Integrated pretreatment with capacitive deionization for reverse osmosis reject recovery from water reclamation plant

• Published in: Water research (Oxford) 2009-10, Vol.43 (18), p.4769-4777
• Main Authors: Lee, Lai Yoke, Ng, How Yong, Ong, Say Leong, Tao, Guihe, Kekre, Kiran, Viswanath, Balakrishnan, Lay, Winson, Seah, Harry
• Format: Article
• Language: English
• Subjects: activated carbon; Adsorption; Applied sciences; Biodegradation; Biodegradation, Environmental; Biofilms; Biological activated carbon; Capacitive deionization; Deionization; Exact sciences and technology; Feasibility Studies; Hydrogen-Ion Concentration; Inorganics removal; Membranes; Membranes, Artificial; Microscopy, Electron, Scanning; Organic Chemicals - chemistry; Organic Chemicals - isolation & purification; Organic Chemicals - metabolism; organic matter; Organics removal; osmosis; Other industrial wastes. Sewage sludge; Pollution; Pretreatment; Quality Control; Recovery; Reproducibility of Results; Reverse osmosis; Reverse osmosis reject; total dissolved solids; ultrafiltration; Ultrafiltration - instrumentation; Ultrafiltration - methods; Waste Disposal, Fluid - instrumentation; Waste Disposal, Fluid - methods; Wastes; wastewater treatment; Water Microbiology; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - isolation & purification; Water Pollutants, Chemical - metabolism; Water Purification - instrumentation; Water Purification - methods; Water quality; Water reclamation; water reuse; Water Supply - analysis; Water Supply - standards; water treatment; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2009.08.006

Reverse osmosis (RO) reject recovery from the water reclamation process was demonstrated feasible using an integrated pretreatment scheme followed by the Capacitive Deionization (CDI) process. The RO reject had an average total dissolved solids (TDS) of 1276 ± 166 mg/L. Water recovery of 85% with water quality comparable with the RO feed was achieved. Pretreatments using biological activated carbon (BAC) and BAC–ultrafiltration (UF) attained total organic carbon (TOC) removal efficiencies of 23.5 ± 6.0% and 39.9 ± 9.0%, respectively. Organics removal of RO reject was attributed to simultaneous adsorption and biodegradation in the BAC pretreatment, while further biodegradation in the submerged UF membrane tank provided additional organics removal. Membrane and CDI fouling was reduced by pH adjustment of the pretreated RO reject to approximately 6.5, which prolonged the CDI operation time by at least two times. The CDI process was able to achieve more than 88 and 87% TDS and ion removals, respectively, while PO 4 3− and TOC removals were at 52–81% and 50–63%, respectively.