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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 497652
Title Management of eutrophication in Lake De Kuil (The Netherlands) using combined flocculant - lanthanum modified bentonite treatment
Author(s) Waaijen, G.; Oosterhout, F. van; Douglas, G.C.; Lurling, M.F.L.L.W.
Source Water Research 97 (2016). - ISSN 0043-1354 - p. 83 - 95.
Department(s) Aquatic Ecology and Water Quality Management
Publication type Refereed Article in a scientific journal
Publication year 2016
Abstract Eutrophication of Lake De Kuil (The Netherlands, 6.7 ha, maximum depth 9 m) has frequently caused cyanobacterial blooms resulting in swimming bans or the issue of water quality warnings during summer. The eutrophication was mainly driven by sediment phosphorus (P)-release. The external P-loading was in the range of the critical loading for phytoplankton blooms. Hence, the reduction of the internal P-loading provided a promising way to reduce cyanobacterial blooms. To mitigate the cyanobacterial blooms, the combination of a low dose flocculant (iron(III)chloride; Flock) and a solid phase phosphate fixative (lanthanum modified bentonite; Lock) was applied in May 2009. This combined approach both removed cyanobacterial biomass from the water column and also intercepted P released from the bottom sediments. Immediately after treatment, the Secchi depth increased from 1.5 m up to 5 m. Sediment P-release decreased from 5.2 mg P m−2 d−1 (2009) to 0.4 mg P m−2 d−1 (2010) but increased in later years. Mean summer concentrations of total P decreased from 0.05 mg L−1 (1992–2008) to 0.02 mg L−1 (2009–2014) and chlorophyll-a from 16 μg L−1 (1992–2008) to 6 μg L−1 (2009–2014). Mean summer Secchi depth increased from 2.31 m (1992–2008) to 3.12 m (2009–2014). The coverage of macrophytes tripled from 2009 to 2011. In the winter of 2010/2011 Planktothrix rubescens bloomed, but cyanobacterial biomass decreased during the summers after the Flock and Lock treatment in comparison to prior years. After the Flock & Lock the bathing water requirements have been fulfilled for six consecutive summers. As the sediment P-release has gradually increased in recent years, there is a risk of a reversion from the present mesotrophic state to a eutrophic state.
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