Biodiesel Industry Waste: A Potential Source of Bioenergy and Biopolymers

Abstract

Biodiesel has been recognized as a good source of energy and its production is increasing rapidly. During biodiesel production, effluent containing 70-75 % glycerol is generated, which accounts for 10 % of the total produce. This has led to a scenario where the price of glycerol has declined dramatically and its disposal is becoming uneconomical. Recent efforts to extend the biotechnological applications of glycerol for producing hydrogen and polyhydroxyalkanoates have been quite encouraging. Bacillus spp. are among those few organisms, which have the potential to metabolize glycerol to produce energy and biopolymers. Bacillus may thus be recognized as the Power-Horse of the future.

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

“…In a recent report, glycerol was observed to produce PHB with higher M w and improved mechanical strength than that observed on other sugars [4,45]. Addition of precursor substrates further improves the copolymer composition towards non-3HB monomers.…”

“…The advantage of using mixed cultures is the production of co-polymers with a broad range of PHA composition depending on the substrate used due to their metabolic capacities to utilize a wider range of substrates [8,40]. Moreover, mixed cultures have better survival under stringent environmental conditions and variations occurring specially in biowaste feed, thus, providing an economical option by eliminating the need to sterilize the feed [17,[41][42][43][44][45].…”

“…Substrates used for PHA production cover a wide range including sugars (glucose, fructose, sucrose, maltose, and lactose), starch, glycerol, FAs and its derivatives, methanol etc. [35,45,47]. Among biowastes-agricultural, industrial and dairy byproducts have been used as a cheap source of raw material [3,4,35,45,[47][48][49].…”

“…[35,45,47]. Among biowastes-agricultural, industrial and dairy byproducts have been used as a cheap source of raw material [3,4,35,45,[47][48][49]. While a combination of different substrates, especially the addition of precursor substrates may lead to different combinations of monomers, feeding regime also affects the PHA monomeric compositions [50,51].…”

Biorefinery for Glycerol Rich Biodiesel Industry Waste

“…This has lead to a drastic decline in CG prices to such an extent that its disposal has become a burden for the Environmental and Health Departments. Research efforts are being made to derive value added products from CG as a feed: propanediols, ethanol, hydrogen, methane, methanol, single cell oil, biosurfactants, and organic acids [7][8][9][10][11][12][13].…”