Seetha N, Bhargava Renu, Gurjar B R
Department of Civil Engineering, Indian Institute of Science, Bangalore-560 012, Karnataka, India.
J Environ Sci Eng. 2013 Oct;55(4):517-36.
Wastewater treatment plants (WWTPs) are identified as potential emission sources of greenhouse gases (GHGs) and bioaerosols. This paper reviews and analyse the potential sources of GHGs and bioaerosols from different unit operations and processes of WWTPs. Aeration tanks of activated sludge process (ASP) are found to be the most important sources of GHGs as well as bioaerosol emissions. Nitrification and denitrification processes are found to be important sources of nitrous oxide (N2O) emissions. To minimize the N2O emissions from WWTPs, dissolved oxygen (DO) concentration should be kept greater than 2 mg/L in nitrification process, whereas purely anoxic condition (0 mg/L DO) is required in denitrification process. Diffused aeration emits fewer microbes into the air than surface aerators. It is observed that fixed-film processes emit microbes by two orders of magnitude less than aeration tanks. The various WWTPs discussed in this study used different methods of treatment sample collection and species of microorganisms studied. It is realised that the standardisation of the microorganisms to be analysed and methods of sample collection needs to be done. It is also found that from the microbiological point of view, there is no clean air in the vicinity of a WWTP.
污水处理厂（WWTPs）被视为温室气体（GHGs）和生物气溶胶的潜在排放源。本文回顾并分析了污水处理厂不同单元操作和工艺中温室气体和生物气溶胶的潜在来源。活性污泥法（ASP）的曝气池被发现是温室气体以及生物气溶胶排放的最重要来源。硝化和反硝化过程被发现是一氧化二氮（N₂O）排放的重要来源。为了尽量减少污水处理厂的N₂O排放，硝化过程中溶解氧（DO）浓度应保持大于2mg/L，而反硝化过程需要纯缺氧条件（0mg/L DO）。与表面曝气器相比，扩散曝气向空气中排放的微生物更少。据观察，固定膜工艺排放的微生物比曝气池少两个数量级。本研究中讨论的各种污水处理厂采用了不同的处理样本采集方法和所研究的微生物种类。人们意识到需要对要分析的微生物和样本采集方法进行标准化。还发现，从微生物学角度来看，污水处理厂附近不存在清洁空气。
