O池溶解氧水平对石化废水A/O工艺污染物去除效果和污泥微生物群落的影响

以实际石化废水为处理对象,研究溶解氧浓度对A/O反应器生物降解特性的影响.A、B两组反应器平行运行以进行对比,O段的溶解氧浓度分别控制在2~3 mg·L-1和5~6 mg·L-1.反应器稳定运行近半年的结果表明:在HRT为20 h时,A组反应器出水的COD(72.5 mg·L-1±14.8 mg·L-1)略高于B组(68.7 mg·L-1±14.6 mg·L-1),COD平均去除率分别为67.0%和68.8%;出水氨氮的平均浓度和去除率为0.8 mg·L-1和95%左右.出水的BOD5均低于5 mg·L-1.表明A/O反应器对有机物的生物降解比较彻底,溶解氧浓度对其没有显著影响.对O段污泥进行454高通量测序结果表明:变形菌门、浮霉菌门和拟杆菌门细菌所占比例较高,在A、B组反应器中的比例分别为58.7%和59.2%、14.7%和12.7%以及10.8%和12.4%.高溶解氧运行的反应器B具有较高的菌群丰度和多样性,氨氧化菌Nitrosomonas、亚硝酸氧化菌Nitrospira和专性好氧菌如Planctomyces的比例较高.厌氧反硝化菌如Azospira和Acidovora在反应器A中的含量较高.在属的水平,鉴定出的Novosphingobium、Comamonas、Sphingobium和Altererythrobacter属细菌具有降解多环芳烃、氯代硝基苯、农药和石油化合物的功能,有利于石化废水的降解.

Effects of Dissolved Oxygen in the Oxic Parts of A/O Reactor on Degradation of Organic Pollutants and Analysis of Microbial Community for Treating Petrochemical Wastewater

Effects of dissolved oxygen (DO) on the biodegradation of organic pollutants were investigated using A/O reactors for the treatment of actual petrochemical wastewater. Two A/O reactors, DO were controlled at 2-3 mg·L^-1 in the oxic parts of reactor A and 5-6 mg·L^-1 of reactor B, were operated in parallel for comparison. The nearly a half of year operation results showed that the effluent COD in reactor A (72.5±14.8 mg·L^-1) was slightly higher than that in reactor B (68.7±14.6 mg·L^-1) at a HRT of 20 h. The average COD removal efficiencies were 67.0% and 68.8%, respectively. The effluent ammonium concentration was maintained at 0.8 mg·L^-1 and approximately 95% of ammonium removal was achieved. The effluent BOD₅ concentration was lower than 5 mg·L^-1. This indicated that the organic pollutants could be degraded thoroughly by the A/O processes, which were affected slightly by DO. Results of 454 pyrosequencing analysis of the sludge in oxic parts showed that at the phylum levels, sequences belonged to Proteobacteria, Planctomycetes and Bacteroidetes were abundant with 58.7% and 59.2%, 14.7% and 12.7%, 10.8% and 12.4% of total bacterial sequences in reactor A and B, respectively. Ammonium oxidation bacteria Nitrosomonas, nitrite oxidizing bacteria Nitrospira and obligate aerobic bacteria were highly enriched in reactor B with high DO levels, while the anaerobic denitrifiers Azospira and Acidovora were highly enriched in reactor A with low DO levels. The identified bacteria belonged to genera Novosphingobium,Comamonas, Sphingobium and Altererythrobacter were reported to degrade PAHs, chloronitrobenzene, pesticides and petroleum, which contributed to the degradation of petrochemical wastewater.