Based On Thermal Hydrolysis And High-Solid Content In Ammonia Recovery Of The Sludge Anaerobic Digestion Process Improvement Research

With the city sewage treatment plant sludge volume increased year by year,the sludge treatment and disposal problems facing a severe test,the conventional sludge treatment process has been unable to meet the current demand,hot water solution and the anaerobic digestion process for treatment of high solid content sludge has obvious advantages.In order to improve the stability of sludge treatment system,both at home and abroad to carry out related research of solid sludge thermal pretreatment and anaerobic digestion process of high water,optimization and system stability etc.mainly in process parameters,and to solve the control problem with high nitrogen and phosphorus fixation in sludge related research.This paper takes Xi'an city fourth sewage treatment plant sludge dewatering treatment,the separation of ammonia solution hot water pretreatment device,the design of different alkali dosage and time of orthogonal test,through the organic compound hydrolysis rate,total nitrogen and total amount of methane production indicators such as the optimal separation of ammonia pretreatment thermal hydrolysis.The optimal solution of hot water ammonia separation pretreatment(0.05gCaO·gTS^-1-90min)after the use of the sludge to the middle temperature and high temperature two completely mixed anaerobic digestion reactor,the design of SRT for 20days,on the anaerobic digestion process of carbon,nitrogen and phosphorus transformation rules.At the same time,for the study of anaerobic digestion reactor ammonia inhibition,different ammonium chloride dosage,the biochemical methane potential?Biochemical Methane Potential,BMP?test in accumulative gas production,conversion rate of organic matter and other indicators,the inhibitory effect of threshold ammonia test in anaerobic digestion reactor,and cause digestive reaction the reason for the low rate of carbon conversion,to provide a theoretical reference for the engineering application of high solid content sludge thermal pretreatment and anaerobic digestion process.Main conclusions are as follows:?1?By using different alkali dosage and time of ammonia separation hot wat er pretreatment orthogonal test analysis of high solid content sludge,SS,VSS aft er the reaction,the hydrolysis rate of average COD dissolution rate,soluble total nitrogen,the hydrolysis rate of cumulative methane production index that 0.05g CaO·gTS^-1-90min?0.15gCaO·gTS^-1-150min?0.2gCaO·gTS^-1-90min three group was b etter.Due to the effect of three groups are similar,considering the amount of alka li,pretreatment time and operating costs and other conditions,the final choice of 0.05gCaO·gTS^-1-90min solution pretreatment scheme for optimal separation of ammonia water,and as the operation parameters of anaerobic reactor.?2?The water solution of ammonia separation after pretreatment of sludge anaerobic digestion reactor COD from dissolved form,two reactors for biogas production 0.28-0.40m³·kgVSS^-1,>0.75m³·kgVSS^-1,indicating that it is not efficiently converted into organic compounds the biogas,adding CaO as alkaloids water solution pretreatment can effectively improve the efficiency of anaerobic digestion.?3?Due to the addition of a certain amount of Ca²⁺in the early stage,phosphate precipitation was generated from the sludge in the reactor,resulting in an increase of insoluble phosphorus in anaerobic digestion.Phosphate precipitation can be carried out with the digestive juice.After dehydration,the phosphorus content in the filtrate decreases,and the phosphorus content in the mud cake increases,thus achieving the purpose of controlling the phosphorus content in the digestion reactor.?4?According to the literature report,in the ammonia nitrogen(>3300mg·L^-1)under the condition that may lead to reactor ammonia inhibition,but this experiment was due to the early separation of ammonia hot water of high solid content sludge hydrolysis pretreatment,the ammonia nitrogen content of two stage anaerobic digestion reactor is reduced to 3880mg·L^-1 and no ammonia inhibition test and sludge ammonia inhibition threshold.?5?Ammonia inhibition threshold of anaerobic digestion of high solid sludge was studied.The threshold of ammonia inhibition was 4700mg·L^-1.?6?Through analysis of COD hydrolysis rate,acid production rate,methane production rate and other indicators,it is concluded that hydrolysis stage is the rate limiting step of anaerobic digestion of high solid sludge.At the same time,the inefficient conversion of protein is an important factor in the rate of hydrolysis rate.