Gas nanobubble technology in wastewater treatment and anaerobic digestion

Abstract

Nanobubbles (NBs) are gas-filled cavities with diameters around 100 nm, exhibiting unique properties such as high surface area-to-volume ratios, negative zeta potential (ζ-potential), and prolonged stability in liquids. These attributes make NBs highly effective in enhancing gas transfer, microbial activity, and pollutant removal. This study aims to assess the impact of NBs on wastewater treatment and anaerobic digestion processes. In a wastewater treatment plant, NBs aeration increased dissolved oxygen levels by 35% and improved organic matter breakdown. It was also found that nano-aeration could potentially reduce energy consumption compared to conventional aeration systems. The study also examines the effect of introducing oxygen NBs into the fermentation liquid on the concentration of hydrogen sulfide (H₂S) in biogas production. The results demonstrated that in a methane digestion plant, oxygen NBs reduced H₂S concentrations by over 90%, while causing a slight increase in methane production. Despite these benefits, challenges such as limited sludge flotation and the need for enhanced oxygen delivery systems were identified. This research underscores the potential of NBs to enhance biogas production and wastewater treatment efficiency while highlighting operational challenges that warrant further exploration.