Tripling Biogas Yield: Effect of Sorghum Stover and Winery Solid Wastes Co-Digestion with Iron Oxide Nanoparticles

Abstract

Currently, the world is exploring different methods and processes for optimizing biogas production to improve waste management and energy security. Due to the current environmental disposal and treatment methods, South Africa’s solid waste disposal problems are huge. Anaerobic digestion is one of the renewable energy technologies that can produce biogas from a variety of biomass sources. The addition of Iron oxide nanoparticles (ION) has been touted to increase biogas production significantly. Therefore, the purpose of this study was to examine the ability of ION to increase biogas production through anaerobic co-digestion of Sorghum stover (SS) and winery solid waste (WSW). Under mesophilic conditions (37°C±0.5), SS and WSW were used to test the potential of biomethane in batch reactors in the absence or presence of ION both singly and in combination (1:1). A 30-day retention time was used for all tests. Results from mono-digestion showed the pretreated WSW yielded 36.3 mLCH4.gVS -1 added, while the non-pretreated gave only 9.5 mLCH4.gVS -1 added under the same conditions. Similarly, the pretreated SS gave 29.3 mLCH4.gVS-1 as against 18.5 mLCH4.gVS -1 added obtained from the non-pretreated. The co-digestion results followed a simialr pattern with the pretreated WSW+SS (50:50) having a higher yield of 60 mLCH4.gVS -1 added compared to 44.6 mLCH4.gVS -1 added obtained from the non-pretreated. The results of the co-digestion experiment produced more biogas than single digestion. In some cases, the ION had a significant impact on biogas production, during which biogas yield was tripled. These results are of great significance to the winery industry as well as in agriculture especially commercial farmers involved in the cultivation of sorghum.

Keywords: anaerobic digestion, biomass, Nanoparticles, Sorghum Stover, Winery solid waste