Aeration is the most energy intensive unit operation in municipal wastewater treatment. To improve oxygen transfer rate, fine-pore diffusers have been wildly applied in aeration practice. However, during operation, this type of diffuser suffers from fouling and scaling problems, which cause a rapid decline in aeration performance and significant increase in energy consumption. Diffusers must be cleaned periodically to reduce energy costs. The cleaning frequency of diffusers is site-specific, and can be evaluated by oxygen transfer efficiency (OTE) measurements over time in operation. Off-gas testing is the only technique that directly measures oxygen transfer efficiency in real-time. This paper presents a time-series of off-gas measurements which demonstrate the value of implementing energy-conservation practices. Our results include the real-time prediction of plant load and alpha factors from off-gas testing, as well as the quantification of the increased energy costs caused by fouling. Our off-gas analyzer can be used to develop an aeration efficiency monitoring protocols, and an aeration feedback control system for blowers.

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