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The growth curve of the cell life cycle is related to the effectiveness <br /> of BODS removal within the treatment process. In all cases,removal NOTES <br /> of BODS is dependent upon aerator detention time. <br /> Growth and predominance of microorganisms are controlled by a <br /> variety of circumstances, including type of food matter, metabolic <br /> rate, and microorganism size.Because a definite type of microorgan- <br /> ism lives best under certain conditions, it is possible to relate treat- <br /> ment efficiency to microorganism type. This is a determining factor <br /> for good batch process detention design. <br /> As the BOD remaining in the batch decreases, ciliated protozoa <br /> increase in number. A general guide as to relative predominance of <br /> protozoa and efficiency in the process may be characterized in the <br /> following chronological order: <br /> TYPE PROCESS EFFICIENCY <br /> 1. Sarsodina Plant startup or recovery <br /> 2. Holophytic flagellates High organic overloading <br /> 3. Holozoic flagellates Decreasing organic overloading <br /> 4. Ciliates Lowering efficiency <br /> 5. Stalked ciliates Elevating efficiency <br /> G. Rotifers High BOD efficiency, rapid <br /> oxidation <br /> High rotifer concentration will occur when the BODS removal effi- <br /> ciency is high; therefore, additional detention capacity is required. <br /> The aerator size required to achieve this efficiency is based upon <br /> F:M ratio criteria between 0.1 and 0.5 pound BOD/pound MLVSS. <br /> The quantity of microorganisms can be represented by the quantity <br /> of MLVSS. Ideally, the living or active microorganisms would simply <br /> be counted, but this is not feasible; studies show the MLVSS is a <br /> good approximation of microorganism concentrations in the MLSS. <br /> Data obtained are calculated using a moving seven-day average. <br /> Equation 4 predicts that 1.83 moles of oxygen are required to con- <br /> vert one mole of ammonium into nitrate and new biomass. This is <br /> equivalent to 4.2 mg/I of 02 per mg/I of NH,- N converted to new <br /> cells and nitrate.Therefore, <br /> O=x Q = O (5) <br /> where <br /> Oz = 4.2 mg/f or ppm <br /> Q = NH4 <br /> O = mg/I air required <br /> The overall equation predicts that 1.98 moles of H are produced per <br /> mole of ammonium converted, or 7.14 mg of alkalinity as CaCO, is <br /> destroyed per mg of NH,- N converted. The equation also predicts <br /> that 0.17 mg of cells are produced per mg of NH,-N converted. <br /> 14 <br />