兰炭粉末对剩余污泥浓缩脱水的影响及机理探究

以陕西榆林高挥发分烟煤在中低温条件下干馏热解所得的兰炭粉末对污水处理厂剩余污泥进行调理,在对兰炭粉末及其调理前后城市污泥理化特性分析的基础上,研究经兰炭粉末调理后城市污泥的沉降、浓缩、脱水性能的改善,并通过Zeta电位、显微镜、扫描电镜、红外光谱分析,探讨了兰炭粉末调理污泥的机理。实验结果表明:兰炭粉末按质量比(兰炭粉末/干污泥)为250%投加时,污泥过滤比阻由3.22×1013m/kg降到了4.33×1011m/kg,沉降速率由3.0mL/min提高到了34.3mL/min,污泥浓缩含水率也从98.6%降到了91.2%,滤饼含水率从87.8%降到了63.6%,污泥的热值从10.68MJ/kg提高到21.77MJ/kg。兰炭粉末调理污泥的机理主要是通过吸附作用改善污泥絮凝性能,在抽滤过程中通过构建骨架结构以保持泥饼的高渗透性,减弱污泥亲水性,增强污泥疏水性。

Effect and mechanism of semi-coke powder on concentration and dehydration of excess sludge

Objective The semi-coke powder was selected from a factory producing semi-coke with high volatile bituminous coal under medium-low temperature carbonization and pyrolysis.The semi-coke powder was used to conditioning the excess sludge from waste water treatment plant.Based on the physicochemical properties analysis of semi-coke powder,raw sludge and treated sludge by semi-coke powder,concentrating,filtering and dewatering property of sludge was researched through experiments.Meanwhile,the mechanism of conditioning sludge with semi-coke was analyzed by Zeta potential,microscope,infrared spectrum and scanning electron microscope.The experimental results showed: when semi-coke dosage was 250%,the specific resistance of filtration decreased significantly from 3.22×1013m/kg (raw sludge) to 4.33×1011m/kg,the water content of sludge after concentration was reduced from 98.6% to 91.2%,the settling velocity of sludge obviously accelerated from 3.0mL/min to 34.3mL/min,the water content of filter cake was low down from 87.8% to 63.6%,and the low calorific value of sludge increased from 10.68MJ/kg to 21.77MJ/kg.The mechanism of semi-coke powder conditioning sewage sludge were adsorption and flocculation abilities to improve the settling performance,skeleton construction forming rigid frame structure with many channels and intervals which could prevent sludge cake compression and maintain high permeability during air-pump filtration,weakening the hydrophilicity and increasing the hydrophobicity of sludge.