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Technical Description The growth curve of the cell life cycle is related to the effectiveness of BODS removal within the treatment process. In all cases, removal of BOD, is d:nendent upon aerator detention time. Growth and predominance of microorganisms are controlled by a variety of circumstances, in- cluding type of food matter, metabolic rate, and microorganism size. Because a definite type of microorganism lives best under certain conditions, it is possible to relate treatment efficiency to microorganism type. This is a determining factor for good batch process detention design. As the BOD remaining in the batch decreases, ciliated protozoa increase in number. A general guide as to relative predominance of protozoa and efficiency in the process may be characterized in the following chronological order: TYPE PROCESS EFFICMENCY 1. Sarcodina Plant startup or recovery 2. Holophytic flagellates High organic overloading 3. Holozoic flagellates Dec*easing organic overloading 4. Ciliates Lowering efficiency 5. Stalked ciliates Elevating efficiency 6. Rotifers High BOD efficiency, rapid oxidation High rotifer concentration will occur when the BODS removal efficiency is high; therefore, addi- tional detention capacity is required. The aerator size required to achieve this efficiency is based upon F:M ratio criteria between 0. 1 and 0.5 pound BOD/pound TMLVSS. A second method of determining retention time is a microscopic examination of the stalked cili- ates. Groupings of 3 to 4 stalks indicate a healthy sludge; less or more groupings indicate sludge f is either too young or too old. If The quantity of microorganisms can be represented by thl-quantity of MLVSS. Ideally, the living or active microorganisms would simply be counted, but this is not feasible; studies show the MLVSS is a good approximation of microorganism concentrations in the MLSS. Data obtained are calculated using a moving seven-day average. Equation 4 predicts that 2.5 moles of oxygen are required to convert one mole of ammonium into 2 moles of nitrate ions for new biomass and water.This is equivalent to 4.2 mg/L of 02 per mg/L of NT14—N converted to new cells and nitrate. Therefore, j 02 x Q = 0 (SO2+ 2N1-14 2NO3 +4H,0) (5) where 02 = 4.2 mg/L Q = NH, 0 = N05 + 1420 3 + CO2 +N0'+PO4 3+SD4 Z }�) The overall equation predicts that 1.98 moles of H are produced per mole of ammonium con- verted, or 7.14 mg of alkalinity as CA CO; is destroyed per mg of N114—N converted. The equa- tion also predicts that 0.17 mg of cells is produced per mg of NH —N converted. The first two parameters (oxygen requirement and alkalinity destruction) are important in the de- sign detention of any hybrid, heterotrophic/autotrophic treatment system. - 12- 7-H Technical Services Group,Inc.