverse temperature effects on biological wastewater treatment: a network-scale analysis of thermal-hydraulics in sewers

Heat recovery from wastewater is a robust and straightforward strategy to reduce water-related energy consumption. Its implementation, though, requires a careful assessment of its impacts across the entire wastewater system as adverse effects on the water and resource recovery facility and competition among heat recovery strategies may arise. A model-based assessment of heat recovery from wastewater therefore implies extending the modeling spatial scope, with the aim of enabling thermal-hydraulic simulations from the household tap along its entire flow path down to the wastewater resource recovery facility. With this aim in mind, we propose a new modeling framework interfacing thermal-hydraulic simulations of (i) households, (ii) private lateral connections, and (iii) the main public sewer network. Applying this framework to analyze the fate of wastewater heat budgets in a Swiss catchment, we find that heat losses in lateral connections are large and cannot be overlooked in any thermal-hydraulic analysis, due to the high-temperature, low-flow wastewater characteristics maximizing heat losses to the environment. Further, we find that implementing shower drain heat recovery devices in 50% of the catchment's households lower the wastewater temperature at the recovery facility significantly less – only 0.3 K – than centralized in-sewer heat recovery, due to a significant thermal damping effect induced by lateral connections and secondary sewer lines. In-building technologies are thus less likely to adversely affect biological wastewater treatment processes. The proposed open-source modeling framework can be applied to any other catchment. We thereby hope to enable more efficient heat recovery strategies, maximizing energy harvesting while minimising impacts on biological wastewater treatment.
Hadengue, B.; Joshi, P.; Figueroa, A.; Larsen, T. A.; Blumensaat, F. (2021) In-building heat recovery mitigates adverse temperature effects on biological wastewater treatment: a network-scale analysis of thermal-hydraulics in sewers, Water Research, 204, 117552 (11 pp.), doi:10.1016/j.watres.2021.117552, Institutional Repository

Removal of pharmaceuticals from human urine during storage, aerobic biological treatment, and activated carbon adsorption to produce a safe fertilizer

Urine has great potential to be an effective fertilizer due to its high nutrient content, however, it can contain potentially worrying pharmaceuticals. Our objective was to study whether urine storage and aerobic biological treatment, i.e. nitrification, was sufficient to remove pharmaceuticals or an additional treatment with activated carbon was necessary to produce a fertilizer from urine. We investigated the abatement of twelve pharmaceuticals, including antibiotics and antivirals, in laboratory experiments representing the treatment steps of anaerobic storage of source-separated human urine, stabilization using partial and full nitrification under acclimatized and non-acclimatized conditions, and treatment of nitrified urine using powdered activated carbon (PAC). Two-month-long-term storage of urine was insufficient to substantially degrade the pharmaceuticals, except for hydrochlorothiazide (>90%). In the partial and full nitrification fed-batch reactors, atazanavir, ritonavir, and clarithromycin were rapidly removed, with biotransformation rate constants greater than 10 L gSS−1d−1. Darunavir, emtricitabine, trimethoprim, N4-acetylsulfamethoxazole, sulfamethoxazole, atenolol, diclofenac, and hydrochlorothiazide were degraded slowly, with biotransformation rate constants of < 1 L gSS−1d−1. With 200 mg PAC L−1, at least 90% of each investigated pharmaceutical was removed. Yeast estrogen screen tests and bioluminescence inhibition tests revealed efficient removal of estrogenicity (99%) and toxicity (56%) using nitrification, and a reduction of 89% and 64%, respectively, using 200 mg PAC L−1. With our study, we provide biotransformation rate constants of compounds never previously investigated. We also show that a combination of nitrification and PAC adsorption enables the production of a safe fertilizer with sufficiently low pharmaceutical concentrations and no removal of beneficial nutrients.
Özel Duygan, B. D.; Udert, K. M.; Remmele, A.; McArdell, C. S. (2021) Removal of pharmaceuticals from human urine during storage, aerobic biological treatment, and activated carbon adsorption to produce a safe fertilizer, Resources, Conservation and Recycling, 166, 105341 (10 pp.), doi:10.1016/j.resconrec.2020.105341, Institutional Repository

The potential contribution of urine source separation to the SDG agenda - a review of the progress so far and future development options

Sanitation and wastewater management are highly relevant for reaching a number of interconnected sustainable development goals (SDGs), especially SDG 6, the provision of safe drinking water and adequate sanitation for all as well as protection of water resources against pollution, and SDG 14.1, reducing nutrient emissions to the marine environment. Recent evidence increasingly shows that conventional sewer-based wastewater management will not be able to reach these targets. Rather than further optimizing and diffusing this ageing infrastructure paradigm, radical innovations like urine source separation technologies could help to leapfrog towards faster achievement of the SDGs. The technology would simplify on-site sanitation and develop a closed-loop nutrient cycle, thereby allowing for exceptionally high nutrient removal from wastewater and direct reuse in agriculture from the first day of implementation. Radical innovations, however, need decades to materialize. Based on a review of relevant academic and grey literature, we show how the past three decades of development of urine source separation have brought breakthroughs in toilet design and treatment processes, enabling the technology's value chain to reach the brink of maturity. In a short outlook, we discuss how the technology may reach global diffusion over the next decade, with the main remaining challenges relating to the creation of mass-markets for urine-diverting toilets, automation and mass-production of treatment systems, and the legitimation of fertilizer produced from urine in the agricultural sector.
Larsen, T. A.; Gruendl, H.; Binz, C. (2021) The potential contribution of urine source separation to the SDG agenda - a review of the progress so far and future development options, Environmental Science: Water Research and Technology, 7(7), 1161-1176, doi:10.1039/D0EW01064B, Institutional Repository

Making waves: why water reuse frameworks need to co-evolve with emerging small-scale technologies

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.
Reynaert, E.; Hess, A.; Morgenroth, E. (2021) Making waves: why water reuse frameworks need to co-evolve with emerging small-scale technologies, Water Research X, 11, 100094 (5 pp.), doi:10.1016/j.wroa.2021.100094, Institutional Repository

Modeling the water-energy nexus in households

One third of the global carbon emissions are emitted by the building sector. Over the last decades, space heating loads have decreased in modern buildings, and domestic hot water (DHW) is now oftentimes the largest energy consumer in the household. We developed the WaterHub modeling framework to assess the potential of technologies or measures targeting DHW energy demand. The framework combines process-based technological models and stochastic water demand modeling in a modular way to allow for holistic simulations of complex DHW systems. In two rigorous tests of the modeling framework, we demonstrated the importance of water consumption dynamics in the modeling of DHW systems, showing that static modeling leads to underestimated heat losses and wrong energy consumption predictions. In an exemplary case study, we identified and quantified the synergistic interactions between water boiler temperatures and a drain water heat recovery device, demonstrating the strength of this methodology for optimizing strategies targeting DHW systems. With its modular structure, this open-source modeling framework can be extended to include any DHW-related technology, providing a useful common platform for collaboration between technology developers and water experts.
Hadengue, B.; Scheidegger, A.; Morgenroth, E.; Larsen, T. A. (2020) Modeling the water-energy nexus in households, Energy and Buildings, 225, 110262 (10 pp.), doi:10.1016/j.enbuild.2020.110262, Institutional Repository

Influence of intermittent flow on removal of organics in a biological activated carbon filter (BAC) used as post-treatment for greywater

