This free digital download is on the removal of nitrate from water:
The goal of this study is to observe the removal of nitrate from the water over time by the microalgae. The formation of new biomass requires nutrients from the environment. For plants including algae, nitrogen is the second largest element behind carbon. Nitrogen can be supplied to algae cultures in the form of sodium nitrate. As nitrate it is easily measurable using a simple colorometric dip-stick test. Testing over time can show the rate at which nitrate is being removed from the system.