In addition to the chemicals and biomass specified in example 5.1, assume there is also sulfate in the water at the concentration of 3.0 mmol/L. The initial sulfate reducing bacteria has the concentration of 1.0×10-6 mol-biomass/L.
Sulfate reduction (Fs = 0.08 and Fe = 0.92) goes as follows:
$\begin{array}{l}
0.125 \mathrm{SO}_{4}^{2-}+0.13525 \mathrm{CH}_{3} \mathrm{COO}^{-}+0.004375 \mathrm{NH}_{4}^{+}+0.0065 \mathrm{H}^{+} \rightarrow \\
0.004375 \mathrm{C}_{5} \mathrm{H}_{7} \mathrm{O}_{2} \mathrm{~N}_{S R B}+0.250 \mathrm{HCO}_{3}^{-}+0.013 \mathrm{H}_{2} \mathrm{O}+0.125
\end{array}$
Sulfate reduction rate parameters are specified in Table 2. Note that it has two inhibition terms because it has both O2 and NO3 above in the redox ladder.
Reactions | $\mu_{\max }(\mathrm{mol} / \mathrm{mol}-\mathrm{biomass/yr})$ | $\begin{array}{l} K_{m, \text { acceptor }} \\ \text { (mol/kgw) } \end{array}$ | $\begin{array}{c} K_{m, \text { donor }} \\ \text { (molkgw) } \end{array}$ | $\begin{array}{c} K_{I, O 2(a q)} \\ \text { (molkgw) } \end{array}$ | $\begin{array}{c} K_{I, \mathrm{NO} 3(a q)} \\ (\mathrm{molkgw}) \end{array}$ |
---|---|---|---|---|---|
Sulfate reduction | 35000 | 1.25x10-3 | 1.25x10-3 | 1.00x10-6 | 1.00x10-3 |
*Range of relevant parameters is from Cheng et al., 2016; Li et al., 2010.
Questions:Extension: In Problem 1, we mainly discuss how O2(aq) affects the microbe-mediated reactions. Other thermodynamics and kinetic parameters, including maximum biomass grow rate, half saturation of the electron donor and acceptor, and the concentrations of electron donor and acceptor, also affect the biomass reactions. Please use the input and database files from Problem 1 as the base case to do the following analysis comparing N2(aq) and sulfide evolution: