Application Of Immobilized Biocatalyst To Sludge Reduction In Municipal Wastewater Treatment Plant

The activated sludge process is the most popular method in wastewater treatment plant,which will be resulted with a large number of by-products_excess sludge. Excess sludgecontains pathogens, heavy metals and residual organisms, being harmful to people and theenvironment. What's more, it could cause secondary pollution if not being treated properly.The extremely high disposal expense of sludge also becomes one difficult problem for themunicipal wastewater treatment plant and the city development. Thus, developing aneconomic and efficient technology for sludge reduction is of very important practicalsignificance.In this thesis, bioaugmentation is used in the sewage treatment system with immobilizedbiocatalysts to achieve sludge reduction from the sources. The catalyst through theimmobilization technology will be able to make a multi-functional microbial agents by fixingon wheat bran by the amylase, lipase, protease, cellulose enzyme, lactose enzyme and lacticacid bacteria and yeast, bacillus, etc. Adding IBC to the sewage treatment system couldoptimize the microbial colonies structure, promote the rapid mineralization and degradation oforganic matter in the sewage treatment as well as make it into harmless substance as CO2,H2O, and N2. Because of the low concentration of organic matter, most of the sludge in thesystem is in the endogenous respiration state with high oxidation rate, producing less excesssludge, achieving the sludge reduction of sludge from the sources.This paper using immobilized biocatalysts(IBC) as research materials to carry out smallscale and pilot test. The contents and conclusions are below:(1) Immobilized biocatalysts used in Sequencing Batch Reactor (SBR) to study thesludge reduction. The results showed that sludge reduction of dosing group is55.28%lessthan contrast group. At the same time, the treatment effects of COD, NH3-N, TP of dosinggroup were better than the contrast group. The average removal rate of TP is7.21%higherthan the contrast group. From The31th to the80th days, MLVSS/MLSS of dosing group was8.50%lower than the control group.(2)Immobilized biocatalysts was applied in a municipal wastewater treatment plant ofzhongshan tested for142days. The outcomes showed that sludge production of the dosing pool was76.79%less than the contrast pool and discharged63.58%less sludge. After dosingIBC for a month,sludge concentration reduced gradually. About75days later, sludgeconcentration was about1600mg/L and50%lower than the contrast pool. From the secondmonth, the sludge emission reduced gradually. There is no discharge sludge in the3rd and4thmonths. From the31th to142th days, the average value of MLVSS/MLSS of dosing pool was6.74%lower than the contrast pool. Moreover, the effluent quanlity of dosing pool was betterthan the control pool. The mean removal ratio of TP increase by11.73%.The amount of TP insludge of dosing pool is0.76%higer than contrast pool, saving11.44%electricityconsumption.(3)Pilot study of adding immobilized biological catalyst (IBC) in a municipal wastewatertreatment plant of Guangzhou. The results showed that the sludge production of the dosingpool is21.04%less than the contrast pool. And the sludge sedimentation of dosing pool wasimproved. After40days of the experiment, the sludge concentration reduced gradually. Thevalue of MLVSS/MLSS of dosing pool was6.24%less than contrast pool. From the40th daysto the106th days, dosing tank was8.33%lower than the control pool. What's more, waterqualitys, such as pH, SS, COD, NH3-N, TP of dosing pool were superior than control pool.Average removal rate of TP was6.30%higer than the contrast. Dosing pool consume13.24%less electricity and the sludge resistance was47.14%lower than the contrast pool.(4)By the sludge microscopic experiment, the results showed that the morphology ofactivated sludge in dosing pool was significantly changed. The sludge flocculation was tighterand bigger than contrast pool. Results also showed that the immobilized biological catalysthas an effect on the type and quantity of dominant species of the biochemical system. Itstrengthened the function of the activated sludge, promoting the organic decomposing intoCO2and H2O, which reduced the excess sludge.(5) The benefit analysis indicated that adding immobilized biological catalyst was a kindof economic and efficient technology that realized the sludge reduction from the source.What's more, it also produces economic, social and environmental values.