核桃壳添加改善污泥压缩性能研究

Walnut shell aided to improve sludge compressibility

污泥压缩阶段的高压缩性使得污泥脱水困难.物理调理剂可以作为骨架构建剂改善污泥的紧实性和压缩性,从而改善污泥的脱水性.本研究采用农业废弃物——核桃壳作为物理调理剂,对污泥进行预处理调节,以污泥比阻、泥饼含水率、压缩系数等为测定指标,研究了其对污泥的压缩性和脱水效果的影响.试验结果显示：核桃壳和阳离子聚丙烯酰胺（CPAM）单独或者混合使用时,污泥比阻（SRF）和脱水后泥饼含水率相比于原泥都有所减小,改善了污泥的压缩性能,提高了污泥的脱水效果;此外,压缩系数的变化趋势进一步证实了污泥的压缩性确实得到改善.本研究中污泥压缩性改善的最佳条件是：核桃壳的投加比例（核桃壳与干污泥质量比）为3∶7、粒径为0.25-1mm、阳离子聚丙烯酰胺（CPAM）的投加量为100mg/L,污泥压缩系数从原泥的1.576 8增加到调理后的1.997 8,抽滤后泥饼的含水率由原泥的80.59%降为73.23%.

The main difficulty in mechanical dewatering is the high compressibility of the flocculated sludge except for the block of the filter media.Physical conditioners are usually used to improve sludge dewatering by reducing the sludge compressibility and strengthening sludge permeability.In the study,walnut shell which is an agricultural waste of China was selected to condition sludge used as physical conditioner which played a role of skeleton builders.During the course of experiments,sludge resistance of filtration(simplified as SRF),water content of sludge cake,coefficient of compressibility were taken as indicative parameters of sludge compressibility.The experiment results showed that SRF and water content of sludge cake decreased when sludge was conditioned with walnut or cationic polyacrylamide(simplified as CPAM),or co-condition with walnut and CPAM.This identified that sludge compressibility was improved and so increased dewatering rate of sludge.In addition,the variation trend of compressibility coefficient also showed that sludge compressibility had been improved.The fittest condition was that the ratio of walnut shell to dry solid(ratio of weight)was 3∶7,particle size of walnut shell was 0.25~1mm and the dose of CPAM was100mg/L.The coefficient of compressibility increased from 1.576 8of raw sludge to 1.997 8of treated sludge conditioned with walnut shell and CPAM.Water content of sludge cake filtered with vacuum pump decreased from 80.59% without any condition to 73.23% after conditioned under the fittest condition.