模拟曝气生物滤池去除邻苯二甲酸二(2-乙基己基)酯试验研究

Study on Removal of Di-(2-Ethylhcxyl) Phthalate by Using of Small-Scale Biological Aerated Filter

采用陶粒滤料曝气生物滤池(BAF)处理邻苯二甲酸二(2-乙基己基)酯(DEHP)模拟废水,考察了空床接触时间(EBCT)、温度对DEHP去除效果的影响,运用气质联用仪(GC-MS)分析了中间降解产物并推测其可能的降解途径.结果表明,当温度为25℃,空床接触时间(EBCT)为8 h时,BAF对DEHP的降解效果良好,去除率达到90.3%;BAF对DEHP的去除率随着温度的升高和EBCT的增加而增大,EBCT为去除效果的主要影响因素;BAF对DEHP的降解满足一级反应动力学方程.BAF出水中检测到邻苯二甲酸单2-乙基己基酯(MEHP)、邻苯二甲酸丁基酯2-乙基己基酯(BEHP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二甲酯(DMP)以及邻苯二甲酸(PA)等降解产物,据此推测邻苯二甲酸二(2-乙基己基)酯的生物降解途径可能为其长烷基支链先断裂为较短的直链,而后断裂一个酯键形成单酯,接着再断裂另一酯键形成邻苯二甲酸,最终分解成二氧化碳和水.

Ceramsite medium biological aerated filter （BAF） was used to treat the sewage containing di-（2-ethylhcxyl） phthalate （DEHP）. The treatment efficiency under different empty bed contact time （EBCT） and temperatures was investigated and the major intermediate products of biodegradation of DEHP were analyzed via GC-MS. Results show that the removal rate of DEHP can be highly achieved at 90. 3% under the conditions of 25℃ and 8 hours of empty bed contact time. The removal efficiency will be increased after raising temperature or EBCT. The EBCT plays the main role between two influencing factors. The biodegradation of DEHP in BAF is expressed in the first-order kinetics. The major intermediate products of biodegradation of DEHP are made up of mono-2-ethylhexyl phthalate（MEHP） , bisethylhexyl phthalate（BEHP） , dibutyl phthalate（ DBP）, dimethyl phthalate（DMP） and phthalic acid（PA）. It is supposed that the possible pathway of the biodegradation of di-（2-ethylhcxyl） phthalate is that the long alkyl side-chain of DEHP may be cleavaged into a shorter and more straight one, then PA is formed after cleavaging the two ester bonds, and finally being oxidized into CO2 and H2O.