Comparison of three flocculants for heavy cyanobacterial bloom mitigation and subsequent environmental impact

Cyanobacteria can accumulate as a heavy biomass on the leeward side of large eutrophic lakes, posing a potential threat to public health. The mitigating capacity of three flocculants and their potential impacts on the major environmental features of water and sediments was evaluated. Results indicat...

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Bibliographic Details
Published in:Journal of oceanology and limnology 2022-09, Vol.40 (5), p.1764-1773
Main Authors: Liu, Kaixuan, Jiang, Lei, Yang, Jinsheng, Ma, Shuzhan, Chen, Kaining, Zhang, Yufeng, Shi, Xiaoli
Format: Article
Language:English
Subjects:
Aquatic plants
Biomass
Blooms
Cations
Chitosan
Chlorophyll
Chlorophyll a
Cyanobacteria
Dissolved oxygen
Earth and Environmental Science
Earth Sciences
Environmental impact
Eutrophic lakes
Eutrophication
Ferric chloride
Flocculants
Lake restoration
Lysis
Macrophytes
Mitigation
Nutrients
Oceanography
Organic carbon
Phosphorus
Pollution
Public health
Sediment
Sediments
Starch
Total organic carbon
Water circulation
Water column
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Summary:Cyanobacteria can accumulate as a heavy biomass on the leeward side of large eutrophic lakes, posing a potential threat to public health. The mitigating capacity of three flocculants and their potential impacts on the major environmental features of water and sediments was evaluated. Results indicate that polyaluminum chloride (PAC) and ferric chloride (FeCl 3 ) are efficient flocculants that can rapidly mitigate cyanobacterial blooms with chlorophyll- a concentrations higher than 1 500 µg/L within 15 min. In comparison, cationic starch with chitosan could only treat cyanobacterial blooms in chlorophyll- a concentrations of less than 200 µg/L. The addition of FeCl 3 caused a decline in the pH value, while dissolved oxygen in the water column dropped to 2 mg/L during cationic starch with chitosan treatment for a high cyanobacterial biomass group. Thus, a combination of flocculants and oxygenators should be considered when treating high-concentration cyanobacterial blooms for emergency purposes. Additionally, the cell lysis of cyanobacteria caused by cationic starch with chitosan can result in an increase in total dissolved phosphorus and total dissolved nitrogen. Furthermore, the high accumulation of nutrients in sediments after the settling of cyanobacteria can cause high internal phosphorus pollution. The increase in the total organic carbon of the sediments can threaten lake restoration achieved by planting submerged macrophytes.
ISSN:2096-5508
2523-3521
DOI:10.1007/s00343-022-1351-7