I. 1. Write an overall stoichiometric equation (R) that includes energy and growth for bacteria using wastewater organic matter (C₁₀H₁₉O₃N) for substrate and NO₃^- as an electron acceptor producing N₂.

2. Using the equation above calculate the mg/l of NO₃-N removed per mg/l of C and mg/ of COD removed, and the mg/l of biomass produced per mg/l removed.

3. Instead of the bacteria using NO₃ as an electron acceptor, the bacteria instead use O₂ as an electron acceptor. Which overall reaction will obtain more energy? (Refer to table 7-6 in Metcalf and Eddy for Gibbs free Energy values)

II. Methanol (CH₃OH) is sometimes used as substrate to drive denitrification (Bacteria breathing NO₃ to produce N₂).

1. Write an overall equation that describes this process assuming that fs and fe=0.5

2. Determine how much methanol (g/l as CH₃OH) is required to remove 1g/l of NO₃-N.

3. Determine the mg/l of biomass produced as COD per mg/l of methanol consumed as COD.

4. Determine whether a bacteria eating NH₄⁺ producing NO₂^- as an end product while breathing O₂ or a bacteria eating NO₂^- producing NO₃^- as an end product and breathing O₂ will obtain more energy? Your response should include the result based on a per mol e^- basis as well as per g N converted to the waste product. (Refer to table 7-6 in Metcalf and Eddy for Gibbs Free Energy values).