Abstract:
The treatment of raw foul air that could escape to the atmosphere from the head space of the incoming wastewater sewer lines into a Southern California Water Resource Recovery Facility was evaluated by using a 1/20th scale pilot unit consisting of three different granular activated carbon filter technologies, operating side by side, under similar operating conditions, each having an average 3.8-s contact time. The three activated carbon filters contained each 0.07 m3 of coconut, coal, and coconut mixed with permanganate media. The foul air entering the granular activated carbon filters contained 82% to 83% relative humidity. No moisture removal mechanism was used prior to treatment. The removal of six different odor characters from eight chemical odorants present in the foul air were assessed. These were rotten egg (hydrogen sulfide), rotten vegetables (methyl mercaptan), canned corn (dimethyl sulfide), rotten garlic (dimethyl disulfide), earthy/musty (2-methyl isoborneol and 2-isopropyl 3-methoxy pyrazine), and fecal (skatole and indole). This is the first time a study evaluates the removal of specific odors by simultaneously employing sensory analyses using the odor profile method, which defines the different odor characters and intensities, together with chemical analyses of the odorants causing these odors. The results show that the three granular activated carbon filters, before hydrogen sulfide breakthrough, provided significant improvement in odor intensity and odorant removal. Breakthrough was reached after 57 days for the coconut mixed with permanganate, 107 days for the coconut, and 129 days for the coal granular activated carbon filter. Breakthrough (the critical saturation point of the activated carbon media) was considered reached when the hydrogen sulfide percentage removal diminished to 90% and continued downward. The coconut mixed with permanganate granular activated carbon filter provided the best treatment among the media tested, achieving very good reduction of odorants, as measured by chemical analyses, and reasonable removal of odor intensities, as measured by the odor profile method. The coconut mixed with permanganate granular activated carbon is recommended for short-term odor control systems at sewer networks or emergency plant maintenance situations given its shorter time to breakthrough compared with the other granular activated carbons. The coal and coconut granular activated carbon filters are generally used as the last stage of an odor treatment system. Because of the observed poor to average performance in removing odorants other than hydrogen sulfide, the treatment stage(s) prior to the use of these granulated activated carbons should provide a good methyl mercaptan removal of at least 90% in order to avoid the formation of dimethyl disulfide, which, in the presence of moisture in the carbon filter, emit the characteristic rotten garlic odor. The differences observed between the performances based on odorant removal by chemical analysis compared with those based on sensorial analyses by the odor profile method indicate that both analyses are required to understand more fully the odor dynamics. PRACTITIONER POINTS: Three virgin granulated activated carbon media were evaluated in a field pilot unit using raw collections foul air. Coal, coconut, and coconut mixed with permanganate were tested until breakthrough. Samples were analyzed both chemically (odorants) and sensorially (odors). Coconut mixed with permanganate proved to be the media that better reduced odorants and odors.
摘要:
通过使用由三种不同的颗粒活性炭过滤技术组成的1/20规模的中试装置,对可能从进入南加州水资源回收设施的污水下水道管线的顶部空间逸出到大气中的原始污浊空气的处理进行了评估。并肩操作,在类似的操作条件下,每个人的平均接触时间为3.8-s。三个活性炭过滤器每个包含0.07m3的椰子,煤炭,和椰子混合高锰酸盐介质。进入颗粒活性炭过滤器的污浊空气含有82%至83%的相对湿度。在处理之前不使用水分去除机制。评估了从污浊空气中存在的八种化学气味剂中去除六种不同的气味特征。这些是臭鸡蛋(硫化氢),腐烂的蔬菜(甲硫醇),玉米罐头(二甲基硫醚),腐烂的大蒜(二甲基二硫化物),土质/霉味(2-甲基异冰片和2-异丙基3-甲氧基吡嗪),和粪便(粪臭素和吲哚)。这是一项研究首次通过使用气味特征方法同时采用感官分析来评估特定气味的去除。它定义了不同的气味特征和强度,以及导致这些气味的气味的化学分析。结果表明,三种颗粒活性炭过滤器,在硫化氢突破之前,在气味强度和气味去除方面提供了显着改善。用高锰酸盐混合的椰子在57天后取得了突破,107天的椰子,煤颗粒活性炭过滤器129天。当硫化氢去除百分比减少到90%并继续向下时,认为达到突破(活性炭介质的临界饱和点)。与高锰酸盐颗粒活性炭过滤器混合的椰子在测试的介质中提供了最好的处理,实现非常好的减少气味,通过化学分析测量,并合理去除气味强度,通过气味轮廓法测量。与高锰酸盐颗粒活性炭混合的椰子被推荐用于下水道网络或紧急工厂维护情况下的短期气味控制系统,因为与其他颗粒活性炭相比,其突破时间较短。煤和椰子颗粒活性炭过滤器通常用作气味处理系统的最后阶段。由于观察到的除硫化氢以外的气味剂的平均性能差,在使用这些粒状活性炭之前的处理阶段应提供至少90%的良好甲硫醇去除,以避免二甲基二硫化物的形成。which,在碳过滤器中存在水分的情况下,发出特有的腐烂大蒜气味。观察到的基于通过化学分析去除气味剂的性能与通过气味特征方法进行感官分析的性能之间的差异表明,两种分析都需要更全面地了解气味动态。实践要点:使用原始收集物污染空气,在现场中试单元中评估了三种原始的颗粒状活性炭介质。煤炭,椰子,与高锰酸盐混合的椰子进行测试,直到突破。对样品进行化学分析(气味剂)和感官分析(气味)。椰子与高锰酸盐混合被证明是更好地减少气味和气味的介质。