Volatile Fatty Acids (VFA) Production Through Altered Anaerobic Digestion (AD) Process for Efficient Utilization of Residual Liquid Stream of Pretreated Lignocellulosic Biomass.

Autor: More, Pooja P., Gore, Suhas, Dargode, Priyanka, Sharma, Manju B., Lali, Arvind M.
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Zdroj: BioEnergy Research; Sep2022, Vol. 15 Issue 3, p1616-1625, 10p
Abstrakt: Recently biorefinery-based models for complete utilization of lignocellulosic biomass (LBM) feedstock for the production of valuable products with zero/minimum waste generation are gaining wide attention. However, pretreatment of LBM is a prerequisite due to its recalcitrant and complex nature. The pretreatment processes generate residual liquid streams which need further management. The present study utilizes such residual liquid stream (RLS) obtained post-pretreatment of rice straw for volatile fatty acids (VFA) production through altered anaerobic digestion (AD). Two strategies, viz., (a) bromoethano-sulphonate (BrES-chemical methanogenic inhibitor) and (b) alkaline pH of 9.0, were employed for altering the AD process. Batch studies with both BrES and alkaline pH completely inhibited methane generation, though the VFA yield obtained was higher at alkaline pH (0.57 g/g) than that observed with BrES (0.51 g/g). Moreover, the alkaline pH also resulted in complete nitrate removal. Continuous reactor studies with alkaline pH strategy for organic loading rate (OLR) optimizations (2–16 gCOD/L·day) resulted in maximum VFA yield and productivity. VFA yield of 0.63 g/g COD utilized, and productivity of 6.4 gCOD/L·day was achieved at OLR of 12 and 16 gCOD/L·day, respectively, at constant hydraulic retention time (HRT) of 1 day. Community analysis of the samples using the 16S rRNA sequencing tool showed phyla Firmicutes and Bacteroidetes as the predominant ones. The present study shows that VFA production from the residual liquid stream of LBM will provide new avenues for value addition to the existing lignocellulosic ethanol plants. It will further assist in developing a biorefinery model for LBM. Research Highlights: VFA production using a residual liquid stream of rice straw pretreatment process. Alkaline pH resulted in enhanced VFA production and complete nitrate removal. Maximum VFA yield 0.63 g/g COD utilized and productivity of 6.4 gCOD/L·day achieved. Developed AD process shall open new avenues for LBM based biorefinery models. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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