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Open AccessArticle

Exploring Submerged Forward Osmosis for Water Recovery and Pre-Concentration of Wastewater before Anaerobic Digestion: A Pilot Scale Study

1
Catalan Institute for Water Research (ICRA), Emili Grahit Street, 101, 17003 Girona, Spain
2
Campus Montilivi, University of Girona, 17003 Girona, Spain
3
LEQUiA, Laboratory of Chemical and Environmental Engineering, Campus Montilivi, University of Girona, 17071 Girona, Spain
4
Eurecat, Centre Tecnològic de Catalunya. Plaça de la Ciència, 2. 08242 Manresa, Spain
*
Author to whom correspondence should be addressed.
Membranes 2019, 9(8), 97; https://doi.org/10.3390/membranes9080097
Received: 7 June 2019 / Revised: 30 July 2019 / Accepted: 31 July 2019 / Published: 5 August 2019
(This article belongs to the Special Issue Forward Osmosis: Modelling and Applications)
Applying forward osmosis directly on raw municipal wastewater is of high interest for the simultaneous production of a high quality permeate for water reuse and pre-concentrating wastewater for anaerobic digestion. This pilot scale study investigates, for the first time, the feasibility of concentrating real raw municipal wastewater using a submerged plate and frame forward osmosis module (0.34 m2) to reach 70% water recovery. Membrane performance, fouling behavior, and effective concentration of wastewater compounds were examined. Two different draw solutions (NaCl and MgCl2), operating either with constant draw concentration or in batch with draw dilution over time, were evaluated. Impact of gas sparging on fouling and external concentration polarization was also assessed. Water fluxes up to 15 L m−2 h−1 were obtained with clean water and 35 g NaCl/L as feed and draw solution, respectively. When using real wastewater, submerged forward osmosis proved to be resilient to clogging, demonstrating its suitability for application on municipal or other complex wastewater; operating with 11.7 g NaCl/L constant draw solution, water and reverse salt fluxes up to 5.1 ± 1.0 L m−2 h−1 and 4.8 ± 2.6 g m−2 h−1 were observed, respectively. Positively, total and soluble chemical oxygen demand concentration factors of 2.47 ± 0.15 and 1.86 ± 0.08, respectively, were achieved, making wastewater more suitable for anaerobic treatment. View Full-Text
Keywords: forward osmosis; real municipal wastewater; pilot scale; submerged membrane; anaerobic digestion; water reuse; wastewater concentration forward osmosis; real municipal wastewater; pilot scale; submerged membrane; anaerobic digestion; water reuse; wastewater concentration
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MDPI and ACS Style

Ferrari, F.; Pijuan, M.; Rodriguez-Roda, I.; Blandin, G. Exploring Submerged Forward Osmosis for Water Recovery and Pre-Concentration of Wastewater before Anaerobic Digestion: A Pilot Scale Study. Membranes 2019, 9, 97.

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