Biohydrogen Production from Wastewaters

Biohydrogen production technology is an emerging field for the advanced wastewater treatment with cogeneration of energy. Besides, hydrogen is an excellent candidate with high energy value (122 kJ/g) than other known carbon‐based fuels with no adverse effects to the environment as it releases only water vapor as the by‐products during the combustion. Biohydrogen production technology can be assisted through two major pathways: (a) light‐dependent reaction (biophotolysis and photofermentation) and (b) light‐independent reaction (dark fermentation and microbial electrohydrogenesis cells). The light‐dependent reaction can be catalyzed by photosynthetic bacteria, whereas the dark fermentation catalyzed by the heterotrophic bacterial group of facultative and obligate anaerobes. The wastewaters are a rich source of organic nutrients which supports the growth of hydrogen producers along with the disposal of waste and energy recovery. In the present chapter, the recent advancements on biohydrogen production technology from wastewaters with respect to the (a) inoculum development, (b) process optimization, (c) scale‐up and (d) the challenges and perspectives toward the improvement of this emerging technology for the wastewater treatment

Biofuel policy in India: A review of policy barriers in sustainable marketing of biofuel

Global warming issue due to the combustion of fossil fuel pushes the world to produce renewable and environmental friendly energy from sustainable feedstock. There are several measures on different levels to reduce the global warming including clean energies from wind, solar, and biomass. There are different aspects in bringing these technologies into a reality including development of technology, economic feasibilities, environmental sustainability and finally, support from the government in the form of effective policies and public awareness. Adequate R&D efforts could overcome all the factors but only an effective policy could drive those efforts to reality. Therefore, in this connection this review initially addresses the present state of energy demand, progression of biofuel sources and the bottlenecks in microalgal biofuel production and commercialization. The biofuel policies are essential to change the world’s dependence on fossil fuels for a better tomorrow. Hence, this review addresses the salient features of National Biofuel policy of India that helps in regulating the biofuels production and their marketing. As a part of Policy implementation, government of India introduced several schemes and programs in last two-decades, which includes mandate blending of ethanol with gasoline, diesel with biodiesel, for the future clean energy vision, and incentivizing bio-based products/fuels. In addition, participation of both federal and state governments for clean energy initiatives, capital investments and tax credits were described in detail. Many policies lack easy outreach among public and industries, which needs marketing by the government that secures a clean energy future in India. Though India is in the process of evolution, it might be quite difficult to enact a dedicative legislation to deal with the challenges of biofuel marketing. Therefore, recent initiatives and scope were summarized in this review for future endeavors

Advanced biohydrogen production using pretreated industrial waste: outlook and prospects

In order to address existing environmental concerns as a result of non-renewable energy sources and to meet future energy demands, biohydrogen offers a suitable alternative energy reserve. Discrete as well as integrative methods of biohydrogen production have been analyzed over time, optimized for achieving high yields. In addition, key process parameters such as temperature, pH, hydraulic retention time, substrate concentration etc., which influence the rate of production have been clarified. Several studies have exploited industrial waste as feed sources for the production of biohydrogen; however, lower yields from these add an additional requirement for suitable pretreatment methods. The present communication examines various pretreatment methods used to increase the accessibility of industrial wastewater/waste for biohydrogen production. Furthermore, a brief overview addresses challenges and constraints in creating a biohydrogen economy. The impacts of pretreating wastes on biohydrogen generation and the latest trends are also supplied. This study helps in the critical understanding of agro-industrial wastes for biohydrogen production, thereby encouraging future outcomes for a sustainable biohydrogen economy

Molecular biology interventions for activity improvement and production of industrial enzymes

Metagenomics and directed evolution technology have brought a revolution in search of novel enzymes from extreme environment and improvement of existing enzymes and tuning them towards certain desired properties. Using advanced tools of molecular biology i.e. next generation sequencing, site directed mutagenesis, fusion protein, surface display, etc. now researchers can engineer enzymes for improved activity, stability, and substrate specificity to meet the industrial demand. Although many enzymatic processes have been developed up to industrial scale, still there is a need to overcome limitations of maintaining activity during the catalytic process. In this article recent developments in enzymes industrial applications and advancements in metabolic engineering approaches to improve enzymes efficacy and production are reviewe

Effect of reaction conditions on the lifetime of SAPO-34 catalysts in methanol to olefins process – A review

There is a rising demand for light olefins production to meet the increase in human population, burgeoning transportation network and rapid pace of industrialization. Methanol-to-olefins (MTO) conversion process is the most preferentially-selected route to synthesize olefins even though obtaining the high selectivity remains a challenge to this day. Methanol is industrially-produced via two-steps catalytic routes, viz. gasification of coal to syngas followed by syngas conversion. Due to the abundance of methanol, conversion of methanol to light olefins (ethylene and propylene) or polyolefins (polypropylene and high-density polyethylene) is most desired. Although, natural gas or syngas routes are well established and implemented at industrial level but still direct or indirect transformation of methanol to petrochemicals gained core interest. Significantly, the use of molecular sieves as a catalyst support or directly as a catalyst has been an area of active commercial developments for the past two decades. The engineered molecular sieves possess specialized topographical structure that can efficiently reduce the rate of coke deposition, enhance mass transport and improve the catalytic performance, viz. lifetime and olefins selectivity for methanol to olefins reaction. In this regard, the SAPOs molecular sieves are highly selective for the synthesis of ethylene and propylene. Among them, SAPO-34 molecular sieves exhibit the best performance for the MTO process. The current review highlights the importance of SAPO-34 supported catalysts in terms of lower chain hydrocarbon (C2–C4) selectivity, lower paraffinic and aromatic by-products ratio, catalyst stability, and renderability. In addition, the conditions causing the SAPO-34 catalysts deactivation such as coking, crystal size, water content, pressure metal incorporation, acid site strength, and influence of process conditions on triglyceride-based feeds are also thoroughly reviewed

Microbiome involved in anaerobic hydrogen producing granules: A mini review

This mini review overviewed the latest updates on the anaerobic hydrogen fermentation using the granulation technology and the microbiome involved in the process. Additionally, the implication of various reactor design and their microbial changes were compared and provided the new insights on the role of microbiomes for rapid granules formation and long term stable operation in a continuous mode operation. The information provided in this communication would help to understand the key role of microbiomes and their importance in anaerobic hydrogen producing granular systems. Keywords: Aggregation, Biofilm, Biogranules, Bioreactor, Clostridium, Granulation, Self-flocculatio

Editorial Preface of the Special Issue on “The 5th International Conference on Alternative Fuels, Energy & Environment: Futures and Challenges (ICAFEE 2021)”

The excessive combustion of fossil fuels and non-renewable fuels is the key driver of global warming (GW) and Climate Change (CC). Sustainable production of energy and clean fuels is vital in both securing the energy demand besides protecting our environment. Environmentally friendly fuels can be developed from various renewable energy resources such as sun, bioenergy, wind, wastes etc. The transformation into circular bioeconomy and the United Nations (UN) sustainable development goals (SDGs) by 2030 includes some of the following goals; affordable and clean energy, climate action, responsible consumption and production and sustainable cities and communities. Integrating the production of biofuels and green products through the implementation of integrated biorefineries provides many solutions to the world by promoting niche markets, developing a circular bioeconomy and reducing the transport of supply feedstock.Scopu