Evaluation of the Dosage of Nickel and Cobalt Nanoparticles on Energy Generation and Enhanced Anaerobic Digestion of Abattoir Effluent

Abstract

Abattoirs have many activities that produce biodegradable organic waste, which can be utilized in anaerobic digestion as it is energy rich. Anaerobic digestion of abattoir waste (blood, rumen contents, cow dung) has positive environmental effects since it simultaneously achieves waste management, biogas, and fertilizer production. Abattoir effluent has large amounts of organic matter, suspended solids, and it is associated with repugnant odour. It is paramount to find ways of its sustainable management. During anaerobic digestion of abattoir waste, when proteins and lipids are degraded there is formation of potentially inhibitory compounds. These inhibitory compounds can make the process unstable and prone to failure. This research was carried out to investigate the effects of different concentrations of nickel and cobalt nanoparticles on biogas production, as a means to make the process more stable and enhance biogas production. In this study, the effects of individual and combined dosage of nickel and cobalt nanoparticles on AD of abattoir effluent was investigated when operated under mesophilic condition (370C) in a batch mode.A concentration of 20 mgL-1 of nickel, cobalt nanoparticles and their combination was observed to be the most effective as compared with 0.5, 2 and 11 mgL-1. Addition of 20 mgL-1 of cobalt, nickel and both nickel and cobalt nanoparticles produced 386, 448 and 438 mL-1 of methane, and 595, 695, and 682 mL-1 of biogas, respectively. The individual dosage of cobalt nanoparticles increased the methane and biogas by 194.65 and 180.65 %, the individual dosage of nickel nanoparticles increased the methane and biogas by 241 and 226.8 %, the digester dosed with both nickel and cobalt nanoparticles increased methane and biogas by 234 and 220 % as compared with the control (131 mL of methane and 213 mL of biogas). Individual dosage of nickel nanoparticles yielded the highest biogas and methane production as compared with individual dosage of cobalt nanoparticles and a combination of both nickel and cobalt nanoparticles. The addition of nanoparticles was observed to increase not only the biogas and methane production but also the degradation rate of volatile solids and the energy potential of the abattoir waste.