Valorization of Cheese Whey by Electrohydrolysis for Hydrogen Gas Production and COD Removal
ABSTRACT Diluted cheese whey (CW) solutions with different initial COD contents (4,800–25,000 mg l−1) were electro-hydrolyzed by application of constant DC voltage (3 V) for hydrogen gas production and COD removal. The highest cumulative hydrogen production (3,923 ml), hydrogen yield (1,719 ml H2 g−1 COD), hydrogen formation rate (699 ml d−1), and percent hydrogen (99.2 %) in the gas phase were obtained with the highest initial COD of 25,025 g COD l−1 with an energy conversion efficiency of 90.3 %. Hydrogen gas production in water and cheese whey controls were negligible indicating no significant H2 gas production by electrolysis of water and fermentation of cheese whey. Percent COD removals were between 18 and 20 % for initial CODs above 11,500 mg l−1. Major COD removal mechanism was anaerobic fermentation of carbohydrates producing volatile fatty acids (VFA) and CO2. Hydrogen gas was produced by reaction of (H+) ions released from VFAs and electrons provided by DC current. Electro-hydrolysis of CW solution was proven to be an effective method of H2 gas production with simultaneous COD removal.
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ABSTRACT: Hydrogen is a valuable gas as a clean energy source and as feedstock for some industries. Therefore, demand on hydrogen production has increased considerably in recent years. Electrolysis of water, steam reforming of hydrocarbons and auto-thermal processes are well-known methods for hydrogen gas production, but not cost-effective due to high energy requirements. Biological production of hydrogen gas has significant advantages over chemical methods. The major biological processes utilized for hydrogen gas production are bio-photolysis of water by algae, dark and photo-fermentation of organic materials, usually carbohydrates by bacteria. Sequential dark and photo-fermentation process is a rather new approach for bio-hydrogen production. One of the major problems in dark and photo-fermentative hydrogen production is the raw material cost. Carbohydrate rich, nitrogen deficient solid wastes such as cellulose and starch containing agricultural and food industry wastes and some food industry wastewaters such as cheese whey, olive mill and bakers yeast industry wastewaters can be used for hydrogen production by using suitable bio-process technologies. Utilization of aforementioned wastes for hydrogen production provides inexpensive energy generation with simultaneous waste treatment. This review article summarizes bio-hydrogen production from some waste materials. Types of potential waste materials, bio-processing strategies, microbial cultures to be used, bio-processing conditions and the recent developments are discussed with their relative advantages.Enzyme and Microbial Technology. 01/2006;
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ABSTRACT: An uninterruptible power supply (UPS) based on hydrogen technologies has been designed, manufactured and tested. The system consists of a proton exchange membrane fuel cell running on hydrogen and oxygen, a gas storage section and a water electrolyser for hydrogen and oxygen production. The UPS is of fail-safe design, completely silent and very reliable, thanks to the complete absence of moving parts. The prototype has an output of 5 kW for a maximum period of 5 h. A 3 kW advanced alkaline electrolyser produces hydrogen and oxygen at 1.5 MPa, which are stored in metal hydride tanks of capacity and a cylinder stack, respectively. Upon grid power interruption, the fuel cell takes up the load, with the help of a battery during the first minutes of operation. The results of the operation of this prototype are presented and discussed.International Journal of Hydrogen Energy. 01/2007;
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ABSTRACT: Biologically produced hydrogen using biomass and mixed bacterial cultures is one approach to generate renewable H2. Response surface methodology (RSM) was used to study the effect of initial pH (3.88–8.12) and initial substrate concentration (0.86–29.14 g/L) on both hydrogen molar yield (HMY) and volumetric H2 production rate (VHPR). Lactose, cheese whey powder (CWP) and glucose were used as substrates and heat-treated anaerobic granular sludge as inoculum. For lactose, 3.6 mol H2/mol lactose and 5.6 mmol H2/L/h were found at pH 7.5 and 5 g lactose/L. CWP yielded 3.1 mol H2/mol lactose at pH 6 and 15 g CWP/L while 8.1 mmol H2/L/h were attained at pH 7.5 and 25 g CWP/L. Glucose yielded 1.46 mol H2/mol substrate (pH 7.5, 5 g glucose/L), with a VHPR of 8.9 mmol H2/L/h, at pH 8.12 and 15 g glucose/L. Acetic and butyric acids were the main organic metabolites detected. HMY and VHPR obtained in this study were found at initial pH above the reported optimum pH value for hydrogen production. These findings could be of significance when alkaline pretreatments are performed on organic feedstock by eliminating the need to lower the pH to acidic levels before fermentation start-up.International Journal of Hydrogen Energy. 01/2008;