Date of Award

19-2-2024

Document Type

Thesis

School

School of Chemical & Biotechnology

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr. Kiran Babu Uppuluri

Keywords

Haracterization Of Prosopis Juliflora Pods, Cellulase And Xylanase Enzyme Production, Pretreatment And Hydrolysis Of Prosopis Juliflora Pods

Abstract

The rapid consumption of fossil fuels has resulted in the energy crisis and many environmental issues, including air pollution and the greenhouse effect. Hydrogen is the independent source of the highest energy content, with 122 KJ g-1. Biohydrogen produced from lignocellulosic biomass (LCB) is an excellent alternative fuel for its cleanability, renewability and sustainability. Biohydrogen production from dark fermentation using lignocellulosic biomass provides low cost and a sustainable pathway to utilize a vast amount of waste.

Dark fermentation has considerable potential for hydrogen production because it does not require sunlight, allowing for full-time operation and minimizing bioreactor complexity. The major bottleneck of lignocellulosic-based biohydrogen production is separating and breaking the major polymers into fermentable sugars. Inoculum plays an essential factor in biohydrogen production under dark fermentation. Anaerobic sludge containing mixed microbial cultures could offer a complete pathway during biomass to biofuel conversion.

Mixed consortia could metabolize and tolerate metabolic compounds that act as metabolic inhibitors, such as acetic acid and hydroxy methyl furfural. Process integration using enzyme cocktails in the LCB biorefinery requires fewer enzymes, improving product formation and reducing cost. HHF involves integrating simultaneous hydrolysis and fermentation of biomass without compromising the hydrolysate yield.

Thus, the present study evaluated the hybrid enzymatic hydrolysis and fermentation of Prosopis juliflora pods (Pj pods) for the enhanced Biohydrogen production from the activated anaerobic sludge through the waste-to-energy approach (WtE). The onsite-produced cellulolytic enzyme cocktail from the newly isolated Trichoderma harzianum BPGF1 hydrolyzed the sulfuric acid-treated Pj pods. After the separate enzymatic hydrolysis, the acid- treated Pj pods produced 342.51 mg/gds glucose. The sesame oil-treated anaerobic sludge has more hydrogen-producing Clostridium species and less hydrogen-consuming bacteria.

After the optimization, a maximum biohydrogen yield of 7366±164.12 μmole H2/gds and 108.690±2.82 mmole H2/L was achieved under anaerobic conditions. Thus, the HHF was proven to be a more efficient and reliable approach for biomass's enzymatic hydrolysis and fermentation to produce biofuels & biochemicals. Using onsite-produced enzymes for the Hybrid hydrolysis and fermentation for biohydrogen production is new and novel in the present report. Also, the present study, for the first time, explored sesame oil as a source of LCFAs for suppressing hydrogen consumers in the inoculum.

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