期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 635, 期 -, 页码 716-724出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.scitotenv.2018.04.162
关键词
Highly toxic coke wastewater; Hybrid anaerobic-anoxic-oxic process; PAHs; Adsorption; Risk
资金
- National Natural Science Foundation of China [51408425, 21577033, 21777042]
- Beijing Key Laboratory for Emerging Organic Contaminants Control
- Fundamental Research Funds for the Central Universities
Elimination of polycyclic aromatic hydrocarbons (PAHs) from coke wastewater is crucial to minimize the PAHs contamination levels to the environment. Knowledge about the characteristics of PAHs removal in biological treatment processes, especially hybrid systems, for real coke wastewater treatment has been very scarce. In this study, a lab-scale hybrid anaerobic-anoxic-oxic (A(1)/A(2)/O) process was used to treat highly toxic coke wastewater and operated more than 600 d at total hydraulic retention time (HRT) of 50 h, 40 h, 30 h, 20 h and internal mixed liquor recirculation ratio (R) of 3, 6, 9. Removal performance and behaviors of priority PAHs in the hybrid A(1)/A(2)/O system were investigated. The results showed that the appropriate total HRT and R from oxic reactor to anoxic reactor for organics and nitrogen removal was 40 h and 3, respectively. The concentrations of total PAHs were very high (254-488 mu g/L) in the raw coke wastewater, and effectively reduced to 4.1-4.5 mu g/L in the final effluent by the present system under the optimized operational conditions. Among the three treatment units, anoxic reactor made the largest contribution to the total PAHs removal. Large amounts of PAHs (415-1310 mu g/g) were adsorbed to the activated sludge in the anoxic and oxic reactor, leading to a much higher load of PAHs (2535 mu g/d) in the excess sludge than that in the treated coke wastewater (93 mu g/d) at SRT 60 d. Therefore, the excess sludge was identified as the major emission source of PAHs in coke wastewater during the hybrid A(1)/A(2)/O process, and might pose an environmental risk if the excess sludge was not properly treated and disposed. (C) 2018 Elsevier B.V. All rights reserved.
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