Utilization of nanoparticles for biogas production focusing on process stability and effluent quality

Abstract

One of the most important techniques for converting complex organic waste into renewable energy in the form of biogas and effluent is anaerobic digestion. Several issues have been raised related to the effectiveness of the anaerobic digestion process in recent years. Hence nanoparticles (NPs) have been used widely in anaerobic digestion process for converting organic wastes into useful biogas and effluent in an effective way. This review addresses the knowledge gaps and summarizes recent researchers’ findings concentrating on the stability and effluent quality of the cattle manure anaerobic digestion process using single and combinations nanoparticle. In summary, the utilization of NPs have beneficial effects on CH4 production, process optimization, and effluent quality. Their function, as key nutrient providers, aid in the synthesis of key enzymes and co-enzymes, and thus stimulate anaerobic microorganism activities when present at an optimum concentration (e.g., Fe NPs 100 mg/L; Ni NPs 2 mg/L; Co NPs 1 mg/L). Furthermore, utilizing Fe NPs at concentrations higher than 100 mg/L is more effective at reducing H2S production than increasing CH4, whereas Ni NPs and Co NPs at concentrations greater than 2 mg/L and 1 mg/L, respectively, reduce CH4 production. Effluent with Fe and Ni NPs showed stronger fertilizer values more than Co NPs. Fe/Ni/Co NP combinations are more efficient in enhancing CH4 production than single NPs. Therefore, it is possible to utilize NPs combinations as additives to improve the effectiveness of anaerobic digestion. Article highlights Single NPs (e.g., Fe, Ni, and Co NPs) in low concentrations are more effective in increasing CH4 production than reducing H2S production. Optimal Fe, Ni, and Co NP concentrations enhance anaerobic digestion process performance. Addition of Fe, Ni, and Co NPs above tolerated concentration causes irreversible inhibition in anaerobic digestion. Effluent with Fe, Ni, and Co NPs showed stronger fertilizer values. Nanoparticle combinations are more effective for increasing the CH4 production than signal NPs.

Effects of Iron, Lime, and Porous Ceramic Powder Additives on Methane Production from Brewer’s Spent Grain in the Anaerobic Digestion Process

“…Overload, as well as depletion of specific trace metals, will result in the inhibition of AD microorganisms. The effect does not only depend on total metal concentration but also its chemical forms, pH, and redox potential [34,35]. Each group of AD microorganisms has its optimal trace element concentration, and it is believed that acidogens are more resistant to heavy metals overloading than methanogens [35].…”

“…For this reason, different results regarding iron supplementation among studies can be found. In the work of Andriamanohiarisoamanana et al [36], iron powder (85% Fe3O4) was added to dairy manure at a Although the iron powder did not do its job and no increase in electrical conductivity was observed, many studies show that iron supplementation can enhance methane production, substrate conversion, process stability, and increase the reduction of H 2 S [34]. Iron is one of many essential trace metals needed during the AD process and, similar to other heavy metals, constitutes part of enzymes that drive various AD reactions.…”

Influence of Fe2O3 Nanoparticles on the Anaerobic Digestion of Macroalgae Sargassum spp.

“…Fe-NPs include zero-valent iron (ZVI) with paramagnetic properties and iron oxide NPs (IONPs) with ferromagnetic properties. Recently, their influence on the fundamental mechanisms of the anaerobic digestion process and on the fertility of effluents have been extensively discussed [11,12]. Among IONPs, magnetite (Fe 3 O 4 ) NPs have been widely applied in recent years for their magnetic properties, non-toxicity, high coercivity, biocompatibility, and ability to improve electron transport efficiency, increasing the activity of enzymes during methanogenesis, providing nutrients to microorganisms, reducing the inhibiting effect of sulphate-reducing bacteria.…”