Our selection of open access publications on water reuse – February 2023
Here is our selection of open-access articles published this quarter on indirect potable reuse as a solution to face drought events in Spain; Electrochemical advanced oxidation for sustainable water reuse, sensor setpoints for membrane bioreactor and chlorination treatment in on-site water reuse systems, potential application of hybrid reverse electrodialysis (RED)-forward osmosis (FO) system for industrial water reuse, and treatment of laundry wastewater for reuse. These articles are published in Science of the Total Environment, Chemosphere, Water Research X, Desalination, and Journal of Environmental Chemical Engineering.
Indirect potable reuse
Title: Indirect potable water reuse to face drought events in Barcelona city. Setting a monitoring procedure to protect aquatic ecosystems and to ensure a safe drinking water supply.
Authors:Munné, A., Solà, C., Ejarque, E., Sanchís, J., Serra, P., Corbella, I., Aceves, M., Galofré, B., Boleda, M.R., Paraira, M., Molist, J.
In: Science of the Total Environment
Abstract:The climate change and increasing anthropogenic pressures are expected to limit the availability of water resources. Hence, active measures must be planned in vulnerable regions to ensure a sustainable water supply and minimize environmental impacts. A pilot test was carried out in the Llobregat River (NE Spain) aiming to provide a useful procedure to cope with severe droughts through indirect water reuse. Reclaimed water was used to restore the minimum flow of the lower Llobregat River, ensuring a suitable water supply downstream for Barcelona. A monitoring was performed to assess chemical and microbiological threats throughout the water treatment train, the river and the final drinking water, including 376 micropollutants and common microbiological indicators. The effects of water disinfection were studied by chlorinating reclaimed water prior to its discharge into the river. Data showed that 10 micropollutants (bromodichloromethane, dibromochloromethane, chloroform, EDDP, diclofenac, iopamidol, ioprimid, lamotrigine, ofloxacin and valsartan) posed a potential risk to aquatic life, whereas one solvent (1,4-dioxane) could affect human health. The chlorination of reclaimed water mitigated the occurrence of pharmaceuticals but, conversely, the concentration of halogenated disinfection by-products increased. From a microbiological perspective, the microbial load decreased along wastewater treatments and, later, along drinking water treatment, ultimately reaching undetectable values in final potable water. Non-chlorinated reclaimed water showed a lower log reduction of E. coli and coliphages than chlorinated water. However, the effect of disinfection vanished once reclaimed water was discharged into the river, as the basal concentration of microorganisms in the Llobregat River was comparable to that of non-chlorinated reclaimed water. Overall, our study indicates that indirect water reuse can be a valid alternative source of drinking water in densely populated areas such as Barcelona (Catalonia – NE Spain). A suitable monitoring procedure is presented to assess the related risks to human health and the aquatic ecosystem.
Article available here.
Technologies for water reuse
Title: Evaluation of pathogen disinfection efficiency of electrochemical advanced oxidation to become a sustainable technology for water reuse.
Authors: Forés, E., Mejías-Molina, C., Ramos, A., Itarte, M., Hundesa, A., Rusiñol, M., Martínez-Puchol, S., Esteve-Bricullé, P., Espejo-Valverde, A., Sirés, I., Calvo, M., Araujo, R.M., Girones, R.
Abstract: Water treatment and reuse is gaining acceptance as a strategy to fight against water contamination and scarcity, but it usually requires complex treatments to ensure safety. Consequently, the electrochemical advanced processes have emerged as an effective alternative for water remediation. The main objective here is to perform a systematic study that quantifies the efficiency of a laboratory-scale electrochemical system to inactivate bacteria, bacterial spores, protozoa, bacteriophages and viruses in synthetic water, as well as in urban wastewater once treated in a wetland for reuse in irrigation. A Ti|RuO2-based plate and Si|BDD thin-film were comparatively employed as the anode, which was combined with a stainless-steel cathode in an undivided cell operating at 12 V. Despite the low resulting current density (<15 mA/cm2), both anodes demonstrated the production of oxidants in wetland effluent water. The disinfection efficiency was high for the bacteriophage MS2 (T99 in less than 7.1 min) and bacteria (T99 in about 30 min as maximum), but limited for CBV5 and TuV, spores and amoebas (T99 in more than 300 min). MS2 presented a rapid exponential inactivation regardless of the anode and bacteria showed similar sigmoidal curves, whereas human viruses, spores and amoebas resulted in linear profiles. Due the different sensitivity of microorganisms, different models must be considered to predict their inactivation kinetics. On this basis, it can be concluded that evaluating the viral inactivation from inactivation profiles determined for bacteria or some bacteriophages may be misleading. Therefore, neither bacteria nor bacteriophages are suitable models for the disinfection of water containing enteric viruses. The electrochemical treatment added as a final disinfection step enhances the inactivation of microorganisms, which could contribute to safe water reuse for irrigation. Considering the calculated low energy consumption, decentralized water treatment units powered by photovoltaic modules might be a near reality.
