Integrated pretreatment with capacitive deionization for reverse osmosis reject recovery from water reclamation plant.
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.
Lee
Lai Yoke
LY
Centre for Water Research, Division of Environmental Science & Engineering, Faculty of Engineering, National University of Singapore, Singapore.
Ng
How Yong
HY
Ong
Say Leong
SL
Tao
Guihe
G
Kekre
Kiran
K
Viswanath
Balakrishnan
B
Lay
Winson
W
Seah
Harry
H
D000327:Adsorption; D001673:Biodegradation, Environmental; D018441:Biofilms; D005240:Feasibility Studies; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D009930:Organic Chemicals / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D011786:Quality Control; D015203:Reproducibility of Results; D014462:Ultrafiltration / Q000295:instrumentation / Q000379:methods; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*; D014881:Water Supply / Q000032:analysis* / Q000592:standards
D008567:Membranes, Artificial; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical