生物强化SBR系统中邻苯二甲酸二甲酯的降解

Bioaugmentation Treatment of Dimehyl Phthalate in Sequencing Batch Reactor

为实现低温条件下DMP的快速降解,在SBR反应器中,加入耐低温DMP降解菌Rhodococcus fascians STX-5,考察生物强化系统对DMP的去除效果,并通过设计特异引物,对邻苯二甲酸双加氧酶降解基因(phtA)进行扩增,利用荧光原位杂交(FISH)和实时荧光定量(q-PCR)对降解基因分布和丰度进行检测。结果表明,生物强化可显著提高DMP降解率(p<0.05),强化反应器在20℃和15℃的条件下,运行后期对1 000 mg/L的DMP平均去除率分别达90%和71%,而未经强化系统对DMP去除率为54%和32%。FISH结果显示,phtA基因在反应器运行不同时段其分布特征不同,当DMP降解率上升时,其分布范围变宽且更均匀。q-PCR结果进一步表明,phtA基因丰度与DMP降解成正相关,在反应器运行的后期MLVSS与phtA基因丰度成显著正相关(r=0.97,p<0.05)。当温度从20℃降至15℃时,未经强化系统中phtA基因从3.5×10~8copies/mg MLVSS下降到0.73×10~8copies/mg MLVSS,经强化的系统phtA基因数量在短暂下降后保持在4.5×10~8copies/mg MLVSS。

A laboratory experiment was conducted in a bench-scale SBR for degradation of DMP （dimethyl phthalate） to investigate DMP removal rate at low temperature with a bio-augmentation measure, i.e., a DMP-degrading bacteria Rhodococcus fascians STX-5DMP was inoculated in the reactor, and the phthalate dioxygenase gene （phtA） fragment was amplified by using designed primers, in addition, real-time quantitative PCR and FISH （fluorescence in situ hybridization） techniques were employed to detect the distribution and abundance of phtA gene. The experimental study showed that removal rates of DMP of concentration of 1 000 mg/L in the bio-angmented reactor, when operated at 20 ℃ and 15 ℃, were 90% and 71%, respectively; the FISH test demonstrated that the distribution ranges of phtA gene changed at the different reaction stages, the distribution range broadened and became uniform as degradation rate increased; and q-PCR showed that the abundance of phtA gene was positively correlated with DMP degradation rate, while MLVSS was significantly positive correlated with phtA gene abundance （r=0.97, p〈0.05）. Furthermore, when temperature declined from 20 ℃ to 15 ℃, the phtA gene copies drop from 3.5×10^8 to 0.73×10^8 copies/mgMLVSS in the reactor with no bio-augmentation measure; but in the reactor with bio-augmentation phtA gene copy number recovered quickly after a short-time decline and kept in 4.5 ×10^8 copies/mgMLVSS.