Research

Research on Water Recycling and Reuse

Research actively contributes to the development and success of water reuse schemes in Europe. And for this reason, one of our missions at WRE is to promote research and innovation on water reuse across Europe.

Below you will find highlights of research projects that are taking place in Europe and beyond, and a focus on recently published research articles on water reuse.

If you are involved in research and development on water reuse, and would like to let our community know on this page, contact us at: info@water-reuse-europe.org

Projects selection

A full list of current and past Water Reuse projects is available in our Members area.

Articles selection - November 2022

Want to keep up to date on the latest research on water reuse? Every quarter Water Reuse Europe selects for you five open-access trending articles on water reuse.

Enjoy the reading!

Title: Impact of wastewater treatment plants on microbiological contamination for evaluating the risks of wastewater reuse

Authors: Bonetta, S., Pignata, C., Gasparro, E., Richiardi, L., Bonetta, S., Carraro, E.

In: Desalination

Publisher: Environmental Sciences Europe

Abstract: Background: Wastewater reuse represents a promising alternative source of water supply considering the water scarcity related to climate change. However, if not adequately treated, wastewater represents a source of microbiological health risk. The purpose of this work was to investigate the role of wastewater treatment on microbiological contamination by evaluating the possible risks associated with wastewater effluent reuse, taking into account new EU legislation (2020/741) on minimum requirements for water reuse. E. coli that produce Shiga toxins (STEC) and thermotolerant Campylobacter were monitored using an enrichment step associated with specific PCR, while Salmonella spp. and Legionella were detected with both cultural and molecular methods (PCR and q-PCR, respectively). Culture method was also used for the enumeration of different microbial indicators. The bacteria detection was compared in different wastewater plants with membrane bioreactor (MBR) system or with disinfection step with chlorine dioxide (ClO2). Moreover a comparison between molecular and culture methods was discussed. Results: The results obtained showed good abatement performance for WWTPs equipped with MBR. The high concentrations of E. coli (range between 0.88 and 5.21 Log MPN/100 mL) and contamination by Salmonella spp. in effluent disinfected with ClO2 (17% of samples) showed the need to control the quality of this effluent. In addition, despite the absence of Legionella spp. with the culture method required by EU regulation, high concentrations of Legionella spp. (range between 2 and 7 log GU/L) and the presence of Leg. pneumophila with qPCR (15% of samples) highlight the need to carry out further investigations for reuse associated with aerosol formation (e.g. spray irrigation in agriculture). Conclusions: The results obtained underline that the MBR technology can be suitable for wastewater reuse applications allowing to achieve the requirement proposed by the new European legislation. More attention should be given to wastewater reuse of effluents treated with ClO2. The use of the molecular methods for pathogens detection in wastewater could allow a more precautionary risks estimation associated with reuse. The overall results highlight that an evaluation of the effectiveness of the wastewater treatments is required for the prevention of a possible risk to public health. © 2022, The Author(s).

Article available here.

Title: Bayesian estimation of seasonal and between year variability of norovirus infection risks for workers in agricultural water reuse using epidemiological data

Authors: Seis, W., Rouault, P., Miehe, U., ten Veldhuis, M.-C., Medema, G.

In: Water Research

Publisher: Elsevier

Abstract: Norovirus infections are among the major causes of acute gastroenteritis worldwide. In Germany, norovirus infections are the most frequently reported cause of gastroenteritis, although only laboratory confirmed cases are officially counted. The high infectivity and environmental persistence of norovirus, makes the virus a relevant pathogen for water related infections. In the 2017 guidelines for potable water reuse, the World Health Organization proposes Norovirus as a reference pathogen for viral pathogens for quantitative microbial risk assessment (QMRA). A challenge for QMRA is, that norovirus data are rarely available over long monitoring periods to assess inter-annual variability of the associated health risk, raising the question about the relevance of this source of variability regarding potential risk management alternatives. Moreover, norovirus infections show high prevalence during winter and early spring and lower incidence during summer. Therefore, our objective is to derive risk scenarios for assessing the potential relevance of the within and between year variability of norovirus concentrations in municipal wastewater for the assessment of health risks of fieldworkers, if treated wastewater is used for irrigation in agriculture. To this end, we use the correlation between norovirus influent concentration and reported epidemiological incidence (R²=0.93), found at a large city in Germany. Risk scenarios are subsequently derived from long-term reported epidemiological data, by applying a Bayesian regression approach. For assessing the practical relevance for wastewater reuse we apply the risk scenarios to different irrigation patterns under various treatment options, namely “status-quo” and “irrigation on demand”. While status-quo refers to an almost all-year irrigation, the latter assumes that irrigation only takes place during the vegetation period from May – September. Our results indicate that the log-difference of infection risks between scenarios may vary between 0.8 and 1.7 log given the same level of pre-treatment. They also indicate that under the same exposure scenario the between-year variability of norovirus infection risk may be > 1log, which makes it a relevant factor to consider in future QMRA studies and studies which aim at evaluating safe water reuse applications. The predictive power and wider use of epidemiological data as a suitable predictor variable should be further validated with paired multi-year data.

