Protection of Environment through Application of Methanogenic Digestate to Agricultural Field : Behavior of Estrogen and Refractory Organic Matter

利用畜禽粪便中的产甲烷菌群作为肥料可能会导致周围水生生态系统的污染，其中含有数十ppb浓度的雌激素。为了评估引入农业生产系统的雌激素对环境的潜在影响，雌激素的降解成为一个重要因素。有几份关于雌激素在未经处理的牲畜粪便和废水中降解的报告，但没有关于稻田施用有机肥中雌激素降解的报告。在这项研究中，我们研究了降解雌酮的两个孵育试验和分馏试验，采用离心超滤在β-淀粉样蛋白状态。从稻田中收集的土壤提取物中的微生物迅速降解了处于亚稳态的雌酮，而处于亚稳态的土著微生物和BOD种子中的微生物降解不多（哈赫，科罗拉多）。雌激素与溶解的有机物在厌氧状态的结合是不显着的，并表明散装有机物质在厌氧状态可能没有贡献的雌激素在土壤微生物培养前的缓慢降解。结果表明，施用到稻田中的雌激素在微生物降解过程中迅速降解，对生态系统造成污染的可能性较小。

Usage of methanogenic digestate of livestock excrements as fertilizer may lead to pollution of the surrounding aquatic ecosystems with estrogens contained in the digestate in the concentration order of several tens of ppb. To evaluate the potential environmental impacts of estrogens introduced to the agricultural production system, degradation of estrogens becomes an important factor. There are several reports concerning the degradation of estrogens in untreated livestock excrements and wastewater whereas there is no report on the degradation of estrogens in organic fertilizer applied to paddy fields. In this study, we investigated degradation of estron in the digestate by two incubation tests and a fractionation test using centrifugal ultrafiltration. Estron in the digestate was degraded rapidly by microbes in the extract of the soil collected from a paddy field whereas it was not degraded much by indigenous microbes in the digestate and the microbes in the BOD seed (HACH, Colorado). The binding of the estrogens with dissolved organic matter in the digestate was not significant, and suggesting that bulk organic substances in the digestate could not have contributed to the slow degradation of estron in the before the incubation of soil microbes. The results indicate that estrogens in the digestate applied to the paddy field should be rapidly degraded by microbes in the soil, and the possibility of ecosystems pollution is low.