Impact of additives (macronutrient and nanoparticles of micronutrients) on the anaerobic digestion of food waste: Focus on feeding strategy for improved performance

Abstract

This work was aimed to investigate the impact of addition of supplements in the form of nanoparticles (NPs) of nickel, cobalt, molybdenum, Granular activated carbon (GAC), and a composite additive comprising Ni, Co, Mo, and GAC in two phases of experiments. Phase I experiments were conducted in glass reactor bottles of 1 L in batch mode and the results are compared to the control reactor. In phase II of experiments, two semi-pilot scale reactors of 20 L were operated in parallel with fed-batch mode of feeding pattern. One of the semi pilot-scale reactors was supplemented with composite additives and the performance is compared to that of the control reactor. The process performance of experiments in both the phases has been evaluated in terms of biogas and methane yield, and organic matter removal. The microbial diversity analysis through 16S rRNA sequencing of the reactors was also carried out to understand the modifications in microbial ecology. Results revealed that the reactors supplemented with either NPs or composite additives resulted in the generation of improved biogas with a minimum increase by 15% to a maximum of 63%. The fed-batch reactors resulted in the biogas yield that increased from 0.05 to 0.18 m3/(kg VSadded) in the FBR-Control reactor and 0.32 m3/(kg VSadded) in the FBR-Composite reactor till day 40 whereas it increased to 0.37 and 0.64 m3/(kg VSadded) till day 60. About 72.9% increase in biogas generation was achieved by the addition of composite additives in required dosages.