High salinity in molasses wastewaters shifts anaerobic digestion to carboxylate production

Vrieze, Jo De; Coma, Marta; Debeuckelaere, Matthias; Meeren, Paul Van der; Rabaey, Korneel

doi:10.1016/j.watres.2016.04.035

Cited by 60 publications

(27 citation statements)

References 52 publications

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“…However, methane production was reduced from 200 to less than 70 L CH 4 kg −1 VS in period c, indicating potential disturbance of the anaerobic process, while the acetate content was more than 35 mmol L −1 . This observation is in line with the results of De Vrieze et al who reported that methane production was significantly decreased when OLR was sharply increased in a UASB reactor working with molasses wastewater. The OLR value was maintained for a period of about 2 weeks, but no improvement was observed in methane production rate and the effluent quality.…”

Section: Resultssupporting

confidence: 92%

Start‐up and steady‐state results of a UASB reactor treating high pH baker's yeast molasses wastewater for methane production

Mischopoulou

Kalamaras

Naidis

et al. 2016

J of Chemical Tech & Biotech

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BACKGROUND The baker's yeast industry is a major market and due to the intensified production large quantities of waste are generated. Wastewater from the baker's yeast industry with high content of molasses was treated anaerobically in an upflow anaerobic sludge blanket (UASB) reactor for the production of methane (CH4). RESULTS The molasses wastewater obtained from industry had a high pH value around 8.0 ± 0.5, which remained constant during the experimental period. The system was operated at an organic loading rate (OLR) of 2.4–7.65 g of volatile solids per liter per day (g VS L−1 d−1) and the best results were observed at 4 g VS L−1 d−1, where methane production exceeded 350 L CH4 kg−1 VS. Anaerobic chemical oxygen demand removal was also examined and it was found that for the latter conditions of optimum OLR, it was more than 35%. VFA analysis revealed that acetic acid concentration in the reactor was more than 25 mmol L−1 even under optimum conditions. CONCLUSIONS The tested hydraulic retention time (HRT) values did not affect methane production, unlike the OLR. The increased acetic acid concentration in the UASB reactor and the high pH were credited to the inhibition of aceticlastic microorganisms. © 2016 Society of Chemical Industry

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Section: Resultssupporting

confidence: 92%

Start‐up and steady‐state results of a UASB reactor treating high pH baker's yeast molasses wastewater for methane production

Mischopoulou

Kalamaras

Naidis

et al. 2016

J of Chemical Tech & Biotech

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“…Both classes, Methanobacteria and Thaumarchaeota have been related with high salinity environments. For instance, De Vrieze et al [67] showed than in anaerobic digestion tanks, Methanobacteriales were selectively enriched as increasing salinity, and Guan et al [68] showed that Thaumarchaeota were the most prevalent Archaea in oceanic deep hypersaline anoxic basins (DHABs). The wide tolerance of these organisms to salinity may allow their presence along the salinity gradient studied.…”

Section: Plos Onementioning

confidence: 99%

Carbon metabolic rates and GHG emissions in different wetland types of the Ebro Delta

et al. 2020

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Deltaic wetlands are highly productive ecosystems, which characteristically can act as Csinks. However, they are among the most threatened ecosystems, being very vulnerable to global change, and require special attention towards its conservation. Knowing their climate change mitigating potential, conservation measures should also be oriented with a climatic approach, to strengthen their regulatory services. In this work we studied the carbon biogeochemistry and the specific relevance of certain microbial guilds on carbon metabolisms of the three main types of deltaic wetlands located in the Ebro Delta, northeastern Spain, as well as how they deal with human pressures and climate change effects. We estimated the metabolic rates of the main carbon-related metabolisms (primary production and respiration) and the resulting carbon and global warming potential balances in sites with a different salinity range and trophic status. With the results obtained, we tried to define the influence of possible changes in salinity and trophic level linked to the main impacts currently threatening deltaic wetlands, on the C-metabolisms and GHG emissions, for a better understanding of the mitigating capacity and their possible enhancement when applying specific management actions. Metabolic rates showed a pattern highly influenced by the salinity range and nutrients inputs. Freshwater and brackish wetlands, with higher nutrient inputs from agricultural runoff, showed higher C-capture capacity (around 220-250 g C m-2 y-1), but also higher rates of degradative metabolisms (aerobic respiration and CH 4 emissions). Contrastingly, the rates of C-related metabolisms and C-retention of Salicornia-type coastal salt marshes were lower (42 g C m-2 y-1). The study of the microbial metacommunity composition by the16S RNA gene sequencing revealed a significant higher presence of methanogens in the salt marsh, and also higher metabolic potential, where there was significantly more organic matter content in sediment. Salinity inhibition, however, explained the lower respiration rates, both aerobic and anaerobic, and prevented higher rates of methanogenesis despite the major presence of methanogens. Conservation measures for these wetlands would require, overall, maintaining the sediment contributions of the river basin intending to overcome the regression of the Delta and its salt marshes in a climate change scenario. Particularly, for reducing degradative metabolisms, and favour C-retention, nutrient inputs should be controlled in freshwater and brackish wetlands in order to reduce eutrophication.

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“…FO-concentration of A-sludge increased the VFA conversion efficiency from 10 % to 45 % (4.4-fold), which is higher than previously reported [11]. It has been described that high salinity and high conductivity (above 30 mS cm -1 ) negatively affect methanogenesis while acetogenic bacteria can acclimatize to high salt concentration and produce VFA [34]. FO-concentration of A-sludge could be a strategy to increase VFA production (sections 3.4 and 3.5) and, inhibit methanogens due to RSD, thus allowing VFA accumulation in a continuous system.…”

Section: Strategies To Further Increase Vfa Production After A-sludgementioning

confidence: 54%

“…Higher concentrations still might be needed in order to produce VFA from FO-concentrated domestic wastewater, however this would further increase contact time in the FO, le ading to more draw solutes leaking and increased conductivity. Such highly conductive feedstocks could be used for VFA accumulation as conductivity above 30 mS cm -1 negatively affects methanogenesis while acetogenic bacteria still produce VFA at high salt concentrations De Vrieze et al [26]. However, an economic assessment would be required as draw solute leakage comes at a cost.…”

Section: Fermentation Yields Of the Different Streamsmentioning

confidence: 99%

Increased carboxylate production in high-rate activated A-sludge by forward osmosis thickening

Cagnetta

D’Haese

Coma

et al. 2017

Chemical Engineering Journal

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Domestic wastewater represents a considerable feedstock for organics but the high dilution makes their recovery typically unsuccessful. Here we investigated three routes to 10-fold concentrate the organics using Forward Osmosis (FO) (Draw solution (DS) 2.2 M MgCl 2): directly on domestic wastewater, Asludge, or secondary sludge, with the end goal of increasing volatile fatty acid (VFA) yield from subsequent 9-day fermentation tests. Forward osmosis concentrated the total COD by a factor of 8.2 ± 1.2, 10.1 ± 2.4 and 4.8 ± 0.2 with respect to the raw streams of wastewater, secondary sludge and Asludge. The soluble fraction of the COD was concentrated up to 3.5 times in the A-sludge and 2.1 times in the secondary sludge; the result of a combined effect of the chemical action of Mg 2+ (diffused from the DS) on sludge disaggregation and cell lysis, and the physical action of recirculation and air-scouring of the A-sludge in the FO-unit. The FO-concentrated A-sludge produced 445 ± 22 mg COD-VFA g-1 COD fed , which was 4.4 times higher than for the untreated A-sludge. No VFA were produced from untreated secondary sludge, but after FO-concentration 71 ± 5 mg COD-VFA g-1 COD fed could be reached. Due to the low organics in wastewater even after FO-concentration (1.08 ± 0.08 g COD L-1), no notable VFA production occurred. The combination of A-stage technology and membrane technology for dewatering and COD concentration could be a key advancement to increase VFA production from domestic wastewater, whereby at least 45% of the COD can be recovered as valuable VFA.

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High salinity in molasses wastewaters shifts anaerobic digestion to carboxylate production

Cited by 60 publications

References 52 publications

Start‐up and steady‐state results of a UASB reactor treating high pH baker's yeast molasses wastewater for methane production

Start‐up and steady‐state results of a UASB reactor treating high pH baker's yeast molasses wastewater for methane production

Carbon metabolic rates and GHG emissions in different wetland types of the Ebro Delta

Increased carboxylate production in high-rate activated A-sludge by forward osmosis thickening

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