title: [NH4+-N removal stability of zeolite media packed multistage-biofilm system for coke-plant wastewater treatment].
abstract: The practical ammonia stripping effectiveness of coke-plant wastewater treatment may vary widely, and high NH4+-N shock loading will lead to the fluctuation of residual NH4+-N concentration of biological effluent. A zeolite media packed multistage-biofilm system (ZMBS) was used for coke-plant wastewater treatment for enhancing the NH4+-N treatment ability of the bio-system to shock loading, as well as achieving high COD removal efficiency. Treatment performance during steady-state and shock loading and transformation of organic pollutants in the system were investigated systematically. The experiment results indicated that when the system was operated at NH4+-N loading 0.21 kg/(m3 x d) and COD loading < or = 1.35 kg/(m3 x d), the average effluent NH4+-N and COD concentrations were (2.2 +/- 1.2) mg/L, (228 +/- 60) mg/L with average removal efficiencies of (99.1 +/- 0.5)% and (86.0 +/- 2.6)%. During the twice NH4+-N shock loadings [0.03 kg/(m3 x d) and 0.06 kg/(m3 x d)], ZMBS showed a strong resisting ability with average removal efficiencies of 99.0% and 92.9% higher than those of a compared system's 96.8% and 89.3%. By monitoring the change of water quality along the length of the ZMBS's cells, two function zones for different pollutant removal were found to exist, named as decarbonization/nitrification (C/N) zone and nitrification (N) zone, and the NH4+-N removal rate in N zone was 2-8 times as that in C/N zone. TOC concentrations of organic matters with relative molecular weight < 1 x 10(3), 1 x 10(3) to 1 x 10(4), and > 1 x 10(4), were 227.6, 104.8 and 35.0 mg/L in raw wastewater, and 31.2, 22.9 and 31.5 mg/L in the effluent, respectively. Organic matters with relative molecular weight < 1 x 10(3) and 1 x 10(3) to 1 x 10(4) in raw wastewater were removed effectively by ZMBS, but those with relative molecular weight > 1x 10(3) were the main remained substances in the effluent.
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China. zwt02@mails.tsinghua.edu.cn
authors.forename: Wen-Tao
authors.initials: WT
authors.lastname: Zhao
authors.forename: Xia
authors.initials: X
authors.lastname: Huang
authors.forename: Miao
authors.initials: M
authors.lastname: He
authors.forename: Peng-Yi
authors.initials: PY
authors.lastname: Zhang
authors.forename: Chen-Yan
authors.initials: CY
authors.lastname: Zuo
mesh_terms: D001673:Biodegradation, Environmental; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology; D003077:Coke; D009584:Nitrogen / Q000302:isolation & purification / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000302:isolation & purification / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification / Q000378:metabolism; D017641:Zeolites / Q000737:chemistry*
chemical_list: D003077:Coke; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D017641:Zeolites; D009584:Nitrogen