Energy consumption of agitators in activated sludge tanks: actual state and optimization potential
Date
2018
Authors
Fureder, K.
Svardal, K.
Frey, W.
Kroiss, H.
Krampe, J.
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Journal article
Citation
Water Science and Technology, 2018; 77(3):800-808
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Abstract
Depending on design capacity, agitators consume about 5 to 20% of the total energy consumption of a wastewater treatment plant. Based on inhabitant-specific energy consumption (kWh PE120 -1 a-1; PE120 is population equivalent, assuming 120 g chemical oxygen demand per PE per day), power density (W m-3) and volume-specific energy consumption (Wh m-3 d-1) as evaluation indicators, this paper provides a sound contribution to understanding energy consumption and energy optimization potentials of agitators. Basically, there are two ways to optimize agitator operation: the reduction of the power density and the reduction of the daily operating time. Energy saving options range from continuous mixing with low power densities of 1 W m-3 to mixing by means of short, intense energy pulses (impulse aeration, impulse stirring). However, the following correlation applies: the shorter the duration of energy input, the higher the power density on the respective volume-specific energy consumption isoline. Under favourable conditions with respect to tank volume, tank geometry, aeration and agitator position, mixing energy can be reduced to 24 Wh m-3 d-1 and below. Additionally, it could be verified that power density of agitators stands in inverse relation to tank volume
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Link to a related website: https://iwaponline.com/wst/article-pdf/77/3/800/213006/wst077030800.pdf, Open Access via Unpaywall
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Copyright 2018 IWA Publishing