强化混凝-光电氧化组合工艺深度处理垃圾渗滤液膜滤浓缩液

采用强化混凝-光电氧化组合工艺对北京某垃圾填埋场垃圾渗滤液膜滤浓缩液进行处理。探讨了不同混凝剂投加量、电流密度和反应时间对COD去除率的影响,并考察了溶解性有机物的分子量和结构在本工艺中的变化。结果表明:同时投加Ca(OH)2、Fe2(SO4)3和PAM混凝后,COD去除率为28.00%,含量由4 700 mg/L降低到3 384 mg/L;同时投加KMnO4、Fe2(SO4)3和PAM进行二次混凝,COD去除率为60.20%,含量为1 870 mg/L;混凝后水样在电流密度为400A/m2,经3 h光电氧化后,COD去除率为86.20%,含量为650 mg/L。本工艺将垃圾渗滤液膜滤浓缩液中部分大分子量有机物降解为小分子量有机物;光电氧化后,有机物结构被迅速破坏。

Treatment of biotreated leachate nanofiltration reject by enhanced coagulation and photoelectro-oxidation process

A combination of enhanced coagulation and photoelectro-oxidation was used to treat concentrate reject stream. The effects of different coagulants dosages, current densities and reaction time on COD removal were investigated. Test results showed that when dosing Ca(OH)₂, Fe₂(SO₄)₃ and PAM, the removal efficiency of COD with initial concentration of 4 700 mg/L was 28.00%; when dosing KMnO₄, Fe₂(SO₄)₃ and PAM after the first coagulation, the removal efficiency of COD with concentration of 1 860 mg/L was 60.22%. When the current density was 400 A/m², the removal of COD was 86.20%, and the DOM was destroyed in the photoelectro-oxidation process. Furthermore, the changes of molecular weight of dissolved organic matter (DOM) were investigated via ultrafiltration; the structure variation of DOM was evaluated via FTIR and 3DEEM, respectively. It was observed that the fraction with large molecular weight was changed into the fraction with small molecular weight. Based on the analysis of FTIR and 3DEEM results, it could be inferred that coagulation had little effect on characteristic structure of DOM, whereas the aromatic structure of the DOM were transformed into hydrophilic organics because of hydroxyl radical in photoelectro-oxidation process, such as ketones, carbohydrates, sugars, amino and carboxylic acids.