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A New Activated Sludge Process Control Test Uncovers Secondary Clarifier Inefficiencies
Author: Eric J. Wahlberg, Sidney Biesterfeld, David Farmer, David Kinnear, Leonard Robb
Date: 10/01
Presented at WEFTEC 2001, Oct. 2001, in Atlanta, GA.

A program was implemented at the Littleton/Englewood Wastewater Treatment Plant to monitor the flocculating, settling, and compacting characteristics of the TFSC sludge on a routine basis. These sludge quality characteristics were quantified in terms of the flocculated suspended solids (FSS) concentration, the 5-minute settled sludge volume, and the 30-minute settled sludge volume, respectively, performed in a single, modified settlometer test. The paper discusses the use of these sludge quality characteristics in making process control decisions. Comparison of the FSS and secondary effluent suspended solids (ESS) concentrations demonstrated why effluent quality (in this case, the ESS concentration) should not be used to make process control decisions. Changes in SRT caused changes in the settling and compacting characteristics, but additional, unknown factors are at play. The settling and compacting characteristics of the sludge did not affect the sludge’s flocculation potential. Low air temperatures worsened the hydraulic inefficiencies of the Littleton/Englewood secondary clarifiers.