Simulation Study On Anaerobic Digestion Process Of Urban Sludge Based On ADM1 Model

With the increase of sewage treatment capacity,sludge as a "derivative " of sewage treatment has also increased dramatically.At present,the sludge anaerobic digestion technology is a very widely used method for sludge reduction,stabilization and recycling,but its application rate is very low in China.This paper analyzes the material balance in the anaerobic digestion process.In order to improve the treatment effciency of the digestion tank,the paper uses the ADM1 mathematical model launched by the International Water Association and take the fifth sewage treatment plant in Xi'an as the research object to simulate the digestion process.The main conclusions are as follows:(1)The material balance analysis of COD component and C component was carried out on 19 biochemical kinetic processes of anaerobic digestion;the mass balance equation of component in each state component i in the reactor unit was listed;ASM1 was listed The principle of component conversion between the two models of ADM1 and ADM1,and explain the conversion steps.(2)Taking the sludge anaerobic digestion system of Xi'an Fifth Sewage Treatment Plant as the research object,a sludge anaerobic digestion process model was established and related sensitivity parameters were corrected,and the corrected model was fitted with actual operating data good.(3)Based on the sludge single-stage anaerobic digestion process of the original sewage plant,an improved process of two-stage anaerobic digestion and two-phase anaerobic digestion is proposed.It can be seen that,under the condition that the water content of the sludge is 96%and the hydraulic retention time is 20 days,compared with the single-stage anaerobic digestion process,the two-stage anaerobic digestion process of sludge increases the gas production of the digester from 2000m3/d to 2381m3/d,where the volume fraction of methane gas increased from 61%to 62%.Compared with the single-stage anaerobic digestion process,the two-phase anaerobic igestion process of sludge increases the gas production of the digester from 2000m3/d to 3647m3/d,and the volume fraction of methane gas increases from 61%to 64%.(4)Analyzed the influence of the moisture content of the sludge and the sludge ratio on the operation of the two anaerobic digestion processes,mainly from the pH gas production in the digester,the proportion of methane gas components,the microorganisms such as hydrogen degraders and acetate degraders,and the VSS removal rate,to optimize the process operating conditions.Comprehensive consideration shows that for the two-stage anaerobic digestion process of sludge,the optimized process operating conditions are:the water content of the sludge is 94%,and the sludge feed rate is 6%.For the sludge two-phase anaerobic digestion process,the optimized process operating conditions are:the water content of the sludge is 93%,the hydraulic retention time of the acid-generating phase is 3 days,and the hydraulic retention time of the methane phase is 10 days.