Poznyak Tatyana, Bautista G Luis, Chaírez Isaac, Córdova R Ivan, Ríos L Elvira
Superior School of Chemical Engineering, National Polytechnic Institute (ESIQIE-IPN), Edif. 7, UPALM, C.P. 07738, Mexico, DF, Mexico.
J Hazard Mater. 2008 Apr 15;152(3):1108-14. doi: 10.1016/j.jhazmat.2007.07.098. Epub 2007 Aug 3.
This study deals with evaluation of organic matter from Mexico City waste sanitary landfill leachate of Bordo Poniente (including domestic and industrial) by ozonation after a coagulation treatment with Fe2(SO4)(3) (2.5 g/L at pH 4-5). The content of humic substances after the coagulation treatment decreases up to 70%. Then leachate obtained from a solid with initial COD=1511 mg/L and the pH 8.5 was treated by ozone. The aqueous samples by a UV-vis and HPLC technique were analyzed. The partial identification of the initial composition of the organic matter as well as of intermediates and final products was carried out after the extraction of the initial and ozonated leachate with benzene, chloroform:methanol (2:1) and hexane. Then the extracts with a gas chromatograph with mass detector and FID were analyzed. In the HPLC results we identify malonic and oxalic acids. The initial concentrations of these acids were 19 mg/L and 214 mg/L, respectively. The oxalic acid is formatted and accumulated in ozonation. The obtained results show that the color disappears (visually) at 100% during 5 min of ozonation. The organic substances, extracted with chloroform-methanol, may be destructed during 15 min of ozonation; the organic matter, extracted with benzene, destructs completely by ozone during 5 min, and the organic compounds extracted with hexane have a low ozonation rate. The toxic compounds presented in leachate decompose completely during 15 min of ozonation. The ozonation rate constants for each group of organics (as observed constants) were calculated applying simplified mathematical model and the recurrent least square method using the program MATLAB 6.5.
本研究探讨了对墨西哥城博尔多波尼恩特垃圾卫生填埋场渗滤液（包括生活和工业渗滤液）中的有机物进行评估的方法。首先用Fe2(SO4)(3)（2.5 g/L，pH值为4 - 5）进行混凝处理，然后进行臭氧化处理。混凝处理后腐殖质含量降低了70%。接着对初始化学需氧量（COD）为1511 mg/L、pH值为8.5的固体渗滤液进行臭氧处理。采用紫外可见光谱（UV-vis）和高效液相色谱（HPLC）技术对水样进行分析。在用苯、氯仿:甲醇（2:1）和己烷分别萃取初始渗滤液和臭氧化后的渗滤液后，对有机物的初始成分以及中间产物和最终产物进行了部分鉴定。然后用配有质谱检测器和氢火焰离子化检测器（FID）的气相色谱仪对萃取物进行分析。在HPLC结果中我们鉴定出了丙二酸和草酸。这些酸的初始浓度分别为19 mg/L和214 mg/L。草酸在臭氧化过程中形成并积累。所得结果表明，在臭氧化5分钟时颜色（肉眼可见）完全消失。用氯仿 - 甲醇萃取的有机物质在臭氧化15分钟内可能被破坏；用苯萃取的有机物在5分钟内被臭氧完全破坏，而用己烷萃取的有机化合物臭氧化速率较低。渗滤液中存在的有毒化合物在臭氧化15分钟内完全分解。使用MATLAB 6.5程序，通过简化数学模型和递推最小二乘法计算了每组有机物的臭氧化速率常数（观测常数）。
