Methane yield enhancement by the addition of new novel of iron and copper-iron bimetallic nanoparticles

The potential effect on methane content from anaerobic digestion of municipal sludge was systematically examined by implementing wide-range concentrations of copper iron-based bimetallic (nZVI/Cu°) nanoparticles and was compared by the results with zero-valent iron nanoparticles (nZVI) influences. The effective concentrations that yielded the highest methane content were determined by tracing the iron dissolution ions. Through the experimental work, bio-digester systems were assembled and used. The most effective concentration of nZVI/Cu° was 1500 mg/L while it increased the biogas production three times the control. The bimetallic concentration of 3000 mg/L showed inhabitation of methanogens due to its disruption of cell integrity. The relatively high nZVI additives also proved biogas stimulation and exposed the sludge to only 50 and 100 mg/L nZVI concentration conversely confirmed inhibitory effects and the biogas generation decreased from 229 mL that the control produced to 192 and 209 mL respectively. The methane content results showed that the methane was constantly accelerated due to the plenty of iron ions which demonstrated that both the nanoparticles could act as electron donors and the dissolved ions could be direct electron transfer, in which methanogens work as iron oxidizer, taking electron from the nanoparticles to reduce the carbon dioxide to methane.