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 (NH-N) were measured in systems with different AAP lengths and pH. After 24 days, the best removal efficiencies of APP for COD and NH-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 NH-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.

Driving Factors for Black-Odor-Related Microorganisms and Potential Self-Remediation Strategies

“…In contrast, metal sulfideoxidizing bacteria and aerobic chemo-heterotrophic bacteria (Tables S2 and S3), such as Acinetobacter (0.01-34.27%), Mycobacterium (0.004-7.91%), and Acidovorax (0.005-5.22%), are significantly related to eliminating the black-odor phenomenon of this river. Among these genera, Acinetobacter and Acidovorax have been reported to degrade refractory organics in the restoration process [8,52,53]. The genus Mycobacterium, which can utilize morpholine, a chemical industry pollutant, as its sole source of carbon, nitrogen, and energy, has been recognized as an ecological indicator of its pollution [25].…”

“…An interaction between physicochemical and biological factors causes the formation and remediation of black-odor phenomena in waterbodies [1,7]. According to the issuance of the Chinese Ministry of Housing and Urban-Rural Development, the definition of blackodorous water contains the value of oxidation reduction potential (ORP) < 50 mV [1,8]. Anaerobic microbial reactions are dominant in overlying water where the ORP is less than 50 mV.…”