For the dairy wastewater, algae were cultured outdoors in six
40-L rectangular glass aquarium tanksFig. 2. The tanks were
filled with 20 L of effluent from the anaerobic digester. To better
simulate light conditions in ponds, sunlight was allowed to enter
the tanks only through the top water surface by masking the tank
walls up to the waterline with black tape. A Plexiglas cover excluded rainfall, but a gap was provided between the cover and the
tanks for ventilation.