酸碱法预处理低有机质污泥的效果研究及条件优化

以高含固率(10％)低有机质(VS/TS＜ 50％)污泥为研究对象,探讨不同pH值的酸碱预处理对污泥融胞效果的影响,并结合化学药剂投加和厌氧消化产甲烷潜力(BMP)实验,从经济性与处理效果两个角度筛选出酸碱预处理最优的pH条件.结果表明,COD、蛋白质、碳水化合物和DNA在不同的pH条件下有着基本相似的溶出规律,即其溶出浓度在碱性条件下随着pH的升高不断增加,而在酸性条件下正好相反,且碱性预处理的溶出效果要明显优于酸性预处理.当预处理pH为9、10、11、12和13时,COD的溶出率分别达到6.5％、18.0％、36.7％、65.5％和83.5％.氨氮和磷酸盐的溶出规律与有机物不同,其酸性条件下的溶出效果比碱性条件更明显.此外,随着碱性处理pH的升高,需投加的化学试剂的量也在不断增加.当pH≥12时,OH-反应率则迅速下降,不再具有经济性.而较低的pH(如pH =9)对甲烷产率和VS去除率的提高效果有限.因此,从处理效果提高和碱性试剂消耗两个角度来考察,选择pH=10或11作为低有机质污泥碱性预处理的控制条件是较为适宜的.

Effect and optimization of acid-base method in pretreating sludge with low organic content

Effect of acidic and alkaline pretreatment on the disintegration of high solid sludge with low organic content was studied. The pretreatment condition was also optimized based on the economy of chemical reagent addition and the performance of anaerobic biochemical methane potential experiment. Experimental results showed that the solubilizations of COD, protein, carbohydrate and DNA were almost the same, i.e. the related concentrations increased with pH under alkaline conditions, but decreased under acidic conditions, and the performance of alkaline pretreatment was superior to that of acidic pretreatment. The solubilization rate of COD at pH 9, 10, 11, 12 and 13 was 6.5%, 18.0%, 36.7%, 65.5% and 83.5%, respectively. It was also observed that the solubilizations of ammonia and phosphorus were different from those of organic matters, i.e. the related performances under acidic conditions were better than those under alkaline conditions. In addition, the consumption of chemical reagents increased with alkaline pHs and the reaction ratio of OH^- decreased sharply when pH was higher than 12. However, alkaline treatment at low pHs (such as 9) showed limited enhancement of methane productivity and volatile solids (VS) removal performance. Therefore, the optimal condition of acidic and alkaline pretreatment on high solid sludge with low organic content was determined as pH 10 or 11, considering the treatment performance and consumption of alkaline reagent.