【作者】 张文义；

【导师】 杨世迎；

【作者基本信息】 中国海洋大学 ， 环境工程， 2011， 硕士

【摘要】 垃圾渗滤液中含有大量腐殖酸（HA）,是化学需氧量（COD）的重要组成部分。HA是一类典型的大分子难降解有机物,它能够络合重金属离子、影响色味,还可以形成有毒副产物。HA的降解是垃圾渗滤液处理的关键之一。因其难生化,不易被传统生物法降解。过硫酸盐高级氧化技术是近年来兴起的新型高级氧化技术。过二硫酸盐（PS）传统的活化方法包括热、光、过渡金属离子。微波（MW）具有加热快、高效、均匀等特点,可以快速活化PS形成硫酸根自由基（SO₄^-）。实验在一台改装后的的家用微波炉（功率为800 W）中进行,通过研究影响因素和自由基机理等内容,探讨微波辅助过二硫酸盐（MW+PS）技术对垃圾渗滤液中HA的降解。研究内容如下:（1）通过检测254 nm下吸光度(UV₂₅₄)变化、400 nm下吸光度（VIS400）变化、紫外可见光谱等指标,研究了MW+PS氧化法对HA降解的可行性。结果表明5 mmol/L的PS在MW中被活化,反应30 min后对100 mg/L的HA降解率接近100%。通过对反应前后总有机碳（TOC）的表征发现,MW+PS不仅能够降解HA,还能将其矿化,MW反应30 min,100 mmol/L的PS对100 mg/L HA的TOC去除率可达到98%。HA降解效率随PS浓度的升高而增加,随HA浓度的增加而降低;pH = 4,7,10,12.8条件下,MW+PS对HA的降解效率都很高。叔丁醇（TBA）和甲醇（MA）被用作化学探针验证反应过程中自由基的种类,实验结果发现,在降解HA过程中,酸性条件下,SO₄^-占主导,碱性条件下,羟基自由基（·OH）占主导。（2）用树脂吸附分离法对渗滤液中HA进行分离与提取,采用MW+PS对提取的HA进行降解。通过对UV-vis光谱和不同pH下的UV₂₅₄、VIS₄₀₀检测表征MW+PS对垃圾渗滤液中HA的降解效果。结果发现,MW+PS工艺对TOC和COD去除率分别为55%和58.9%,而且不同初始pH下（pH = 3,7,13）HA反应30 min后UV₂₅₄和VIS₄₀₀去除率均可到到95%以上。（3）垃圾渗滤液液中含有大量的Cl-,国标法测COD不能有效消除Cl^-的干扰。比较了重铬酸钾回流法、快速消解分光光度法、碱性高锰酸钾法以及紫外分光光度法对COD的检测,对Cl^-所产生的干扰进行讨论。确定在水质稳定的垃圾渗滤液中采用紫外分光光度法检测COD可以避免Cl-带来的干扰,可以快速准确的检测渗滤液中COD。（4）探讨了MW+PS工艺对实际垃圾渗滤液（COD浓度为3074.4 mg/L,Cl-浓度为5325 mg/L）的降解情况,同时比较了MW辅助过氧化氢（MW+H₂O₂）、MW辅助过一硫酸盐（MW+PMS）对COD去除率的作用,结果发现氧化剂浓度为0.3 mol/L情况下,MW+H₂O₂、MW+PMS、MW+PS在30 min内的COD去除率分别为42%、80%、97%,MW+PS的去除率更高、反应更温和、更利于控制。其中氧化剂浓度越高,COD去除率越高;渗滤液中含有大量Cl-,因能够捕获反应中的自由基生成Cl₂而影响COD的去除效率,其中加入H₂O₂和PS的溶液COD去除率有一定程度的增加,加入PMS的溶液COD去除率稍有降低。MW+PS工艺在酸性、中性、碱性条件下（pH = 2 - 12）对垃圾渗滤液COD的去除率都很高;当温度大于等于85℃时,MW加热比传统加热方式去除率高;活性炭在MW+PS技术处理垃圾渗滤液中具有明显的增强作用,可以使COD去除率升高,但是反应过程中PS的加入量是主要因素。更多还原

