Design of a continuous bio-electrochemical reactor system for enhancement of wastewater treatment

Abstract

A wastewater recycling system with enhanced efficiencies is needed to satisfy the water need for places suffering from water scarcity and in a closed loop environment required by NASA's Environmental Control and Life Support Systems (ECLSS). One of the primary pollutants of water in space is urea. This project focuses on urea removal from wastewater using a bioreactor system combined with an ammonia oxidation reactor. For the removal of urea, it is used urease which hydrolyzes urea. The urease is from a microorganism, <em>P. vulgaris</em>, in a bioreactor system that removes urea from synthetic and real human urine. As of result of urea hydrolysis, there is a production of ammonia. Ammonia is also removed electrochemically, incorporating an ammonia oxidation reactor, which removes 90% of the ammonia in the human urine systems. Furthermore, different working electrodes were constructed to enhance the ammonia oxidation reaction. The electrodes were built from carbon fiber brush (CFBE) modified with different proportions of Pt: Ni nanoparticles (100:0, 80:20, 60:40, 40:60 %w). The CFBEs were tested in synthetic human urine processed by&nbsp;<em>P. vulgaris</em>, which could remove up to 30% of the ammonia in the system.