Kinetic modeling and microbial assessment by fluorescent in situ hybridization in anaerobic sequencing batch biofilm reactors treating sulfate-rich wastewater

Abstract

-This paper reports the results of applying anaerobic sequencing batch biofilm reactors (AnSBBR) for treating sulfate-rich wastewater. The reactor was filled with polyurethane foam matrices or with eucalyptus charcoal, used as the support for biomass attachment. Synthetic wastewater was prepared with two ratios between chemical oxygen demand (COD) and sulfate concentration (COD/SO 4 2-) of 0.4 and 3.2. For a COD/SO 4 2-ratio of 3.2, the AnSBBR performance was influenced by the support material used; the average levels of organic matter removal were 67% and 81% in the reactors filled with polyurethane foam and charcoal, respectively, and both support materials were associated with similar levels of sulfate reduction (above 90%). In both reactors, sulfate-reducing bacteria (SRB) represented more than 65% of the bacterial community. The kinetic model indicated equilibrium between complete-and incomplete-oxidizing SRB in the reactor filled with polyurethane foam and predominantly incomplete-oxidizing SRB in the reactor filled with charcoal. Methanogenic activity seems to have been the determining factor to explain the better performance of the reactor filled with charcoal to remove organic matter at a COD/SO 4 2-ratio of 3.2. For a COD/SO 4 2-ratio of 0.4, low values of sulfate reduction (around 32%) and low reaction rates were observed as a result of the small SRB population (about 20% of the bacterial community). Although the support material did not affect overall performance for this condition, different degradation pathways were observed; incomplete oxidation of organic matter by SRB was the main kinetic pathway and methanogenesis was negligible in both reactors.

Effect of Sulfate Loading Rate and Organic Loading Rate on Anaerobic Baffled Reactors Used for Treatment of Sanitary Landfill Leachates

“…Previous studies had reported COD/SO 4 2-ratios ranging from 6.6 to 1.7 as optimal for CODr (Choi and Rim, 1991;Friedl et al, 2009;Mockaitis et al, 2010;Silva et al, 2011;Camiloti et al, 2013).…”

Factorial Analysis on Sulfide Removal from Petrochemical Industry Wastewater using Acclimatized Activated Sludge

“…However, there was no significant difference of sulfide removal between 0 rpm and 100 rpm of agitation where the sulfide removal achieved 99.3% and 99% at 0 rpm and 100 rpm, respectively. The difference of sulfide removal at both agitation rate maybe due to the sensitivity of the microbes to the agitation where the agitation reduced the performance of the microbes in AS and reduced the sulfide removal [9]. Figure 2b showed that sulfide removal was increased proportionally to WW/AS ratio where sulfide removal achieved 99.4% at 3:1 ratio and 99.2% at 1:1 ratio.…”

“…At 100 rpm of agitation sulfide removal decreased when the temperature increased. The sulfide removal decreased with agitation because the microbes were sensitive to the presence of agitation and reduced the performance of the microbes in the wastewater [9]. Figure 3d showed the interaction effect between HRT and different WW/AS ratios on sulfide removal.…”

The "Chemical Oxygen Demand / Total Volatile Acids" Ratio as an Anaerobic Treatability Indicator for Landfill Leachates

“…As this configuration presented good results treating synthetic wastewaters (removal efficiency up to 86%), the AnSBBR started to be studied and developed (Ratusznei et al, 2003;Rodrigues et al, 2003;Cubas et al, 2004;Pinho et al, 2004;Siman et al, 2004;Bezerra et al, 2010;Costabile et al, 2010). The AnSBBR was also tested and optimized with many types of wastewaters, including diluted whey (Damasceno et al, 2007), sewage (Sarti et al, 2007) wastewater of the personal-care industry (Oliveira et al, 2009), biodiesel production effluent (Selma et al, 2010;Bezerra et al, 2010), sucrose-based wastewater (Manssouri et al 2013) among other studies for optimization and improvement of the AnSBBR Silva et al, 2011;Vich et al, 2011).…”