INFLUENCIA DE LA INTENSIDAD LUMÍNICA EN LA ELIMINACIÓN DE NUTRIENTES DEL EFLUENTE DE UN REACTOR ANAEROBIO DE MEMBRANAS MEDIANTE MICROALGAS

Abstract

In wastewater treatment with microalgae light is the most important parameter. It has to be supplied at the proper intensity to achieve their maximum nutrient removal performance. Three experiments were carried out with different light intensity (216, 432 and 648 µmolm-2s-1) in an indigenous microalgal-bacterial culture dominated by Scenedemus sp., ramaining constant pH (7.5 ± 0.3), solids retention time and hydraulic retention time (STR=HRT=8 days) and temperature (22 ± 1ºC). Ammonium removal reached 100% in all the experiments. Nevertheless, the presence of nitrite and nitrate at low light intensity was observed due to the elimination of some quantity of ammonium by nitrification. This fact confirmed the competence in the ammonium removal between microalgae and nitrifying bacteria. Regarding phosphorous, removal rate was 96% at low light intensity and 100% in the other experiments. It was concluded that an increase of light intensity benefits microalgae growth therefore reducing the competence with nitrifying bacteria, diminishing the nitrification process and accomplishing a higher soluble nitrogen removal rate. Besides, this light intensity raise allowed a higher phosphorus removal rate as microalgae are able to subtract an upper amount of this element than nitrifying bacteria.