Study on the performance of micro/nano-aeration and submerged plants against exogenous pollution

Abstract

Exogenous pollution contributes to river eutrophication and sediment deterioration, posing a global challenge. Traditional solutions, such as artificial aeration and submerged plants, often face efficiency and adaptability limitations. Micro/nano aeration (MA) technology, generating bubbles smaller than 1 μm with higher oxygen transfer efficiency than conventional aeration, has emerged as a promising alternative. In addition, this technology has been demonstrated to promote plant growth and increase microbial abundance. This study integrated MA with submerged plants to enhance pollutant interception and sediment restoration. High-frequency MA (1 h aeration every 2 days) facilitated rapid water quality stabilization, achieving stability within 20 days in L-MA1 and 34 days in H-MA1. During the stable period, the average removal efficiencies of COD, NH₄⁺-N, and TP were 51.83 %, 86.02 %, and 40.36 % in L-MA1, and 56.37 %, 92.74 %, and 57.54 % in H-MA1, respectively. These removal efficiencies were consistently higher than those observed in the control and conventional aeration groups. MA also reduced sediment OM, TN, and TP by over 50 %. The findings of the plant experiments demonstrated that Vallisneria natans and Elodea nuttallii exhibited robust growth in the MA input, with biomass levels being twice as high as those observed in CK group, standard nitrogen metabolism, and a certain degree of antioxidant capacity. Furthermore, MA altered microbial communities, increasing Chloroflexi while reducing Proteobacteria and Bacteroidota. Pseudomonas, a key heterotrophic nitrification-aerobic denitrification bacterium, facilitated simultaneous NH₄⁺-N and NO₃⁻-N removal. These findings suggest that MA, combined with submerged plants, provides an efficient approach for exogenous pollution control and sediment restoration.