Biological Sulfate Reduction Using Molasses as a Carbon Source

Abstract

The feasibility of using a laboratory-scale upflow anaerobic sludge blanket process for sulfate reduction with molasses as a carbon source was demonstrated. Competition between methaneproducing bacteria (MPB) and sulfate-reducing bacteria (SRB) was influenced by the chemical oxygen demand-to-sulfur (COD:S) ratio in the feed. Sulfate removal greater than 80% could be achieved at COD:S greater than 10 when MPB predominated. Activity of MPB and SRB was inhibited at a dissolved sulfide concentration of approximately 200 mg/L. Competition between MPB and SRB was intense as the COD:S was reduced from 5 to 2. Further reduction in the COD:S to 0.7 led to the formation of sulfidogenic granules. The COD removal decreased to approximately 30% at a COD:S less than 2 because of accumulation of sulfurous precipitates and the nonbiodegradable portion of molasses in the sludge. Reduced gas production rates further imposed limitations on diffusion of the organic substrate into granules. Sulfidogenic process operation yielded sulfate removal as great as 70% at a COD:S of approximately 3.5. Water Environ. Res., 73, 118 (2001).

The bioactivation procedure for increasing the sulphate-reducing bacteria in a UASB reactor

“…However, due to the complexity of the substrate used (molasses), it may be assumed that not all the organic matter was available. So, in fact, the COD/sulphate ratio may have been lower than the one shown in Table 3, what would make it easier to obtain sulphidogenic anaerobic sludge (Annachhatre & Suktrakoolvait, 2001). Also, it should be pointed out that the bioactivation procedure adopted in this study not only involved an increase in SRB in the inoculated anaerobic sludge, but also the adaptation of these microorganisms to a complex source of carbon/energy.…”

“…These acids can be used by SRB as the source of carbon. The other components of molasses, approximately 50 to 70% (w/w), are not easily biodegradable; thus carbon availability to SRB may be reduced (Annachhatre & Suktrakoolvait, 2001). In this case, the composition of the source of carbon/energy added to the synthetic effluent was 50% lactate and 50% molasses, expressed as COD.…”

“…Table 2 shows that for run I the COD removal efficiency remained lower, although the organic matter concentration increased (55 th to 90 th day). In other words, microbial consortia were not able to metabolize complex organic molecules present in the molasses (Annachhatre & Suktrakoolvait, 2001). Nevertheless, due to lactate reduction in the composition of the source of carbon/energy from 50% to 25% (run II), an increase in COD removal efficiency was observed.…”

Biological sulphate reduction using food industry wastes as carbon sources

“…Several natural sources of organic materials serving as electron donors and carbon sources have been already investigated: molasses, bagasse, sewage sludge, leaf mulch, wood chips, animal manure, vegetal compost, sawdust, mushroom compost, whey, and other agricultural wastes (Coetser et al 2006;Costa and Duarte 2005;Annachhatre and Suktrakoolvait 2001;Waybrant et al 1998;Christensen et al 1996;Hammack et al 1994;Dvorak et al 1992). The selection of the carbon source depends to a great extent on the degradability of the organic substrate.…”

Application of sugarcane bagasse for passive anaerobic biotreatment of sulphate rich wastewaters

“…However, utilization of various environmental contaminants for instance, halogenated compounds and petroleum hydrocarbons' constituents has been reported by researchers (Fauque et al 1991;Hao et al 1996;Harms et al 1999;Morasch et al 2004). In addition, several different kinds of organic wastes have been employed in bioremediation processes using SRB and include animal manure, leaf mulch, molasses, mushroom compost, sawdust, sewage sludge, vegetal compost, watermelon rind, whey, wood chips and other agricultural wastes (Dvorak et al 1992;Hammack et al 1994;Christensen et al 1996;Waybrant et al 1998;Annachhatre and Suktrakoolvait 2001;Costa and Duarte 2005;Coetser et al 2006;Hussain and Qazi 2012;Hussain et al 2014).…”