Experimental investigation and modelling of the effect of sulfate on anaerobic biodegradation processes in municipal solid waste

The experimental investigations have been carried out in two parts. First, the biodegradation of the organic compounds in the municipal solid waste has been investigated with focus on different sulfate concentrations influencing the methane formation. Second, the inhibition effect of hydrogen sulfide in solution (H₂S_aq) on the acetate, and methane formation, respectively, has been studied at different pH and temperature values. In solution the equilibrium of hydrogen sulfide (H₂S_(aq)) and the hydrogen sulfide anion (HS^-_(aq)) mainly depends on pH. At pH 6.3 the favoured species is H₂S_(aq) whereas at pH 7.7 the HS^-_(aq) species is favoured. Additionally, the experiments have been carried out at two different temperatures (35°C and 55°C). According to the acetate and methane formation the H₂S_(aq) species is observed to have an inhibitory effect. All simulations based on a biodegradation model represented are in good agreement with the experimental data obtained.