Article available here.

Title: Adoption of water reuse technologies: An assessment under different regulatory and operational scenarios

Authors: Cagno, E., Garrone, P., Negri, M., Rizzuni, A.

In: Journal of Environmental Management

Publisher: Elsevier

Abstract: Water reuse technologies may alleviate the water scarcity problems that affect many world regions, but their adoption is still limited. In particular, key actors in the adoption of water reuse technologies are water utilities, that provide both urban water and wastewater treatment services. Water utilities are embedded in the urban water system, which includes several stakeholders (urban water users, citizens at large, the environment) that may drive or pose barriers to water reuse adoption. Therefore, to ensure a smooth introduction of water reuse technologies, it is fundamental to understand how water reuse interacts with the existing urban water system and impacts its stakeholders. This paper contributes to the ongoing debate on water reuse by conceptualizing the interaction between water reuse technologies and the urban water system and its stakeholders, and addressing the adoption decision of water utilities by assessing its economic and environmental consequences. Based on a review of literature, policy and other secondary documents, and on primary data coming from interviews with experts from a water utility operating in Southern Italy, the study models the utility’s response to a shift from urban to reuse water. It then simulates how reuse water introduction impacts on the utility and other stakeholders of the water system, under various regulatory and operational scenarios defined through a thorough analysis of policy documents and literature. Results show that the adoption of water reuse reduces the utility’s margin by cannibalizing urban water demand, but appropriate policy measures may enhance the economic sustainability of reuse. System-level performances, such as impact on freshwater savings, costs for users, effects on the public budget, are also assessed, showing how different regulatory options moderate the intensity of impacts for the different stakeholders of the water system. Furthermore, the adoption of reuse water by the most distant users is found to enhance the economic sustainability of reuse and positively impact the utility’s margin.

Article available here.

Title: The status of potable water reuse implementation

Authors: Jeffrey, P., Yang, Z., Judd, S.J.

In: Water Research

Publisher: Elsevier

Abstract: A review of the current status of direct and indirect potable water reuse (DPR/IPR) implementation has been conducted, focusing on the regulatory and practical aspects and with reference to the most recent published literature. The review encompasses (a) the principal contaminant types, their required removal and the methods by which their concentration is monitored, (b) regulatory approaches and stipulations in assessing/ratifying treatment schemes and maintaining treated water quality, and (c) existing full-scale installations. Analytical methods discussed include established in-line monitoring tools, such as turbidity measurement, to more recent polymerase chain reaction (PCR)-based assay methods for microbial detection. The key risk assessment tools of quantitative microbial risk assessment (QMRA) and water safety plans (WSPs) are considered in relation to their use in selecting/ratifying treatment schemes, and the components of the treatment schemes from 40 existing IPR/DPR installations summarised. Five specific schemes are considered in more detail. The review reveals: 1 over half of the schemes identified employ reverse osmosis (RO) followed by UV disinfection, with UV-based advanced oxidation used in many modern schemes as the final step; 2 Whilst quantitative PCR appears to offer many advantages for microbial detection, due to its sensitivity and specificity, it nonetheless demands pre-concentration of the sample and is subject to interference leading to possible false positives; 3 QMRA studies suggest that the risk imposed by DPR and, in particular, IPR is very small compared with de facto reuse, the latter being subject to far less regulatory scrutiny; 4 There appears to be no evidence of acute conditions, and diarrhoeal disease specifically, from the few epidemiological studies which have been conducted; and. 5 IPR implementation becomes challenging if unbounded environmental waters are used as a buffer, since “zero deterioration” in environmental quality must then be demonstrated. Whilst there are a number of ongoing projects where RO is not used because of the challenge imposed by disposal of RO concentrate, the prevalence of the sequential RO-UV combination implies the importance of quantifying the impact of process upsets on these unit operations.

