Electrochemical Wastewater Treatment: Nutrient Recovery and Selective Contaminant Removal

Electrochemical approaches and technologies have the potential to be used and applied to a wide range of water and wastewater treatment needs, particularly if these technologies are paired with a renewable energy source such as solar energy. Renewable-powered electrochemical technology can be used for rural, remote applications and in other scenarios where non-chemical approaches are desirable. Electrochemical technologies can also be potentially used where electrode and electrocatalyst design can be tailored to address specific treatment requirements, such as selective contaminant removal, resource recovery, and disinfection. The research results presented here focus on two applications of electrochemical technology to wastewater treatment: electrochemical precipitation of magnesium ammonium phosphate, known as struvite, for nutrient recovery and simultaneous ammonia oxidation and disinfectant generation for aquaculture wastewater. Experiments on electrochemical struvite precipitation comparing a pure magnesium and a magnesium alloy electrode demonstrated that the pure magnesium electrode produces more current; both anodes result in a crystalline struvite precipitate, as confirmed by x-ray diffraction. Cyclic voltammetry studies for aquaculture wastewater treatment using graphite and graphite-supported PtRu films as the anode demonstrate that the presence of PtRu reduces the voltage required for ammonia oxidation. When graphite is used as the cathode, the disinfectant molecule hydrogen peroxide is produced, suggesting electrochemical disinfection is possible in parallel with ammonia oxidation.