Study On Hyperthermophilic Aerobic Composting Technology Of Sewage Sludge

The hyperthermophilic aerobic composting inoculated with external hyperthermophilic bacteria is applied to treat sewage sludge above 80 °C,which can effectively improve the shortcomings of traditional aerobic composting of sewage sludge,such as low composting temperature,slow temperature rising and long fermentation period,and accelerate resource utilization process.However,few studies are available about the composite thermophilic bacteria agents and sewage sludge hyperthermophilic aerobic composting.In this study,functional thermophilic bacteria and hyperthermophilic bacteria,which can adapt to different temperature stages of composting,were screened and identified.To explore the effect of hyperthermophilic aerobic composting was accomplished by the mixed composting of sewage sludge,rice husk powder and composite thermophilic bacteria agents.The main results are as follows:1)The thermophilic bacteria TZ-1,TD-4 and the hyperthermophilic bacteria HX-4were screened by plate dilution method and streak plate method.The results of hydrolytic circle experiment indicted that TZ-1、TD-4 and HX-4 had great fat,protein and cellulose degradation abilities,respectively.Using the molecular biology identification of 16 S r DNA,TZ-1,TD-4 and HX-4 were identified as Baenibacillus barengoltzii,Bacillus licheniformis and Geobacillus thermodenitrificans,respectively.2)The suitable growing conditions of TZ-1/TD-4/HX-4 should be selected as the temperature in 45 °C/50 °C/65 °C,the p H in 7.5/7.0/7.0 and the rotation speed in 200rpm/200 rpm/190 rpm in 24/34/32 hours.The hyperthermophilic aerobic composting was accomplished by inoculating the 122 bacterial agents with the ratio of TZ-1: TD-4: HX-4in 1:2:2.3)Compared with blank control group(SSC),the sludge rice husk powder composting experimental group(ZDX),inoculated by 122 bacterial agents,have been accomplished the hyperthermophilic aerobic composting with rapid heating rate,a maximum temperature of 85.25 and 5℃-day hyperthermophilic period(≥80 °C)during the 21 st day of composting.The decreasing rates of contents of fat,protein and cellulose in ZDX(69.2%,50.5% and 26.81%)were faster than those in SSC(23.14%,17.8% and5.21%).Additionally,according the Disposal of Sludge from Municipal Wastewater Treatment Plant-Quality of Sludge used in Gardens or Parks(GB/T 23486-2009),the composting product of ZDX achieved the corresponding quality standards.Instead,the product of SSC needed longer composting period to accord with standards.