The high dependence on fossil fuels has escalated the challenges of greenhouse gas emissions and energy security. Biohydrogen is projected as a future alternative energy as a result of its non-polluting characteristics, high energy content (122 kJ/g), and economic feasibility. However, its industrial production has been hampered by several constraints such as low process yields and the formation of biohydrogen-competing reactions. This necessitates the search for other novel strategies to overcome this problem. Cell immobilization technology has been in existence for many decades and is widely used in various processes such as wastewater treatment, food technology, and pharmaceutical industry. In recent years, this technology has caught the attention of many researchers within the biohydrogen production field owing to its merits such as enhanced process yields, reduced microbial contamination, and improved homogeneity. In addition, the use of immobilization in biohydrogen production prevents washout of microbes, stabilizes the pH of the medium, and extends microbial activity during continuous processes. In this short review, an insight into the potential of cell immobilization is presented. A few immobilization techniques such as entrapment, adsorption, encapsulation, and synthetic polymers are discussed. In addition, the effects of process conditions on the performance of immobilized microbial cells during biohydrogen production are discussed. Finally, the review concludes with suggestions on improvement of cell immobilization technologies in biohydrogen production.

The challenges of increasing energy demand and advanced materials for infrastructural development in developing countries have necessitated the search for sustainable sources of raw materials. The high amount of agricultural residues generated in Africa owing to vast availability of arable land has been an impetus for solving some of these challenges. Therefore, this review article provides information on beneficiation and challenges of the two largely generated agricultural residues, corncobs and sugarcane bagasse, in Nigeria and South Africa. The estimated quantities of corncob and sugarcane bagasse generated by these countries are reported. The potentials of beneficiating corncob and sugarcane bagasse in energy generation, in materials development and in other purposes such as production of platform chemicals are reviewed and discussed. Various technologies deployable in the beneficiation of these wastes are enumerated, and the benefits and challenges that are associated with beneficiating these wastes are briefly discussed