A Study On The ATAD Sludge Reduction And Stabilization Technique

The autothermal thermophilic aerobic digestion process is the most concerned sludge reduction and stabilization technique during these days. Under aerobic conditions, by the micro-organisms own exothermic reaction, one part of the heat is to supplement the system energy consumption, the other part is to increase the reaction temperature to high-temperature reaction environment. Under high-temperature conditions the cells dissolved, and sludge can be sterilized, which reduces the number of parasites in the raw sludge. This research based on summarizing of a lot of studies and investigations on the relevant areas of sludge aerobic digestion and from a new perspective analyzed the factors that affect the digestion results of the autothermal thermophilic aerobic digestion process.The autothermal thermophilic aerobic digestion (ATAD) reactor used in this research was designed and assembled by ourselves and take advantage of the dewatered sludge of Xi'an Beishiqiao wastewater treatment center, with intermittent reaction mode and a response cycle from 13 to 15 days. By changing the operating parameters and continuous monitoring of sludge VSS, total phosphorus, total nitrogen, ammonia nitrogen, soil temperature, COD and other indicators to determine and optimize the operation parameters. The optimum operating parameters through continuous testing is that: sludge input concentration 5%~8%, aeration rate 0.4L/min～0.8L/min, stirring rate 120r/min. Under this operation condition, the temperature of sludge could be raised automatically to 48℃and the removal rate of VSS is 40.2%, DHA decreasing rate is 94.33%, which could obtain the purpose of disinfection and sludge stabilization; but the dewatering behavior of sludge is declined. Under the optimum operation condition, by monitoring the variation of DHA and COD, the effect of the autothermal thermophilic aerobic digestion process on the stabilization and disinfection of sludge was studied; by analyzing the variation of sludge specific resistivity the dewatering-ability of sludge was studied. By analyzing the variation of TOC, TP and nitrogen the reason of the incidence of cell-dissolving; by monitoring the EPS and compared with sludge specific resistivity the effect of cell-dissolving on sludge dewatering was researched. By connecting TOC and EPS variation rule the relation between cell-dissolving and protein ration was studied. By the comparative study of EPS and DHA, the bio-reorganization in the process of autothermal thermophilic aerobic digestion process was discussed.