The Screening Of Microorganism Using For Sludge Dewatering And Sludge Reduction And Their Applied Research

At present, excess sludge has become an environmental problem while high moisturecontent, large volume and low dewaterability. This work adopts microbial technology toachieve the purpose of reducing the volume of excess sludge.This paper obtains46strains of mold and25strains of bacteria isolated from the pond ofa lake and gets49strains of mold and35strains of bacteria isolated from the sediment of apool, and then the screening of the microorganism suitable for sludge dewatering and sludgereduction are done respectively.1. the microorganism suitbale for sludge dewatering（1） The screening obtains the mold of M14, M15and the bacteria of Z4, Z11and Z22,all of which have been isolated from the pond of a lake; the mold of D20, D41and thebacteria of C32, C34, which have been isolated from the sediment of a pool. Rescreening getsthe strain M14, D41and Z4, they make the sludge specific resistance reduce by56.8%（12h）,49.1%（24h） and52.7%（48h）, respectively. Compound and UV mutagenesis can′tmake the sludge specific resistance decrease, so the D41is chosen as the optimalmicroorganism for sludge dewatering.（2） The experiments in the condition of the cultivation of strain D41show the sucrose（carbon source） is25.0g/L, NaNO3（nitrogen source） is3.0g/L. The experiments in thecondition of the application confirm the sludge specific resistance reduce56.7%when theinoculum size is20%, pH is6.0, speed is120rpm, temperature is25℃.（3） The moisture content reduces to78.3%under the fundition of D41. The analyses findthat the MLVSS and TOC of sludge decrease first and then increase with time, and the TOCof filtrate increases by time. The polysaccharides of EPS （extracellular polymeric substance）in sewage sludge lessens significantly, but the protein doesn′t change obviously when addingthe mold of D41. The moisture content drops due to the reduction of polysaccharides.（4） Coupling of the D41and the Fenton reagent can reduce furtherly the sludge moisturecontent （72.5%）. The assessment of risk finds that the Fe²⁺almost deposites in the sludge, thecontent of H₂O₂in the sludge and filtrate can meet disposal requirement. 2. the microorganism suitbale for sludge reduction.（1） The screening finds the mold of M16, D40and the bacteria of Z5, Z25isolated fromthe sediment of a lake and the bacteria of C35isolated from the pond sediment of a pool, theycan make the solid content of the sludge reduce. The rescreening shows bacteria of C35andZ5make the solid content of the sludge reduce. The bacteria of C35is chosen as the optimalmicroorganism for sludge reduction after the compound.（2） The removal efficiency of MLSS is10.4%under the fundition of C35when initialconcentration of the excess sludge is13000mg/L, temperature is30℃, pH is8.0, speed is150rpm. Attributing to a lower pH value caused by the metabolites of C35, which enhancesthe dissolution of sludge, therefore the sludge reduction is obtained.