Anaerobic fermentation of glycerol: A path to economic viability for the biofuels industry

Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, TX 77005, USA.
Current Opinion in Biotechnology (Impact Factor: 7.12). 07/2007; 18(3):213-9. DOI: 10.1016/j.copbio.2007.05.002
Source: PubMed


Although biofuels such as biodiesel and bioethanol represent a secure, renewable and environmentally safe alternative to fossil fuels, their economic viability is a major concern. The implementation of biorefineries that co-produce higher value products along with biofuels has been proposed as a solution to this problem. The biorefinery model would be especially advantageous if the conversion of byproducts or waste streams generated during biofuel production were considered. Glycerol-rich streams generated in large amounts by the biofuels industry, especially during the production of biodiesel, present an excellent opportunity to establish biorefineries. Once considered a valuable 'co-product', crude glycerol is rapidly becoming a 'waste product' with a disposal cost attributed to it. Given the highly reduced nature of carbon in glycerol and the cost advantage of anaerobic processes, fermentative metabolism of glycerol is of special interest. This review covers the anaerobic fermentation of glycerol in microbes and the harnessing of this metabolic process to convert abundant and low-priced glycerol streams into higher value products, thus creating a path to viability for the biofuels industry. Special attention is given to products whose synthesis from glycerol would be advantageous when compared with their production from common sugars.

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Available from: Syed Shams Yazdani
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    • "Glycerol of biodiesel production is well utilized by microorganisms (Papanikolaou et al., 2008; Temudo et al., 2008). Studies have investigated whether the utilization of glycerol by microorganisms is a great possibility to convert that into value-added products (Barbirato et al., 1998; Johnson and Taconi, 2007; Yazdani and Gonzalez, 2007). The measurment of biologically active functions of organic matter, such as microbial biomass C, N, P and potential C, N and P mineralization were better able to reflect changes in soil quality and productivity (Patel et al., 2010). "

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    • "Thus, we consider the treatment of cannery wastewater as the environmental problem that needs to be mitigated, and the merging of other waste streams of glycerol waste and algal biomass as a means to make that treatment economically feasible. Glycerol waste is a by-product of biodiesel production and is generated approximately 10% of oil material used [9]. Its global production is currently more than 3,000,000 tons and is expected to be around 4,600,000 tons by 2020 due to increasing in demand of using biodiesel [10]. "
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    ABSTRACT: We investigated the feasibility of using Microcystis sp; blue green algae (MB) as a co-substrate to improve the mesophilic anaerobic digestion of cannery seafood wastewater (CSW) supplemented with 1% (v/v) glycerol waste (GW), to maximize bio-methane production. The MB content was set at 5, 10 and 15% (v/v) to find a near optimal methane yield. The maximum 291mL CH4/g VS-added methane yield, corresponding to 4.4 m3-CH4/m3 - mixed wastewater, was achieved with a CSW: GW: MB mixture at the volumetric 94:1:5 ratio. The methane yield of CSW digested alone was 278mL CH4/g VS-added (2.2 m3 CH4/ m3 of wastewater). The yields from our other experiments ranged within 81– 150 mLCH4/g VS-added. Ratios of MB: CSW exceeding 5% (v/v) gave lower than optimal methane yields. The energy content of methane from 1 m3 of mixed wastewater, with the near optimal mixture ratio 94:1:5, was 157MJ or equivalently 44 kWh.
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    • "Ethanol can be produced directly from fermentable feedstocks, starchy materials, and lignocellulosic materials and from industrial and urban wastes (Praveen Kumar et al., 2014). The cost of ethanol production from glycerol is almost 40% less than that of production from corn-derived sugars, when both feedstock demand and operational cost are considered (Yazdani et al., 2007). "
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    ABSTRACT: Crude glycerol is effectively utilized as substrate for the production of value added bio products such as acetic acid, citric acid, DHA, ethanol, etc. It has several advantages over commercial substrates which includes low cost nutrients, as a good carbon and energy source for the microorganisms to grow with high product conversion rate. In this research ethanol a primary alcohol, an alternate biofuel was produced by various bacterial sp. and the yield of ethanol were compared. The crude glycerol is pretreated and neutralised with H3PO4, further centrifuged to remove impurities present in it, which helps to increase the concentration of glycerol and yield. The production of ethanol from purified glycerol was compared by maintaining the same condition with various organisms .The product obtained from purified glycerol fermentation was confirmed as ethanol by simple qualitative test and further by GC-MS. When compared with other organisms, concentration of ethanol obtained from Zymomonas mobilis, on purified glycerol using phosphoric acid yields 5.1 %.
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