Article available here.
Title: Sensor setpoints that ensure compliance with microbial water quality targets for membrane bioreactor and chlorination treatment in on-site water reuse systems
Authors: Reynaert, E., Gretener, F., Julian, T.R., Morgenroth, E.
In: Water Research X
Abstract: Widespread implementation of on-site water reuse systems is hindered by the limited ability to ensure the level of treatment and protection of human health during operation. In this study, we tested the ability of five commercially available online sensors (free chlorine (FC), oxidation-reduction potential (ORP), pH, turbidity, UV absorbance at 254 nm) to predict the microbial water quality in membrane bioreactors followed by chlorination using logistic regression-based and mechanism-based models. The microbial water quality was assessed in terms of removal of enteric bacteria from the wastewater, removal of enteric viruses, and regrowth of bacteria in the treated water. We found that FC and ORP alone could predict the microbial water quality well, with ORP-based models generally performing better. We further observed that prediction accuracy did not increase when data from multiple sensors were integrated. We propose a methodology to link online sensor measurements to risk-based water quality targets, providing operation setpoints protective of human health for specific combinations of wastewaters and reuse applications. For instance, we recommend a minimum ORP of 705 mV to ensure a virus log-removal of 5, and an ORP of 765 mV for a log-removal of 6. These setpoints were selected to ensure that the percentage of events where the water is predicted to meet the quality target but it does not remains below 5%. Such a systematic approach to set sensor setpoints could be used in the development of water reuse guidelines and regulations that aim to cover a range of reuse applications with differential risks to human health.
Article available here.
Title: Potential application of hybrid reverse electrodialysis (RED)-forward osmosis (FO) system to fertilizer-producing industrial plant for efficient water reuse.
Authors: Elmakki, T., Zavahir, S., Gulied, M., Qiblawey, H., Hammadi, B., Khraisheh, M., Shon, H.K., Park, H., Han, D.S.
Abstract: This study presents an experimental investigation and a parametric analysis of the applicability of agricultural fertigation and power generation using a reverse electrodialysis-forward osmosis (RED-FO) hybrid system, with a water stream discharged from a fertilizer-producing plant. The results of this study demonstrated the possibility of achieving high salinity power generation from the RED system utilizing high-salinity brine and low-salinity ammonia solution that simulates reverse osmosis (RO) brine and wastewater streams released by the fertilizer-producing industry. The feasibility of stream dilution for fertigation application is demonstrated when the resulting moderately saline RED effluent is introduced into the FO process as a draw solution. The effect of external load addition, flow velocities variation, and concentration changes of the working solutions on the overall stack internal resistance and, thereby, RED performance was evaluated. As such, the lowest internal resistance converged to a threshold value of 4.03 Ω, giving the highest gross power density of 2.17 W/m2 when a flow velocity of 1.18 cm/s, 10 Ω external load, and 0.015 M (NH4)2SO4/1 M NaCl solution pair were utilized. In addition, the effect of the number of ion exchange membrane pairs and wastewater stream recycling was studied and optimized to amplify the osmotically generated power. As a result, the most consistent power generation was achieved when using 20 pairs of membrane cells in a single-pass flow mode operation. The applicability of the RED effluent to a subsequent FO system as a draw solution (DS) was investigated, showing a dilution rate (17 %) and a conductivity (1–2 mS/cm of DS) suitable for agricultural fertigation applications.
Article available here.
Decentralised Water Reuse
Title: Treatment of laundry wastewater by different processes: Optimization and life cycle assessment
Authors: Melián, E.P., Santiago, D.E., León, E., Reboso, J.V., Herrera-Melián, J.A.
In: Journal of Environmental Chemical Engineering
Abstract: Wastewater from industrial laundries is often difficult to treat because it usually presents high turbidity and chemical oxygen demand (COD). We studied several processes for the treatment of laundry wastewater which was provided by a hotel in the south of Gran Canaria, Spain. More specifically, we studied coagulation with iron (III) sulphate, Fenton, photo-Fenton and a biological treatment (using a biofilter, and a granular activated carbon, GAC, filtration). The coagulation and Fenton processes produced large amounts of sludge and could not meet the required standards for water reuse in Spain. The use of photo-Fenton and the BF resulted in complete turbidity removal and high COD removal. However, we found that the effluent from the BF did not meet the COD removal criteria for water reuse, and thus a GAC filtration post-treatment was employed to reduce COD to acceptable levels. The photo-Fenton process alone did meet the criteria for water reuse. The estimated cost to treat 1 m3 of wastewater was 6.72 € for photo-Fenton and 0.71 € for BF + GAC. The cost and life cycle assessment analyses that were also performed revealed that the acquisition of the necessary reagents is the main contribution to the overall economic and environmental costs for both options, and that the BF + GAC option is notably cheaper. Additionally, this option also causes much lower environmental impacts than photo-Fenton..
Article available here.