Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction

Anaerobic digestion of energy crops, residues, and wastes is of increasing interest in order to reduce the greenhouse gas emissions and to facilitate a sustainable development of energy supply. Production of biogas provides a versatile carrier of renewable energy, as methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle fuel. For biogas production, various process types are applied which can be classified in wet and dry fermentation systems. Most often applied are wet digester systems using vertical stirred tank digester with different stirrer types dependent on the origin of the feedstock. Biogas is mainly utilized in engine-based combined heat and power plants, whereas microgas turbines and fuel cells are expensive alternatives which need further development work for reducing the costs and increasing their reliability. Gas upgrading and utilization as renewable vehicle fuel or injection into the natural gas grid is of increasing interest because the gas can be used in a more efficient way. The digestate from anaerobic fermentation is a valuable fertilizer due to the increased availability of nitrogen and the better short-term fertilization effect. Anaerobic treatment minimizes the survival of pathogens which is important for using the digested residue as fertilizer. This paper reviews the current state and perspectives of biogas production, including the biochemical parameters and feedstocks which influence the efficiency and reliability of the microbial conversion and gas yield.

Biogas production: current state and perspectives

Recycling and recovery routes of plastic solid waste (PSW): A review

Modeling chemical and physical processes of wood and biomass pyrolysis

This book offers comprehensive coverage of the design, analysis, and operational aspects of biomass gasification, the key technology enabling the production of biofuels from all viable sources--some examples being sugar cane and switchgrass. This versatile resource not only explains the basic principles of energy conversion systems, but also provides valuable insight into the design of biomass gasifiers. The author provides many worked out design problems, step-by-step design procedures and real data on commercially operating systems. After fossil fuels, biomass is the most widely used fuel in the world. Biomass resources show a considerable potential in the long term if residues are properly handled and dedicated energy crops are grown. 5 years of the author's research in the area Biomass fuel production First book devoted to Biomass Gasification Includes step-by-design procedures, cases studies and worked out numerical examples

Biomass Gasification and Pyrolysis: Practical Design and Theory

Hydrogen from food processing wastes via photofermentation using Purple Non-sulfur Bacteria (PNSB) – A review

Desulfurization and hydrogenation of aromatics in diesel oil were investigated in an isothermally operated trickle-bed reactor 500 mm long and with a 19-mm ID, using commercial bifunctional NiMo/Al2O3 catalysts. The operating temperature, pressure, liquid hourly space velocity, gas/oil ratio, and the initial concentration of H2S were 300–380°C, 2–8 MPa, 1–4 h−1, 100–500 m3(NTP)/m3 and 0–8 vol %, respectively. The increase in pressure and decrease in liquid hourly space velocity lead to deeper desulfurization and hydrogenation of both aromatics. Although a higher gas-to-oil ratio and lower initial concentration of H2S enhance the desulfurization reaction, these parameters play almost no role for hydrogenation. Desulfurization increases sharply with increased temperature, but with the same change in temperature the conversion of aromatics increases only up to 360°C, above which it falls sharply. This behavior is explained by the approaching of chemical equilibria by the reversible hydrogenation reactions of the aromatics at higher temperatures. A mechanistic mathematical model was developed for a two-phase flow reactor, considering both mass transfer and chemical reaction in the reactor. The kinetic equations for desulfurization and for the hydrogenation of mono-, di- and polyaromatics were established. Simulated results are compared satisfactorily with the experimental observations.

Trickle‐bed reactor model for desulfurization and dearomatization of diesel

The issue of E-waste disposal is concerning all the stakeholders, from policymakers to the end users which have accelerated the research and development on environmentally sound disposal of E-waste. The recovery of metals (gold, tantalum, copper, iron etc.) from E-waste has become an important focus. The mechanical recycling, thermo-chemical processes like pyrolysis, pyro-, hydro- and biometallurgical processes can play important roles in the Metal Recovery from E-waste (MREW) technology. For the industrial application of the MREW technology, it is important to analyze the sustainability. In this paper, two case studies have been presented on E-waste recycling industries in India and China. Based on the literature data, an attempt has been made to assess qualitatively the overall sustainability of MREW technology considering the three pillars, i.e., environmental, economic and social. Two conceptual frameworks with (Option-2) and without (Option-1) pyrolysis for integrated MREW units have been developed and the generalized energy and environmental impact analysis has been made using the principles of LCA. The impacts of two options have been compared. Option 2 has been found to be more efficient and sustainable. It has been realized that climate change, fossil fuel depletion, water depletion, eutrophication, acidification, fresh and marine water ecotoxicity are possible impact categories. The recommendations based on the generalized assessment are in good agreement with the findings of previous researchers on individual steps of MREW unit. The findings of this paper are expected to be beneficial to researchers and stakeholders for research directions and decision making on MREW.

Sustainability of metal recovery from E-waste

Sustainability of cereal straws for the fermentative production of second generation biofuels: A review of the efficiency and economics of biochemical pretreatment processes

The utilization of mixed consortia or mixed culture has become a current research trend of applied microbiology, bioprocess engineering and biotechnology. The constituent microorganisms of such mixed cultures can jointly perform complex processes efficiently, yielding the desired product at an augmented rate, in comparison to monocultures. It is understandable that the interactions between the microbial partners in these mixed cultures are expected to have a significant impact on the combined performance of the microorganisms and the bioprocess as a whole. Prevalence of positive interactions (commensalism or mutualism) among microbial members of a mixed culture or consortia can significantly enhance the product outcome of the bioprocess, ensuring their industrial application and long-term stability. On the contrary, negative interaction (parasitism, predation or ammensalism) leads to elimination of microbial members from the consortia causing the destruction of community structure as well as disruption of cumulative performance. Therefore, a priori knowledge on the type of interaction between the microorganisms is also essential for the optimization of the performance of the designed consortia. This could only be achieved through the study of inter-microbial interaction prevailing in a mixed culture. In the present article, different bioprocess applications of mixed cultures, currently in practice along with types of positive microbial interactions involved, have been reviewed. Complexity of mixed cultures from the perspective of multiple types of intra-culture relationships has been explained in detail. Overall, the necessity for more in-depth research studies on "microbial interaction" in mixed culture bioprocesses has been stressed in the article.

Ranjana Chowdhury

Papers

Hydrogen from food processing wastes via photofermentation using Purple Non-sulfur Bacteria (PNSB) – A review

Trickle‐bed reactor model for desulfurization and dearomatization of diesel

Sustainability of metal recovery from E-waste

Sustainability of cereal straws for the fermentative production of second generation biofuels: A review of the efficiency and economics of biochemical pretreatment processes

Mixed consortia in bioprocesses: role of microbial interactions