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*ft.. Because the total daily air requirement is dependent upon the pounds of BOD applied, the pounds of BOD entering the treatment plant NOTES must be known and can be calculated as follows: BxFx8.34 = A where B = mg/1 BODS F = MGD A = lbs of BOD entering daily DENITRIFICATION O,ALLOCATION The conversion of ammonium to nitrate demands a support process to sustain the reaction. With oxygen being the only common accep- tor, OZ demand/delivery is taken into the design consideration of the batch process. The energy produced by oxidation of NH,and NO,is used by nitrify- ing organisms primarily to produce new biomass. These bacterial cells can be represented by the approximate chemical formulation CSH,O,N. The biomass synthesis reaction for nitrosomonas and ni- trobacter is: NH, + HCO3 + 4CO, + H2O — C5H2O,N + 502 (3) This synthesis reaction requires an input of energy to proceed. Dur- ing nitrification,this energy is obtained from NH,and NO,oxidation equations 1 and 2; therefore, reactions shown in equations 1 and 3 usually occur simultaneously. The energy yield from the oxidation of one mole of NH, or NO, is much less than the energy required to produce one mole of bacterial cells as(CSH,O,N). Equations 1,2, and 3 then must be proportioned so that after energy transfer efficiencies are taken into account, the energy used equals the energy produced. The biological nitrification is then expressed as: NH, + 1.83 OZ + 1.98 HCO3—0.021 C1H'02N (4) + 0.98 NO3 + 1.041 H30 + 1.88 H2CO3 which can be used to estimate the three important parameters asso- ciated with the nitrification process: oxygen requirements, alkalinity consumption, and nitrifier biomass production. AERATION DETENTION A superior system results by combining the complete mix hydraulic design with the detention times of the extended aeration designs. This combination effectively produces a low FM ratio and a subse- quent high MCRT.This promotes the development of specific, high- process microorganisms. 13