微氧水解酸化处理石化废水的生物降解特性

本研究采用微氧水解酸化技术处理石化废水,以抑制硫酸盐的还原,减少硫化氢的产生.同时,通过与厌氧水解酸化的对比试验,研究了微氧水解酸化的生物降解特性.微氧反应器的ORP控制在(-290±71)m V,厌氧反应器的ORP为(-398±31)m V.反应器运行近7个月的结果表明,在进水COD为202~514 mg·L-1、硫酸根浓度为350~650 mg·L-1及HRT为12 h时,微氧水解酸化反应器COD的平均去除率为31.2%,高于厌氧水解酸化的26.4%.厌氧出水的VFA浓度((2.34±0.60)mmol·L-1)高于微氧出水((1.89±0.48)mmol·L-1).微氧出水的平均比紫外吸收值(UV254/DOC)为0.017,显著低于厌氧出水(0.025),表明微氧环境可以提高兼性水解酸化菌的生理代谢功能,强化难降解芳香有机物和含共轭双键大分子化合物的去除.微氧水解酸化出水的硫离子浓度((0.11±0.04)mg·L-1)显著低于厌氧出水((1.27±1.22)mg·L-1).454焦磷酸测序结果表明:微氧水解酸化菌群中,变形菌门、绿弯菌门和放线菌门菌群丰度(所占比例分别为39.7%、20.3%、1.9%)高于厌氧水解酸化菌群(分别为36.9%、17.5%、1.3%),对难降解大分子有机物的去除效果好;厌氧水解酸化菌群中拟杆菌门和酸杆菌门所占比例较大,酸化效果更好.在属的水平上,微氧水解酸化污泥中鉴定出的硫酸盐还原菌的种群多样性和丰度均低于厌氧污泥,这与其出水较低的硫离子浓度一致,表明微氧环境能够有效抑制硫酸盐还原菌的活性.上述研究结果表明,微氧水解酸化是一种很有前途的石化废水预处理技术.

Biodegradation characteristics of petrochemical wastewater by micro-aerobic hydrolysis acidification

Micro-aerobic hydrolysis acidification process was developed to inhibit sulfate reducing and decrease the production of hydrogen sulfide in the treatment of petrochemical wastewater. The biodegradation characteristics of micro-aerobic hydrolysis acidification were investigated in comparison to anaerobic hydrolysis acidification. Oxidation reduction potential (ORP) was remained at (-290±71) mV in the micro-aerobic reactor and (-398±31) mV in the anaerobic reactor, respectively. The results during nearly seven months of operation showed that the COD removal efficiency in the micro-aerobic reactor (31.2% on average) was higher than that in the anaerobic reactor (26.4%) with influent COD of 202~514 mg·L^-1, sulfate of 350~650 mg·L^-1 and hydraulic retention time of 12 h. The effluent VFA concentration of the anaerobic reactor was (2.34±0.60) mmol·L^-1, which was higher than that of the micro-aerobic reactor((1.89±0.48) mmol·L^-1). The ratio of effluent UV₂₅₄/DOC of the micro-aerobic reactor (0.017) was much lower than that of the anaerobic reactor (0.025), indicating that the metabolic activities of the facultative hydrolytic and acidogenic bacteria could be enhanced and that the removal of organics with aromatic and conjugated double bond could be improved at the micro-aerobic conditions. The effluent S^2- concentration of the micro-aerobic reactor ((0.112±0.037) mg·L^-1) was much lower than that of the anaerobic reactor ((1.267±1.224) mg·L^-1). A pyrosequencing analysis of the sludge showed that bacteria belonging to Proteobacteria, Chloroflex and Actinobacterium dominated the microbial community in the micro-aerobic sludge with 39.7%, 20.3% and 1.9% of the total bacterial sequences, respectively. These values were higher than those in the anaerobic sludge (36.9%, 17.5% and 1.3%, respectively), which indicated that the macromolecular refractory organics could be degraded effectively at the micro-aerobic conditions. Bacteroidetes and Acidobacteria were highly enriched in the anaerobic reactor, leading to better acidification at the anaerobic conditions. At the genus level, the diversity and abundance of sulfate reducing bacteria in the micro-aerobic sludge were less than those in the anaerobic sludge, which was consistent with less effluent sulfide concentration of the micro-aerobic reactor. Sulfate reduction was therefore inhibited effectively at the micro-aerobic conditions. These results demonstrated that micro-aerobic hydrolysis acidification is a promising technique for pre-treatment of petrochemical wastewater.