Design and Efficiency of a Domestic Sewage Treatment System with Microorganism-membrane on Island Based on Entropy Theory

Abstract

Domestic sewage treatment by water drainage network plus septic tank is not suitable on very small islands because of traffic and urban infrastructure problem. This study deals with a microorganism-membrane domestic sewage treatment system on small islands, which can degrade and clean the domestic sewage locally by effective microorganism and membrane system and makes the emission in market. Eight kinds of commercial complex microorganisms decompose powder were chosen to analysis the activities of protease, lipase, cellulose and amylase. And relating model based on entropy theory was constructed to evaluate the effect of enzyme activity, then the best commercial complex microorganism decompose powder was confirmed. The designed microorganism- membrane wastewater treatment system was applied to treat domestic sewage on a small island. The results showed that the removal rate of organic matters including the five-day Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD) and ammonia nitrogen (NH 3-N) reached more than 98%. The removal rate of Total Dissolved Salts (TDS) of the outlet water was higher than 99%. This system was especially suitable for small islands domestic wastewater treatment.