好氧污泥絮体与厌氧颗粒污泥的剪切稳定性分析

通过标准的剪切实验装置检测了好氧污泥絮体和厌氧颗粒污泥在不同剪切条件下剥离的分散胶体浓度的变化.结果表明,厌氧颗粒污泥的剪切敏感性(KSS)比好氧活性污泥高1个数量级,证明了好氧活性污泥的剪切稳定性更好.好氧活性污泥絮体在剪切下剥离的分散胶体平衡浓度(md,∞)分别随着污泥悬浊液的固体浓度(mT)和剪切强度(G)的增加而增加.AE模型的模拟结果显示,好氧活性污泥絮体样品1在剪切作用下粘附-剥离的平衡常数(Km)比样品2的高,相应的DG0adh/RT值更小,证明其在剪切作用下的粘附过程更易发生.修正AE模型可以更好地模拟不同剪切强度下污泥絮体上分散胶体的剥离过程,其不仅能够给出未施加剪切的稳定状态时因布朗运动而导致的分散胶体浓度,而且能确定与污泥絮体上分散胶体的剥离能量相关的DH/R值.模拟结果表明,好氧活性污泥絮体样品1上分散胶体的剥离需要更多的能量,剪切强度的升高对样品2的影响更加明显.活性污泥剪切稳定性的差异证明了其与污泥结构、性质以及污水处理厂运行效果之间的关系比较复杂.

Analysis of the shear stability of aerobic sludge flocs and anaerobic sludge granules

The shear stability of some aerobic activated sludges and anaerobic sludge with determining the mass concentration changes of dispersed colloids eroded from some aerobic activated sludge flocs and anaerobic sludge granules were examined with standard shear test devices. Aerobic activated sludge in A2/O process possessed better shear stability, and the shear sensitivity (KSS) of their flocs was an order of magnitude less than the anaerobic sludge granules of ABR. Both the increase of total solid concentration (mT) of activated sludge and the increase of shear intensity (G) could result in increment in the dispersed mass concentrations of colloid particles at equilibrium (md,∞). Moreover, adhesion of small colloids on the aerobic flocs of sample 1 could be more prone to occur than that of sample 2, which could be testified by the higher adhesion–erosion equilibrium constant Km and more negative DG0adh/RT value of sample 1 estimated from the non-linear regression of md,∞versus mT with adhesion–erosion(AE)-model. With taking into account the effect of Brownian motion on colloid particle erosion dynamics, the modified AE-model could not only describe the concentration of small colloid particles in sludge solution without artificial shear, but also quantitatively model the shear data. Based on the regression results, the values for the equilibrium dispersed mass concentration of colloid particles prior to shear (m0) and DH/R could be determined. Modeling results indicated that more energy could be demanded for the deflocculation process with sample 1 than that with sample 2, but sample 2 was more remarkably affected by strengthened shear intensity. The discrepancy of shear stability between sample 1 and sample 2 of aerobic sludges implies some complex relations existed among shear stability, structure, properties of sludge and wastewater treatment effect in A2/O process.