Influence evaluation of substrate concentration on biogas production of discarded tomato waste (DTW): a simulation study

Discarded tomato waste was anaerobically digested under mesophilic condition to evaluate the influence of substrate concentration on biogas production rate and accumulation. Substrate concentrations of 100, 50 and 30 g VS/l were respectively digested in biodigesters labeled BD1, BD2 and BD3. BD3 biodigester had the maximum biogas production rate while BD2 produced the minimum rate. The biogas production accumulation followed similar pattern as production rate. ANOVA result showed that substrate concentration had no significant influence on maximum biogas production rate but significantly influence biogas production accumulation. Normal distribution Gaussian equation was used to simulate the biogas production rate, while the biogas production accumulation was simulated using first order exponential rise, logistic growth and Gompertz equations. Coefficient of determination values for the normal Gaussian equation ranged from 0.9848–0.9965 illustrating good simulation. The logistic growth and Gompertz equation showed better simulation of the biogas production accumulation than the first order exponential rise equation due to their high coefficient of determination values.