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

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 ADMI7.6 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.