Deodorization of livestock odors utilizing photoinduced hydrophilicity and decompodition on TiO_2

最近，有一个郊区农业的家附近的牲畜场，这引起了附近很多关于牲畜气味的投诉。因此，需要对畜禽粪便进行除臭处理。利用TiO_2表面的光致亲水性和光催化降解作用，设计了一种用于无窗猪舍和封闭式堆肥设施的除臭系统。该系统包括两个步骤，第一步是在生物滤池上自然培养的微生物细胞的处理，第二步是光催化处理。首先，我们选择了“光催化滤池”作为光催化材料，它能充分吸附和分解氨气，并能很容易地洗出氨氧化产生的硝酸盐。接下来，在实际的无窗猪舍和封闭的堆肥设施中构建具有两层生物过滤器（SKOV Co.丹麦）和一层光催化过滤器的系统，并评价除臭效果。例如，封闭堆肥设施中的氨气浓度为70-120 vppm，在通过两层生物过滤器后其变化小于10 vppm，最后在通过一层光催化过滤器后其降低小于2 vppm。即使是低浓度的恶臭气体，如硫化物（H_2S、SO_2）和有机酸（丙酸、正戊酸、异戊酸）也可以通过两个过滤器去除。在不锈钢表面镀上TiO_2膜，制备了高耐久性的光催化过滤器，并对氨气的去除效果进行了评价。所制备的光催化过滤器具有与当前过滤器几乎相同的光催化活性。

Recently, there has been the livestock field near home zone from a suburban agriculture, which causes a lot of complaints for livestock odors from the neighborhood. Thus, the technology of deodorant for livestock odor is required. We have designed a deodorant system for the odors from the windowless pig house or the closed compost facility utilizing photoinduced hydrophilicity and decomposition on TiO_2 surfaces. The system involves two steps, one step is the treatment by microbial cells cultivated naturally on the biofilter and continuous step is photocatalytic treatment.First, we have selected "photocatalytic filter" as a photocatalytic material which can enough adsorb and decomposed ammonia gas and can easily wash out nitrate generated from ammonia oxidation. Next, the systems having two layers of biofilters (SKOV Co. Denmark) and one layer of photocatalytic filter were constructed in an actual windowless pig house and a closed compost facility, and were evaluated for the deodorant effect. For example, the concentration of ammonia gas in the closed compost facility was 70-120 vppm, and it changed less 10 vppm after passing through biofilters of two layers, and finally it decreased by less 2 vppm after passing through photocatalytic filter of one layer. The bad odors even with low concentration such as sulfur compounds (H_2S, SO_2) and organic acids (propionic acid, n-, iso-valeric acid) can be also removed by passing through both filters. Furthermore, a photocatalytic filter with high durability was prepared by coating stainless steel with TiO_2 film, and evaluated far the removing effect of ammonia gas. The prepared photocatalytic filter had almost same photocatalytic activity as the current filter.