Nanobubble aeration enhanced wastewater treatment and bioenergy generation in constructed wetlands coupled with microbial fuel cells

Artificial aeration is a widely used approach in wastewater treatment to enhance the removal of pollutants, however, traditional aeration techniques have been challenging due to the low oxygen transfer rate (OTR). Nanobubble aeration has emerged as a promising technology that utilise nano-scale bubbles to achieve higher OTRs owing to their large sur -face area and unique properties such as longevity and reactive oxygen species generation. This study, for the first time, investigated the feasibility of coupling nanobubble technology with constructed wetlands (CWs) for treating livestock wastewater. The results demonstrated that nanobubble-aerated CWs achieved significantly higher removal efficiencies of total organic carbon (TOC) and ammonia (NH4+-N), at 49 % and 65 %, respectively, compared to traditional aeration treatment (36 % and 48 %) and the control group (27 % and 22 %). The enhanced performance of the nanobubble-aerated CWs can be attributed to the nearly three times higher amount of nanobubbles (o < 1 & mu;m) generated from the nanobubble pump (3.68 x 108 particles/mL) compared to the normal aeration pump. Moreover, the microbial fuel cells (MFCs) embedded in the nanobubble-aerated CWs harvested 5.5 times higher electricity energy (29 mW/m2) compared to the other groups. The results suggested that nanobubble technology has the potential to trigger the inno-vation of CWs by enhancing their capacity for water treatment and energy recovery. Further research needs are pro-posed to optimise the generation of nanobubbles, allowing them to be effectively coupled with different technologies for engineering implementation.

Automated summary

This study investigated the feasibility of coupling nanobubble technology with constructed wetlands for treating livestock wastewater. The results showed that nanobubble-aerated CWs achieved significantly higher removal efficiencies of TOC and NH4+-N compared to traditional aeration treatment and the control group. The MFCs embedded in the nanobubble-aerated CWs also harvested a much higher electricity energy. These findings suggest that nanobubble technology has the potential to enhance the capacity of constructed wetlands for water treatment and energy recovery.