超声联合热碱预处理促进剩余污泥中温厌氧消化研究

Upgrading Semi-Continuous Mesophilic Anaerobic Digestion of Waste Activated Sludge by Combined Ultrasonic,Thermo-Alkaline Pretreatment

基于超声联合热碱破解污泥最佳工艺参数,对预处理污泥进行半连续式中温厌氧消化研究。结果表明,预处理污泥日产甲烷量是原泥的1. 94倍,达234 mL·d^(-1)。运用修正的冈珀兹模型进行累计甲烷产量动力学分析,发现预处理污泥和原泥累计产甲烷曲线与修正的冈珀兹模型拟合系数R2分别达0. 998和0. 993。预处理污泥的动力学参数如下:最大累计产气量达5 376. 4 mL,最大产甲烷速率达394. 8 mL·d^(-1),细菌产甲烷的延迟时间为2. 8 d。预处理污泥的甲烷转化率为82. 17%。从有机物浓度变化来看,厌氧消化期间预处理污泥溶解性化学需氧量、溶解性蛋白质和多糖浓度均远高于原泥,最大值分别是原泥的2. 09、3. 94和3. 95倍。预处理污泥在预处理阶段和厌氧消化阶段的总悬浮物和挥发性悬浮物去除率分别达54. 9%和61. 8%。超声联合热碱预处理不仅能促进污泥有机质破解,还能提高破解有机质的生物可利用性,极大改善污泥厌氧消化效率。

Semi-continuous mesophilic anaerobic digestion assays were performed to assess the influence of combined ultrasonic,thermo-alkaline pretreatment on biodegradability of waste activated sludge(WAS).The pretreated WAS was obtained at optimal conditions of temperature 73 ℃,alkaline dosage 0.085 g·g^-1 total solids(TS)and specific energy 9551 kJ·kg^-1 TS.During anaerobic digestion,the average daily methane production of pretreated WAS was as high as 234 mL,which was 1.94 times that of untreated WAS.Furthermore,modified-Gompertz model was introduced to predict the methane production and evaluate the kinetic parameters.The modified-Gompertz models(R^2:0.998 and 0.993 for pretreated and untreated WAS,respectively)show good fit to the experimental results.For pretreated WAS,kinetic constants of methane production model using modified-Gompertz were P(methane production potential,5376.4 mL),Rm(maximum methane production rate,394.8 mL·d^-1),λ(minimum time to produce methane,2.8 days).Besides,the ratio of methane conversion of pretreated WAS achieved at 82.17%.During anaerobic digestion,concentrations of soluble chemical oxygen demand(SCOD),soluble protein(SP),and soluble carbohydrates(SC)of pretreated WAS were much higher than that of the untreated WAS.Therefore,the reductions of total suspended solids(TSS)and volatile suspended solids(VSS)were 54.9% and 61.8% for pretreated WAS after pretreatment and anaerobic digestion.Based on results obtained above,it is suggested that combined ultrasonic,thermo-alkaline pretreatment improves sludge disintegration as well as increases biodegradability,resulting to anaerobic digestion enhancement.