초록
<P><B>Abstract</B></P> <P>In a view to uplift the biodiesel industry as a major energy carrier, new approach of minimizing the waste and utilizing generated waste needs to be explored. The spent media generated from the co-culture system is cost effective and can serve as renewable supplement for mixed-culture based hydrogen (H<SUB>2</SUB>) production and lipid production. Direct conversion of spent media along with crude glycerol (CG) at 20 g/L using heat-shock pretreated wastewater sludge resulted in 38.12 ± 0.84 mmol/L of H<SUB>2</SUB>. In another approach, the spent media was used as co-supplement along with fresh media at 3:2 for algal growth, resulting in 0.098 ± 0.007 g/L of lipid. The spent media contained dead biomass, residual media nutrients, biomolecules and unutilized glycerol together acting as supplementary source during H<SUB>2</SUB> and lipid production. According to the closed system results, the H<SUB>2</SUB> produced (1.47 × 10<SUP>9</SUP> L of H<SUB>2</SUB>) can be converted into energy (1.87 × 10<SUP>4</SUP> GJ) for electricity (1.77 × 10<SUP>4</SUP> GJ) and heat (4.32 × 10<SUP>3</SUP> GJ). The produced H<SUB>2</SUB> can be used as in-house energy source and the lipids can be used as third generation feedstock. The study explores the utilization of CG and spent media valorization towards an efficient closed system approach for a competitive biodiesel industry.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spent media developed as cost-effective and renewable supplement. </LI> <LI> H<SUB>2</SUB> production of 38.12 ± 0.84 mmol/L benefited with 29.53% increase. </LI> <LI> Low-cost spent media co-supplement produced 0.098 ± 0.01 g/L of lipid. </LI> <LI> Efficient closed system approach developed for crude glycerol utilization. </LI> <LI> The closed system can make the biodiesel industry competitive. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>