垃圾填埋场选址问题的模糊数学模型研究

为有助于在环境和经济框架内评价垃圾填埋场选址决策,本文建立了关于该问题的多目标模型,模型中既考虑了安置和运营设施需要的固定成本和可变成本,也考虑了居民区承受的风险,以及各居民区承担风险的公平性。并进一步讨论了用模糊方法处理的一般多目标规划模型的模糊最优解与有效解及弱有效解之间的关系。最后使用两种模糊目标规划方法求解数值例子以分析所建模型的适用性,结果表明,加权模糊方法可以为决策者提供更接近期望值的满意方案。     

Programmed Temperature Vaporization Injection (PTV) in the Analysis by Gas Chromatography-Mass Spectrometry (GC-MS) of the Constituents of Landfill Gas

Abstract

Trace volatile compounds emitted from both domestic and industrial landfills have been identified by programmed temperature vaporization injection (PTV) coupled to gas chromatography with detection by ion-trap mass spectrometry (GC-ITD/MS). The PTV injection system has been developed using a combination of two six-port valves to achieve problems of interference in GC-MS while loading sample. A large volume of landfill gas was re-concentrated onto a sorbent trap, then rapidly liberated into the GC-ITD/MS system by programmed thermal desorption. Using this method, trace volatile compounds in gases from both domestic and industrial landfills such as aromatic hydrocarbons, terpenes, chlorinated hydrocarbons, and sulfur compounds can be identified and quantified.     

Quantitative determination of toluene,ethylbenzene, and xylene degradation products in contaminated groundwater by solid-phase extraction and in-vial derivatization

Benzylsuccinic acid (BSA) and methylbenzylsuccinic acids (mBSAs) are unambiguous indicators of anaerobic toluene and ethylbenzene/xylene degradation, and so the determination of these compounds in landfill leachates and contaminated groundwater is highly relevant. Samples were diluted to <0.8?mS?cm^?1 in order to reduce their ionic strength, and subsequently extracted through strong anion exchange disks, followed by simultaneous in-vial elution and methylation. A detection limit of 0.1?µg?L^?1 was obtained for 100?mL samples. Using this method, 19.3?µg?L^?1 of BSA was measured in a landfill leachate, and low µg?L^?1 levels of all of the mBSAs were measured in gasoline-contaminated groundwater. The results were compared with the findings of BSAs at 16 other contaminated sites, and BSAs as indicators of biodegradation were evaluated. The estimation of biodegradation rates based on parent hydrocarbons and BSA concentrations or ratios is questionable. However, the degradation products serve as good qualitative in situ indicators for anaerobic biodegradation in contaminated groundwater.     

Development and application of an analytical protocol for evaluation of treatment processes for landfill leachates. II. Evaluation of leachate treatment efficiency of different steps in a constructed pilot plant

Different methods for treatment of leachate from a municipal solid waste (MSW) landfill were tested in a pilot plant. Raw leachate was pre-treated with aeration and sedimentation, followed by several parallel individual steps such as bioremediation, chemical oxidation, ozonation, and geo-bed filters. The efficiency of different treatment steps was evaluated according to one previously developed protocol, which includes measurements of several parameters such as conductivity, pH, nutrients, chloride, metals, organic compounds, and acute toxicity before and after a treatment step. The treatment steps which showed the highest efficiency towards organic pollutants in leachate were ozone treatment and chemical oxidation. The use of an adsorption filter, a geo-bed with a mixture of peat and bottom ash with ca 10% remaining carbon, also had good effects. A combination of pre-treatment and a geo-bed filter with peat and carbon ash gave the best overall treatment results when water-quality parameters such as total organic carbon and ammonia-nitrogen were also considered.     

垃圾场渗滤液中十二烷基硫酸钠的光度测定

三峡库区令人担忧的严重问题之一是城市生活垃圾填埋场渗滤液的迁移污染.渗滤液成分复杂,水质变化大,色度深、有恶臭.高浓度有机废水会污染地表水和地下水,破坏原有水体的用途,甚至危及原有的生态系统,若不妥善处理渗滤液,有害成分发生迁移转化,就会带来严重的二次污染,对库区环境构成严重危胁.     

