多重环境因素对Fe^(2+)作用下化学反硝化去除亚硝的影响

Multiple Environmental Factors Affect the Nitrite Removal Efficiency of Chemo⁃Denitrification by Fe^(2+)

为了提高以Fe^(2+)作为还原剂的NO_(2)^(-)去除工艺在实际应用中的效率,设计了外源阴离子、Fe^(2+)浓度以及反应温度3个环境因素来探明其对Fe^(2+)化学还原NO_(2)^(-)过程的影响.结果表明,虽然提高Fe^(2+)浓度可以明显促进NO_(2)^(-)厂的去除速率,但同时降低了Fe^(2+)的利用率,除此以外,升高温度和添加HCO_(3)^(-)/CO_(3)^(2-)都可以提高NO_(2)^(-)去除速率和程度.另外铁氧化所形成的副产物类型也受到温度和HCO_(3)^(-)的调控,温度在55℃以下(30℃,40℃)时铁氧化产物以纤铁矿和针铁矿为主,温度高于55℃时铁氧化产生磁铁矿.而在HCO_(3)^(-)体系中,磁铁矿可以在更低温度(40℃)条件下形成.这些发现对改进Fe^(2+)作用下的化学反硝化应用模式和副产物的二次处理利用提供了实验参考,为推动其在实际工程中应用提供了理论依据.

To improve the efficiency of the NO_(2)^(-)removal process using Fe^(2+)as a reducing agent in practical applications,this research designed three environmental factors of exogenous anions,Fe^(2+)concentration,and reaction temperature to investigate their effects on the chemical reduction of NO_(2)^(-)by Fe^(2+).The results showed that although increasing the Fe^(2+)concentration could significantly promote the removal rate of NO_(2)^(-),it also reduced the utilization rate of Fe^(2+).In addition,raising the temperature and adding HCO_(3)^(-)/CO32−could both increase the removal rate and extent of NO_(2)^(-).The type of by-product formed by iron oxidation was also regulated by temperature and HCO_(3)^(-).At temperatures below 55℃(such as 30℃ and 40℃),the by-product of iron oxidation was mainly goethite and magnetite.At temperatures above 55℃,Magnetite was the only by-product.But magnetite can be formed at a lower temperature(40℃)with HCO_(3)^(-).These results provide experimental references for improving the application mode and by-product secondary treatment utilization of Fe^(2+)-based Chemo-denitrification and provide theoretical basis in actual engineering.