Kastner James R, Das K C
Department of Biological and Agricultural Engineering, Driftmier Engineering Center, The University of Georgia, Athens 30602, USA.
J Air Waste Manag Assoc. 2002 Apr;52(4):459-69. doi: 10.1080/10473289.2002.10470800.
The promulgation of odor control rules, increasing public concerns, and U.S. Environmental Protection Agency (EPA) air regulations in nonattainment zones necessitates the remediation of a wide range of volatile organic compounds (VOCs) generated by the rendering industry. Currently, wet scrubbers with oxidizing chemicals are used to treat VOCs; however, little information is available on scrubber efficiency for many of the VOCs generated within the rendering process. Portable gas chromatography/mass spectrometry (GC/MS) units were used to rapidly identify key VOCs on-site in process streams at two poultry byproduct rendering plants. On-site analysis was found to be important, given the significant reduction in peak areas if samples were held for 24 hr before analysis. Major compounds consistently identified in the emissions from the plant included dimethyl disulfide, methanethiol, octane, hexanal, 2-methylbutanal, and 3-methylbutanal. The two branched aldehydes, 2-methylbutanal and 3-methylbutanal, were by far the most consistent, appearing in every sample and typically the largest fraction of the VOC mixture. A chlorinated hydrocarbon, methanesulfonyl chloride, was identified in the outlet of a high-intensity wet scrubber, and several VOCs and chlorinated compounds were identified in the scrubbing solution, but not on a consistent basis. Total VOC concentrations in noncondensable gas streams ranged from 4 to 91 ppmv. At the two plants, the odor-causing compound methanethiol ranged from 25 to 33% and 9.6% of the total VOCs (v/v). In one plant, wet scrubber analysis using chlorine dioxide (ClO2) as the oxidizing agent indicated that close to 100% of the methanethiol was removed from the gas phase, but removal efficiencies ranged from 20 to 80% for the aldehydes and hydrocarbons and from 23 to 64% for total VOCs. In the second plant, conversion efficiencies were much lower in a packed-bed wet scrubber, with a measurable removal of only dimethyl sulfide (20-100%).
气味控制规则的颁布、公众关注度的提高以及美国环境保护局（EPA）对未达标区域的空气法规，使得对 Rendering 行业产生的多种挥发性有机化合物（VOCs）进行修复成为必要。目前，使用带有氧化化学品的湿式洗涤器来处理 VOCs；然而，关于 Rendering 过程中产生的许多 VOCs 的洗涤器效率的信息却很少。便携式气相色谱/质谱（GC/MS）装置被用于在两家禽副产品 Rendering 工厂的工艺流中快速现场识别关键 VOCs。鉴于如果样品在分析前保存 24 小时，峰面积会显著减少，所以现场分析被认为很重要。在工厂排放物中始终鉴定出的主要化合物包括二甲基二硫醚、甲硫醇、辛烷、己醛、2-甲基丁醛和 3-甲基丁醛。这两种支链醛，2-甲基丁醛和 3-甲基丁醛，是迄今为止最稳定出现的，出现在每个样品中，并且通常是 VOC 混合物的最大组成部分。在一个高强度湿式洗涤器的出口鉴定出一种氯代烃，甲磺酰氯，并且在洗涤溶液中鉴定出几种 VOCs 和氯代化合物，但并非始终如此。不可冷凝气流中的总 VOC 浓度范围为 4 至 91 ppmv。在这两家工厂，导致气味的化合物甲硫醇分别占总 VOCs 的 25%至 33%和 9.6%（v/v）。在一家工厂，使用二氧化氯（ClO₂）作为氧化剂的湿式洗涤器分析表明，气相中的甲硫醇几乎 100%被去除，但醛类和烃类的去除效率范围为 20%至 80%，总 VOCs 的去除效率范围为 23%至 64%。在第二家工厂，填充床湿式洗涤器的转化效率要低得多，仅可测量地去除了二甲基硫醚（20% - 100%）。
