Abstract
The pulp and paper industry discharges large quantities of lignocellulosic wastewater which if not properly managed, will cause serious environmental pollution. The current study hereby examined the influence of lignocellulosic hydrolysate on biohydrogen production in the presence of furfural. Synthetic lignocellulosic hydrolysate, consisting primarily of 76% xylose, 10% glucose, 9% arabinose, and a mixture of other sugars such as galactose and mannose, was employed as the substrate. Various substrate concentrations ranging from 2 to 32 g/L were tested, along with furfural concentrations of 0, 1, and 2 g/L. The investigation aimed to assess the effects of initial substrate concentration, initial furfural concentration, furfural-to-biomass ratio (F/B), and furfural-to-substrate ratio (F/S) on biohydrogen production yields. The maximum specific substrate utilization rates at different substrate concentrations were effectively characterized using Haldane's substrate inhibition model. Among the tested concentrations, 16 g/L emerged as the optimal substrate concentration. The initial furfural concentration was identified as the most significant parameter impacting biohydrogen production, with complete inhibition observed at a furfural concentration of 2 g/L. Higher F/S ratios at substrate concentrations ranging from 2 to 16 g/L resulted in reduced maximum specific hydrogen production rates (MSHPR) and hydrogen yields. Substrate inhibition was observed at 24 g/L and 32 g/L. Lactate was the predominant volatile fatty acid (VFA) in all batches containing 2 g/L furfural, as well as in batches with 1 g/L furfural at substrate concentrations of 24 and 32 g/L. Furfural at a concentration of 1 g/L was not inhibitory in any of the batches.