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Iron-mediated physico-oxidative treatment of high strength recalcitrant organic wastewater: Landfill leachate.

机译：铁介体物理氧化处理高强度难降解有机废水：垃圾渗滤液。

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摘要

Emerging contaminants in high strength wastewaters such as landfill leachate are causing environmental concerns due to their adverse impacts on the aquatic environment. Current treatment technologies are limited by high operating costs, low treatment efficiencies, or sensitive operating conditions. In this study, laboratory scale tests were conducted to evaluate the feasibility of iron-mediated oxidation processes---Fenton and hydrogen peroxide (H2O2) enhanced iron-mediated aeration (IMA)---to treat such wastewater for removal of organic content, in addition to reduction of ammonia nitrogen and electrical conductivity. Landfill leachate was selected as the model wastewater, due to recent disallowance of leachate for discharge to municipal sewer in Florida. First, the effects of initial pH, Fenton reagent doses, aeration, and number of dosing steps on chemical oxygen demand (COD) removal by the Fenton process were investigated. Also, a set of Taguchi orthogonal array experiments was conducted to investigate the effects of initial pH, iron grade, aeration rate, and H2O2 addition rate for COD removal on H2O2-enhanced IMA process. Second, preliminary comparison was made on these bases, and tests were conducted to study the interaction of coagulation and oxidation on overall processes. In Fenton treatment, oxidation played an important dual role, contributing to COD removal, while degrading organics to smaller, more soluble species less amenable to coagulation. In H2O2-enhanced IMA treatment of glyoxylic acid in simulated natural water, the known •OH radical scavenger, para-chlorobenzoic acid (pCBA), was found not to inhibit the decomposition rate of glyoxylic acid at pH 7.0-7.5, effectively ruling out hydroxyl radicals as the principal oxidant, suggesting that either H2O2 or ferryl species might play an important role. In addition, aeration was shown to slow the auto-decomposition of H2O2, enhance release of Fe 2+ from Fe0 corrosion, and slightly improve COD removal, suggesting that molecular oxygen took part in the oxidation of organics, and differentiating the H2O2-enhanced IMA process from the Futon reaction using Fe0. Tests showed that both processes could remove COD by >50%. However, H2O2-enhanced IMA process was shown, in addition, to simultaneously reduce ammonia nitrogen and electrical conductivity in the effluent, whereas the Fenton process removed little ammonia nitrogen and substantially increased electrical conductivity due to pH adjustment and FeSO4 input. Finally, kinetics tests of the H2O2-enhanced IMA process were conducted with respect to H2O2 decay, overall COD removal, and COD oxidation. Mathematical models utilizing measured reaction data were established and verified, which adequately predicted H2O2 concentration, overall COD removal rate, and COD oxidation removal rate under different conditions.
机译：高强度废水中的新兴污染物（如垃圾渗滤液）由于对水生环境造成不利影响而引起环境问题。当前的处理技术受到高运行成本，低处理效率或敏感的运行条件的限制。在这项研究中，我们进行了实验室规模的测试，以评估铁介导的氧化过程（芬顿和过氧化氢（H2O2）增强铁介导的曝气（IMA））的可行性，以处理此类废水以去除有机物，除了减少氨氮和导电性。垃圾填埋场渗滤液被选为示范废水，因为最近不允许渗滤液排入佛罗里达州的市政下水道。首先，研究了初始pH，Fenton试剂剂量，曝气和加药步骤数对通过Fenton工艺去除化学需氧量（COD）的影响。此外，进行了一组Taguchi正交阵列实验，以研究初始pH，铁级，通气速率和H2O2添加速率对COD去除对H2O2增强的IMA过程的影响。其次，在这些基础上进行了初步比较，并进行了测试以研究混凝和氧化在整个过程中的相互作用。在Fenton处理中，氧化起着重要的双重作用，有助于去除COD，同时将有机物降解为更小的，更易溶解的，不易凝结的物质。在模拟的天然水中用H2O2增强的IMA处理乙醛酸时，发现已知的•OH自由基清除剂对氯苯甲酸（pCBA）在pH 7.0-7.5时不会抑制乙醛酸的分解速率，从而有效地排除了羟基自由基作为主要氧化剂，表明过氧化氢或小分子物种可能起重要作用。此外，曝气还可以减缓H2O2的自分解，增强Fe2 +从Fe0腐蚀中的释放，并略微提高COD的去除率，这表明分子氧参与了有机物的氧化，并区分了H2O2增强的IMA。使用Fe0从Futon反应中进行反应。测试表明，这两个过程都可以去除COD超过50％。但是，H2O2增强的IMA工艺还显示出可同时降低废水中的氨氮和电导率，而Fenton工艺由于pH值调节和FeSO4输入而去除了很少的氨氮并大大提高了电导率。最后，针对H2O2衰减，总COD去除和COD氧化进行了H2O2增强的IMA过程的动力学测试。建立并验证了利用测得的反应数据的数学模型，该模型可以充分预测不同条件下的H2O2浓度，总COD去除率和COD氧化去除率。

著录项

  • 作者

    Deng, Yang.;

  • 作者单位

    University of Miami.;

  • 授予单位 University of Miami.;
  • 学科 Engineering Sanitary and Municipal.; Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 228 p.
  • 总页数 228
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;环境污染及其防治;
  • 关键词

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