Effect of hydraulic retention time on suppression of methanogens during a continuous biohydrogen production process using molasses wastewater

The Start-Up of Continuous Biohydrogen Production from Cheese Whey: Comparison of Inoculum Pretreatment Methods and Reactors with Moving and Fixed Polyurethane Carriers

This article presents the results of the start-up of continuous production of biohydrogen from cheese whey (CW) in an anaerobic filter (AF) and anaerobic fluidized bed (AFB) with a polyurethane carrier. Heat and acid pretreatments were used for the inactivation of hydrogen-scavengers in the inoculum (mesophilic and thermophilic anaerobic sludge). Acid pretreatment was effective for thermophilic anaerobic sludge to suppress methanogenic activity, and heat treatment was effective for mesophilic anaerobic sludge. Maximum specific yields of hydrogen, namely 178 mL/g chemical oxygen demand (COD) and 149 mL/g COD for AFB and AF, respectively, were obtained at the hydraulic retention time (HRT) of 4.5 days and organic load rate (OLR) of 6.61 kg COD/(m3 day). At the same time, the maximum hydrogen production rates of 1.28 and 1.9 NL/(L day) for AF and AFB, respectively, were obtained at the HRT of 2.02 days and OLR of 14.88 kg COD/(m3 day). At the phylum level, the dominant taxa were Firmicutes (65% in AF and 60% in AFB), and at the genus level, Lactobacillus (40% in AF and 43% in AFB) and Bifidobacterium (24% in AF and 30% in AFB).

Continuous production of biohydrogen from brewery effluent using co-culture of mutated Rhodobacter M 19 and Enterobacter aerogenes

This study investigated the biohydrogen production from brewery effluents using free and immobilized co-culture of mutated Rhodobacter M 19 and Enterobacter aerogenes obtained from random mutagenesis with ultra violet (UV) and ethidium bromide (EtBr) treatment. The best mutant for biohydrogen production was screened based on the sugar utilization efficiency. Maximum hydrogen production of 87% was achieved with immobilized EtBr mutated co-culture. The mutant immobilized strains showed around 30% enhanced hydrogen production than wild strains at pH 6.9. Gompertz and Richard's model were used to fit the augmenting biohydrogen production and Logistics equation determines the fitness of biomass growth data. The maximal biomass concentration of co-cultures strains was 3.145 g/L with carrying capacity coefficient 0.137 h^-1. Gompertz model showed the best fit with minimal error in predicting the biohydrogen potential.