RESUMEN
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.
Asunto(s)
Reactores Biológicos , Nitrógeno/metabolismo , Compuestos de Amonio Cuaternario/metabolismo , Eliminación de Residuos Líquidos/métodos , Zeolitas/química , Biodegradación Ambiental , Biopelículas , Reactores Biológicos/microbiología , Coque , Nitrógeno/aislamiento & purificación , Compuestos de Amonio Cuaternario/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Contaminantes Químicos del Agua/metabolismoRESUMEN
The method of Fenton oxidation cooperated with coagulation for biologically treated coking wastewater was conducted. Based on both of the removal performance and the operating costs, optimal reaction condition was proposed. Operating at H2O2 concentration 220 mg/L, Fe2+ concentration 180 mg/L, PAM concentration 4.5 mg/L, reaction time 0.5h and pH = 7, about 44.5% of COD was removed and chroma reached 35. In addition, through analyzing of the changes of molecular weight distribution and constitute of organic compounds in effluent, the pollutant transformation rule was put forward. The result shows that the effluent treated by Fenton oxidation cooperated with coagulation can reach the wastewater secondary discharge standard, and the operation costs are acceptable. This implies that the technique of Fenton oxidation cooperated with coagulation has promising in practice.