Electrochemical Removal of Ammonium Ion from Bioreactor Effluent

Ammonium ion is a byproduct of the oxidation of nitrogen-containing substances occurring in the initial treatment steps of water recovery systems. Removal of ammonium ions from the effluent stream from 1000 ppm to less than 0.25 ppm is an imperative need as a part of the space life support infrastructure. Drawbacks associated with processes proposed in the past include the generation of a secondary waste, cost, size, and/or the use of consumables that need to be stored or supplied. The proposed technology is based on an innovative, environmentally friendly electrochemical process for the effective removal of ammonium ions. It does not use consumables but oxygen gas from air, readily available. It will not generate a secondary waste. By controlling operational conditions, the ammonium ions will be transformed to nitrogen gas, which can be removed from the liquid phase in microgravity conditions by the use of a gas separation module. In addition, it is an energy efficient process, operates at room temperature, and is microgravity compatible. The purpose of Phase I is to demonstrate the feasibility of the electrochemical oxidation of the ammonium ions to nitrogen gas and to test its efficiency using a bioreactor effluent simulant.