Abstract:

In this experiment, hypochlorite coupled with FeCl₃ flocculation was used to study the dewatering performance of sludge. The optimal pretreatment conditions were determined by single factor experiment. The mechanism of the pretreatment promoting the sludge dewatering performance was analyzed and clarified by using characterization methods such as zeta potential, protein polysaccharide, DNA content, magnetic field nuclear resonance, three-dimensional fluorescence and cell visualization. Pearson correlation analysis was used to further analyze the reasons for the improvement of sludge dewatering performance. The results showed that the sludge dewatering efficiency reached the highest when the dosage of NaClO was 50mg/g TS and FeCl₃ was 100mg/g TS. The specific resistance and CST of the original sludge decreased from 2.45×10¹²m/kg and 119.7s to 9.3×10¹¹m/kg and 27.9s, respectively. Sludge lost the most water and dehydrates the fastest. Under the combined action of oxidation and flocculation, the EPS structure of the sludge was destroyed, the sludge particles were loose, and the internal bound water was released. The increase of DNA content in sludge and the visualization analysis of sludge showed that the cell membrane of microorganism in the floc was destroyed, resulting in the release of intracellular water, thus improving the dehydration efficiency of activated sludge.

Key words: sludge, dewatering performance, oxidation, flocculation, hypochlorite, ferric chloride

摘要：

采用次氯酸盐耦合FeCl₃絮凝对污泥脱水性能进行研究，通过单因素实验确定了最佳预处理条件，采用zeta电位、蛋白质多糖、DNA含量、磁场核共振、三维荧光以及细胞可视化等表征手段，分析阐明了该预处理促进污泥脱水性能提高的作用机理，利用Pearson相关性分析进一步分析促进污泥脱水性能改善的原因。结果表明：在NaClO投加量为50mg/g TS（含固率），FeCl₃投加量为100mg/g TS条件下污泥脱水效率达到最高，污泥比阻与毛细吸水时间（CST）分别由原污泥的2.45×10¹²m/kg和119.7s降低至9.3×10¹¹m/kg和27.9s，污泥的水分损失量最多，脱水速率最快。在氧化与絮凝的共同作用下，污泥的胞外聚合物（EPS）结构被破坏，污泥颗粒松散，内部结合水被释放。污泥中DNA含量的增加和污泥的可视化分析表明，絮体中微生物细胞膜被破坏，导致胞内水释放，从而提高活性污泥的脱水效率。

关键词: 污泥, 脱水性, 氧化, 絮凝, 次氯酸盐, 氯化铁