Screening Of Advanced Oxidation Processes For Coking Wastewater Pretreatment And Removing Rule Of Phenol And Phenylamine

Coking wastewater is a typical toxic organic wastewater which are difficult to dispose;it accounts for one of the largest discharges of industrial wastewater in China.The high concentrations of phenols,cyanide and ammonia cause many problems in biological treatment which can be solved by pretreatment.In this study,we screened high feasibility of advanced oxidation processes for coking wastewater pretreatment.Under the concept of " treat waste with waste ",the advanced oxidation methods were screened and the manganese ore tailings in pretreatment process was investigated.This study is based on actual coking wastewater.First screen and combine advanced oxidation pretreatment process by experiment,including Fenton,analogous Fenton,ozone,manganese ore tailings catalytic.Then optimize the selected pretreatment process and study the characterized pollutant removal and transformation mechanisms including phenol and phenylamine by water and solid analysis.Finally study the biodegradability and toxicity of pretreatment process effluent and evaluate the pretreatment process and supply reasonable pretreatment processes.The results show that:(1)The UV254 can reflect biodegradability of coking wastewater.In this study,the equation of UV254 and B/C is y = 0.4347x-1.905,R2 = 0.9928.(2)In low concentrations of coking wastewater pretreatment process,manganese ore tailings can replace divalent iron of Fenton reagent.The COD removal rate can reach 55.4% and B/C value can reach 0.43 when the dosage of manganese ore tailings is 15g/L and the hydrogen peroxide is 2g/L at room temperature.(3)The best combination pretreatment of high concentrations of coking wastewater is using manganese ore tail + ozone after Fenton reagent.The COD removal rate can reach 53.3% and B/C value can reach 0.539,when the hydrogen peroxide: divalent iron is 10: 1,the hydrogen peroxide dosage 7g/L reaction time is 30 min,the manganese ore tailings dosage is 1g/L and the ozone access time is 30 min at room temperature.(4)Phenol and phenylamine removal rate can reach 88.3% and 71.0% in high concentrations of coking wastewater after pretreatment,and are all transformed to quinone as intermediate.The manganese ore tailings have a preference for phenylamine removal characteristic,when phenol and phenylamine exist at the same time.The manganese ore tailings have catalytic oxidation rather than adsorption in the pretreatment process as the major mechanism to remove COD.(5)The activated sludge dehydrogenase inactivation rate reduced from 93% to 36.8% after the pretreatment of coking wastewater.(6)Recommendation of the pretreatment process: low concentrations of coking wastewater flows past a packed column of manganese ore tailings after adding hydrogen peroxide;high concentrations of coking wastewater flows past a packed column of manganese ore tailings after treated by Fenton reagent and ozone at the bottom the same time.