Highly variable flow has to be expected in decentralized greywater treatment and can lead to intermittent operation of the treatment system. However, few studies have addressed the influence of variable flow on the treatment performance of a biological activated carbon filter (BAC). In this study, we investigated the influence of intermittent flow using small-scale BAC columns, which treat greywater as a second treatment step following a membrane bioreactor (MBR). Three operating strategies to respond to variable flow were evaluated. The activated carbon was characterized before and after the experiments in terms of biological activity and sorption capacity. The performance of the BAC filters was assessed based on total organic carbon (TOC) removal, TOC fractions and growth potential. No significant differences were observed between constant flow compared to on-off operation with intermittent flow over the range of tested influent concentrations. Peaks with high TOC during 24 h periods were attenuated by sorption and biological degradation. Adsorbed TOC was released after switching back to normal concentrations for influent concentrations more than 5 times higher than usually observed, the BAC functioned as a temporary sink. In line with these results, the high influent TOC values led to increased biological activity in the filter but did not influence the sorption capacity. The experiments showed that intermittent flow does not negatively impact the performance of a BAC and that there is no need for additional equalization tanks to buffer the variable flow, for example in household-scale greywater treatment.
Hess, A.; Bettex, C.; Morgenroth, E. (2020) Influence of intermittent flow on removal of organics in a biological activated carbon filter (BAC) used as post-treatment for greywater, Water Research X, 9, 100078 (10 pp.), doi:10.1016/j.wroa.2020.100078, Institutional Repository

Removal of pharmaceuticals from nitrified urine by adsorption on granular activated carbon

Nitrification and distillation of urine allow for the recovery of all nutrients in a highly concentrated fertilizer solution. However, pharmaceuticals excreted with urine are only partially removed during these two process steps. For a sustainable and safe application, more extensive removal of pharmaceuticals is necessary. To enhance the pharmaceutical removal, which is already occurring during urine storage, nitrification and distillation, an adsorption column with granular activated carbon (GAC) can be included in the treatment train. We executed a pilot-scale study to investigate the adsorption of eleven indicator pharmaceuticals on GAC. During 74 days, we treated roughly 1000 L of pre-filtered and nitrified urine spiked with pharmaceuticals in two flow-through GAC columns filled with different grain sizes. We compared the performance of these columns by calculating the number of treated bed volumes until breakthrough and carbon usage rates. The eleven spiked pharmaceuticals were candesartan, carbamazepine, clarithromycin, diclofenac, emtricitabine, hydrochlorothiazide, irbesartan, metoprolol, N4-acetylsulfamethoxazole, sulfamethoxazole and trimethoprim. At the shortest empty bed contact time (EBCT) of 25 min, immediate breakthrough was observed in both columns shortly after the start of the experiments. Strong competition by natural organic material (NOM) could have caused the low pharmaceutical removal at the EBCT of 25 min. At EBCTs of 70, 92 and 115 min, more than 660 bed volumes could be treated until breakthrough in the column with fine GAC. The earliest breakthrough was observed for candesartan and clarithromycin. On coarse GAC, only half the number of bed volumes could be treated until breakthrough compared to fine GAC. The probable reason for the later breakthrough with fine GAC is the smaller intraparticle diffusive path length. DOC and UV absorbance measurements at 265 nm indicated that both parameters can be used as indicators for the breakthrough of pharmaceuticals. In contrast to pharmaceuticals and DOC, the nutrient compounds ammonium, nitrate, phosphate, potassium and sulfate were not removed significantly. A comparison with literature values suggests that the amount of GAC needed to remove pharmaceuticals from human excreta could be reduced by nearly two orders of magnitude, if urine were treated on site instead of being discharged and treated in a centralized wastewater treatment plant.
Köpping, I.; McArdell, C. S.; Borowska, E.; Böhler, M. A.; Udert, K. M. (2020) Removal of pharmaceuticals from nitrified urine by adsorption on granular activated carbon, Water Research X, 9, 100057 (10 pp.), doi:10.1016/j.wroa.2020.100057, Institutional Repository

Water Hub im NEST-Gebäude. Eine Plattform zum Testen von innovativen ressourcenorientierten Sanitärsystemen

Mit innovativen Technologien werden im Water Hub unter realen Bedingungen Ressourcen aus dem Abwasser gewonnen und Kreisläufe geschlossen. Die Forschung in diesem Living Lab erlaubt es, praxisnahe Erfahrungen zu machen, Schwachstellen schnell zu identifizieren und das System zu optimieren. Bei der Implementierung dieser dezentralen Technologien spielen die lokalen Herausforderungen und Begebenheiten stets eine wichtige Rolle.
Doll, C.; Larsen, T. A.; Strande, L.; Udert, K. M.; Morgenroth, E. (2020) Water Hub im NEST-Gebäude. Eine Plattform zum Testen von innovativen ressourcenorientierten Sanitärsystemen, Aqua & Gas, 100(2), 52-57, Institutional Repository

To char or not to char? Review of technologies to produce solid fuels for resource recovery from faecal sludge

Resource recovery from faecal sludge can take many forms, including as a fuel, soil amendment, building material, protein, animal fodder, and water for irrigation. Resource recovery as a solid fuel has been found to have high market potential in Sub-Saharan Africa. Laboratory- and pilot-scale research on faecal sludge solid fuel production exists, but it is unclear which technology option is most suitable in which conditions. This review offers an overview and critical analysis of the current state of technologies that can produce a dried or carbonized solid fuel, including drying, pelletizing, hydrothermal carbonization, and slow-pyrolysis. Carbonization alters fuel properties, and in faecal sludge, it concentrates the ash content and decreases the calorific value. Overall, a non-carbonized faecal sludge fuel is recommended, unless a carbonized product is specifically required by the combustion technology or end user. Carbonized and non-carbonized fuels have distinct characteristics, and deciding whether to char or not to char is a key judgement in determining the optimal solid fuel technology option. Based on the existing evidence, this review provides a decision-making structure for selecting the optimal technology to produce a faecal sludge solid fuel and identifies the top research needs prior to full-scale implementation.
Andriessen, N.; Ward, B. J.; Strande, L. (2019) To char or not to char? Review of technologies to produce solid fuels for resource recovery from faecal sludge, Journal of Water Sanitation and Hygiene for Development, 9(2), 210-224, doi:10.2166/washdev.2019.184, Institutional Repository

Evaluation of conceptual model and predictors of faecal sludge dewatering performance in Senegal and Tanzania

Unpredictable dewatering performance is a barrier to the effective management and treatment of faecal sludge. While mechanisms of dewatering in sludges from wastewater treatment are well understood, it is not clear how dewatering of faecal sludge fits into the framework of existing knowledge. We evaluate physical-chemical parameters, including EPS and cations, and demographic (source), environmental (microbial community), and technical factors (residence time) as possible predictors of dewatering performance in faecal sludge, and make comparisons to the existing conceptual model for wastewater sludge. Faecal sludge from public toilets took longer to dewater than sludge from other sources, and had turbid supernatant after settling. Slow dewatering and turbid supernatant corresponded to high EPS and monovalent cation concentrations, conductivity, and pH, but cake solids after dewatering was not correlated with EPS or other factors. Faecal sludges with higher EPS appeared less stabilised than those with lower EPS, potentially a result of inhibition of biological degradation due to high urine concentrations. However, distinct microbial community compositions were also observed in samples with higher and lower EPS concentrations. Higher EPS faecal sludge was comparable in dewatering behaviour and EPS content to anaerobically digested and primary wastewater sludges. However lower EPS faecal sludges had different dewatering behaviour than wastewater sludges and may be governed by different mechanisms.
Ward, B. J.; Traber, J.; Gueye, A.; Diop, B.; Morgenroth, E.; Strande, L. (2019) Evaluation of conceptual model and predictors of faecal sludge dewatering performance in Senegal and Tanzania, Water Research, 167, 115101 (13 pp.), doi:10.1016/j.watres.2019.115101, Institutional Repository

Chemical composition, nutrient-balancing and biological treatment of hand washing greywater

