Treatment Of LAS Wastewater By Ultrafiltration Membrane And Immobilized Cells In Bioreactor

An immobilization technique called "CA-CaCb method" was used for the preparation of immobilized cells. Biodegradation of LAS by immobilized cells was studied at different temperature, pH, cell diameter and bacteria quantity. The suitable operational condition of biodegradation of LAS by immobilized cells was given: T=20~35癈; pH=5~9; the less the diameter of immobilized cells was, the higher the ratio of LAS biodegradation was; when bacteria quantity increased from 1 per cent to 4 per cent, the ratio of LAS biodegradation only raised 11 per cent, while the strength of immobilized cells decreased clearly. When suitable Ca2+ was put into the wastewater, the strength of immobilized cells didn't change in a long time and immobilized cells, were prevented from spoilage and could be used repeatedly.In batch fluidized bed reactor, the best operational conditions of LAS biodegradation were investigated by orthogonal test. At these conditions, the biodegradation rate of LAS was maximum and LAS biodegradation by immobilized cells confirmed to zero-order equation.Tests in successive fluidized bed reactor displayed that rate of LAS biodegradation was different in the different HRT. Immobilized cells in successive fluidized bed reactor could remove LAS quickly. This reactor showed high resistance to the shock loading of LAS.Through the experiments, nanofiltration membrane had the highest retention of LAS and ultrafiltration membrane's retention decreased with the retention molecular weight increasing. Ultrafiltration membrane was contacted to concentrate the LAS wastewater. With the feed concentration increasing, water flux continually decreasing. While LAS and CODcr concentration did not raise doubly and retention rate some-what increased.The process that the LAS wastewater was pretreated by the ultrafiltration membrane and then was treated by fluidized bed reactor, which was filled immobilized cells, could not only benefit environment but also benefit the economy and society. It would be prospective process that treats LAS wastewater.