Author(s): Mateo Bruno Pastur Romay; Eva Mena; Benoit Lefevre; Jose Luis Cortina; Julio Lopez; Celia Castro-Barros; Joana Tobella

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Keywords: Reuse; Brines; Nutrients; Salinity

Abstract: Water reuse has been evidenced as the most sustainable alternative to the use of freshwater sources in terms of cost and environmental impact. However, wastewater salinity is a challenge in wastewater treatment (WWTP) and reclamation (WRP) plants where collectors receive industrial brines, agricultural runoff waters and/or marine intrusion. Conventional WWTP or WRP are not designed for salinity removal, which becomes a limiting water quality parameter in water reuse. This limitation entails consumption of freshwater sources for non-potable uses instead of more sustainable alternatives, as well as the discharge of effluents with nutrients to natural water bodies. Its reuse would prevent eutrophication by diverting the nutrients to irrigation applications, where they would be fixated by plants. The overall objective of LIFE CONQUER is the demonstration of an innovative water reclamation process based on the use of Smart Nanofiltration (NF) that will divide salinity and nitrates, obtaining a produced reclaimed water rich in nutrients to re-use it for irrigation, and remove dissolved salts by concentrating them in brines. Additionally, it will demonstrate the use of electrochemical processes to valorize generated brines and transform concentrated salinity in valuable by-products (sodium hypochlorite) needed in treatment processes. A semi-industrial prototype able to treat up to 20 m3/h has been designed and will be operated 24/7 from February 2022 to January 2024 to evaluate the technical and economic advantages of the process. Prototype consists on NF membranes, Mono-Selective Electro reversal Dialysis and electrooxidation process to produce sodium hypochlorite. Prototype feed water is the effluent of Zarandona WRP, Murcia, which treatment consists of a Sequencing Batch Reactor followed by Ultrafiltration (UF) membranes. WRP effluent has a high salinity, 3.5±1 mS/cm, above the limit established by the Spanish legislation (3.0 mS/cm). During the design phase, different ionic compositions are being assessed to know the effect of wastewater variability in the WRP. Initial results show that 30% of WRP effluent will be treated through the 20 m3/h NF prototype with permeate recovery of 80%. The NF rejection values are: 15-30% of NaCl, 99% of MgSO4 and 5-10% of dissolved nitrates. NF will be blended with WRP effluent to produced 0.5 hm3 per year of reclaimed water rich in nutrients and will be injected in the Urban Irrigation Network of Murcia. It will avoid the discharge of 1.3 ton of Neq into the environment. The brine valorization treatment will first concentrate the NaCl up to 5.000 mg/L, and then apply an electrooxidation process that will produce (3 kg NaClO/h) 26 ton per year of sodium hypochlorite. The aim of the presentation will be to explain in more detailed the scope of the project, design of the units and initial operational results after 4 months of continuous operation.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221634

Year: 2022