Anoxic conditions formation formulas

The rates of sulfur and nitrogen compounds transformation processes in the model describe by the following equations:

Am = K_Am [Norg] F_Am (O2) - ammonification;

Nf1 = K_Nf1 [NH4+] F_Nf (O2) - first stage of nitrification;

Nf2 = K_Nf2 [NO2-] F_Nf (O2) - second stage of nitrification;

Nr1 = K_Nr1 [NO3-] F_Nr (O2) - nitrate reduction;

Nr2 = K_Nr2 [NO2-] F_Nr (O2) - denitrification;

Th1 = K_Th1 [H2S] F_Th (O2) - first stage of hydrogen sulfide oxidation;

Th2 = K_Th2 [S0] F_Th (O2) - second stage of hydrogen sulfide oxidation;

Th3 = K_Th3 [S2O32-] F_Th (O2) - third stage of hydrogen sulfide oxidation;

Sr1 = m1 K_Sr1 [Norg] F_Sr (O2) - first stage of sulfate reduction;

Sr2 = K_Sr2 [S2O32-] F_Sr (O2) - second stage of sulfate reduction;

Td = K_Td [H2S] F_Td (NO3-) - thiodenitrification;

As = p1Th1 + p1Th2 + p1Th3 + p2Nf1 + p2Nf2 + p3Td - ammonium assimilation by autotrophic microorganisms (chemosynthesis in nitrogen unites).

Where, Ki - constants of corresponding reactions, mi - stoicheometric coefficients, Fi (O2), Fi (NO3-) - dependencies of reaction rates from oxygen and nitrate content respectively, pi - the quantity of consumed nitrogen of NH4+ in unite of consumed substrate (S ₂^-, S⁰, S₂O₃^2-, NH₄⁺, NO₂^-).

Thus, the general form of the source equations for all blocks of the model is:

R_Norg = -Am - m2Nr1 - m3Nr2 - m4Sr1 + As;

R_NH4+ = Am + m4Sr1 - Nf1 - As;

R_NO2- = Nf1 - Nf2 + Nr1 - Nr2;

R_NO3- = Nf2 - Nr1 - m5Td;

R_H2S = -Th1 + Sr2 - Td;

R_S0 = Th1 - Th2;

R_S2O32- = Th2 - Th3 + Sr1 - Sr2;

R_SO42- = Th3 - Sr1 + Td;

R_O2 = -m6Th1 - m7Th2 - m8Th3 - m9Nf1 - m10Nf2 - m11Am, where mi (i = 2-11) - stoicheometric coefficients of the model.

Table. Constants and coefficients used in the model.