Evaluation of oxygen transfer efficiency and alpha‐factor on a variety of diffused aeration systems

Abstract

Because the aeration system in an activated sludge wastewater treatment plant typically represents more than 50% of total plant energy requirements, designers and operators can substantially reduce overall plant energy costs by using accurate oxygen transfer information to make the aeration system as energy efficient as possible. This paper presents data from 65 off‐gas analysis tests performed at 21 wastewater treatment plants. The effect of various factors on oxygen transfer was evaluated by comparing pairs of tests in which all factors but one were held relatively constant. Factors evaluated were diffuser type, diffuser layout, diffuser age, solids retention time, and level of nitrification. Flexible membrane diffusers had more than a 30% higher oxygen transfer efficiency than coarse bubble diffusers. Grid layouts had higher oxygen transfer efficiencies than spiral roll layouts. Flexible membrane diffusers that were 3.5 years old had a 20% lower oxygen transfer efficiency than new flexible membrane diffusers. Systems at low solids retention times that were not nitrifying had lower oxygen transfer efficiencies than nitrifying systems at high solids retention times. For some wastewater systems, use of this information on solids retention time in plant design and operation can decrease overall energy costs despite the additional oxygen required to meet the nitrogenous oxygen demand.

Factors Affecting the Oxygenation Capacity of Disc Aerators in an Oxidation Ditch System

“…Gillot et al (2005) Bayramoglu et al (2000 developed models to determine oxygen transfer rates in diffused air aeration tanks and found that as water depth increased, the oxygen transfer rate increased. Groves et al (1992) found that perforated membrane diffusers provided better oxygen transfer than coarse bubble diffusers due to increases in bubble surface area to volume ratio.…”

The Influence of Optic and Polarographic Dissolved Oxygen Sensors Estimating the Volumetric Oxygen Mass Transfer Coefficient (KLa)

“…Factors to be considered when studying oxygen transfer in fine-pore aeration systems covers a wide range: diffuser-related issues (Groves, Daigger, Simpkin, Redmon & Ewing, 1992;Mueller, Boyle & Popel, 2002;Diego Rosso & Shaw, 2015), aerobic reactor characteristics (Eckenfelder, 1959;Mueller et al, 2002;Pittoors, Guo & Van Hulle, 2014;Schierholz, Gulliver, Wilhelms & Henneman, 2006) and operating conditions (Henkel, 2010;D Rosso, Iranpour & Stenstrom, 2005).…”

Performance Evaluation of an Oxidation Ditch System with a Disc Aerator

“…(Pell and Worman, 2008;LaPara and Alleman, 1998;Groves et al, 1992;Fenlon and Mills, 1980). The main functions of any aeration device are to: (a) supply a sufficient quantity of oxygen to the liquid medium to maintain aerobic conditions, (b) circulate the liquid to keep solids in suspension and avoid settling, (c) distribute the oxygenated liquid throughout the liquid body to avoid anaerobic zones and (d) keep good contact between the microbial cells, nutrients and dissolved oxygen to ensure efficient biodegradation of the organic matter (Gresch et al, 2010).…”