Article available here.

Title: Recycled water acceptance: Data from two Spanish regions with opposite levels of scarcity

Authors: Vila-Tojo, S., Sabucedo, J.-M., Andrade, E., Gómez-Román, C., Alzate, M., Seoane, G.

In: Data in Brief

Publisher: Elsevier


Abstract: The dataset presented in this paper were collected for testing a perceptive-axiological model of recycled water acceptance for low and high contact uses. Participants were selected by proportional random sampling by sex and age the two Spanish communities with the most extreme values of water stress (Galicia, the rainiest region and Murcia, the driest). Data were collected by a company specialized in market research using an online survey housed on Qualtrics. Participants who matched the specified profile were contacted by email. The company compensated them financially. The final sample size consisted of 726 valid responses. The survey collected data on a variety of variables related to three conceptual dimensions: the diagnosis of the environmental situation, the axiological influence and the public perceptions regarding recycled water. The survey also collected demographic data from respondents. The survey was designed and reviewed by four experts in social psychology and two experts in methodology. The dataset featured in this article provides the raw survey data plus sociodemographic distribution, survey items, and other statistical data. This is the first and most comprehensive set of comparative data known to the authors on public acceptance of water reuse for high and low contact uses comparing regions with and without water scarcity. The authors have published an open access paper based on this data set, which are linked to this paper. Water industry professionals, policymakers, researchers and other stakeholders aiming to implement wastewater reuse systems in society may be interested in using the data as a point of comparison for their own study on public acceptance of water reuse or examining the data for relationships not yet explored in the literature.

Article available here.

Articles selection - May 2021

Want to keep up to date on the latest research on water reuse? Every quater Water Reuse Europe selects for you five open-access trending articles on water reuse.

Enjoy the reading!

Title: Treatment of greenhouse wastewater for reuse or disposal using monovalent selective electrodialysis

Authors: Ahdab, Y.D., Schücking, G., Rehman, D., Lienhard, J.H., V.

In: Desalination

Publisher: Elsevier

Abstract: Minimal liquid discharge (MLD) in greenhouses minimizes the volume of discharged wastewater, thereby increasing the volume of effluent that may be reused. Sodium accumulation in wastewater is often considered the main bottleneck to achieving 100% reuse. Consequently, greenhouses have begun adopting reverse osmosis (RO), the most commonly used desalination technology for wastewater treatment. RO removes ions from wastewater indiscriminately, including multivalent nutrients to crops (Ca2+, Mg2+, SO42−, PO43−). In contrast, monovalent selective electrodialysis (MSED) selectively removes monovalent sodium while retaining multivalent nutrients in solution. For greenhouses that have not achieved MLD, MSED has an alternative application of reducing levels of nitrate, a monovalent ion and agricultural pollutant, in wastewater for disposal. This paper investigates the monovalent selectivity and potential of the widely-used Neosepta MSED membranes and the new Fujifilm MSED membranes to treat wastewater in greenhouses for reuse or discharge. Eight effluent compositions are tested as feedwater in a laboratory MSED system. Both membranes demonstrate selectivity towards sodium and nitrate across the tested compositions. Fujifilm cation-exchange membranes remove two to six sodium ions, compared to Neosepta’s two to eight, for every magnesium ion. Fujifilm anion-exchange membranes remove two to seven nitrate ions, compared to Neosepta’s two to six, for every sulfate ion.

Article available here

water droplet with a reflectionTitle: Fate of N-nitrosodimethylamine and its precursors during a wastewater reuse trial in the Llobregat River (Spain)

Authors: Šereš, M., Innemanová, P., Hnátková, T., Rozkošný, M., Stefanakis, A., Semerád, J., Cajthaml, T.

