Study On Vermicomposting Of Urban Sewage Treatment Plant Sludge

With rapid urbanization and economic growth, urban sewage treatment business has been rapid development, sewage sludge production increased rapidly year by year, which has brought greater challenges on sewage sludge treatment and disposal. The development of new disposal technology, to make sludge to get timely and effective treatment and resource utilization, has become a hot research at home and abroad. Using sewage treatment plant sludge as the research object, it was studied that the influencing factors and the fertility of sludge after treated by Vermicomposting,which was expected to provide a reference to the whole process of trial and detailed data to support related research.Three factors and three levels orthogonal experiment results showed that:when the temperature is higher than32.9℃, it was feasible that earthworms treat pure sludge (control group); under high temperatures, earthworm biomass growth of each test group was severely limited. In the condition of moisture content of70%, earthworm stocking density of0.20g/cm2, C/N of25, earthworms daily growth multiples was lowest to-0.012d-1,while the control group earthworms daily growth multiples was-0.002d-1, greater than the test groups; moisture content played an important role on the degradation of organic matter, the three experiental groups with70%moisture content had the highest organic matter degradation rate in the test group; vermicompost production rate and had an unpositive correlation relationship with mixed matrix degradation ratio.This paper focused on the influence of different earthworm stocking density on physicochemical properties and nutrient content of pure sludge. It was showed that: Vermicomposting can significantly reduce sludge organic matter content, but it was not obvious for moisture content reducing, raise TN and TP contents of sludge and had the same influence on available nitrogen and phosphorus obviously; earthworm stocking density had significant influence on earthworm growth. The biggest earthworm daily growth multiples was 0.0746d-1, and the strongest reproductive capacity was7.4egg cocoons every one earthworm, when earthworm stocking density was10earthworm every kilogram sludge.Vermicompost maturity was investigated through cabbage seed germination experiment. The results showed that:the sludge after earthworm treatment basically reached maturity, and the overall effect is better than the control group. That sludge and soil ratio was5%promoted seed growth significantly, and the value of each group seed GI were all greater than100%. within a certain range, the amount of sludge applied had an evident effect on seed germination potential, but little effect on seed germination rate.