Macrophytes and Methanol-Based Denitrification in a Novel Nitrate Filtration System

The commercial, economic, and recreational values of the Chesapeake Bay have been threatened in recent decades as rising nitrate levels have led to eutrophication of its waters, with excess algae depleting oxygen levels and devastating local ecosystems. Methanol-based denitrification has proven effective, but methanol exerts adverse effects upon the aquatic ecosystem; however, recent research has indicated the viability of C3 macrophytes in removing methanol from water, a breakthrough for the water treatment industry. The purpose of the experiment was to test the viability of a methanol-based system to remove nitrates from water while using C. demersum to absorb the methanol, negating adverse environmental impact. Deionized water treated with 1.1 mg/L of nitrate was anoxified and pumped through a system of clear PVC pipes at a flux of 1.8 L/hr. Spending approximately 40 minutes in the anoxic carbon-based denitrification chamber before entering the macrophytic chamber for 40 minutes, the water was then sampled, six times, for 4.5 minutes every 30 minutes. The final mean nitrate value of 0.28 mg/L was significantly lower than the starting value of 1.1 mg/L, indicating that the system was effective at reducing approximately 74.5% of nitrates present in the water. While definitive methanol testing could not be conducted due to equipment restraints, qualitative testing indicated a decrease in methanol concentration. A chi-square test indicated a significant difference between the means of the groups (χ² =8.41>3.841). The results from this experiment show that the filtration system tested has the potential to revolutionize denitrification efforts within aquatic ecosystems. The indication that such a system could be scientifically sound is in concurrence with research by Kazasi, et al. (2013), who found methanol to be an effective initiator of nitrate-consuming bacterial growth.