【Abstract】 There are lots of humic acid （HA） in landfill leachate, which is a high contribution to chemical oxygen demand （COD）. HA is a topic recalcitrant pollutant and it can not only adversely affect appearance and taste, but can also be halogenated to form potentially carcinogenic chlorinated organic compounds. However, it is difficult to remove HA from landfill leachate by traditional biological processes.Advanced oxidation technologies, in which persulfate （PS） is used as oxidant, have come forth recently for the degradation of non-biodegradable contaminants. The conventional activation methods of PS consist of heat, UV and metal activation. Microwave （MW） heating presents several attractive advantages, such as shorter reaction times, higher yields, and cleaner reactions. A modified domestic MW furnace （800 W） is used to supply MW energy and activate PS to generate sulfate radical （SO₄^-）. MW assisted persulfate （MW+PS） is investigated for the degradation of HA. Specific studies are as follows:（1） The effects of various operating conditions such as initial HA concentration, initial PS concentration, initial pH value, HCO₃^-/CO₃^2-and granular activated carbon （GAC） are examined. Degradation is evaluated by the decreases of absorbance at 254 nm (UV₂₅₄) and 400 nm (VIS₄₀₀)and total organic carbon （TOC）. According to the results, nearly 100% of 100 mg/L HA is degraded by MW+PS process at 800 W in 30 min. Higher initial PS concentration could accelerate the HA degradation efficiency, while higher initial HA concentration could cause a lower degradation efficiency. The UV254 and VIS400 of HA kept high at pH 4 - 12.8. PS could not only oxidize functional groups of HA, but also mineralize it and the removal efficiency of TOC is about 98% under MW irradiation when PS dosage is 100 mmol/L. Methanol （MA） and tert-butyl alcohol （TBA） are applied as chemical probe compounds to detect the free radicals. The results show that both SO₄^- and·OH may exist in the MW+PS technology. Whether SO4?? or·OH playing a predominant role in HA degradation depends on the pH of the solution.（2） Humic substance is extracting from landfill leachate by resin. Experiments are carried out on the degradation of extracted HA by MW+PS technology. The results show that the removal efficiency of TOC and COD are 55% and 58.9% respectively. Furthermore, the degradation of UV254 and VIS400 are both more than 95% in 20 min when initial pH is 3, 7 and 13.（3） COD is one of the most important determination indicators of landfill leachate. However, the presence of high concentration chloride in leachate generates interference when detacting COD by national standard method. Compared potassium dichromate reflux method, rapid digestion-spectrophotometric method, basic potassium permanganate method with UV spectrophotometry method, it is found that UV spectrophotometry could not only shorten the measure time and improve the efficiency, but avoid the interference from chloride. UV spectrophotometry method is used to detect COD in landfill leachate.（4） The treatment of actual landfill leachate （cCOD = 3074.4 mg/L, cCl- = 5325 mg/L） by MW+PS is conducted compared with MW assisted hydrogen peroxide （H2O2） and peroxy-monosulfate （PMS）. COD removal efficiencies are respectively 97%, 42% and 80% when the oxidants are 0.3 mol/L. The higher of the concentration is, the higher of the removal efficiency is. For H2O2 and PS, chloride ion in landfill leachate could improve COD removal slightly. While for PMS, chloride ion captures its radical and generates chlorine gas escaping out of the reactor, so that COD removal gets a bit decrease. COD removal efficiency of landfill leachate is all high in the pH value of 2, 7, 8.2, and 12. MW heating is more efficient than traditional water-bath heating when the temperature is above 85℃. GAC plays a synergism effect in the treatment of landfill leachate by MW+PS. When 0.1g/L GAC is added in MW+PS, COD removal is enhanced from 78% to 96% in 10 min compared with no GAC. PS dosage and GAC dosage are explored, and the results show that PS dosage plays the main role in MW+PS+GAC technology.更多还原