Abstract
Currently, black-odor river has received great attention in China. In this study, the micro-nano bubble technology (MBT) was used to mitigate the water pollution rapidly and continuously by increasing the concentration of dissolved oxygen (DO) in water. During treatment, the concentration of DO increased from 0.60 mg/L to over 5.00 mg/L, and the oxidation reduction potential (ORP) also changed from a negative value to over 100.00 mV after only five days aeration. High throughput pyrosequencing technology was employed to identify the microbial community structure. At genus level, the dominant bacteria were anaerobic and nutrient-loving microbes (e.g., Arcobacter sp., Azonexus sp., and Citrobacter sp.) before, and the relative abundances of aerobic and functional microbes (e.g., Perlucidibaca sp., Pseudarcicella sp., Rhodoluna sp., and Sediminibacterium sp.) were increased after treatment. Meanwhile, the water quality was significantly improved with about 50% removal ratios of chemical oxygen demand (CODCr) and ammonia nitrogen (NH4+-N). Canonical correspondence analysis (CCA) results showed that microbial community structure shaped by COD, DO, NH4+-N, and TP, CCA1 and CCA2 explained 41.94% and 24.56% of total variances, respectively. Overall, the MBT could improve the water quality of urban black-odor river by raising the DO and activate the aerobic microbes.
Highlights
Urban watercourses are essential and important to the urban ecosystem, landscape ecology and citizen’s life
micro-nano bubble technology (MBT) was applied to mitigate the pollution of an urban black-odor river in South China
It has been reported that the secondary the MBT treatment, the concentration of dissolved oxygen (DO) was increased and the microbial community was metabolism are well known for the ability to inhibit other microorganisms [40]
Summary
Urban watercourses are essential and important to the urban ecosystem, landscape ecology and citizen’s life. Unlike the normal macro bubbles (with diameter 1–10 mm), the micro-nano bubbles would swell and burst in liquid with high mass transfer [15], and significantly increase the concentration of dissolved oxygen (DO) in water, reaching to the possible oversaturation. For these excellent properties, MBT would resolve the problem of hypoxia in polluted river efficiently. MBT was used for aeration and enhance the concentration of DO in an urban black-odor river, and the long term performance of MBT treatment was investigated. The relationship between microbes and physicochemical factors of water was investigated
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