Treatment Of Excess Sludge By Peracetic Acid

With the waste water discharge rises continuously in China, the efficiency of treatment is significantly improved. As time, a lot of sludge is also accompanied. Sludge treatment has become the current high-profile problems. Sludge formed by a variety of microorganisms, contains a large number of recalcitrant organics, highly perishable.Anaerobic digestion is one of the commonly used method of sludge treatment and considered as the best way to decreasing and reusing waste activated sludge. Anaerobic digestion is a very slow process, caused a great deal of pressure on the environment in the treatment. But the hydrolysis of sludge solid is the key step of sludge aerobic digestion. This is due to the cell wall structure of the sludge hindered easily degradable substances hydrolysis in cells. To solve this problem, it is necessary to adopt a variety of ways to crack the cell wall, damage the cell membrane structure, intracellular substances released to improve the rate of hydrolysis. Peracetic acid as a clean oxidizing agent sludge, the sludge is not only achieved remarkable results in the crack in the cell wall, but also improve the effect of anaerobic digestion.Effects of PAA treatment on characteristics of sewage sludge were investigated in this paper.. The effects of different operation, such as reaction time, dosages of PAA were mainly investigated to sludge. treatment condition. The concentration of SCOD, TN,TP, NH4+-N, protein and sugar in sludge solution after PAA treatment were compared with the raw sludge, And the effects of anaerobic digestion after PAA preprocessing were also investigated. Effect of pretreatment on the biogas production and the SCOD、TP、VSS、VFA and alkalinity of sludge solution were analyzed, too.The results showed that PAA combined with continuous mixing treatment accelerated the lysis of sewage sludge. In the optimal operation, churning time of120min, the PAA dosage of30g per kg SS, the sludge dissolving ratio increased to24.5%. In this operation, more microbial extracellular polymeric substances were decomposed, and more intracellular material were released to the liquid phase. The concentration of SCOD increased to818mg/L which were respectively about6.5times as compared with the initial one. The concentration of TP、TN、NH4+-N increase1.8times、1.2times and1.2times respectively, The protein contents、the sugar contents and increase53%、49%and respectively. Pretreatment of excess sludge by peracetic acid in anaerobic digestion, Average daily rate in anaerobic digestion of excess sludge not only is more than the untreated sludge, and the occurrence of peak gas production has also brought forward. Total gas production also increased by20%than that of without pretreatment. The concentration of SCOD is increased. In addition, The concentration of VSS decreased by around10.4%, opposite and change trend with SCOD. Various acids released into the liquid phase, volatile fatty acid content increased from288mg/L to795mg/L;TP、total alkalinity concentration also increased,which increased by1.5times,1.6times.