ABSTRACT

Sludge-recycling enhanced flocculation (SEF) is an effective method for enhancing flocculation. In the conventional SEF process, the settled sludge is recirculated into the flocculation process without any further treatment. However, studies have shown that the efficacy of the SEF process could be improved by pre-treating the sludge. In this work, the acid activation of sludge was performed using a range of pH values (1.0–6.0) and charge states, with and without long-chain bridging. The resulting residual turbidities, floc fractal dimensions and floc morphologies were then analyzed, to examine the effects of sludge activation on the efficacy of SEF. In the absence of long-chain bridging, it was found that flocculation was enhanced by pH values between 2.0 and 5.0 in the electrostatic patch (EP) and near charge neutrality (NCN) states. In the EP state, the optimal pH for SEF enhancement was pH = 2.0; in the NCN state, the optimal pH was pH = 3.0. In terms of floc morphology, pH values between 2.0 and 5.0 resulted in larger average floc sizes and lower floc fractal dimensions than conventional SEF. However, in the presence of long-chain bridging, sludge activation did not enhance flocculation; residual turbidity increased with decreases in pH, in both the EP and NCN states. Based on these results, it may be surmised that the acid activation of sludge is suitable for cases without long-chain bridging.

摘要

污泥循环强化絮凝（SEF）是一种有效的强化絮凝方法。在传统的 SEF 工艺中，沉降的污泥无需任何进一步处理即可重新循环进入絮凝工艺。然而，研究表明，SEF 过程的功效可以通过预处理污泥来提高。在这项工作中，污泥的酸活化是使用一系列 pH 值 (1.0–6.0) 和电荷状态进行的，有和没有长链桥接。然后分析产生的残余浊度、絮凝物分形维数和絮凝物形态，以检查污泥活化对 SEF 功效的影响。在没有长链桥接的情况下，发现在静电贴片 (EP) 和接近电荷中性 (NCN) 状态下，pH 值在 2.0 和 5.0 之间会增强絮凝作用。在 EP 状态下，SEF 增强的最佳 pH 为 pH = 2.0；在 NCN 状态下，最适 pH 为 pH = 3.0。就絮凝物形态而言，2.0 和 5.0 之间的 pH 值导致比传统 SEF 更大的平均絮凝物尺寸和更低的絮凝物分形维数。然而，在存在长链桥接的情况下，污泥活化并没有增强絮凝作用；在 EP 和 NCN 状态下，残余浊度随着 pH 值的降低而增加。基于这些结果，可以推测污泥的酸活化适用于没有长链桥接的情况。在存在长链桥接的情况下，污泥活化不会增强絮凝；在 EP 和 NCN 状态下，残余浊度随着 pH 值的降低而增加。基于这些结果，可以推测污泥的酸活化适用于没有长链桥接的情况。在存在长链桥接的情况下，污泥活化不会增强絮凝；在 EP 和 NCN 状态下，残余浊度随着 pH 值的降低而增加。基于这些结果，可以推测污泥的酸活化适用于没有长链桥接的情况。