切削液废水处理过程中溶解性有机物分子质量分布和光谱特征的转化规律

Transformation of the molecular weight distribution and spectral characteristics of dissolved organic matter during cutting liquid wastewater treatment process

以隔油-混凝沉淀-水解酸化-好氧共代谢为组合工艺处理切削液废水,探究各处理单元对不同种类有机物的转化规律和去除能力;对各处理单元出水中的溶解性有机物(DOM),采用超滤膜法进行分子质量分级,应用紫外-可见吸收光谱、三维荧光光谱等方法对各单元出水及其滤后液进行了分析。结果表明,隔油池出水DOM分子质量主要分布在<1 kDa小分子质量区间和>100 kDa的大分子质量区间,分子质量占比分别为46.04%、42.79%,混凝沉淀对大分子质量的DOM有较好的去除效果,混凝沉淀出水、水解酸化池出水、好氧池出水的DOM主要分布在<1 kDa区间。切削液废水处理过程中出现5个荧光峰,其中峰A和峰B可能为多环芳香烃和杂环化合物的混合物;峰C为石油类;峰D可能是废切削液中滋生的微生物和细菌的细胞物质及其分泌物或单环芳香烃;峰E可能为杂环化合物或多环芳烃类腐殖酸。经一级处理(隔油和混凝沉淀)后峰A和峰B的去除率分别为60%和35%;峰C和峰D去除率均大于99%。经二级处理(水解酸化和好氧共代谢),峰A和峰B的去除率分别为23%和48%。该工艺流程对切削液废水中的有机物有较好的去除效果,石油类、COD、TOC、BOD^5的总去除率可达99.99%、98.81%、98.74%、99.78%,达到了《污水排入城镇下水道水质标准》中的B级标准。

A combined process of oil separation-coagulation sedimentation-hydrolysis acidification-aerobic cometabolism was used as to treat cutting fluid wastewater,and the transformation and removal performance of different organics in each treatment unit were investigated.The dissolved organic matters(DOM)in the effluent from each treatment unit were subjected to molecular weight fractionation by ultrafiltration membrane,and the effluent from each treatment unit and its filtrate were analyzed by ultraviolet absorption spectrum and threedimensional fluorescence spectrum.The results showed that the DOM molecular weight in the effluent from oil separator mainly distributed within the small molecular weight range(<1 kDa),and the large molecular weight range(>100 kDa),their molecular weight ratios accounted for 46.04%and 42.79%,respectively.Coagulation precipitation has a good removal performance on DOM with large molecular weight,and DOM in the effluents of coagulation sedimentation,hydrolysis acidification tank and aerobic tank mainly distributed within the molecular weight range lower than 1 kDa.There were five fluorescent peaks during the cutting fluid wastewater treatment process,of which peak A and peak B could be assigned as a mixture of polycyclic aromatic hydrocarbons and heterocyclic compounds.Peak C was petroleum.Peak D could correspond to the microbial and bacterial cell material and its secretions or mono-aromatic hydrocarbons in the used cutting fluid.Peak E could respond to a heterocyclic compound or a polycyclic aromatic hydrocarbon humic acid.Through primary treatment(oil separation and coagulation sedimentation),the removal efficiencies for peak A and peak B were60%and 35%,respectively,for peak C and peak D were over 99%,respectively.Through the secondary treatment(hydrolysis acidification and aerobic co-metabolism),the removal efficiencies for peak A and peak B were 23%and 48%,respectively.The treatment process had good removal performance on organic matter in cutting fluid wastewater,and the total removal efficiencies of petroleum,COD,TOC and BOD^5 could reach99.99%,98.81%,98.74%and 99.78%,respectively,and the organics indices in effluent could meet the B Class Standard of Wastewater Quality Standard for Discharge to Municipal Sewers(GB/T 31962-2015).