Activated Sludge · Sludge Age and Food-to-Microorganism Ratio
What Is Sludge Age?
Sludge age describes the average time biological solids remain in the activated sludge process. It is also called solids retention time, or SRT, and often mean cell residence time, or MCRT.
Sludge age affects which organisms can remain in the system, how much new sludge is produced, how completely food is used, and whether slower-growing organisms can be maintained.
A short sludge age generally means a younger, faster-growing population. A longer sludge age generally means less food is available per unit of biomass and more cell material undergoes endogenous respiration, which is the use of stored cell material for maintenance.
The proper control range is plant-specific. Treatment goals, temperature, load, basin configuration, settling behavior, and permit needs must all be considered.
Key point: Sludge age, SRT, and MCRT name the same idea. A short sludge age means a young, fast-growing population.
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Activated Sludge Process Control for Wastewater Operators
This page comes from the course. It covers aeration, settling tests, solids inventory, return and waste flows, sludge age, microscopy, process upsets and daily records, one step at a time, with short knowledge checks and a certificate of completion.
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