低温热水解处理对污泥流变特性的影响

EFFECT OF LOW-TEMPERATURE THERMAL HYDROLYSIS PROCESS ON SLUDGE RHEOLOGY

流变特性对污泥处理至关重要,广泛应用于厌氧消化反应器、泵送运输、热交换器及污泥脱水等的设计。系统研究了低温热水解预处理对污泥流变特性的影响,结果表明:热水解过程中COD增溶与热历时呈对数关系。热水解48 h后污泥的流变曲线均符合Power law模型,流动性显著增强。低剪切速率范围内热水解污泥的黏度较原污泥有所降低,但在高剪切速率范围内黏度却略有增加。热水解后污泥极限黏度的增大与sCOD(溶解性化学需氧量)的释放呈线性关系,表明污泥流变有望成为评价热水解效率的新工具。热处理造成的污泥极限黏度、流变指数(n)的增大及稠度系数(k)的降低与温度均呈直线关系。当热水解温度为80℃时,n值增大、k值降低与热历时均呈良好的对数关系。

Rheological properties of sludge play key roles in sludge treatment,being widely used in the design of anaerobic digesters,pumps and pipes,heat exchangers,sludge dewatering,etc.This study systematically investigated the impact of low-temperature thermal hydrolysis process(LTHP)on sludge rheology.Results showed that,COD solubilization increased logarithmically with extension of the heating duration.All sludge flow curves were well described by the power law model after 48-hour thermal treatment,indicating a significant enhancement on sludge fluidity.The apparent viscosity of hydrolyzed sludge was lower in comparison to that of the untreated sludge in low shear rate range,while there was a slight increase at high shear rates.The rate of infinite viscosity increased due to that thermal treatment was linearly proportional to the increase of sCOD,which indicated that sludge rheology had the potential to serve as a new tool to evaluate the efficiency of thermal hydrolysis.The increase of infinite viscosity and the flow index(n),as well as the decrease of consistency coefficient(k)all followed a linear correlation with the heating temperature.Especially,a logarithmic relationship existed between the duration of treatment and increase of n and decrease of k,at the temperature of 80℃.