铁盐和铝盐混凝对印染废水生化出水中溶解性有机污染物的去除特性

以三氯化铁和硫酸铝为混凝剂,印染废水二级生化出水为研究对象,并利用XAD-8/XAD-4吸附树脂联用技术将印染废水生化出水中溶解性有机物分为疏水酸、非酸疏水物质、弱疏水物质及亲水物质4类有机物,通过小试实验探讨了2种混凝剂对生化出水中各类溶解性有机物的去除效果及特点。实验结果表明,对于该印染废水的生化出水,溶解性有机物的主要成分是疏水性物质,以DOC表征时占总DOC的75%,其中疏水酸约占41%,疏水性物质也是引起色度的主要物质,所占比例以ADMI7.6表征时为89%,其中以非酸疏水物质的贡献最大,达到52%,并且非酸疏水物质中不饱和双键或芳香环有机物的含量较高。在三氯化铁和硫酸铝各自最佳的混凝条件下,均能够有效去除由疏水性物质（疏水酸和非酸疏水物质）引起的色度,但三氯化铁对弱疏水性物质以及亲水物质的去除率高于硫酸铝,这使得三氯化铁对印染废水生化出水中的溶解性有机物的去除效果优于硫酸铝。并且三氯化铁和硫酸铝混凝工艺均能明显降低生化出水的毒性。

Characteristic of different organic fractions removal from bio-treated effluents of textile and dyeing wastewater by ferric and aluminum coagulation

In this study, bio-treated effluents of textile and dyeing wastewater were treated by ferric chloride and aluminum sulfate coagulation process. Meanwhile, the dissolved organic matter from this bio-treated effluents was divided into four different fractions, hydrophobic acids, non-acid hydrophobics, transphilics and hydrophilics, by tandem XAD-8 and XAD-4 resins fractionation. Both characteristics and removal efficiency of different organic fractions were investigated through the pilot coagulation experiments. Results show that the hydrophobic organic fractions are the largest group in this bio-treated effluent, accounting for 75% in term of DOC, and hydrophobic acids account for 41%. Hydrophobics is also the dominating cause for the color of this effluent, accounting for 89% of the total ADMI_7.6 value, and non-acid hydrophobics account for 52%. Non-acid hydrophobics have higher aromatic carbon contents than other organic fractions. Under the optimized condition of each coagulant, color caused by hydrophobics in this bio-treated effluent(both hydrophobic acids and non-acid hydrophobics fractions) can be removed significantly. But ferric salts have higher removal efficiency on transphilics and hydrophilics, which make ferric chloride have a better performance on the removal of dissolved organic matters from this bio-treated effluents than aluminum sulfate. The toxicity is obviously decreased through the coagulation process by each coagulant.