Study On Sludge Reduction And Growth Characteristics Of Function Microbe

Removal of organic pollutants is always accompanied with sludge yield inactivated sludge process.As China’s rapid devolopment in sewage treatment, alarge amount of excess sludge will inevitably be produced, which posed a seriouschallenge to wastewater treatment plants from both operating costs andenvironmental security. Based on that, extensive and in-depth research for sludgereduction technologies have been carried out at home and abroad. Among thesetechnologies, Researchers are gradually paying more attention to the microbialenhancement technology. To filter fine microorganism and investigate differentmicrobial strains’ sludge reduction efficiency is a key in the application.After a review of relevant literature and summarizing previous work, theresearch selects yeast E7, lactobacillus L2, Bacillus B135as the research objects.In the sludge increase experiment at high F/M and low F/M conditions, the bestrespective dosing quantity of each strain were got. The sludge reduction rates ofhigh F/M conditions are27.87%,18.56%,32.23%and low F/M conditions are16.07%,11.73%,4.45%. Sludge reduction of yeast E7and Lactobacillus L2rootsin less MLVSS increment. Sludge reduction of Bacillus B135roots in consumingmore COD. Mixed culture experiment showed best mixture ratio of functionmicrobe, yeast E7:Lactobacillus L2:Bacillus B135should be10~4CFU/mL:10~4CFU/mL:10~2CFU/mL. Experiment also show that both respective functionalmicrobe cast and mixed culture cast can significantly affect the content of proteinand polysaccharide of EPS.As the sludge load increases, the effect of mixed culture gradually increased;the higher concentration of sludge, the lower sludge reduction rate. When usingwastewater as substrate, sludge reduction rate by mixed culture cast is lower thanthe glucose substrate test. Best acting temperature of mixed culture was23~31℃,and the optimal pH was6.0to7.5.By investigating the affect of functional microbe to endogenousmetabolism of sludge system, the research show that an appropriate dosingquantity of yeast E7or mixed culture can increase the endogenous metabolic rateof sludge system, and promote the reduction of sludge biomass. Through data ofthe sludge proliferation bench-scale test and experiment of endogenousmetabolism to determine the microbial growth kinetics parameters: attenuationcoefficient of the control group is0.0049, the real growth rate is0.407, attenuation coefficient of mixed culture group is0.0055, real growth rate is0.3329.The optimal culture conditions: culturing time of yeast E7, Lactobacillus L2and Bacillus B135were20h,20h and8h; the growth temperatures were30℃,35℃and35℃, initial pH were6.0,6.0and7.0. For complex solid agents, theoptimal mixing ratio of carriers and bacterial suspension was3:1, yeast E7andLactobacillus L2optimal drying temperature was37℃, Bacillus best dryingtemperature was42℃. The complex solid agents can be preserved at roomtemperature for3months under sealed conditions. For complex microbialpreparation,2%glucose,1.5%corn steep liquor powder,0.2%MgSO4,0.2%CaCl2were selected as fermentor culture medium, with different inoculation timeand inoculation ratio, initial pH6.0, temperature25℃, aeration in1:0.3, stirringrate60r/min continuous culture for20h, the biomass of yeast can be achieved10~8CFU/mL, the biomass of lactobacillus and bacillus were10~8CFU/mL and10~6CFU/mL.