Preliminary study on the effect of Fenton oxidation on black odor river sediment

Abstract

沉积物中有机质的削减是黑臭水体治理的关键.Fenton（Fe²⁺+H₂O₂）试剂在有机污染废水和土壤原位修复中的应用广泛且效果良好；Fenton试剂也能很好地去除黑臭水体中的色度和浊度，但其氧化沉积物有机质的研究未见报道.为探究Fenton试剂对黑臭水体沉积物的氧化效果，本研究通过室内模拟实验用Fenton氧化法对黑臭河道沉积物进行处理，考察氧化过程沉积物特征和性质的变化；分析覆水后沉积物中污染物的释放特征，并和H₂O₂体系（无Fe²⁺）进行比较.结果表明：Fenton体系显著提高了沉积物与上覆水的氧化还原电位，对黑臭河道沉积物中的有机质具有很强的氧化效率.在温度为28℃、H₂O₂为20% Q（Q为体系中沉积物有机质完全矿化的理论H₂O₂用量）和Fe²⁺：H₂O₂（摩尔比）为0.5：1时，反应1 d，酸挥发性硫化物去除率为70.13%，沉积物总有机碳减少了22.14%，总有机氮减少了87.60%，生成了较多的铵态氮和硝态氮；由于铁对磷的钝化，沉积物中溶解性反应磷含量大幅减少.H₂O₂体系的氧化速度较Fenton体系慢，覆水后对体系中的Eh提高不明显.值得注意的是，Fenton体系会降低上覆水的pH，释放较多的铵态氮.需要联合其他技术（如微生物法），强化水体中有机质和氨氮的降解，以取得理想的修复作用.;The reduction of organic matter in the sediment is key to solve the issue of black odor river. Fenton (Fe^{2 +} + H₂O₂) reagent is effectively in the treatment of organic contaminated water or soil. Fenton reagent has been also found to remove the coloration and turbidity of black odor water effectively. But the research on the treatment of organic matter in sediment by Fenton reagent has not been reported until now. In order to explore the oxidation effect of Fenton reagent on the sediment of black odor river, in this study, Fenton reagent was used to treat black odor river sediment. The changes of sediment characteristics were investigated during the oxidation process, also the release of pollutants from the sediment was analyzed. In addition, the treatment of the sediment by H₂O₂ system (without Fe^{2 +}) was compared with Fenton treatment. The results showed that under the condition of T=28℃, input (H₂O₂) =20%Q (Q is the theoretical dosage to mineralize completely organic carbon in sediment), the molar ratio of Fe²⁺ to H₂O₂=0.5∶1, the Fenton treatment significantly increased the redox potential of the sediment and overlying water, and had a strong oxidation efficiency for organic matter in black odor sediment. During Fenton treatment, the removal of acid volatile sulfide, total organic carbon, and total organic nitrogen were 70.13%, 22.14%, and 87.60%, respectively. A substantial amount of ammonium nitrogen and nitrate nitrogen were produced. Due to the presence of iron, the concentration of soluble reactive phosphorus in the sediment was greatly reduced. Compared to Fenton treatment, the oxidation rate of H₂O₂ system was slower, and the improvement of redox potential in the system was not obvious. The release of organic acids and ammonium nitrogen to the overlying water during the Fenton treatment should be paid attention to. It is suggested that the post-treatment of the overlying water, such as biological methods, should be used to obtain the ideal repair effect.