Physicochemical and Algal Study of Three Dams (Algeria) and Removal of Microalgae by Enhanced Coagulation

The Boukerdène, Lakhel and Ghrib Dams, located in northern Algeria, are used for both drinking water supply and irrigation. Microalgae (MA) and phytoplankton are able to proliferate when environmental conditions are favorable. These phases of proliferation can have harmful consequences on the functioning of aquatic ecosystems but also on their use. The objective of this work is to acquire a better knowledge on the proliferation of these MA in these three Dams, to describe and quantify their species, as well as to study their impact on a physicochemical treatment, namely conventional coagulation and enhanced coagulation. In addition, a physicochemical study is developed to assess the water quality of these Dams. Laboratory analyses have shown that the levels of MA in these waters are high, and jar tests have proven that the application of enhanced coagulation under controlled conditions (coagulant dose, acidification of the medium) leads to better performance compared to conventional coagulation. Enhanced coagulation is not fully effective in removing micropollutants and needs always to be aided by additional treatment technologies, such as ozonation and activated carbon adsorption. The SEM analysis carried out clearly shows the changes that took place in the morphology of the collected flocs thus binding the AM debris. As a perspective, the future studies have to focus on other physicochemical parameters such as alkalinity