| With the municipal sludge production increased year by year,the problem of sludge disposal is very serious.Process of Thermal hydrolysis combined with anaerobic digestion is an effective technology to the bottleneck of sludge disposal and utilization.This paper studies the effects of the anaerobic digestion of sladge under different conditions of hot water solution,different residence time of anaerobic digestion and different inoculation sludge.and on the basis of the process design of the demonstration project,the four conditions of economic analysis,aimed at the implementation of the industrialization of the technology for the design and operation parameters provide reference.The main research contents and results are as follows:When the temperature is 90?,retention time is 24h and temperature is 140?,the residence time is 0.5h,the physical and chemical properties of municipal sludge changed greatly under this two different conditions of thermal hydrolysis.It was mainly reflected in which the pH was slightly decreased,TVFA was significantly increased by 7.2 to 8.6 times,concentration of TCOD was slightly declined,total alkalinity was increased by 0.65-1.04 times.In the condition of SRT=20d,the methane production rate of sludge after anaerobic digestion by low temperature thermal hydrolysis(90?,24h)or high thermal hydrolysis(140?,0.5h)was better than the original one.The results showed that the methane production rate of original sludge was 51.22mLCH4/VS(g.d),the low temperature thermal hydrolysis(90?,24h)was 70.39mLCH4/VS(g.d),the high thermal hydrolysis(140?,0.5h)was the highest,up to 127.24mLCH4/VS(g.d).High temperature thermal hydrolysis(140?,0.5h)combined with mesophilic(35?)anaerobic digestion process and low temperature thermal hydrolysis(90?,24h)combined with high temperature(55?)anaerobic digestion process,the methane production rate was all reached the maximum at SRT=20d with the two kinds of combined process of anaerobic digestion,and the substrate degradation rate was reached the maximum capacity at SRT=20d.For concrete:when SRT=20d,the methane production rate in the two combined process was 126.66mLCH4/VS(g.d)and 161.05mLCH4/VS(g.d),the removal rate of TCOD were 21.03%and 21.34%,the removal rate of VS was 20.46%and 25.58%respectively;when SRT=10d,the methane production rate was 120.5 mLCH4/VS(g.d)and 137.27mLCH4/VS(g.d),the removal rate of TCOD were 32.53%and 26.98%,the removal rate of VS were 33.94%and 25.82%;when SRT=5d,the methane production rate was 103.3mLCH4/VS(g.d)and 89.90 mLCH4/VS(g.d),the removal rate of TCOD was 22.35%and 20.33%,the removal rate of VS was 26.33%and 23.91%?Under the conditions of SRT=20d,the pH of mesophilic(35?)anaerobic digestion was stable between 7.36-7.55,the high temperature(55?)anaerobic digestion system was stable between 7.81-8.11.The stable ability of former was stronger and stable period was longer than the latter.However,the organic acid conversion time and anti impact ability of latter was faster and stronger in the latter starting period.Considering the safety and stability of operation and application cost,and combined with the experimental results,the feasibility with low temperature thermal hydrolysis(90?,24h)of sludge(solid content was 10%.)combined with mesophilic(35?)anaerobic digestion system under SRT=20d is considered good in the actual engineering.And then,according to the parameters obtained in experiments and in accordance with the design specifications and standards related to environmental engineering,a set of processing design calculation and process drawings for an anaerobic digestion system demonstration project which the processing scale is 5m3/d sludge(the moisture content is 99%)was completed. |
PDF Full Text Request