| abstract |
A method for removing pollutants from water, according to the preferred embodiment of the present invention, comprises the steps of providing algal spores for seeding, providing a source of water for flowing through a floway, and the water contains a quantity of pollutants and has a pH on entry into said floway, providing a growing surface in the floway upon which the algal spores form an attachment, subjecting the algal spores in the floway to operating conditions resulting in the formation of an algal turf in which the algae has cell walls on its surface, adjusting the floway operating conditions such that a predetermined pollutant precipitates onto and/or into the algal cell walls but not into the water, and harvesting a portion of the algal turf including the cell walls onto and/or into which the pollutants have precipitated. By control of such floway operating conditions as water flow rate, light level, intensity and wavelength, water surge rate, recirculation rate, and nutrient concentrations, the pH of the water adjacent the algal cell wall is caused to increase to a level at which the desired pollutants precipitate. Since the operating conditions are carefully adjusted to allow the pH of the water to remain below the pH level normally required for precipitation, precipitation of the pollutants occurs only onto and/or into the algal cell wall, and not into the water column as a whole. No precipitation occurs in the water because its pH does not rise to the pH at which the pollutants of interest precipitate. |