高回収率逆浸透法海水淡水化の提案

抄録

Two types of reverse osmosis (RO) process were proposed to obtain high recovery of fresh water in sea water desalination. The membrane parameters, the reflection coefficient o, the solute permeability P, the pure water permeability L_p, which are necessary in the process simulation were determined by experiments for three kinds of membranes commercially available, NTR-70SWC sea water desalination RO membrane, NTR729HF high flux and low rejection nanofittration (NF) membrane, NTR759HR high rejection NF membrane. Maximum pressure applied for the RO membrane in the experiments was20 MPa, and 10 MPa for the NF membranes. The NaCl concentration in feed ranged from 0.15 to 12 wt%. The process simulated were single-stage one-pass process with NTR-70SWC or NTR759HR and multistage (two or three stages) recycle process with NTR729HF and NTR759HR, and energy consumption and membrane area required were calculated. On the multi stage processes with NF membranes, both the energy and membrane area were almost the same, but the single-stage processes with NF or RO membrane required less energy and more membrane area, especially the membrane area for the process with 70SWC was much more than that for other processes because of the small L_p value.