Studyonurban Sewage Excess Sludgetreatmentbybiologicalcomplex

Because of the increase of municipal wastewater, large amounts of excess sludges had produced. Excess sludge treatment by biological method is now a hot research. Excess sludge is difficult to degrade because of ECPs, ECPs had a good water retention. In this study, excess sludge is treated by biological method. A few of enzymes were put to decompose excess sludge, while bacteria could use the organic matter to breed and grow rapidly and degrade the excess sludge.Enzymes were screened out to deal with excess sludge by determination of excess sludge moisture content and dissolution rate of COD. By single factor experiment, it is determined that the best additional amount of protease, amylase and cellulose are0.6%,0.3%,0.4%. By orthogonal experiment, it is finded that the best ratio of protease, amylase and cellulose are0.6%,0.3%,0.45%, and protease is more important than amylase, amylase is more important than cellulose.Through excess sludge treatment and antagonistic experiment and bacteriostatic experiment, r8, r10,11008,11017were the best strains for the treatment of excess sludge. Through the identification of strains, strain11008is bacillus amyloliquefaciens,11017is Bacillus methylotrophicus. And through a simple optimization of the medium, determined the best medium for11008and11017.By measuring the growth curve of the strain, It is determined that the best culture time of r8, r10,11008,11017are respectively14h,16h,12h,12h. By the single factor experiment, the addition of r8, r10,11008and11017are1%,5%,2%and1%.By steepest ascent experiments, the center point of response surface experiment is determined. Through Design-Expert8.0software ridge design analysis, the addition of strains r8, r10,11008and11017are1.33%,5.47%,1.93%and0.80%respectively, and the response value Y (moisture content of the excess sludge) reaching the minimum is57.66%. The average moisture content of excess sludge is58.12%, approaching the predictive value of57.66%, which proves the model was an effective data.Through single factor experiment, it is determined that the best conditions of speed, temperature and processing time are200r/min,50℃,24hours. And the best ventilation disposal of surplus sludge was2.5L/min of the fermenter.By detecting indicators, post-treatment sludge residue sludge can be applied to soil improvement, pressure filtration residue which added some trace elements, can be used as foliar fertilizer.