污泥回流比对絮体破碎再絮凝及沉后水水质的影响

Effect of Sludge Reflux Ratio on Breakage and Re-growth of Flocs and Settled Water Quality

采用铁盐污泥回流处理低浊、微污染原水，研究了不同污泥回流比对絮体破碎再絮凝特性和沉后水水质的影响。结果表明：与无污泥回流工艺相比，回流2％～10％的污泥可使絮体的絮凝指数（FI值）大幅提高，但不同回流比条件下的FI值差别不显著；污泥回流使絮体的抗破碎能力有所提高，但破碎后絮体的再絮凝能力明显下降；絮体的成长速率和强度因子随着回流比的增大而逐渐提高，而恢复因子却逐渐降低。另外，回流2％～8％的铁盐污泥能够显著提高对浊度和有机物的去除率，且浊度去除率与絮体恢复因子有较好的相关性。

In treatment of low turbidity and micro-polluted water, the formation, breakage and re growth of flocs and settled water quality were investigated by using ferric-salt sludge reflux under different reflux ratios. Compared to non-reflux, the flocculation index （FI） value was significantly increased by 2% to 10% reflux. However, the FI values were almost the same among different reflux ratios. Refluxing sludge enhanced the breakage resistance of flocs but displayed a distinct irreversibility in breakage process. As reflux ratio was increased, the growth rate and strength factor of flocs were gradually increased. However, the recovery factor was reduced. The turbidity and organics removal were significantly improved by 2% to 8% reflux sludge, and the turbidity removal rate had a good correlation with recovery factor.