Application of seawater dilution process to SWRO filtration system for low-energy desalination

摘要

This study evaluated possible application of a seawater dilution process (SDP) to a seawater reverse osmosis (SWRO) filtration system for low-energy desalination. The main experiments of this study are to find the effects of the SDP in an SWRO filtration process to reduce seawater salinity. The measured total dissolved solids values were 29,640 mg/L for seawater, 8,720 mg/L for brackish water, and 2,896 mg/L for treated sewage water. In the experiment, two multiple water were blended with seawater to lower salinity. First experiment was conducted seawater with brackish water and found an increase in the permeate flux at 9.6% in the SWRO process. Second experiment was conducted seawater with treated sewage water and delivered an increase in the permeate flux at 12.9%. During the ultrafiltration (UF) operation, the pressure applied in diluted water increased rapidly comparing to seawater because the high concentrations of particulate and organic matter were detected in pretreatment of UF and main treatment of SWRO due to high silt density index and total organic carbon value in supplemental water. Therefore, to optimize application of the SDP, fouling effects should be considered for a longtime operation in membrane processes.