One of the core pieces of data for monitoring any wastewater system is the solids mass balance. We can use the mass balance to determine sludge age (MCRT), food to microorganism ration (F/M), cell yield, and cell decay (endogenous respiration/digestion).
The missing part is the amount of solids accumulating in the bottom of the ponds. Also we are not sure of the amount of cell lysis (digestion). With good record keeping, and knowledge of the cell lysis rates, it is possible to get a true estimate of cell yield and pond sludge accumulation.
A solids mass balance is much more important in activated sludge treatment systems. All the data is usually collected on a frequent basis, but sometimes it is not put into a spreadsheet model for use in monitoring/auditing the system. We need solids concentration and flow for the following:
While we often calculate sludge age or food/microorganism (F/M) ratios from this data, we can also get an idea for cell yield and amount of in basin endogenous respiration. This can be later evaluated when doing aeration cost evaluations.
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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