絮凝-电化学氧化协同工艺处理兰炭废水  

Treatment of semi-coking wastewater by synergistic process of flocculation-electrolytic oxidation

作　　者：王亚 宋永辉[1] 李金城 尹宁 董萍 王一帆[1] 龙江 李弯弯 WANG Ya;SONG Yong-hui;LI Jin-cheng;YIN Ning;DONG Ping;WANG Yi-fang;LONG Jiang;LI Wan-wan(Key Laboratory of Gold and Resources of Shaanxi Province,Xi'an University of Architecture and Technology,Xi'an 710055,China;School of Water and Environment,Chang'an University,Xi'an 710054,China;Shaanxi Xin neng xing Carbon Energy Co.,Ltd.Xi'an 710199,China)

机构地区：[1]西安建筑科技大学,陕西省黄金与资源重点实验室,陕西西安710055 [2]长安大学水利与环境学院,陕西西安710054 [3]陕西新能星炭能源有限公司,陕西西安710199

出　　处：《中国环境科学》2024年第4期2063-2072,共10页China Environmental Science

基　　金：陕西省自然科学联合基金项目(2019JLM-44)。

摘　　要：采用絮凝-电化学氧化协同工艺处理兰炭废水,探究了反应过程中絮凝剂投加量、反应时间、初始pH值、外加电压以及NaCl添加量对化学需氧量(COD)和氨氮(NH_(3)-N)去除的影响及絮凝-电化学氧化协同作用机制.结果表明,随着絮凝剂聚合氯化铝铁(PAFC)投加量和外加电压的增加,兰炭废水中COD和NH_(3)-N的去除率逐渐升高.当PAFC投加量为50g/L、电压6V、反应时间4h,初始pH=9,NaCl添加量30g/L时,COD和NH_(3)-N去除率分别为82.37%和100%,更换极板进行二次电解COD去除率可达100%.兰炭废水中有机污染物主要是苯酚类､醇类和酰胺类物质,处理后酚类物质含量大幅减少,酮类、醇类和酸类物质相对占比有所增加.絮凝-电化学氧化过程中,PAFC既是絮凝剂又是Cl^(-)的提供者,其水解产生的Cl^(-)与NaCl引入的Cl^(-)在电场作用下向阳极定向迁移.阳极表面发生氧化反应产生的有效氯(Cl_(2)/ClO^(-))将兰炭废水中有机污染物氧化成中间产物氯酚,与絮凝剂中Al^(3+)的水解产物Al(OH)^(2+)、Al(OH)^(+)_(2)及Al(OH)_(3)通过静电和吸附作用结合形成絮凝体被去除.废水中剩余少量的氯酚及酰胺、环己二醇等有机污染物及NH_(3)-N则在ClO^(-)的间接氧化作用下转化为N_(2)、CO_(2)和H_(2)O得以去除.The synergistic process of flocculation-electrochemical oxidation was used to treat the semi-coking wastewater.The effects of flocculant dosage,reaction time,initial pH,applied voltage,and NaCl addition on the removal of chemical oxygen demand(COD)and ammonia nitrogen(NH_(3)-N)and the synergistic mechanism of flocculation-electrochemical oxidation were investigated.The results indicated that the removal rate of COD and NH_(3)-N in the semi-coking wastewater gradually increased with the increase of polyaluminium ferric chloride(PAFC)dosage and applied voltage.Under optimal conditions of 50g/L PAFC dosage,6V voltage,4h reaction time,initial pH of 9,and 30g/L NaCl addition,the removal rates for COD and NH_(3)-N were 82.37% and 100%,respectively.By replacing the electrode plate for the secondary electrolysis,the COD removal rate could reach 100%.The organic pollutants in the semi-coking wastewater before treatment were mainly phenols,alcohols and amides.After treatment,the content of phenols decreased significantly,and the relative proportion of ketones,alcohols and acids increased.During the flocculationelectrochemical oxidation process,PAFC functioned both as a flocculant and provider of Cl^(-).The Cl^(-)dissociated from PAFC hydrolysis,together with Cl^(-)introduced by NaCl,migrated directionally towards the anode under an electric field.The active chlorine(Cl2/ClO-)generated by the oxidation reaction on the anode surface oxidized the organic pollutants in the semi-coking wastewater into intermediate products,chlorophenols,which combined with the hydrolysis products of Al^(3+)from the flocculant,Al(OH)^(2+),Al(OH)_(2)^(+),and Al(OH)_(3),through electrostatic and adsorptive interactions to form flocs that were removed.The remaining traces of organic pollutants such as chlorophenols,amides,cyclohexanediol,and NH_(3)-N in the wastewater were converted into N_(2),CO_(2),and H_(2)O by the indirect oxidation action of ClO^(-).

关 键 词：兰炭废水 絮凝 电解 电化学氧化 协同作用 聚合氯化铝铁(PAFC) 

分 类 号：X703.1[环境科学与工程—环境工程]