Different pollutant removal efficiencies of artificial aquatic plants in black-odor rivers

Abstract

Black-odor rivers have become a prominent environmental problem, especially for developing countries. A laboratory experiment was conducted to determine the optimum operating parameters of artificial aquatic plants (AAP) to provide a theoretical and scientific basis for their application in black-odor rivers. The purification mechanism of operating parameters for AAP was also explored at the micro-organic and genetic levels by high-throughput sequencing. Chemical oxygen demand (COD) and ammonia nitrogen (NH₄⁺-N) were measured in systems with different AAP lengths and pH. After 24 days, the best removal efficiencies of APP for COD and NH₄⁺-N were 90.07 and 82.40% for 100 cm and 90.70 and 91.90% for pH values of 8.0–9.0, respectively. High-throughput sequencing analysis revealed that the relative abundance of Flavobacterium in the AAP was 7.80% at 50 cm, while the proportion increased to 29.30% at 100 cm. The abundance of microorganisms improved continuously with increased length, and the ratio of Acinetobacter increased obviously at pH 8.0–9.0 relative to pH 6.0–7.0. Furthermore, the AAP were used in Qihe Artificial Wetland in Shandong Province, China. The results revealed that the average removal efficiencies of AAP for COD and NH₄⁺-N were 27.75 and 14.34%, respectively, in the artificial wetland. Therefore, AAP was beneficial to the growth of bacteria and could be used in the treatment of black-odor rivers.