Our selection of open access publications on water reuse – November 2022

Here is our selection of open-access articles published this quarter on the impact of wastewater treatment plants on microbiological contamination; Bayesian estimation of seasonal and between year variability of norovirus infection risks for agricultural workers; adoption of water reuse technologies under different regulatory and operational scenarios; acceptance of recycled water use from data from two Spanish regions with opposite levels of scarcity; status of potable water reuse implementation. These articles have been published in Desalination, Water Research, Data in Brief, and Journal of Environmental Management.

Enjoy reading!

Technology for water reuse

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.

Water Reuse for agriculture

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.

Water Reuse Regulation 

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.

Public perception and acceptance of water reuse

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.

Potable Water Reuse

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.