Abstract
For the purpose of the pretreatment of sea water for electrodializer with an ion-exchange membrane for a long time, authors studied on the secondary sea water filtration by the three companies' membranes of superfiltration and ultrafiltration.
The results were as follows:
1) The permeate flux of K, P and S companies' membranes was 280,100 and 200l/m2·h·atm, respectively.
2) On the permeate quality, the decreasing rate of number of suspended matters to the first sand filtrate was over 94%, and the decreasing rate of iron content was in the range of 46-64% except the measured value of P company's membrane at 0.5kg/cm2.
3) In regard to the resistance of permeation, K company's membrane is the least at non adherence on the membrane, but in case of the suspended matters adhered on the membrane, the resistance increases, and the permeate flux has a tendency to decrease as compared with other two membranes.
4) The effective washing method of membrane is a dipping method in sodium hypochlorite solution or sodium hydrooxide solution for two hours, and then the permeate flux recovers about double over the previous level.
5) The quality of the treated sea water by three companies' membranes are fitting for the electrodializer with ion-exchange membranes. But it is considered that the practical use is difficult because of its small scale of apparatus and its high washing cost at the present time.
