Bipro Ranjan Dhar

Bio: Bipro Ranjan Dhar is an academic researcher from University of Alberta. The author has contributed to research in topics: Anaerobic digestion & Biogas. The author has an hindex of 25, co-authored 78 publications receiving 1944 citations. Previous affiliations of Bipro Ranjan Dhar include University of Waterloo & University of Western Ontario.

A critical review on inhibition of dark biohydrogen fermentation

Abstract: Dark fermentation of organic wastes for hydrogen gas (H2) production is an attractive strategy of being renewable and carbon neutral However, various toxic or inhibitory compounds can significantly limit sustainable operation and widespread adoption of this biotechnology The metabolism of fermentative microbes in dark fermentation system can be inhibited by excess substrate, micronutrients, macronutrients, metal ions, high temperature, acidic pH, un-dissociated organic acids, competitive microbes, and substrate-derived toxic substances This review paper introduces these potential inhibitory compounds, inhibition mechanisms, and provides engineering perspectives on the control of inhibition

Overview of pretreatment strategies for enhancing sewage sludge disintegration and subsequent anaerobic digestion: Current advances, full-scale application and future perspectives

Abstract: Sewage sludge management is now becoming a serious issue all over the world. Anaerobic digestion is a simple and well-studied process capable of biologically converting the chemical energy of sewage sludge into methane-rich biogas, as a carbon-neutral alternative to fossil fuels whilst destroying pathogens and removing odors. Hydrolysis is the rate-limiting step because of the sewage sludge complex floc structure (such as extracellular polymeric substances) and hard cell wall. To accelerate the rate-limiting hydrolysis and improve the efficiency of anaerobic digestion, various pretreatment technologies have been developed. This paper presents an up-to-date review of recent research achievements in the pretreatment technologies used for improving biogas production including mechanical (ultrasonic, microwave, electrokinetic and high-pressure homogenization), thermal, chemical (acidic, alkali, ozonation, Fenton and Fe(II)-activated persulfate oxidation), and biological options (temperature-phased anaerobic digestion and microbial electrolysis cell). The effectiveness and relative worth of each of the studied technologies are summarized and compared in terms of the resulting sludge properties, the digester performance, the environmental benefits and the current state of real-world application. The challenge and technical issues encountered during sludge cotreatment are discussed, and the future research needs in promoting full-scale implementations of those approaches are proposed.

Syntrophy Goes Electric: Direct Interspecies Electron Transfer

Abstract: Direct interspecies electron transfer (DIET) has biogeochemical significance, and practical applications that rely on DIET or DIET-based aspects of microbial physiology are growing. Mechanisms for DIET have primarily been studied in defined cocultures in which Geobacter species are one of the DIET partners. Electrically conductive pili (e-pili) can be an important electrical conduit for DIET. However, there may be instances in which electrical contacts are made between electron transport proteins associated with the outer membranes of the partners. Alternatively, DIET partners can plug into conductive carbon materials, such as granular activated carbon, carbon cloth, and biochar, for long-range electron exchange without the need for e-pili. Magnetite promotes DIET, possibly by acting as a substitute for outer-surface c-type cytochromes. DIET is the primary mode of interspecies electron exchange in some anaerobic digesters converting wastes to methane. Promoting DIET with conductive materials shows promise for stabilizing and accelerating methane production in digesters, permitting higher organic loading rates. Various lines of evidence suggest that DIET is important in terrestrial wetlands, which are an important source of atmospheric methane. DIET may also have a role in anaerobic methane oxidation coupled to sulfate reduction, an important control on methane releases. The finding that DIET can serve as the source of electrons for anaerobic photosynthesis further broadens its potential environmental significance. Microorganisms capable of DIET are good catalysts for several bioelectrochemical technologies and e-pili are a promising renewable source of electronic materials. The study of DIET is in its early stages, and additional investigation is required to better understand the diversity of microorganisms that are capable of DIET, the importance of DIET to carbon and electron flow in anaerobic environments, and the biochemistry and physiology of DIET.