剩余污泥与厌氧消化污泥的脱水性能对比

Comparison of Dewaterability between Excess Activated Sludge and Anaerobic Digestion Sludge

为了实现污水厂剩余污泥的资源化,污泥厌氧消化工艺的应用愈加普遍,厌氧消化过程是否会对剩余污泥的脱水性能产生影响是值得研究的问题。为此,利用加药污泥真空抽滤试验考察了污泥的脱水性能,结果表明,中温厌氧消化污泥(MADS)的比阻和过滤时间(TTF50)均大于剩余污泥(EAS)以及含水率接近厌氧消化污泥的浓缩后剩余污泥(TEAS),剩余污泥经浓缩后脱水速率有一定的降低,而厌氧消化过程会使剩余污泥的脱水速率大幅度降低。激光衍射粒度分析仪的测定结果显示,EAS及MADS的平均粒径分别为70.44、42.00μm,比表面积分别为2 122、3 743 cm2/m L;由紫外光谱和傅里叶变换红外光谱对胞外聚合物(EPS)的分析表明,厌氧消化后污泥液相中的核酸量大幅增加,细胞壁被破坏,蛋白质和多聚糖等大分子物质被降解为小分子物质。由污泥理化特性的检测结果可以推断,厌氧消化污泥的脱水速率低于剩余污泥,但若加大脱水压差或延长脱水时间,厌氧消化污泥的泥饼含水率会更低。

Anaerobic digestion process will be widely used to achieve reutilization of excess activated sludge（EAS） in WWTP, and the effects of anaerobic digestion on sludge dewaterability are worth studying. Thus, dewaterability of the conditioned sludge was tested by vacuum filtration. Results showed that, specific resistance and filtration time （TTF50） of mesophilic anaerobic digestion sludge （MADS） were both larger than that of EAS and thickened excess activated sludge （TEAS）. Dewater velocity of TEAS was slightly less than EAS, while anaerobic digestion would lead to remarkable decrease of EAS dewater velocity. The results of laser diffraction panicle size analyzer indicated the mean panicle size of EAS and MADS were 70.44 μm and 42.00 μm, and the specific surface area were 2 122 cm^2/mL and 3 743 cm^2/mL respectively, Analysis of extracellular polymer substance （EPS） by ultravioiet spectra and Fourier transform infrared spectra illustrated that nucleic acid in aqueous phase increased obviously after anaerobic digestion, and cell walls were broken along with protein and polysaccharide were degraded into smaller molecular substances. According to the results of sludge physicochemical characteristics analysis,it could be concluded that the dewater velocity of MADS was less than that of EAS, however, lower water content of anaerobic digestion sludge cake could be achieved through increasing the dewatering differential pressure or prolonging the filtration time.