Electro Catalytic Oxidation Of Simulated Condensate Wastewater And Hygiene Wastewater In Space Station

Water supply is one of the major problems for astronauts’ consumables during spacemissions. Therefore, reuse of spatial wastewater will be a valueable pah to guarantee thedrinking and hygiene wastewater of astronauts, which can effectively reduce the supplycosts. In this study, an electro-catalytic oxidation technology with a boron-doped diamond(BDD) electrode was employed as working electrode to treat the condensate wastewaterand hygiene wastewater. The effects of the cell voltage, the circulation flow rate, and theelectrolyte concentration on the degradation process of condensate and hygienewastewater were investigated. The mechanism of the electro-catalytic oxidationdegradation of the simulated condensate wastewater and hygiene wastewater was alsoanalyzed.The results show that the increase of the electrolyte concentration, the cell voltageand the circulating flow can effectively promote the degradation rate of the organics inhumidity condensate and hygiene wastewater. Conversely, the addition of electrolyteexhibits a negative effect on electrode and the subsequent oxidation process.At the electro-catalytic oxidation process conditions of no electrolyte addition,circulating flow12L/h, cell voltage8V, the removal rate of the organics is96%after12htreatment. Without addition of electrolyte, at the circulating flow of12L/h, the cellvoltage of20V, the removal rate of TOC in hygiene wastewater reaches to88.06%after12h treatment. The kinetic behavior of the organic matter was also studied and it foundthat the TOC removal rate of these two kinds of wastewater can be described by a firstorder reaction equation with reaction rate constant of0.27204h-1and0.17102h-1,respectively.Based on the measurements of TOC and COD, pH, ammonia nitrogen, caprolactamcontent, conductivity, current, acetic acid and formic acid, the degradation mechanism ofcondensate and hygiene wastewater was inverstigated. The results show that themineralization rate of individual component in hygiene wastewater follows the order: N.N-double hydroxyethyl alkyl amide (6501)> ethanol> glycerin; the acetic acid is the main intermediate in the degradation process of humidity condensate wastewater. However, inaddition to acetic acid, some other acidic organic compounds exist as the mainintermediate during the hygiene wastewater degradation process.