Implementation of Nanotechnology for Increasing Biohydrogen Production from Anaerobic Digestion of Biomass

Abstract

Biohydrogen has significant feasibility since biological processes are much less energy intensive compared with electrolysis and thermo-chemical processes. Biological processes and bacterial fermentation are considered as the most environmentally friendly alternatives for satisfying future hydrogen demand. Biohydrogen production from biomass is considered profitable as biomass is abundant, cheap, and biodegradable. The combustion of H₂ with O₂ produces water as its only product: Unlike other fuels, the combustion of H₂ does not produce CO₂, CO, NO_x, or SO₂. Therefore, H₂ is an environmentally friendly fuel. The objective of this study is to increase biohydrogen production from biomass using nanotechnology. In this study, it is hypothesized that the biostimulation of hydrogen-producing purple non-sulfur (PNS) bacteria through the addition of nutrients in form of nanomaterials can enhance the bioresponses of such bacteria, where this leads to increase biohydrogen production from biomass. A biohydrogen production system and a model of photobioreactor were manufactured and installed. Food wastes were collected from kitchen leftovers of different fast-food suppliers and were used in this study as feedstocks for biohydrogen production. The production process was conducted as following: addition of 50 mg/l of nickel nanoparticles to the bacterial inoculum and then mixing them with biomass and water by a ratio of 0.5:1:2 which were then kept in the photobioreactor exposed to white light emitting diodes (LEDs) with a luminous flux of 3600 lumen and at 30^oC for 14 days with mixing for 5 min every 30 min to produce biohydrogen. The results showed that the maximum biohydrogen yield was 40.7 mol H₂/mol sugar (2.68 times control) when Ni nanoparticles were added. Besides, during the active production period the H₂ percentages were ranging from 48.0 to 51.7% when Ni nanoparticles were added which were higher by 15% than the control. It was concluded that the addition of nanomaterials leads to biostimulate the bacterial cells and enhance their activity and growth rate and, therefore, increase biohydrogen production from biomass.