On-site biological hand washing water treatment can improve global access to safe hand washing water, but requires a thorough understanding of the chemical composition of the water to be treated, and an effective treatment strategy. This study first presents a detailed characterization of the individual inputs to hand washing water. We demonstrate (1) that soap is likely the most significant input in hand washing water, representing ∼90% of mass loading, and (2) that inputs to hand washing water have low concentrations of biologically-essential macro- and micro-nutrients (nitrogen, phosphorus, potassium, copper, zinc, molybdenum and cobalt) with respect to carbon, which may impair biological carbon removal. This study next formulates a recipe that recreates a representative composition of hand washing water and develops a procedure to identify and supplement nutrients in which this recipe is estimated to be deficient. Batch testing of the nutrient-supplemented hand washing water with an inoculum of planktonic bacteria demonstrated improved assimilable organic carbon removal (99% vs. 86% removal) and produced lower final DOC concentrations (1.7 mgC/L vs. 3.5 mgC/L) compared to realistic (nutrient-deficient) washing water. Supplementing nutrients did promote cell growth (50x higher final total cell count). Full-scale testing in a biologically activated membrane bioreactor (BAMBi) system treating 75 L/day of nutrient-supplemented hand washing water showed that long-term operation (100 days) can deliver effective carbon removal (95%) without detrimental fouling or other disruptions caused by cell growth. This work demonstrates that biological treatment in a BAMBi system, operated with appropriate nutrient-balancing offers an effective solution for decentralized treatment of light greywater.
Ziemba, C.; Larivé, O.; Reynaert, E.; Morgenroth, E. (2018) Chemical composition, nutrient-balancing and biological treatment of hand washing greywater, Water Research, 144, 752-762, doi:10.1016/j.watres.2018.07.005, Institutional Repository

Safely managed hygiene: a risk-based assessment of handwashing water quality

Sustainable Development Goal (SDG) Indicator 6.2.1 requires household handwashing facilities to have soap and water, but there are no guidelines for handwashing water quality. In contrast, drinking water quality guidelines are defined: water must be “free from contamination” to be defined as “safely managed” (SDG Indicator 6.1.1). We modeled the hypothesized mechanism of infection due to contaminated handwashing water to inform risk-based guidelines for microbial quality of handwashing water. We defined two scenarios that should not occur: (1) if handwashing caused fecal contamination, indicated using Escherichia coli, on a person’s hands to increase rather than decrease and (2) if hand-to-mouth contacts following handwashing caused an infection risk greater than an acceptable threshold. We found water containing <1000 E. coli colony-forming units (CFU) per 100 mL removes E. coli from hands with>99.9% probability. However, for the annual probability of infection to be <1:1000, handwashing water must contain <2 × 10−6 focus-forming units of rotavirus, <1 × 10−4 CFU of Vibrio cholerae, and <9 × 10−6Cryptosporidium oocysts per 100 mL. Our model suggests that handwashing with nonpotable water will generally reduce fecal contamination on hands but may be unable to lower the annual probability of infection risks from hand-to-mouth contacts below 1:1000.
Verbyla, M. E.; Pitol, A. K.; Navab-Daneshmand, T.; Marks, S. J.; Julian, T. R. (2019) Safely managed hygiene: a risk-based assessment of handwashing water quality, Environmental Science and Technology, 53(5), 2852-2861, doi:10.1021/acs.est.8b06156, Institutional Repository

Review of synthetic human faeces and faecal sludge for sanitation and wastewater research

Investigations involving human faeces and faecal sludge are of great importance for urban sanitation, such as operation and maintenance of sewer systems, or implementation of faecal sludge management. However, working with real faecal matter is difficult as it not only involves working with a pathogenic, malodorous material but also individual faeces and faecal sludge samples are highly variable, making it difficult to execute repeatable experiments. Synthetic faeces and faecal sludge can provide consistently reproducible substrate and alleviate these challenges. A critical literature review of simulants developed for various wastewater and faecal sludge related research is provided. Most individual studies sought to develop a simulant representative of specific physical, chemical, or thermal properties depending on their research objectives. Based on the review, a suitable simulant can be chosen and used or further developed according to the research needs. As an example, the authors present such a modification for the development of a simulant that can be used for investigating the motion (movement, settling and sedimentation) of faeces and their physical and biological disintegration in sewers and in on-site sanitation systems.
Penn, R.; Ward, B. J.; Strande, L.; Maurer, M. (2018) Review of synthetic human faeces and faecal sludge for sanitation and wastewater research, Water Research, 132, 222-240, doi:10.1016/j.watres.2017.12.063, Institutional Repository

Comparing the anti-bacterial performance of chlorination and electrolysis post-treatments in a hand washing water recycling system

