Study On Membrane Technology For Demestic Wastewater Treatment

As a global problem, the shortage of water resource has caused high concern ofgovernments. A lot of countries are trying to exploit new water resource and realizedthat both new water resource and water saving should be emphasized in order to solvethe problem. And municipal wastewater has lots of advantages such as abundant, lowtreated expense, easy treated etc. So it can be the most reclaimed water resource.In these years, with the developing of material science, the manufacture cost ofmembrane is lower and the technology of membrane has improved rapidly.MBR which is combined membrane separation technology and biological treatmenttechnology has lots of advantages, such as simple process, good effluent, high levelautomation, little excess sludge, et al. Effluent treated from MBR can fully meet thecriterion of reclaimed water, and can be used for washing toilet, pouring street andgrassland, washing cars and et al.. And continues micro filtration is also appliedrapidly for its high automatic control, low operating costs and simple operation.In the paper, a pilot-scale research on treatment of domestic wastewater fromprimary treatment was carried out using Membrane Bioreactor. The process has beenoperated for one year. During the operation, the removal efficiencies of pollutantswere investigated, and the average removal of COD, turbidity, NH3-N,and SS is 94%,99%, 99% and 98% respectively. During the lab-scale MBR, when SRT was 20d,HRT was 6h, DO was 2mg/L, the time of pump was 10min and the time of stop was3min, the removal eficiency of COD was more than 97% and that of NH3-N was morethan 94%.Studying on sludge characteristics: too long SRT and high MLSS result in a highviscosity in the bio-reactor and the concentration polarization on surface of themembrane;when the experiment runs too long, the activity of organic substancesdegradation and nitration of sludge have a decline to some extent, the reason is thatthe SMP and microbial remains in bioreactor increase.Economic analysis indicates that the total project investment is 4789yuan/m3·dand the running expenditure is 1.3yuan/m3. The two expenses are almost equal to thatof traditional wastewater treatment process.