Study On Control Technology Of Urban Sewage Sludge Aerobic Composting

With the continuous improvement of sewage treatment capacity and rate ofwastewater treatment plants sludge production also increase. However, the sludgedisposal problem of urban sewage treatment plants have long been neglected, and thedevelopment of sludge disposal is lagging behind. As a kind of traditional resourcetechnology, aerobic sludge composting process has been used in northern China.However, part of the technical process during operation is not known, part of theoperating parameters are not detailed, resulting in lower composting efficiency andunstable product quality. In this paper, aerobic sludge composting control technologywas studied by using small scale experimental apparatuses, during which the sewagesludge was taken from a wastewater treatment plant in Changchun. The two mainfactors affecting composting were investigated, such as admixtures added ratio andventilation, and relevant parameters were determined.In1.2m3/h t and2.4m3/h t two ventilations, respectively additive and sludge of2:1and3:1two kinds of volume ratio composting trials, the trials ran in two cycles,each cycle was54days. During the composting, continuous ventilation mode andregular manual churning were used. Rice husks were used as conditioning agents,and straw as bulking agents.Initial moisture content of sludge was from65%to70%, organic matter wasfrom50%to55%. through a cycle of composting test, moisture content dropped toabout35%, and organic matter declined to below30%, compost products reachedmaturity requirements. At the beginning of composting, sludge was heated andmaintained for a period of time. During composting process, pile temperature wasinfluenced by the ambient temperature.The untreated sludge had low levels ofphosphorus, and was weak alkaline. After the process of composting, phosphoruscontent significantly increased from the initial1000mg/kg rose to about8000mg/kg,pH decreased from7.8to about6.0, reached the requirements of " municipalwastewater treatment plant sludge disposal landscaping with argillaceous"(GB/T23486-2009). Daisy seeds were selected as instructing plants. The research showedthat seed germination index rose to75%from the initial45%. During compostingprocess, the GI showed an upward trend, sludge almost no inhibitory effect on cropsafter compost treated, Toxic has been basically eliminated, compost products reachedmaturity.