Assessment of bio-hydrogen production from glycerol and glucose by fermentative bacteria

Abstract

Microorganisms are capable to produce hydrogen during fermentation of organic substrates and industrial waste products can be used as feedstock for hydrogen producing bacteria. One of the substrates that can be effectively used for microbial hydrogen production is glycerol, which is a by-product from the process of biodiesel production, but glucose is mainly used as a model substrate. Different bacterial isolates were tested for hydrogen gas production rates from glucose and glycerol with test-systems constructed in our laboratory. Test-systems were optimised to allow adequate substrate and bacterial strain hydrogen productivity estimation in the liquid and gaseous phases. It was concluded that several of the isolated bacterial strains are suitable for bio-hydrogen production using glycerol as a substrate. Assessment was developed to establish whether microbial conversion of glycerol is an economically and environmentally viable possibility for bio-hydrogen production. The raw material cost noticeably decreases because of large quantities of available crude glycerol after biodiesel production and the highly reduced nature of carbon in glycerol per se.Key words: bio-hydrogen, fermentation, substrates, prototype bioreactor INTRODUCTIONBiological production of hydrogen using bacteria is a promising and advantageous area, especially when hydrogen is gained from a variety of renewable resources [1,2]. Industrial and agricultural organic waste used as feedstock for hydrogen producing bacteria is a perspective way for alternative energy production and it noticeably decreases the raw material cost. During the conversion of organic wastes, in anaerobic environment, hydrogen gas is produced as a by-product. Substantial factors like availability and cost are highly important in the selection of waste materials to be used in hydrogen production with fermentative bacteria [3]. One of the substrates that can be effectively used for microbial hydrogen production is glycerol, which is a by-product from the process of biodiesel production. Because of large quantities available of crude glycerol and the highly reduced nature of carbon in glycerol per se, microbial conversion of it seems to be economically and environmentally viable possibility, 125Assessment of bio-hydrogen production from glycerol and glucose by fermentative bacteria especially because over the last several years the demand and production of biodiesel has remarkably increased [4,5]. Recently several authors have investigated hydrogen production using glycerol as a substrate by fermentative bacteria. Mangayil et al. [6] investigated optimal conditions (pH 6.5; 40 °C and 1 g/L raw glycerol) for hydrogen production using crude glycerol with microbial consortium mainly dominated by Clostridium species. Environmental conditions like medium pH and temperature are the major parameters to be controlled in the hydrogen production because they affect the qualitative and quantitative content of bacterial produced gas and the hydrogen yield and rate. Hydrogen production usi...

Hydrogen production from glycerol by Escherichia coli and other bacteria: An overview and perspectives

“…and Citrobacter freundii [79] and many others [46,[80][81][82][83][84][85][86][87][88][89]; and H 2 is among the end products of higher yield (Table 4). Probably, glycerol can be fermented by different bacteria due to specific enzymes namely glycerol dehydrogenase catalyzing the first steps of fermentation pathways to DHA (see Fig.…”

“…New technology for H 2 production from glycerol containing dairy wastes has been evaluated with syntrophic consortium in single chamber microbial electrolysis cell [95]. Clostridium pasteurianum Batch and continuous culture 7.0 Improved production rate of 256 mL H 2 L À1 h À1 and yield of 1.11 mol H 2 /mol glycerol by 10 g L À1 crude glycerol in batch culture; production rate of 103 mL H 2 L À1 h À1 and yield of 0.5 mol H 2 /mol glycerol by 10 g L À1 pure glycerol or 166 mL H 2 L À1 h À1 and yield of 0.77 mol H 2 /mol glycerol by 10 g L À1 crude glycerol in continuous culture [86] Clostridium sporogenes Batch culture 7.3 High production rate of 1.50 and 1.42 mmol H 2 L À1 h À1 by 22 g L À1 crude glycerol in liquid and in gaseous phases in flasks (200 mL) containing LuriaBertani medium with phosphate buffered saline trace elements, respectively [46,82] Enterobacter aerogenes Batch and continuous aerobic culture, bioreactor Increased H 2 production yield by optimization of the medium composition (15 g L À1 pure glycerol and different salt contents) in 500 mL bioreactor [86,87] Enterobacter aerogenes Response surface culture 5.0 High productivity from pure glycerol of 9 mmol H 2 L À1 h À1 and from crude glycerol of 6.2 mmol H 2 L À1 h À1 ; stability and reusability by the immobilized cells [83,84] Halanaerobium saccharolyticum Batch culture 7.0-7.4 Effective production of 0.6 mol H 2 /mol glycerol under 2.5 g L À1 pure glycerol [78,90,91] Klebsiella pneumoniae Batch culture, bioreactor Increased H 2 production yield by optimization of the medium composition (11 g L À1 glycerol and different salt contents) [77] Klebsiella sp. Batch culture, response surface culture 8.0 Increased H 2 production yield by optimization of the medium composition (20 g L À1 crude glycerol and different salt contents for batch culture in 36 mL medium in 60 mL serum bottle or 11 g L À1 crude glycerol and different salt contents for response surface culture) [85] a Temperature was 35-40°C.…”

Selection and modification of microorganisms and substrates for acquiring and separation of energy carriers

“…Hydrogen usage as an energy carrier is the most important stone in hydrogen economy as it can store the energy from fossil domestic resources (natural gas, coal, oil), biomass and intermittently available renewables such as wind and Sun for use in stationary and mobile applications [1]. The information in this chapter is obtained from PhD thesis of Ilze Dimanta, defended in June, 2016, at the University of Latvia [2], MSc thesis of Sintija Valucka, defended in June 2015, Faculty of Biology, the University of Latvia [3], Bachelor's thesis of Zane Kleinmane, defended in June 2016, Faculty of Biology, the University of Latvia [4], Bachelor's thesis of Matīss Paiders defended in June 2017, Faculty of Biology, the University of Latvia [5], which to some extent is reflected in publications [6][7][8][9][10][11].…”