Development of a simple model for anaerobic digestion based on preliminary measurements of the bacterial sulphur activity in wastewater stabilization ponds

Abstract

The present study was undertaken to develop a simple and practical model for anaerobic digestion, encompassing sulphate reduction and sulphur oxidation, in a waste stabilization pond. The basic microbiological phases of the model consisted of four processes, namely acidogenesis, methanogenesis, sulphate reduction and sulphur oxidation. It also incorporated multiple reaction stoichiometry and substrate utilization kinetics. The study also aimed to investigate the mutual interaction between sulphate-reducing bacteria (SRB) and photosynthetic sulphur bacteria (PSB) in an anaerobic sludge consortia using batch reactors. The results revealed that for an initial concentration of sulphate ranging between 250 and 2800 mg x l(-1), SRB activity ranged between 20 and 190 mgSO4(2-)(reduced). The gVSS(-1) x d(-1) and PSB activity varied between 60 and 320 mgSO4(2-)(produced). gVSS(-1) x d(-1), and PSB activity was noted to be twice as high as that of SRB. PSB can, therefore, be used effectively in the fight against odors. The most important environmental factors affecting the sulphur cycle in the waste stabilization pond were likely to be the availability of sulphate and light for SRB and PSB, respectively.

Anaerobic treatment of sulfate-rich wastewaters: process modeling and control

“…The number of SRB in existing models varies from two (Harerimana et al, 2013;Vavilin et al, 1994) to five (Knobel & Lewis, 2002), although three and four SRB types are the most common approaches, including butyrate-utilizing SRB (bSRB), propionate-utilizing SRB (pSRB), acetate-utilizing SRB (aSRB) and hydrogen-utilizing SRB (hSRB) (Fedorovich et al, 2003;Flores-Alsina et al, 2016). Acetate-and hydrogen-utilizing SRB have been incorporated in most models, which is expected considering that acetate and hydrogen are the final intermediates before methanogenesis and that, under stable conditions, fermentation reactions are relatively fast compared to methanogenesis (Ahmed & Rodríguez, 2018;Peces et al, 2018).…”

A review on anaerobic membrane bioreactors (AnMBRs) focused on modelling and control aspects

“…Figure 2 shows a schematic representation of the biochemical processes included in the model ADM1, including the sulfate-reducing processes modelled by different authors at different complexity levels. For instance, simple models that allow to simulate the competition between methanogens and SRO for acetate (Fomichev and Vavilin, 1997), acetate and hydrogen (Harerimana et al, 2013) or hydrogen (Batstone, 2006) Deferribacteres, while the bulk was dominated by Bacteriodetes and Firmicutes (and Methanosaetaceae).…”

A New Mathematical Model for the Accurate Determination of Volatile Fatty Acids Concentration in Anaerobic Digesters

“…As for the consumption of VFA by methanogenic biomasses, during the methanogenic fermentation phase, the optimal situation is observable at an optimum pH variable according to the authors: 6.6 < pH < 7.4 [21]; 6.8 < pH < 7.4 [42,43]; 6.8 < pH < 8 [44,45] and 6.8 < pH < 7.5 [6,46]. Since sulphate-reducing bacteria (SRB) have an optimum pH of growth equal to 7.0 [47][48][49], they can compete with archaeal methanogens for the consumption of VFA as substrate. These SRB are used to reduce sulphates to hydrogen sulphide [48,49].…”

“…Since sulphate-reducing bacteria (SRB) have an optimum pH of growth equal to 7.0 [47][48][49], they can compete with archaeal methanogens for the consumption of VFA as substrate. These SRB are used to reduce sulphates to hydrogen sulphide [48,49]. Knowing that the concentration of total sulphides is very low in anaerobic digesters [ie.…”