高含固污泥临界剪切应力影响因素的研究
Effect of High？？Solid Sewage Sludge on Critical Shear Stress

为了进一步研究高含固污泥的流变特性,根据污泥含固率rTS选择改进的Herschel？？Bulkley流变模型,以模拟污泥在反应器中的合理流动,并对污泥种类、含固率、剪切速率范围、温度对高含固污泥流变曲线中临界应力的影响进行了实验研究。实验中采用含固率rTS为5.2％~15.8％的厌氧消化污泥,在0.01～1 000 s-1的剪切速率范围内进行稳态流变特性的测试。结果表明:当rTS<8？？8％时,流变曲线符合Herschel？？Bulkley模型;当rTS>8.8％时,流变曲线在1～10 s-1内出现临界剪切应力,符合改进的Herschel？？Bulkley模型;临界剪切应力与污泥含固率、剪切速率范围有关,与污泥的种类、成分组成、测试温度以及厌氧消化时间无关;临界剪切应力对应的临界剪切速率c与含固率之间呈线性关系。该结果可为污泥物理化学性质研究提供一定的参考。
To further study the rheological characteristics of high？？solid sewage sludge, revised Herschel？？Bulkley model was selected according to total solid (rTS) of sludge to simulate flow behavior within digesters reasonably. The effects of sludge type, total solid, the range of shear rate, temperature on the critical shear stress in the flow curve were investigated in the experiments. Anaerobic digested sludge with total solid of 5.2％？？15.8％ was sheared by employing shear rate sweep ranging from 0.01 s-1 to 1 000 s-1 for steady rheological tests. The results indicate that for the sludge with rTS <8？？8％, the flow curve is well fitted by Herschel？？Bulkley model. While for the sludge with rTS>8.8％, a critical shear stress appears in the flow curve within the range of 1.10 s-1, and the flow curve is fitted by the revised Herschel？？Bulkley model. The critical shear stress is correlated to the total solid and the range of applied shear rate, but not to sludge type, composition, tested temperature or digestion time. The critical shear rate c corresponding to the critical shear stress shows a linear relationship with rTS of digested sludge