基于最佳氧化还原电位的O_3-H_2O_2氧化法处理高浓度含锰废水

Treatment of High Content Manganese-containing Wastewater by O_3-H_2O_2 Oxidation Based on Optimal Redox Potential

采用固定最佳氧化还原电位(ORP)的臭氧高级氧化与H2O2-NaOH深度氧化联用技术处理锰渣场渗滤水中高浓度Mn2+.确定了氧化工艺的最佳OPR,并对臭氧、H2O2和NaOH投加量及氧化动力学进行研究.结果表明,臭氧预氧化的最佳ORP为296～299.7 mV,两级臭氧投加量均为0.13～0.15 g/L,Mn2+氧化去除率达91.57%;H2O2-NaOH深度氧化最佳ORP为12.4～12.8 mV,在H2O2浓度2.0 g/L和NaOH浓度2.6 g/L且两者摩尔比为0.9:1(先加H2O2)的条件下,Mn2+去除率高达99.31%,出水Mn2+为1.2 mg/L,可达标排放.臭氧和H2O2-NaOH对含锰废水的降解符合一级反应动力学,一、二级臭氧氧化的反应常数k固定ORP时分别为0.0762和0.0822 min-1,不固定ORP时分别为0.027 9和0.050 8 min-1,H2O2-NaOH氧化的反应常数固定ORP时为0.4758 min-1,不固定ORP时为0.3594 min-1.

Ozonation and H202-NaOH advanced oxidation processes were used to treat high content manganese-containing wastewater based on optimal redox potential （ORP）. The effects of oxidizer （ozone, H202 and NaOH） dosages, and the oxidation kinetics were investigated. Experimental results indicated that the ORP was 296-299.7 mV in the ozonation oxidation, under addition of ozone at 0.13-0.15 g/L in both first and second ozonation oxidation processes, the removal rate of Mn^2＋ reached 91,57%. The ORP was 12.40-12.80 mV in the H2O2-NaOH oxidation, when the dosages of H202 and NaOH were 2.0 and 2.6 g/L respectively, their molar ratio was 0.9：1 and H202 was added first, the removal rate of Mn2＋ reached 99.31%. The treated wastewater had the Mn^2＋ concentration of 1.2 mg/L which was lower than the first level standard （2.0 mg/L） specified in the National Wastewater Discharge Standard GB 8978-1996, The oxidation kinetics indicated that the oxidation processes obeyed first order reaction kinetics. The rate constant k was 0.0762 min^-1 for the first ozonation oxidation and 0.082 2 min-1 for the second one at set ORP, otherwise k was 0.027 9 and 0.050 8 min^-1, respectively. k was 0.475 8 min^-1 for the H202-NaOH oxidation at set OitP, otherwise k was 0.3594 min^-1.