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Relationship between solid retention time and phosphorus removal in anaerobic-intermittent aeration process

Paper ID Volume ID Publish Year Pages File Format Full-Text
22280 43265 2007 7 PDF Available
Title
Relationship between solid retention time and phosphorus removal in anaerobic-intermittent aeration process
Abstract

Solid retention time (SRT) is one of the most important control parameters in biological phosphorus removal. In this study, lab-scale biological nutrient removal (BNR) reactors using anaerobic-intermittent aeration (AIA) were operated at various SRTs (i.e., 15, 20, and 30 d) to evaluate their phosphorus removal efficiencies. Sludge wasting load decreased as SRT increased; however, the phosphorus content in the biomass increased as SRT increased. The highest phosphorus removal efficiency was 93% at an SRT of 20 d and the phosphorus wasting load was also highest at that SRT, which indicates that the optimal SRT for the highest phosphorus removal is not proportional to the phosphorus content in the biomass. Aerobic digestion experiments were also carried out to determine the number of phosphate-accumulating organisms (PAOs) in the biomass produced in different reactors. All three activated sludges from BNR at SRTs of 15, 20, and 30 d showed a slower volatile suspended solid (VSS) destruction rate and a larger amount of phosphorus released than the conventional activated sludge (CAS), suggesting that the activated sludge from BNR has more PAOs than CAS. Also, the sludge at an SRT of 30 d showed a slower VSS destruction rate and a larger amount of phosphorus released than the sludge at an SRT of 15 d, suggesting that PAOs are more predominant at longer SRTs. Thus, to improve phosphorus removal efficiency, it is recommended that SRT be increased to maximize the number of PAOs in the system and that SRT be determined to maximize phosphorus wasting load.

Keywords
aerobic digestion; anaerobic-intermittent aeration; phosphate-accumulating organisms; phosphorus removal; solid retention time
First Page Preview
Relationship between solid retention time and phosphorus removal in anaerobic-intermittent aeration process
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Bioscience and Bioengineering - Volume 103, Issue 4, April 2007, Pages 338–344
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering