Optimization of Sludge Fermentation for Volatile Fatty Acids Production

Sultan K Salamah and Andrew A Randall

International Journal of Low-Carbon Technologies, 2020, vol. 15, issue 1, 149-154

Abstract: Prefermentation of primary solids can produce volatile fatty acids (VFAs), and operational strategies may affect the propionic acid content. In this study, three prefermenter phases were used to optimize VFAs using three separate strategies. The phases were (i) glycerol (biodiesel by-product) co-fermentation with primary solids, (ii) the effect of mixing energy on the co-fermentation of glycerol and primary solids and (iii) the effect of hydrogen gas addition on the co-fermentation of glycerol and primary solids. The Phase 1 data showed that glycerol increased the VFAs production 1.2× over the possible value from the added glycerol alone (427 mg-COD/l), implying that the glycerol addition stimulated additional fermentation of primary solids. In Phase 2, low mixing energy in glycerol increased the VFAs production by 80% while slightly favoring propionic acid over acetic acid compared to the higher mixing energy. The addition of hydrogen gas in Phase 3 did not increase the VFAs total production but significantly increased the concentration of propionic acid by 41%. All three optimization approaches performed well and were able to increase the VFAs production and/or increase propionic acid concentration relative to acetic acid.

Keywords: fermentation; glycerol; hydrogen gas; mixing energy; volatile fatty acids (search for similar items in EconPapers)
Date: 2020
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Persistent link: https://EconPapers.repec.org/RePEc:oup:ijlctc:v:15:y:2020:i:1:p:149-154.

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