Effect Of Hydro-thermal Treatment For The Release Of Substances And Anaerobic Digestion In Sludge

With the development of sewage treatment in China,the yield of sludge is increased year by year,so the disposal and resource utilization of sludge are becoming hot spot of current research.In the numerous disposal methods of sludge treatment,high temperature thermal hydrolysis pretreatment technology has been widely used.The object of the research was the dewatered sludge from a sewage treatment plant in Wuhan.The changes of particle size and the contents of SCOD,ammonia nitrogen,potassium,phosphorus,heavy metal,protein,polysaccharide in the centrifugal supernatant under different thermal hydrolysis conditions?temperature,time,amount of alkaline?were investigated,the influence of different thermal hydrolysis conditions on sludge disintegration,substance release and anaerobic digestion were expored.The experimental results showed that:?1?Compared with non-thermal hydrolysis of sludge,when the sludge was hydrolyzed under 160?for 30min,the centrifugal moisture content of the sludge was reduced respectively by 2.74%,the particle size was 342-955nm,and the contents of SCOD,ammonia nitrogen,potassium,phosphorus,protein and polysaccharide in supernatant were increased by 650%,99%,122.1%,910%and 460%respectively.Although the relative content of heavy metals was increased,most of them still existed in with the solid phase of sludge.?2?When adding alkaline in the thermal hydrolysis,the sludge was hydrolyzed under 160?for 30min,the dosage of Ca?OH?₂ was 0.075 m?Ca?OH?₂?/m?VS?,compared with non-alkaline addition thermal hydrolysis,the centrifugal moisture content of sludge was decreased by 2.74%,the particle size was 1281-1990nm,and the contents of SCOD,ammonia nitrogen,protein and polysaccharide in supernatant were increased by 5.8%,3.5%,31.68%and 46.92%respectively,and the contents of potassium and phosphorus were decreased by 48.3%,34.9%respectively.The effect of different thermal hydrolysis conditions on the release of each substance in sludge supernatant were diversed.?3?By monitoring methane production in the anaerobic digestion of sludge,the optimum thermal hydrolysis condition were determined as follows:the temperature was180?,the retention time was 30min,the dosage of Ca?OH?₂ was 0.075 m?Ca?OH?₂?/m?VS?,and the total output of methane was 1150mL when the thermal hydrolysis of sludge?80m L,centrifugal moisture content of the sludge was 90%?was digestion for 30days.