Innovative solutions are necessary to enable the decentralized recycling of greywater for applications requiring high-quality water, such as hand washing. While physical barriers such as ultrafiltration membranes effectively prevent the passage of bacteria, and chemical and biological treatments can effectively reduce the carbon content of the treated water, there exists a knowledge gap regarding the application of anti-bacterial strategies to prevent the growth of harmful bacteria following treatment. In this study, the effluent water from a household-scale greywater treatment system was fed to seven parallel experimental post-treatment tanks: three receiving direct chlorination with free chlorine residuals of 0.2, 1 or 5 mg Cl2/L, three with chlorine produced through electrolysis at the same residual concentrations, and one control with no chlorine added. For increasing concentrations of direct chlorination, the median total cell count (TCC) values were 9 × 104, 2.9 × 104 and 1.8 × 103 cells/mL, respectively. Electrolysis treatment produced very similar TCC concentrations, 8.8 × 104, 1.1 × 104 and 2.3 × 103 cells/mL. The TCC concentrations were lower than the concentration of the water entering each tank (~3 × 105 cells/mL). Intact cell count (ICC) measurements indicated that the viable cell concentrations, were less than 10% of the TCC values. Though electrolysis treatment can produce powerful oxidants, such as hydroxyl radical, there was no evidence that electrolysis in this system provided additional benefits beyond chlorine production for control of total or intact cell counts. Oxidation of bacteria by chlorine was the dominant anti-bacterial mechanism in our system. Monitoring of dissolved organic carbon (DOC) and assimilable organic carbon (AOC) did not suggest that carbon-limitation significantly impacted cell counts when chlorination or electrolysis treatment was applied. This work demonstrates that either direct chlorination or electrolysis treatment are able to reduce bacteria concentrations over long-term operation of a hand washing water treatment system. We recommend selecting chlorine residual targets such that a chlorine residual is maintained during periods of challenging operating conditions. We observed that a target residual of 1 mg Cl2/L, in our system, maintained the TCC below the concentration found in Zürich drinking water.
Ziemba, C.; Larivé, O.; Deck, S.; Huisman, T.; Morgenroth, E. (2019) Comparing the anti-bacterial performance of chlorination and electrolysis post-treatments in a hand washing water recycling system, Water Research X, 2, 100020 (10 pp.), doi:10.1016/j.wroa.2018.100020, Institutional Repository

Reusing treated wastewater: consideration of the safety aspects associated with antibiotic-resistant bacteria and antibiotic resistance genes

As more countries engage in water reuse, either intended or de facto, there is an urgent need to more comprehensively evaluate resulting environmental and public health concerns. While antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are increasingly coming under the spotlight, as emerging contaminants, existing water reuse regulations and guidelines do not adequately address these concerns. This perspectives paper seeks to frame the various challenges that need to be resolved to identify meaningful and realistic target types and levels of antibiotic resistance benchmarks for water reuse. First, there is the need for standardized and agreed-upon methodologies to identify and quantify ARB and ARGs. Second, even if methodologies are available, identifying which ARB and ARGs to monitor that would best relate to the occurrence of disease burden remains unknown. Third, a framework tailored to assessing the risks associated with ARB and ARGs during reuse is urgently needed. Fourth, similar to protecting drinking water sources, strategies to prevent dissemination of ARB and ARGs via wastewater treatment and reuse are required to ensure that appropriate barriers are emplaced. Finally, current wastewater treatment technologies could benefit from modification or retrofit to more effectively remove ARB and ARGs while also producing a high quality product for water and resource recovery. This perspectives paper highlights the need to consider ARB and ARGs when evaluating the overall safety aspects of water reuse and ways by which this may be accomplished.
Hong, P.-Y.; Julian, T. R.; Pype, M.-L.; Jiang, S. C.; Nelson, K. L.; Graham, D.; Pruden, A.; Manaia, C. M. (2018) Reusing treated wastewater: consideration of the safety aspects associated with antibiotic-resistant bacteria and antibiotic resistance genes, Water, 10(3), 244 (22 pp.), doi:10.3390/w10030244, Institutional Repository

