Evaluating co-substrates to supplement biogas production from tannery solid waste treatment - cattle hair, microalgae biomass, and silicone

The sustainability of bioenergy production depends largely on the biomass resource and technology used. Several types of organic wastes can be converted into biogas via anaerobic digestion. The purpose of this research was to evaluate the influence of the addition of cattle hair waste, microalgae biomass, or commercial silicone as a third co-substrate in the co-digestion of the two solid wastes of major concern to the leather industry: leather shavings and sludge from tannery wastewater treatment plants. The addition of cattle hair did not influence the total cumulative biogas production of 19.4 mL g(-1) of volatile suspended solid added, adsorbed practically all the chromium present, and increased by 16% the organic load of the medium, due to the hydrolysis of the hair damaging the treatment of the residues. The addition of microalgae doubled the cumulative biogas production, tripled the maximum daily biogas production, and adsorbed three times more chromium, showing its beneficial effect on the treatment of tannery solid waste for biogas production. The addition of commercial silicone did not influence the total cumulative biogas production but led to a high adsorption capacity for both chromium and organic matter. (c) 2018 Society of Chemical Industry and John Wiley & Sons, Ltd