曝气生物滤池对邻苯二甲酸二己酯的生物降解试验

Experiment on biodegradation of dihexyl phthalate by biological aerated filter

采用陶粒滤料曝气生物滤池(BAF)处理邻苯二甲酸二己酯(DHP)模拟废水,考察了空床接触时间(EBCT)、温度对DHP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DHP的降解效果良好,去除率达到95.5%;BAF对DHP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出水中检测到邻苯二甲酸二丁酯(DBP)、邻苯二甲酸单丁酯(MBP)、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己酯的生物降解途径可能为邻苯二甲酸二己酯的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。

The present paper is aimed at introducing our study on the biodegradation features and relevant influencing factors of the biologi- cal aerated filter （BAF） for dihexyl phthalate （DHP） removal so as to find a new approach to pollution control of phthalie acid esters （PAEs）. As is known, PAEs are a kind of environmental hormones which become widespread in our water environment and they have been in turn paid more and more attention to due to their teratogenici- ty, mutagenieity and earcinogenicity. DHP is one of the PAEs used widely for manufacturing plastics but contributes to the environmental pollution. Therefore, it is necessary for DHP to get biodegradated so as to remove and reduce its toxicity. It is for this purpose, ceramsite medium biological aerated filter （BAF） has been used to treat the sewage containing DHP. It is also for this purpose of the treatment ef- ficiency that we have done investigations of the optimal temperatures in different empty bed contact time and analyzed the major intermedi- ate products of biodegradation of DHP via GC - MS. The results of our investigation indicate that we have succeeded in increasing the re- moval rate of DHP to 95.5 % under the conditions of 25 ~C and 8 hours of the empty bed contact time. We have also found that it is E- BCT that plays the main role between the two influential factors of the removal effect. At the lower-middle layer of the filter bed, DHP is more efficient in doing the biodegradatiou because there exists higher concentration of organic compounds and active microbes. However, things are just going on the contrary with the upper-middle layer in the filter bed. The major intermediate products of bio-degradation of DHP are made up of dibutyl phthalate （DBP）, monobutyl phthalatc （MBP）, dimethyl phthalate （DMP） and phthalie acid （PA）. It is for this need, we have first of all eleavaged the long chain of the alco- holic ending of DHP into shorter and more straight ones by eleavaging one of the two ester bonds, and then, try to transform and oxidize the monoester and PA into CO2 and H20. The SEM-photographs show that there are quite stable microorganisms adhered to the surface of eeramsite medium. The dominant degrading bacteria of the microor- ganisms found are bacillus and coccus. It can thus be concluded that the biological aerated filter can effectively be used for treating the sewage contaminated by dihexyl phthalate.