Controlling bacterial pathogens in water for reuse: treatment technologies for water recirculation in the Blue Diversion Autarky Toilet

The Blue Diversion AUTARKY Toilet is a urine-diverting toilet with on-site treatment. The toilet is being developed to provide a safe and affordable sanitation technology for people who lack access to sewer-based sanitation. Water used for personal hygiene, hand washing, and flushing to rinse urine- and feces-collection bowls is treated, stored, and recycled for reuse to reduce reliance on external water supplies. The system provides an opportunity to investigate hygiene of water for reuse following treatment. Treatment in the toilet includes a Biologically Activated Membrane Bioreactor (BAMBi) followed by a secondary treatment technology. To identify effective secondary treatment, three options, including granular activated carbon (GAC) only, GAC+chlorine (sodium hypochlorite), and GAC+electrolysis are considered based on the bacterial inactivation and growth inhibition efficiency. Four different hygiene-relevant bacteria are tested: Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, and Salmonella typhimurium. Our evaluation demonstrates that—despite treatment of water with the BAMBi—E. coli, P. aeruginosa, and S. typhimurium have the potential to grow during storage in the absence of microbial competition. Including the indigenous microbial community influences bacterial growth in different ways: E. coli growth decreases but P. aeruginosa growth increases relative to no competition. The addition of the secondary treatment options considerably improves water quality. A column of GAC after the BAMBi reduces E. coli growth potential by 2 log10, likely due to the reduction of carbon sources. Additional treatments including chlorination and electrolysis provide further safety margins, with more than 5 log10 inactivation of E. coli. However, reactivation and/or regrowth of E. coli and P. aeruginosa occurs under in the absence of residual disinfectant. Treatment including the BAMBi, GAC, and electrolysis appear to be promising technologies to control bacterial growth during storage in water intended for reuse.
Nguyen, M. T.; Allemann, L.; Ziemba, C.; Larivé, O.; Morgenroth, E.; Julian, T. R. (2017) Controlling bacterial pathogens in water for reuse: treatment technologies for water recirculation in the Blue Diversion Autarky Toilet, Frontiers in Environmental Science, 5, 90 (13 pp.), doi:10.3389/fenvs.2017.00090, Institutional Repository

Emerging solutions to the water challenges of an urbanizing world

The top priorities for urban water sustainability include the provision of safe drinking water, wastewater handling for public health, and protection against flooding. However, rapidly aging infrastructure, population growth, and increasing urbanization call into question current urban water management strategies, especially in the fast-growing urban areas in Asia and Africa. We review innovative approaches in urban water management with the potential to provide locally adapted, resource-efficient alternative solutions. Promising examples include new concepts for stormwater drainage, increased water productivity, distributed or on-site treatment of wastewater, source separation of human waste, and institutional and organizational reforms. We conclude that there is an urgent need for major transdisciplinary efforts in research, policy, and practice to develop alternatives with implications for cities and aquatic ecosystems alike.
Larsen, T. A.; Hoffmann, S.; Lüthi, C.; Truffer, B.; Maurer, M. (2016) Emerging solutions to the water challenges of an urbanizing world, Science, 352(6288), 928-933, doi:10.1126/science.aad8641, Institutional Repository

Redesigning wastewater infrastructure to improve resource efficiency

Resource efficiency of wastewater management is a question of optimizing at the same time the management of resources in wastewater (e.g. water), the resources spent on treatment and transport (e.g. energy), the natural resources to protect (e.g. the receiving waters), and the anthropogenic resources (e.g. capital). For instance, wastewater can be treated to any given quality, but only at the expense of energy and investment costs. Today, many up-coming problems are solved incrementally, leading to resource consuming solutions optimized for water pollution control in well off countries, whereas large parts of the world have at the best very simple wastewater treatment. From a global point of view, a system change is necessary in order to solve the immense problems arising from global population growth, urban development and climate change. Source separation is a promising concept for resource efficient wastewater management, but a more concerted effort is necessary from the international community in order to develop competitive technologies and overcome the inflexibility of the present end-of-pipe technology. Much more research and development are necessary, not only in the area of engineering, but also with respect to the socio-economic dimensions, especially in the area of regulation, suitable governance and management models, and concerning the involvement of industrial partners.
Larsen, T. A. (2011) Redesigning wastewater infrastructure to improve resource efficiency, Water Science and Technology, 63(11), 2535-2541, doi:10.2166/wst.2011.502, Institutional Repository

