Methane Production From Semi-continuous Anaerobic Digestion Reactor Using Municipal Sludge Pretreated By Low Temperature Thermal Hydrolization

The large amounts of municipal sludge is generated from waste water treatment plants year by year.and it is difficult to be dealed.Sludge can be minimized,stabilized and resourceable by anaerobic digestion.However,the efficiency of anaerobic digestion of sludge is not high,which limits its application in dustrial.Low-temperature thermal hydrolysis sludge can increase the effective content of organic matter in the sludge,which can improve the efficiency of anaerobic digestion.There are few researches on the start-up and operation of the reactor for anaerobic digestion of sludge.The start-up of anaerobic digestion reactor through different start-up modes,in different sludge retention time comparison of gas production and degradation of organic matter and substrate changes,providing the optimum parameters for the demonstration project.Through the comparison and further explore the thermophilic anaerobic digestion in the trial operation parameters and digestibility.The results were as follows.In the process of replacing the material with a thermally hydrolyzed sludge,and gradually feeding into the primary feed start-up reactor,the average methane yield of the system was 171 L/kg·VS,50 L/kg·VS and 10 L/kg · VS,respectively.Step-by-step start-up mode requires a longer start-up time,and the feeding mode is the shortest.The methane concentration of semi-continuous operation system unnder the three start-up modes was between 65%and 75%.In the case of replacement material,the stability of the SRT of 15 d is better,SRT is 10 d and 20 d,the SRT of 5 d is the worst,SRT is 15 d and 10 d gas production is better,respectively,to 191 L/Kg·VS and 224 L/kg·VS;The stability of the system was better at 20 days,15 days and 10 days,and the average methane yield was 223 L/kg·VS.for 15 days and 10 days when the SRT was poor and 240 L/kg·VS.The stability of the SRT is slightly worse than that of the other two methods.The stability of the SRT is 15 d and 10 d is relatively good,and the gas production is better when the SRT is 10 d and 15 d,Respectively,at 181 L/kg·VS and about 227 L/kg·VS.The thermophilic anaerobic digestion of the replacement material showed that the concentration of methane was about 75%and 200 L/kg·VS,and the degradation rate of organic matter was 21%?25%.Compared with the untreated sludge,the biogas production rate was only 44L/kg·VS,but the degradation of organic matter was increased by about 1 times.Anaerobic digestion under the same load:heat treatment sludge high temperature anaerobic digestion>heat treatment sludge medium temperature anaerobic digestion>untreated sludge high temperature anaerobic digestion>untreated sludge medium temperature anaerobic digestion.The results showed that low temperature thermal hydrolysis sludge gradually feed the reactor was best through the comparison of the different starting modes and the residence time on the basis of the stability of the integrated system,methane production and the degradation of organic matter.The SRT was performed at 15 d(feed organic loading at 2 kg·VS/(m3·d)?3 kg·VS/(m3·d))with semi-continuous operation with the best efficiency.