Study On Saline Sewage Treatment Test By Membrane Bioreactor

Membrane bioreactor(MBR) is a new kind of efficient biological treatment technology, which combining the membrane separation technology with biological treatment. It has many advantages compared with other water treatment technology. In recent years, many researchers have kept a watchful eye on membrane bioreactor processes. in sewage have been tested. This test used membrane bioreactor to treat the sewage containing inorganic salt (analysis pure NaCl). Monitor the removal rate of organic matters(COD) and nitrogen, membrane flux and so on, along with the increaseing of system salinity.First,conduct a static test. Adding the salinity gradually take 0.5% (salt content 5g/L) as the changing gradient. Monitor the microbiological activity and the change of MLSS. The result showed that as the salinity is at most 3.0%, the changes of the flocculence and subsidence of sludge performance has no obvious changes. When the salinity is 3.0%, there had some thickness yellow smooth sludge, which no longer exist as activated sludge floc. But when this sludge separated from the reactor, it still had the subsidence performance. The supernate startd to turn muddy at this salinity environment. With the increasing of salinity, the sludge intermixture looks to be nigrescence, the supernate is also turns opacitas. When the salinity is 5.0%, the subsidence and flocculation of sludge almost lost, the supernate is very muddy. When the salinity suddenly reduced too much from 5.0%, the sludge becomes deterioration thoroughly, the flocculence and the settleability hardly lost, the supernate is extremely opacitas. Then we had a result, the high salinity or the salinity suddenly changed would suppress the microorganism's metabolism function and the flocculence of sludge. And the influence that changes from the high salinity to the salt-free environmental is much bigger.Then,the dynamic test is conducted. Take 0.5% salinity as the change grads, adding the salinity gradually from the salt-free to the salinity 4.0% environment. Monitor the removal rate of COD, NH3-N, TN; watch the changes of the MLSS and membrane flux. And then sum up the affect of salinity to the treatment of saliferous sludge. The results show that when the salinity is 0.5%,1.0%,1.5%,2.0%,2.5%,3.0%,3.5%,4.0%, the COD average removal rate is 84.0%,81.8%,78.1%,76.0%, 75.5%,74.4%, NH3-N average removal rate is 91.9%,90.6%,90.1%,87.7%,87.1%,89.7%,84.0%,79.5%, TN average removal rate is 47.1%,41.1%,35.7%,33.8%,31.2%,30.3%,27.8%,25.1%.Membrane pollution is mainly aroused of extracellular polymer secretion of microorganisms in this system. The salinity has influence to membrane fouling is mainly due to the salinity of system has a great influence on the microbial metabolism. As salinity increasing, the concentration and viscosity of sludge, as well as concentration of extracellular polymer secretion in the system all increase, which leed to the speed of membrane fouling expedite.