GATE 2023 ES – Question 55
A reactor consumes all acetate in the reaction $.125CH_3COO^-+.0295NH_4^++ .103O_2\to .0295C_5H_7O_2N+.0955H_2O+.095HCO_3^-+.007CO_2$. Influent acetate is 1 mol/L;ammonia is nutrient. Acetate has 59 g/mol and exerts1.07 gCOD/g;biomass is 113 gVSS/mol. Find observed yield gVSS/gCOD, to two decimals.
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Correct answer: 0.40 to 0.44
Explanation
Use the printed stoichiometric basis. Biomass formed is $.0295(113)=3.3335$ g VSS. Acetate removed is $.125(59)=7.375$ g, corresponding to $7.375(1.07)=7.89125$ g COD. Yield is $3.3335/7.89125=.4224299$,rounded **.42 gVSS/gCOD**. The1 mol/L feed scales both numerator and denominator equally.