Control of production of nitrous oxide from full-scale biological nitrogen removal process in wastewater treatment plant

调查的全规模处理厂以及实验室规模的实验进行。Hanaki和Okaniwa调查了采用间歇曝气方案的粪便处理厂。考察了不同操作条件下氧化亚氮的生成情况。N2O是在反硝化过程中硝酸盐积累时产生的，而N2O是在硝化过程中氨积累时产生的。甲醇的加入减少了一氧化二氮的产生。通过废气排放的一氧化二氮远大于流出物中溶解形式的一氧化二氮。根据不同的条件，氮的排放量变化很大，甚至超过了氮负荷的50%。Hanaki和Matsuo建立了使用稳定的氮同位素作为示踪剂进行实验室规模实验的方法，以确定硝化或反硝化是一氧化二氮产生的主要过程。苍井空调查了另一种粪便，以研究一氧化二氮的产生，以及接收生活污水的天然池塘。Tanaka和Sumino调查了使用传统活性污泥法和使用固定化细胞法进行硝化的污水处理厂。生活污水中的N2O含量小于粪便中的N2O含量。固定化工艺产生的氧化亚氮比常规工艺少。

Surveys of full scale treatment plant as well as laboratory-scale experiments were conducted. Hanaki and Okaniwa surveyed a night soil treatment plant in which intermittent aeration program was used. Nitrous oxide production was surveyed with different operational conditions. Nitrous oxide was produced during denitrification when nitrate was accumulated, and it was produced during nitrification when ammonia was accumulated. Methanol addition reduced production of nitrous oxide. Nitrous oxide emission through off gas was much greater than that contained as dissolved form in the effluent. The emission variates very much depending on conditions and it even exceeded 50% of nitrogen loading.Hanaki and Matsuo established the method of conducting laboratory-scale experiments using stable isotope of nitrogen as tracer to identify whether nitrification or denitrification is major process of nitrous oxide production.Aoi surveyed another night soil to examine the nitrous oxide production as well as a natural pond receiving domestic wastewater. No nitrous oxide was detected in the latter.Tanaka and Sumino surveyed sewage treatment plant using conventional activated sludge and that using immobilized cell process fro nitrification. Nitrous oxide from domestic sewage was smaller than that from night soil. Immobilized process tended to produce less nitrous oxide than the conventional process.