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Assainissement décentralisé :: orienté vers la valorisation

Assainissement décentralisé :: orienté vers la valorisation

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Collaboratrices et collaborateurs

Water Hub @ NEST équipe en automne 2023.

Contact

Giuseppe Congiu Coordinateur Water Hub Tel. +41 58 765 5771 Envoyez un message
Dr. Rosanne Wielemaker Water Hub Coordinator Tel. +41 58 765 6715 Envoyez un message

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À VENIR! Circular Sanitation TOOLBOX

Tournée virtuelle du Water Hub

Verhebets? Ein ressourcenorientierter Apéro

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News

Alt und neu – Teil 2, Abwasser. «Schweiz aktuell» SRF Live (18.07.2023)

Siamo a secco! SRI Falò (04.05.2023)

Documentary: The great toilet battle (04.10.2022)

Verhebts? Ein ressourcenorientierter Apéro, VSA News (29.09.2022)

Schöne Scheisse: Fäkalien sind nicht «wäh», sondern «wow», SRF Input (01.06.2022)

Interview: Abwasseraufbereitung direkt im Haus, Planet Wissen (30.05.2022)

Das nachhaltige Quartier von Morgen, Podiumsdiskussion Swissbau Focus 2022 (06.05.2022)

Spezial Newsletter Fokus: Dezentral Ressourcen aus Abwasser gewinnen, Eawag (Mai 2022)

De nombreuses parties prenantes doivent collaborer pour boucler les cycles des nutriments, Eawag News (05.05.2022)

Produire de l’énergie à partir de matières fécales, Eawag News (12.04.202)

Wasser - Die wertvolle Ressource, SWR Odysso (17.03.2022)

Let's collaborate on developing technologies for resource-oriented sanitation, Wings Newsletter (16.03.2022)

Eaux usées : cocktail toxique ou précieux ?, Arte (24.02.2022)

Partenaires de projet

Projets Partenaires / Pages thématiques

In Autarky entwickeln wir kleine Anlagen für die getrennte Behandlung von Urin, Abwasser und Fäkalien direkt in der Toilette.

Blue Diversion AUTARKY – Abwasserbehandlung ohne Netzanschluss
En récupérant les nutriments contenus dans les urines, nous développons un système sanitaire, qui produit des engrais

VUNA - Récupération de nutriments des urines
Le programme de recherche stratégique inter- et transdisciplinaire vise à développer des systèmes d'approvisionnement en eau et d'assainissement innovants, non raccordés au réseau.

Wings
We are identifying the challenges of modular infrastructure systems for the Swiss economy and society using the example of urban water management.

COMIX: Challenges and Opportunities of Modular water Infrastructures
Ist ein Raumfahrtforschungs- programm, das die Entwicklung eines bioregenerativen Lebenserhaltungssystems für langfristige Raumfahrtmissionen und Weltraumwohnungen zum Beispiel auf dem Mars zum Ziel hat

Melissa «Micro Ecological Life Support System Alternative»
The Lighthouse Project focuses on visible examples of onsite and decentralised urban water management systems, which will play a key role in enabling sustainability transitions.

Lighthouse
Partout dans le monde, les populations sont confrontées à des problèmes d'approvisionnement en eau. Les causes principales sont la demande croissante, des sécheresses accrues, l'épuisement et la contamination des sources d’eau douce, la dépendance de sources uniques et le vieillissement des infrastructures.

Réutilisation des eaux grises à l’Eawag
L’Eawag possède une longue histoire en matière de développement de procédés innovants pour la séparation des eaux usées à la source. En fait partie la séparation des urines via les WC NoMix.

Technologie NoMix