Modelling of dark fermentation of glucose and sour cabbage

Abstract

In the article, modified Anaerobic Digestion Models 1 (ADM-1) was tested for modelling dark fermentation for hydrogen production. The model refitting was done with the Euler method. The new model was based on sets of differential equations. The model was checked for hydrogen production from sour cabbage in batch and semi-batch in 5 g VSS (volatile solid suspension)/L and at the semi-batch process from glucose at 5 and 10 g VSS/L. Added parameters determined the conversion of a substrate, hydrogen production, and stress parameters. In the case of a semi-batch process, for one month, cumulative hydrogen production from sour cabbage of 5 g VSS/L was 0.9 L of cumulative hydrogen volume and from glucose 5 g VSS/L (in case of feeding 2 g VSS/L every two days) 2.5 L of cumulative hydrogen volume. At the bacterial population level, hydrogen production was a continuous process at an adequate range of population size and environmental parameters.

Analysis of Biogas Component Production during Anaerobic Digestion of Sour Cabbage in Microaeration Conditions under Different pH Conditions

“…OFR ranges narrow with a decrease of pH in the case of the sour cabbage. The hydrogen production in low pH was improved by microaeration for fresh sour cabbage [60] just up to 3% higher while for this sour cabbage up to 10% higher.. Dark fermentation in low pH at 5 g VSS/L was from 5 to 50 times higher in the same VSS from neutral pH [58].…”

“…This was caused by a higher pH blocking acetogenesis and methane conversion [79]. The highest methane result for sour cabbage was slightly higher than in acidic pH with nonzero OFR for sour cabbage [60]. It showed a remarkable influence on the VSS level on methane production.…”

“…In the case of 10 g VSS/L, the occurrence of the shift of hydrogen production under influence of microaeration, pH, and VSS degree was observed (see Figure 5). It can be discerned the difference of 1 mL of hydrogen between neutral pH [58] and strictly anaerobic at pH 6.0 (19 mL of hydrogen) from sour cabbage [60] (high VSS) if a proper microaeration parameter was used. Higher concentration led to longer hydrogen production, besides acidic pH that shortened time to 15 or 17 days.…”

“…The water for eliminating carbon dioxide dissolving was on top marked with the mixture by mass 1:10 detergents for dishes (Ludwik ®) and diesel oil. Sour cabbage used for the experiments was 3 months longer fermented than sour cabbage used in [60]. The characteristics of the inoculum are shown in Table 1.…”

“…In 5 g VSS/L of sour cabbage, after adding sour cabbage to inoculum, the pH value of the mixture was lowered (using 38% solution of HCl) from 7.9 to 6.0. The oxygen flow rates (OFR): 0, 0.58, 0.87 mL/h were applied for the substrate load 5 g VSS/L for sour cabbage similar to [60]. OFR was gradually increased until hydrogen production disappeared.…”