Eutrophication of surface water has been an important environmental issue for nearly half
a century. High concentrations of phosphorus contribute to the process of eutrophication,
resulting in the demand for effective and economic methods of phosphorus removal from
treated water. The aim of this study was to evaluate the capacity for phosphorus removal
of a microalgal biofilm during different light regimes. The photobioreactor was operated for
nine months each year over a two-year period without interruption and without any need
of re-inoculation. The algal biofilm was able to remove 97 ± 1% of total phosphorus from
wastewater during 24 h of continuous artificial illumination. The average TP uptake rate in
our experiments was 0.16 ± 0.008 g m2 d1. Phosphorus removal values ranged from 36 to
41% when the algal biofilm was illuminated by natural light (12 h sunlighte12 h night). The
biomass production rate was 12.21 ± 10 g dry weight m2 d1 in experiments with
continuous artificial light and 5.6 ± 1 g dry weight (DW) m2 d1 in experiments with
natural light. These results indicate the great potential of microalgal biofilms in the tertiary
treatment of wastewater.