Effects of Alginate and Chitosan on Activated Carbon as Immobilisation Beads in Biohydrogen Production

Abstract

In this study, the effects of alginate and chitosan as entrapped materials in the biofilm formation of microbial attachment on activated carbon was determined for biohydrogen production. Five different batch fermentations, consisting of mixed concentration alginate (Alg), were carried out in a bioreactor at temperature of 60 °C and pH 6.0, using granular activated carbon (GAC) as a primer for cell attachment and colonisation. It was found that the highest hydrogen production rate (HPR) of the GAC–Alg beads was 2.47 ± 0.47 mmol H2/l.h, and the H2 yield of 2.09 ± 0.22 mol H2/mol sugar was obtained at the ratio of 2 g/L of Alg concentration. Next, the effect of chitosan (C) as an external polymer layer of the GAC–Alg beads was investigated as an alternative approach to protecting the microbial population in the biofilm in a robust environment. The formation of GAC with Alg and chitosan (GAC–AlgC) beads gave the highest HPR of 0.93 ± 0.05 mmol H2/l.h, and H2 yield of 1.11 ± 0.35 mol H2/mol sugar was found at 2 g/L of C concentration. Hydrogen production using GAC-attached biofilm seems promising to achieve consistent HPRs at higher temperatures, using Alg as immobilised bead material, which has indicated a positive response in promoting the growth of hydrogen-producing bacteria and providing excellent conditions for microorganisms to grow and colonise high bacterial loads in a bioreactor.

Biohydrogen production from fermentation of organic waste, storage and applications

“…Notwithstanding all potential process improvement, traditional CSTR fermentative H 2 production is limited by process pathways and operational problems such as low cellular density and biomass retention (Dzul Rashidi et al, 2020). Cell immobilization, by decoupling cell growth from H 2 production, therefore offers a sustainable and cheap solution to improve process yields (Wu et al, 2002).…”

“…Whilst entrapped and protected by the matrix, the cells are unable to diffuse in the media but have the ability to grow and often present an increased metabolic activity (Gotovtsev et al, 2015). The entrapment method has also the advantage to allow the addition in the matrix of nanomaterial (Yang and Wang, 2018), supplements (Dzul Rashidi et al, 2020) or supporting media (such as activated carbon) to enhance the process yields or provide strength to the beads (Wu et al, 2003).…”

Techno-Economic Assessment of On-Farm Anaerobic Digestion System Using Attached-Biofilm Reactor in the Dairy Industry

“…Utilizing cheese whey in co-digestion with cow dung also showed good economic performance and positive returns. Co-digestion with 30% of cheese whey substrate increased the biogas production, resulting in a higher electricity selling price which was the key parameter to determine the accountability of the system [33]. Another researcher evaluated the technical and economic feasibility of anaerobic digestion implementation at a dairy farm in Italy.…”

Special Issue on “Biotechnology for Sustainability and Social Well Being”

“…Apart from that, there are five papers selected as feature papers, with topics covering biohydrogen production, rapid monitoring process for bacteria, the optimization of fermentation process for bacteria, nanofiltration and transesterification enhancement by lipase, and liquid biphasic separation for protein recovery. The study on biohydrogen production investigates the effects of alginate and chitosan entrapped in biofilm formations on activated carbon [2]. A positive response to the higher growth of hydrogen-producing bacteria was obtained in the work.…”