| Traditional sludge anaerobic digestion retention time is long,low efficiency,high water content,high energy consumption and disposal costs.Pretreatment can improve the hydrolysis rate and strengthen the sludge anaerobic digestion.Two-phase anaerobic digestion is a relatively low-cost and efficient sludge treatment method.In this paper,the optimization of the two-phase anaerobic digestion process parameters of high-solid sludge was studied.The excess sludge with total solid content of 10% was used to study the dissolution of sludge,the dissolution of organic matter and the promotion of the acid production stage.The hydrolysis rate and VFA formation of VSS,SCOD,carbohydrate,protein under different HRT were studied.Based on the study,the rule of C,N and P transformation in acid phase,respectively at 55°C and 70°C were studied.The following conclusions were drawn from the comparison of anaerobic digestion with conventional single phase anaerobic digestion at intermediate temperature of 35℃:(1)55 ℃,70 ℃ hydrolysis of acid phase HRT TS,VS hydrolysis rate of little effect,TS hydrolysis rate was 12.21% and 25.13%,VS hydrolysis rate was 16.86% and 27.74%.(2)Carbohydrate is easier to elute relative to protein at 55 ° C.The hydrolysis rate of protein and carbohydrate during hydrolysis at 70 ° C is improved at 55 ° C.The SCOD of the high-solid-containing residual sludge was completely completely eluted after 2 days of hydrolysis,and gradually increased with the gradual increase of HRT to the gas phase.(3)VFA is mainly C2 ~ C5 organic acid that is short chain volatile fatty acids,the concentration of the order of acetic acid> propionic acid> isovaleric acid> isobutyric acid> n-butyric acid> n-valeric acid.VFA generated from the sludge after 5 days from the beginning of the VFA remained stable,so the time to determine the hydrolysis of acid for 5 days.(4)Carbon,nitrogen and phosphorus show different conversion rules during ultra-high temperature anaerobic fermentation.The nitrogen in the acid-producing acid phase is mainly in the form of organic nitrogen,and most of the organic nitrogen is not converted to the liquid phase.The hydrolysis rate of the insoluble organic nitrogen is lower than 70 ℃ at 55 ℃ in 6 cases.Phosphorus in the process of hydrolysis to basically maintain a balance,only a small amount of orthophosphate generated.(5)from the pH,ammonia nitrogen,alkalinity,VFA,R1 reactor(10% sludge by hydrolysis at 70 ℃ acid(HRT = 5d))and R2 reactor(10% sludge directly at 35 ℃ temperature Oxygen digestion(HRT = 20d))were stable.The average removal rate of VS in R1 reactor was maintained at 43.03%,which was much higher than that of R2 reactor 23.86%.(6)From the gas production point of view,R1 gas production rate of 500 ml / L · d,equivalent to R2 production rate of 2 times;R1,R2 decomposition unit mass VS gas production were 0.44m3/kgVS decomposition And 0.47m3/kgVS decomposition.The determination of the gaseous components and the methane content in the biogas component of R1 is also higher than that of R2,which indicates that the high residual solid sludge after hydrolysis is more easily methominated. |