液相色谱串联质谱法同时测定垃圾渗滤液中的邻苯二甲酸酯和烷基酚

利用反相液相色谱-电喷雾-串联质谱法同时分析了水体中的6种邻苯二甲酸酯(DMP、DEP、DBP、DEHP、DOP和DNP)以及OP、NP和BPA。用Waters XTerraTMMS C18色谱柱,乙腈和乙酸铵溶液作为梯度洗脱的流动相。结果表明,9种物质的分离效果良好,邻菲二甲酸酯采用亚离子模式检测,烷基酚采用负离子模式检测。通过多反应监测模式(MRM)对各目标物进行定量,检出限为0.1~1μg/L。该方法已用于北京某垃圾填埋场渗滤液中相关物质的检测,结果表明:原水中邻苯二甲酸酯和烷基酚的总浓度为218~291μg/L,其中主要是DEHP。垃圾渗滤液处理工艺对这些物质有明显的去除效果。     

Repeatedly using the decomposition product of struvite by ultrasound stripping to remove ammonia nitrogen from landfill leachate

In this study, the decomposition of struvite by ultrasound stripping and the recycle use of the decomposition product for the treatment of landfill leachate were investigated. The results indicated that when the decomposition of struvite by ultrasound stripping was performed at 55 °C for 40 min, the ammonium in the struvite could be almost completely eliminated from the solution system. The characterization analysis showed that magnesium phosphate and the dissolved phosphate ions were the main active derivatives. Approximately 90% of the total ammonia nitrogen (TAN) in landfill leachate can be removed by reusing the decomposition product at pH 9 for 60 min. Repeated use of the struvite decomposition product revealed that the TAN removal efficiency decreased with an increase in the number of recycles. However, in the process of multiple recycling, about 90% of TAN removal could be maintained by supplementing a certain amount of the preformed struvite to the solution for every recycle. An economic analysis demonstrated that 79.3% of the treatment cost could be saved by the proposed process compared to the non-recycling process.     

光助/H2O2/草酸铁处理垃圾渗滤液

利用光助／H2O2／草酸铁处理已经过生化处理的垃圾渗滤液(CODcr=450mg／L左右)时，采用365nm、125W的UV灯照射下，光强为Iu=2．9mW／cm^2时，反应较佳条件是pH值=4．0左右及总药剂用量为1．4％(体积比)。草酸铁的用量要适当，投加量过少，混凝效果较差，有效光子不能完全转化为化学能，处理效果不理想；投加量过多，溶液形成棕色浑浊，使紫外光的吸收降低，造成光散射，降低反应速度。而H2O2的投加量过多，将使铁的络合物更加稳定，H2O2的分解速率受到限制，投加量过少，效果也会降低。当总药剂用量为1．4％(体积比，其中30％过氧化氢0．6％，0．1mol／L草酸铁溶液0．8％)时，反应30min后，CODcr去除率可达80％左右，脱色率可达90％以上。     

Measuring nitrate concentration in wastewaters with high chloride content

The presence of chloride ions in wastewaters in concentrations above 50 mg/L poses interference in several methods used for the measurement of nitrate-nitrogen. The aim of this study was to characterise the reliability and costs of some commonly available methods for the analysis of nitrate concentration in landfill leachate which contains high chloride levels. To investigate the effect of chloride interference, several widely used methods [ion chromatography (IC), continuous flow analysis (CFA), the German standard method (DIN), cuvette test (CUV), standard addition method (SAM) and reflectometric test (REF)] were used to measure the nitrate concentration in synthetic solutions containing varying concentrations of chloride and nitrate-nitrogen. Nitrate recoveries of the various methods were found to decrease in the following rank order: CUV (>95%) > IC (>90%) > CFA (89%) > DIN (88%) > REF (70%) > SAM (<80%). In the second part of the study, the same methods were used to measure nitrate concentrations in samples of biologically nitrified landfill leachate with and without chloride elimination. For leachate samples without chloride elimination, CUV results were well correlated (linear regression) with IC results (slope = 1.02/R² = 0.99) but to lesser extents with results obtained by CFA (0.91/0.86), DIN (0.89/0.97) and REF (0.86/0.77), and not correlated with SAM (0.74/–1.3). The incurred measurement costs per sample (in Euros) for the methods were as follows: CFA (<0.1) < DIN (0.6) < REF (0.7) < SAM (3) < CUV (3.8) < IC (15). Cuvette tests are recommended as the method of choice due to their accuracy and lower cost than IC.     

氧化钙改性高岭土对垃圾渗滤液中氨氮的去除研究

采用氧化钙对高岭土进行改性,并用XRD、SEM和FT-IR对改性高岭土进行了表征。将改性高岭土应用于垃圾渗滤液的处理,考察了改性高岭土投加量、渗滤液初始pH、时间等因素对氨氮去除效果的影响,并对其吸附机理进行了研究。结果表明,氧化钙改性高岭土的产物主要是胶凝材料水化物(硅铝酸钙和含Al的C-S-H凝胶),形貌为蜂窝状;向氨氮含量为3520mg/L、pH为7.53~7.80的垃圾渗滤液中投加160g/L吸附剂,吸附60min,氨氮的去除率达82.66%,吸附量为18.19mg/g。氧化钙改性高岭土对氨氮的吸附符合Langmuir等温模型,动力学上符合准二级动力学方程,其相关系数分别为0.9678,0.9989。同时,该吸附过程包含了膜扩散和颗粒内扩散。