The Research Of Coking Wastewater Treatment By SBR-Oxidation-Adsorption Process

The coking wastewater is an organic one with high concentration which has complex ingredient polluting the environment if discharged without treatment. Focused on present treatment difficulties and the characters of coking wastewater, the process of SBR-Oxidation-Adsorption and two-stage SBR-Flocculation were investigated which can provide some reference treating coking wastewater and other organic one with high concentration.In SBR experiment, the impact of reaction time and drainage volume on the treatment effect was studied. The results showed that the removal rate of CODcr was 77.14% from 2105.040mg/L to 481.152mg/L when the influent time was for 10min, the sedimentation time for 2h, the idle time for 1h and the optimal reaction time for 6h. And the impact of drainage volume on the treatment effect was inferior when the influent time was for 10min, the reaction time for 6h, the sedimentation time for 2h, the idle time for 1h and the CODcr of influent from 2332.392 to 2773.120mg/L.Fenton was adopted to treat coking wastewater in oxidation experiment of SBR effluent. For CODcr, several different parameters including reagent dosage, reaction time and initial pH are examined. The results showed that, the removal rate of CODcr was 48.72% from 481.152mg/L to 246.758mg/L under the condition of H₂O₂ dosage of 1.67mL/L, FeSO₄·7H₂O dosage of 1.67g/L and reaction time of 4 hours at pH of 6.5.In adsorption experiment of SBR-Oxidation effluent, the adsorption effects of the activated zeolite with lanthana, the activated zeolite with NaCl and the active carbon after activated zeolite were studied. The results showed that the adsorption effect of activated zeolite with NaCl was more preferable than activated zeolite with lanthana; The removal rate of CODcr was 66.56% from 246.758mg/L to 82.510mg/L when zeolite activated by 0.3 mol/L NaCl solution for 2h, with the dosage of 120g/L, and the removal rate of ammonia-nitrogen was 98.20% from 267.2mg/L to 4.8mg/L (which can be complied with the requirement in Water quality standard for urban miscellaneous water consumption, ammonia-nitrogen(?)5mg/L, GB/T18921-2002). The adsorption isotherm curve of ammonia-nitrogen on activated zeolite with NaCl was well described by Freundlich function. After adsorbed by activated zeolite with NaCl, the effluent of coking wastewater after SBR-oxidation was adsorbed by the active carbon with the dosage of 100g/L, in result the removal rate of CODcr was 88.70% from 82.510mg/L to 9.327mg/L(which can be complied with the requirement in Water quality standard for urban miscellaneous water consumption).In the second stage SBR, the impact of reaction time on the treatment effect was studied. The results showed that the removal rate of CODcr was 43.01% from 725.170mg/L to 413.280mg/L when the influent time was for 1h, the sedimentation time for 2h, the idle time for 3h and the optimal reaction time for 6h.In Flocculation experiment after the second stage SBR, the impact of flocculant types, dosage, flocculation time and pH on the treatment effect was studied. The results showed the removal rate of CODcr was 55.08% from 413.280mg/L to 185.650mg/L and the removal rate of turbidity was 88.98% from 166.9 NTU to 18.4 NTU when optimal flocculant was polyferric sulfate with a dosage of 500mg/L and flocculation time of 10 min at pH of 9.As the results showed , CODcr had decreased from 2105.040mg/L to 9.327mg/L, and ammonia-nitrogen had decreased from 267.2mg/L to 4.8mg/L by the process of SBR-Oxidation-Adsorption to treat coking wastewater. As a result, the effluent can reached the standard grade and reused for production.