四种絮凝剂对印染废水生化出水强化混凝处理的比较研究

印染废水污染严重,通常经生化处理后出水依然难以达标,还需进行深度处理。采用4种絮凝剂(无机多元聚硅酸盐、双氰胺-甲醛缩合剂、硫酸铝及这三种絮凝剂的复合剂)对某印染厂废水的生化出水进行深度处理,并且利用气相色谱质谱仪(GC-MS),分子荧光光谱仪(EEM)对出水前后水样中的有机污染物进行了检测,并利用MTS法对四种絮凝剂去除印染废水生化出水的细胞毒活性进行絮凝剂安全评估。结果表明:处理后的水质指标均达到国家Ⅰ级排放标准,且复合剂对印染废水生化出水的处理效果最好(COD去除率37.5%、TOC去除率71.6%、色度由40降至25)。EEM结果表明,复合剂不仅对蛋白质和腐殖酸类物质的去除能力显著高于其他三种絮凝剂,而且能够去除的难降解类有机物种类也属最多(包括去除三甘醇,磷酸三丁酯等5种主要污染物)。其产生良好效果的原因在于无机絮凝剂电中和能力和有机高分子絮凝剂吸附架桥性能的协同作用。此外,细胞毒活性实验表明,在本实验条件下添加硫酸铝使印染废水生化出水细胞毒活性增加10.5%,其他三种絮凝剂则都在不同程度上使细胞毒活性减小。

COMPARATIVE STUDY ON ADVANCED COAGULATION TREATMENT OF PRINTING AND DYEING WASTEWATER BIOLOGICAL EFFLUENT BY FOUR KINDS OF FLOCCULANTS

Dyeing wastewater has been a serious pollution problem and difficult to deal with.The biological effluent of dyeing wastewater cannot always meet the national standard and advanced treatment is in need.It was investigated the advanced treatment of dyeing wastewater biological effluent by four kinds of flocculants(silicate polymer,dicyandiamide formaldehyde flocculant,Al2(SO4)3·18H2O,compound flocculant of three above).GC-MS and three-dimensional excitation emission matrix(EEM) fluorescence spectroscopy were applied to detect the organic pollutants in the wastewater,and MTS assay was used to evaluate the cytotoxicity of wastewater and detoxification efficiency of the four flocculants.The results showed that the effluent could meet the National Discharge Standard of China after treated by the four flocculants.The compound flocculant had the best treatment performance of dyeing biological effluent,with COD removal rate being 37.5%,TOC being 71.6% and colority decreased from 40 to 25,respectively.Furthermore,the compound flocculant could not only effectively remove the protein and humic substances but also most of the non-biodegradable organic pollutants(5 main organic pollutants including triethylene glycol,tributyl phosphate) in the effluent samples,which was on account of inorganic flocculant’s charge neutralization mechanism and organic flocculant’s adsorption bridging effect enhanced each other.Cytotoxicity experiment showed that cytotoxicity of biological effluent was reduced by the other 3 flocculants except Al2(SO4)3·18H2O.