ABSTRACT

It is a challenging environmental issue to develop a cost-efficient approach for the removal of low-concentration refractory organics in industrial wastewater. In this study, the Fenton-coagulation process was utilised to remove the organics from the industrial effluent. The operational conditions of the Fenton-coagulation process were optimised, and then, the molecular weight (MW) and resin fraction distribution of dissolved organic matter (DOM) were investigated before and after the Fenton-coagulation process. The results showed that the efficiency of organic matter removal was affected by the Fe²⁺/H₂O₂ molar ratio, pH, and reaction time. The removal rate of chemical oxygen demand (COD) by Fenton-coagulation process reached 37.8% under the following conditions: pH = 4.0 − 5.0, H₂O₂ concentration = 34 mg/L, Fe²⁺/H₂O₂ molar ratio = 1.5, and reaction time = 120 min. The resin fraction distribution results showed that hydrophobic bases (HoB) were almost completely removed, and the removal rate of hydrophobic acids (HoA) reached 58%, while hydrophilic matter (HiM) became the dominant form in the final effluent after the Fenton-coagulation process due to the appearance of hydrophilic charged fractions (HiC). The results were explained by a two-step mechanism (Fenton oxidation and Fe³⁺ coagulation). According to the molecular weight (MW), 35.7% removal of the main fractions of organic matter with MW < 1 kDa was achieved. Furthermore, a pilot test proved that the final effluent quality after the Fenton-coagulation process conformed to the first class of the A discharge standard of pollutants for municipal wastewater treatment plants in Tianjin.

摘要

开发一种具有成本效益的方法来去除工业废水中的低浓度难降解有机物是一个具有挑战性的环境问题。在这项研究中，芬顿混凝工艺用于去除工业废水中的有机物。优化了芬顿混凝过程的操作条件，然后研究了芬顿混凝过程前后的分子量（MW）和溶解有机物（DOM）的树脂分数分布。结果表明，有机物去除效率受Fe ²⁺ /H ₂ O ₂摩尔比、pH 值和反应时间。在以下条件下，Fenton-混凝法对化学需氧量（COD）的去除率达到37.8%：pH = 4.0 − 5.0，H ₂ O ₂浓度= 34 mg/L，Fe ²⁺ /H ₂ O ₂摩尔比= 1.5，反应时间 = 120 分钟。树脂馏分分布结果表明，疏水性碱（HoB）几乎完全去除，疏水性酸（HoA）去除率达到58%，而Fenton混凝后最终出水以亲水性物质（HiM）为主。由于亲水性带电部分 (HiC) 的出现而产生的过程。结果由两步机制解释（芬顿氧化和 Fe ³⁺凝固）。根据分子量 (MW)，对 MW < 1 kDa 的主要有机物部分的去除率达到了 35.7%。此外，经中试证明，经芬顿混凝处理后的出水最终出水水质符合天津市污水处理厂污染物一级A排放标准。