制药废水二级出水中溶解性有机物混凝去除特性研究

制药废水二级出水中溶解性有机物(DOM)由于组成复杂、难去除、具有多异质性和分散性,是污水深度处理与回用的主要去除对象和关键限制因子.本论文以发酵制药废水二级出水的DOM为研究对象,采用投加聚合氯化铝(PAC)混凝剂去除DOM,考察混凝剂投加量和混凝pH值对去除效果的影响,并结合分子量分级、亲疏水性分级以及三维荧光光谱-平行因子分析方法等对DOM进行了系统表征和分析,进一步阐述混凝过程DOM的去除特征.结果表明,PAC投加量为250 mg·L~(-1)、pH=7时,混凝沉淀30 min对DOC、UV_(254)、色度和浊度的去除率分别为13.05%±0.29%、23.65%±0.75%、12.66%±1.34%、63.67%±0.89%;混凝对分子量10 kDa的组分和疏水中性(HON)组分去除效果分别为50.33%±0.98%、21.56%±0.42%,而对分子量1 kDa组分去除率较低为2.26%±0.12%;三维荧光光谱-平行因子分析将制药废水二级出水分为2个类腐殖质组分(C1、C3)和1个类蛋白组分(C2),混凝对类腐殖酸组分(C1)最大荧光强度去除率(F_(max))最高为46.22%,而亲水性的小分子和蛋白类物质混凝去除效果较差.

A study on the characteristics of dissolved organic matters and their removal in the secondary treatment effluent of pharmaceutical wastewater by coagulation

The dissolved organic matter (DOM) in the secondary effluent of pharmaceutical wastewater is a key limiting factor for advanced wastewater treatment and reuse, owing to its extensive molecular heterogeneity and polydispersity. This study investigated the removal and characteristics of DOM from secondary treatment effluent of pharmaceutical wastewater during PAC coagulation. The operating parameters, including initial pH, dosage of PAC were optimized. Several methods have been employed to characterize the DOM properties and its transformation during coagulation, including different hydrophobicities, molecular weight and fluorescence excitation-emission-matrix (EEM) spectroscopy. Fluorescence spectra coupled with parallel factor analysis (PARAFAC) was used to characterize the changes of DOM during coagulation process. The results show that, under the optimum condition (250 mg·L^-1 PAC, pH=7, 30 minutes), the highest DOC, UV₂₅₄, color and turbidity removal were 13.05%±0.29%, 23.65%±0.75%, 12.66%±1.34%, 63.67%±0.89%, respectively. Coagulation could remove 50.33%±0.98% macromolecules organic matter (MW > 10 kDa) and 21.56%±0.42% hydrophobic neutral component, the removal rate of components with molecular weight <1 kDa was 2.26%±0.12%. Two humic-like (C1, C3) and one protein-like (C2) components of DOM in secondary effluent of pharmaceutical wastewater were determined by the EEMs coupled with PARAFAC method, and the highest removal efficiency of humic acid fraction (C1) by coagulation was 46.22%.Coagulation might have preferentially reacted with the humic-like hydrophobic fraction rather than protein-like fraction.