Scholarly
    Communications Project


Document Type:Master's Thesis
Name:Gary Pelham Phillips
Email address:gphillip@vt.edu
URN:1998/01010
Title:EFFECT OF SOLIDS RETENTION TIME ON ACTIVATED SLUDGE PROPERTIES AND EFFLUENT QUALITY
Degree:Master of Science
Department:Environmental Engineering
Committee Chair: Dr. John T. Novak
Chair's email:jtnov@vt.edu
Committee Members:Dr. Gregory Boardman
Dr. Clifford Randall
Keywords:Solids retention time, activated sludge, effluent, COD, BOD, protein, polysaccharide, biopolymer, exocellular microbial product, settling
Date of defense:August 26, 1998
Availability:Release the entire work for Virginia Tech access only.
After one year release worldwide only with written permission of the student and the advisory committee chair.

Abstract:

The effect of solids retention time (SRT) or sludge age on activated sludge properties and effluent quality was investigated using laboratory scale reactors. It was found that an increase in SRT resulted in an increase in effluent solution polysaccharide, with the < 3,000 daltons (3K) size fraction contributing up to 68 percent of solution polysaccharides. The feed consisted of low molecular weight, readily degradable protein, suggesting that the observed increases in protein and polysaccharide were due to increased release of exocellular microbial product (EMP). The increase in solution protein and polysaccharide resulted in an increase in effluent chemical oxygen demand (COD). The increase in effluent COD was not accompanied by a similar increase in effluent biological oxygen demand (BOD), indicating that the EMPs released were resistant to biodegradation. At the highest SRT, the resistance to shear decreased and the capillary suction time (CST) increased. Following an initial increase, the sludge volume index (SVI) decreased at higher SRT.

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thes_gpp.pdf

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