预处理低有机质剩余污泥两相厌氧消化

为提高低有机质剩余污泥的厌氧消化效率,采用超声波(40kHz,50W)与生石灰(投量为560mg/L)联合预处理剩余污泥,然后将预处理的剩余污泥进行中温两相厌氧消化.试验污泥取自长春市某污水处理厂,试验中主要考察剩余污泥的消化性能、产气情况及脱水性能变化.结果表明,当剩余污泥的VS/TS比值为0.56、水力停留时间(HRT)为20d时,预处理污泥厌氧消化后VS去除率达到40.8%.在消化过程中系统稳定,产酸相内挥发酸成分以乙酸和丁酸为主,而产甲烷相内以少量乙酸为主.产甲烷相的甲烷产率为0.33L/gVS去除,产气中甲烷平均含量可达到59.2%,但消化后污泥的脱水性能变差.污泥的联合预处理增加了液相中溶解性有机物的含量,提高了进料污泥的pH与碱度,有助于低有机质剩余污泥的后续厌氧消化处理.

Two-phase anaerobic digestion of pretreated waste activated sludge with a low organic content

In order to improve the efficiency of anaerobic digestion of waste activated sludge (WAS) with a low organic content,the combined pretreatment of ultrasonication (40 kHz,50 W) and lime (dosage of 560 mg/L) was used before the mesophilic(35±1 ℃) two-phase anaerobic digestion of WAS. The WAS was obtained from in a wastewater treatment plant (WWTP) in Changchun. The digestion efficiencies,biogas production and dewatering ability of the pretreated sludge in two phases were measured during the anaerobic digestion. The experimental results showed that the VS reduction of two-phase system was 40.8% when the ratio of VS/TS was 0.56 and the hydraulic retention time(HRT) was 20 d. The anaerobic digestion system was stable,acetic acid and butanoic acid were the major intermediate products in the acidogenic phase,and acetic acid was the major component in the methanogenic phase. The methane yield of methanogenic phase was 0.33 L CH4/gVSrem,and the methane content of biogas was 59.2% in average. However,the dewatering ability of digested sludge became poorer after the anaerobic digestion. The combined pretreatment of sludge improves the amount of soluble organic matter in liquid phase,increases the pH value and alkalinity of feeding sludge,which is favourable to the anaerobic digestion of WAS with low organic content.