Control of internal phosphorus loading using coagulants and clays in water and the sediment of a semiarid reservoir susceptible to resuspension

• Published in: Hydrobiologia Vol. 849; no. 17-18; pp. 4059 - 4071
• Main Authors: Cavalcante, H., Araújo, F., Becker, V., Lucena-Barbosa, J. E.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.10.2022; Springer; Springer Nature B.V
• Subjects: Algae; Bentonite; Biomass; Biomedical and Life Sciences; Clay; Coagulants; Deactivation; Ecology; Ecology of Shallow Lakes; Eutrophic environments; Eutrophic waters; Eutrophication; Freshwater & Marine Ecology; Inactivation; Lanthanum; Life Sciences; Phosphorus; Reservoirs; Resuspension; Sediment; Sedimentation; Sedimentation & deposition; Sediments; Sediments (Geology); Simulation; Water; Water circulation; Water column; Zoology; Floc & Lock; Cyanobacterial sedimentation; Capping; Phosphorus inactivation; Floc & Sink
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-021-04737-0

This study aimed to evaluate the efficiency of the application of coagulants and clays, on a microcosm scale, in reducing algal biomass and in controlling the internal phosphorus loading (P) in a eutrophic semiarid reservoir. Water and sediment were collected in the Boqueirão reservoir to carry out the following experiments in laboratory: (1) sedimentation of algal biomass and total P in the water (Floc & Sink); (2) inactivation of P in the sediment (Floc & Lock) and (3) resuspension simulation of the sediment. Polyaluminum chloride and Tanfloc coagulants were used in the experiments, alone and in combination with clays: a natural bentonite and a bentonite modified with lanthanum (LMB). Coagulants alone were enough to promote sedimentation of algal biomass and total phosphorus in the water column. To inactivate P in the sediment, clay with high adsorption capacity is necessary, as in the case of LMB. After resuspension simulation, all treatments showed an increase in P, even minutes after agitation, showing that the technique is vulnerable if the applied environment suffers from recurrent sediment resuspension events.