Exceptional contribution of iron nanoparticle and aloe vera biomass additives to biogas production from anaerobic digestion of waste sludge

This study aims to investigate, for the first time, the improvement of the anaerobic digestion (AD) performance of waste sludge (WS) by utilizing Aloe vera waste (AVW) and Fe0 nanoparticles. Accordingly, a series of biogas generation experiments were conducted at different mixing ratios (AVW:WS = 0:1, 1:1, 2:1, and 3:1), to find out the optimum ratio for maximizing biogas generation. To gain insights into the improved biogas generation by the addition of AVW, pH value was monitored during the fermentation process and adjusted to different initial values (3, 7, and 12). Moreover, the effect of different concentrations (10 and 50 mg/L) and dosing times (0, 6, 12, 24, 48, and 96 h) of Fe0 nanoparticles on the digestion of the optimized ratio (AVW:WS = 2:1) were investigated. Results showed that the optimum ratio (AVW:WS = 2:1) resulted in improving biogas and methane generation by 62.5 % and 96.0 %, respectively, which is an excellent improvement rate of biogas and methane generation compared with the previously reported values in the literature. The addition of Fe0 at the optimum concentration (10 mg/L) and dosing time (12 h) to the optimized ratio (AVW:WS = 2:1) resulted in enhancing methane generation by 146.9 %.