Experimental study of nitrogen removal in the presence of three algal species - Synechocystis, Chlorella, Micractinium - : evaluation of algal uptake rate, nitrification and ammonia stripping process

Trois microalgues, Synechocystis (Picocyanobact?rie), Chlorella et Micractinium (Chlorophyta) se d?veloppant dans le lagunage naturel, ont ?t? mises en culture en milieu ax?nique et ensemenc?es dans des microcosmes d'eau us?e filtr?e, st?rilis?e ou non. Ceci dans le but d'?valuer les voies d'?limination de NH4, apport? par cette eau us?e. L'assimilation algale, la nitrification et le stripping de NH3, se sont r?v?l?es les principales voies d'?limination de l'ammonium dans le milieu non st?rilis?. Par ailleurs, dans le milieu st?rilis?, seuls l'assimilation algale et le stripping sont pr?sents. Les bact?ries h?t?rotrophes a?robies semblent ne pas intervenir dans cette ?limination.Three microalgae species : Synechocystis (Picocyanobacteria), Chlorella and Micractinium (Chlorophyta) isolated from wastewater stabilisation ponds, were cultured on a mineral medium. In order to evaluate the removal rate depending on different processes and microalgae culture conditions, algal growth was studied both on sterilized and non sterilized sewage water filtrate. The results show that algal uptake, nitrification and NH3stripping are the principal process leading to NH4removal under nonsterilized conditions. However, the nitrification process do not occur on sterilized microcosms. It seems that aerobic heterotrophic bacteria did not act on the NH4removal process. According to each process, culture condition and utilized microalgae strain, the evaluation of various nitrogenous removal rates are discussed.