Research On The Technology Of Integrated Treatment Of Domestic Garbage With Sewage Sludge

With the rapid growth of the domestic garbage and the continuous increase in the sewage sludge in our country, the disposal to make them harmless resources is very urgent. When the current techniques in the domestic garbage and sewage sludge treatment were overall summarized, it was found that the complex treatment process would to some extent increase the difficulty of disposal and management and limit the resources utilization of the garbage and sludge if we treated them separately. It is considered that an integration reactor for coordination treatment of domestic garbage with sewage sludge which could provide the temperature condition for the sludge anaerobic digestion with the heat produced by the garbage could not only save lands and be easy to manage, but also save energy and produce new energy. Therefore, upon the base of the TISTD reactor, the development of an integration reactor for coordination treatment of domestic garbage with sewage sludge was introduced in this paper. The main research content included: On the base of TISTD reactor and combining the theory of garbage aerobic/anaerobic treatment, an integration reactor for coordination treatment of domestic garbage with sewage sludge was designed and developed; By taking the kitchen waste and secondary sludge as study objects, the reactor was optimized; The optimized reactor was used to treat domestic garbage in coordination with secondary sludge and the disposal effect was analyzed. The main achievements included:①On the base of the TISTD reactor and combining the theory of waste compost treatment, the design ideas and key points of the reactor were proposed. According to the ratio of actual volume of garbage production in the small town and secondary sludge production of wastewater treatment plant in the same scale town, the volume ratio of the waste compost tank and the TISTD tank was identified (1:1). The effective volume of the reactor is 440L. The design dosage rate is 30%.The sludge phased cultivation method was employed to start up the reactor at the dosage rate of 10%. The anaerobic fermentation method was adopted for the garbage treatment.②The status of the reactor during the start stage was investigated through experiment. The results showed: every part of the reactor showed no significant difference in the changing trend of the temperature during the entire experiment. But the temperature of the two tanks was relatively low. The garbage tank was always in the relatively strong acid environment. Though the garbage tank produced a lot of gas (25L/d at most) which can supplement the stir gas, the period of garbage fermentation was very long. The sludge tank also emerged serious acidification phenomenon. The treatment effect of the organic matter was not well. VS/TS only decreased from 0.4-0.8 to 0.3-0.45 and the removal rate of VSS remains in 0.18-0.25 which showed that the sustained running situation of the reactor was not very well.③According to the shortages of the reactor and on the basis of full analysis on the running effect of the reactor, the reactor was optimized. Through heat equilibrium calculation, the volume ratio of the waste compost tank and the TISTD tank was determined as 4:1.The material of the baffle between the two tanks was changed to polypropylene (PP). Insulation was also added in the exterior of the reactor. The effective volume of the optimized reactor is 710 and that of the garbage tank is 600L.The anaerobic fermentation method was adopted. The TISTD tank is fully surrounded by the garbage tank. The deodorization system was also added.④Through a lot of experiments, the running status of the optimized reactor was investigated. The results showed: the trend of temperature curve of the TISTD tank was consistent with that of the garbage tank. Compared with the garbage tank, the average temperature of the TISTD tank was about 10℃lower. The peak temperature of the garbage tank could achieved 50℃. The temperature of the TISTD tank was in the range which was very suitable for the anaerobic digestion. The pH of the reactor didn't change significantly, which fluctuated up or down from 7.0 a week after start. In the TISTD tank, VS/TS was reduced 32.2% on average and the moisture content was decreased 1.43% on average.20-30 days after the start of the TISTD tank, the gas production gradually tended to stabilization, which was about 15L/d. The specific resistivity of the discharging sludge was 7.2×1011 m/kg～7.9×1011 m/kg; The results illustrated that the reactor were running stably and the treatment effect of the TISTD tank was better than that of the garbage tank. The deodorization effect of the deodorization system against the stench which was produced during the reactor running was good.⑤The cellulase and protease activities in the garbage tank of the optimized reactor fluctuated a lot. However, the protease activities and the concentration of coenzyme F420 in the TISTD tank achieved peak value in the third day and fifth day respectively after the start and both of them remained stable in the next days.⑥The bands of the PCR-TGGE patterns of the garbage and sludge in the reactor were very clear and bright and had no obvious trail and RNA interference phenomenon, which illustrated the system contained a large number of microorganisms. In different running stage, the TGGE patterns of garbage,leachate and sludge contained diverse bands which demonstrated a higher degree of diversity in the microorganism distribution. It showed that diverse microorganisms could exist during the reactor running to ensure the TISTD has a strong resistance to shock load. The TGGE bands showed that the sludge tank had the highest degree of microorganism diversity.The research demonstrated that it was simple and feasible to treat domestic garbage in coordination with sewage sludge in the same reactor. This research finding is very significant for the further optimization of the reactor and the promotion of the reactor in small towns.