Characteristics And Anaerobic Digestion Process Of Thermal Hydrolysis Pretreatment W WTP High-solid Sewage Sludge

The construction of Wastewater Treatment Plants becomes an integral part of the economic development of our country. With the increase of the Wastewater, the production of sludge is more and more. The effect of different temperatures and times on sludge lysing and anaerobic digestion of thermal pretreatment were researched using Biochemical Methane Potential(BMP) test.The WWTP sludge as the research object, which content was adjusted to 10%. On this basis, used the completely mixed reactor(Completely Stirred Tank Reactors, CSTRs)were used to discuss the effect of mesophilic and thermophilic anaerobic digestion on pretreatment sludge. The results are as follows:(1) Setting different temperatures(150 ?,165 ?,180 ?)and different times(20min,50 min,80min),using BMP test to analysis the removal of organic sludge, the SCOD composition, transformation of N and the gas production.The results showed the optimal pretreatment conditions for thermal anaerobic digestion is 165 ?, 50min;(2) The completely mixed reactor(Completely Stirred Tank Reactors, CSTRs) which SRT is 20 d was used to discuss the effect of mesophilic and mesophilic anaerobic digestion on pretreatment sludge.The sludge without thermal hydrolysis pretreatment was the copparision.The results showed: the gas production that the sludge without pretreate is 584.28 m L biogas/g VSSdecomposition and the VS removal rate is 21.31% during the mesophilic aerobic digestion.The gas production that thesludge without pretreate is 352.60 m Lbiogas/g VSSdecomposition and the the VS removal rate is 19.04% during the thermal aerobic digestion. The gas production that the sludge was pretreated is 4359.45 m L biogas/g VSSdecomposition and the VS removal rate is 49.40% during the mesophilic aerobic digestion. The gas production that the sludge was pretreated is only 326.15 m L biogas/g VSSdecomposition and the the VS removal rate is 28.62% during the thermal aerobic digestion.The reason of the gas production decrease is the high concentration of ammonia,which would inhibitate the active of methanogens. Finally the high concentration VFA was leading to acidification. So the thermal aerobic digestin is more suitable for pretreatment sludge;(3) By researching the facility of anaerobic digestion of the number five sewage treatment of Xi'an,the following conclusions is the digestion in poor condition.In this facility,the p H is only 7.17;the ammonia concentration is 243.3mg/L; alkalinity is 2127 mg Ca CO3/L;the VS reduction is 25.1%. Although the biogas producton is approaching the theoretical gas production,the digestion system is in an unstable state according to conventional indicators and organics reduction rate.