Title: Energy consumption of agitators in activated sludge tanks – Actual state and optimization potential
Language: English
Authors: Füreder, Klemens 
Svardal, Karl 
Frey, Wilhelm Peter 
Kroiss, Helmut 
Krampe, Jörg  
Category: Original Research Article
Issue Date: 2018
Journal: Water Science and Technology 
ISSN: 0273-1223
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.
Keywords: agitators; energy optimization; intermittent operation of agitators; mixing power density; municipal wastewater treatment; volume-specific energy consumption
DOI: 10.2166/wst.2017.596
Library ID: AC15376909
URN: urn:nbn:at:at-ubtuw:3-5701
Organisation: E226 - Institut für Wassergüte und Ressourcenmanagement 
E226-01 - Forschungsbereich Wassergütewirtschaft 
Publication Type: Article
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