In: Journal of Hazardous Materials

Publisher: Elsevier

Abstract: Agriculture is being negatively affected by the decrease in precipitation that has been observed over the last few years. Even in the Czech Republic, farmers are being urged to irrigate their fields despite the fact that sources of water for irrigation are rapidly being depleted. This problem might be partially solved via the reuse of treated wastewater in certain agricultural sectors. However, the public perception of the reuse of wastewater remains negative primarily due to unknown risks to the environment and public health. To overcome this barrier, a semi-operated irrigation field was established at Kostelec nad Ohří in the Central Bohemian region of the Czech Republic and planted with common garden crops such as tomatoes (Lycopersicon esculentum), potatoes (Solanum tuberosum) and lettuces (Lactuca sativa L.) irrigated with two different water sources, i.e., treated wastewater from a local nature-based treatment system, a hybrid constructed wetland (HCW), and local fresh water from well. The HCW was put into operation in 2017 and was reconstructed in 2018 and includes both horizontal and vertical flow beds; the trial irrigation field was added in the same year. The reconstruction of the facility significantly enhanced the removal efficiency with respect to all monitored parameters, e.g., biochemical oxygen demand (BOD5), chemical oxygen demand (COD), N–NH4+, total N and the suspended solids (TSS), except for total P. The HCW also ensured the significant removal of several observed pathogenic microorganisms (E. coli, intestinal enterococci and thermotolerant coliforms). During the 2018 and 2019 growing seasons, we observed the significantly enhanced growth of the crops irrigated with wastewater from the HCW due to the fertilizing effect. The risks associated with the contamination of crops irrigated with treated water are not negligible and it is necessary to pay sufficient attention to them, especially when introducing irrigation with wastewater into practice.

 Article available here.

Title: Reuse of treated water in European agriculture: Potential to address water scarcity under climate change

Authors: Hristov, J., Barreiro-Hurle, J., Salputra, G., Blanco, M., Witzke, P.

In: Agricultural Water Management

Publisher: Elsevier

Abstract: The use of reclaimed or treated water from urban wastewater treatment plants for irrigation has been proposed as an alternative water source to address water scarcity issues in Europe. In this paper using agro-economic modelling, we analyse if treated water available for agriculture has the potential to reduce freshwater abstraction and, consequently, water stress. Implementing exogenous treated water quantities as an additional water supply at NUTS 2 level in the CAPRI model, we found that treated water reuse is a possible alternative supply source to address water shortages with a very negligible effect on farmers’ income and food production in the EU. However, the actual water reuse and water stress reduction is very limited due to high costs. Even climate change effects on water availability and precipitation failed to induce higher use. The one-size-fits-all approach modelled via a flat rate water price only encourages the reuse of treated water in a limited number of EU member states. Thus, in order to maximise the potential of reused water to address water scarcity, different rates should be used so as to ensure higher treated water volumes at lower costs.

Article available here.

transparent bar graph with water

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

Authors:Reynaert, E., Hess, A., Morgenroth, E.

In:Water Research X

Publisher: Elsevier

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.

Article available here.

water drop with circles

Title: From Acceptance Snapshots to the Social Acceptability Process: Structuring Knowledge on Attitudes Towards Water Reuse

Authors: Al-Saidi, M.

In: Frontiers in Environmental Science

Publisher: Frontiers Media S.A.

Abstract: Water reuse is considered a technologically viable option to meet the increasing demands of the domestic, industrial and agricultural sectors. Alongside challenges such as environmental health, infrastructure and regulations, water reuse is often hindered by lack of acceptance and dismissive attitudes. This paper seeks to structure knowledge about acceptance of water use. It provides a systematic look at the overall reuse challenges and social attitudes towards water reuse considering the three integrative elements of water reuse, namely the water source, the technology, and the end use. It first maps the challenges and common insights that constitute the enigma of water reuse acceptance. Later, it conceptualizes acceptance as a social process consisting of the interdependent components of public perception, politicization, individual acceptance, and use adaptation. Using this conceptual framework, solutions to increasing water acceptance stemming from different bodies of acceptance studies are reviewed. The paper reiterates the need for a nuanced view on water reuse acceptance that incorporates spatio-temporal considerations as well as knowledge from different disciplines.

Article available here

Our full database of research papers is available in the Members Area.