Microbial desalination cell for concurrent hydrogen peroxide production and desalination

Abstract

Microbial desalination cells (MDCs) are novel desalination approaches because of using biocatalyst, with the ability to convert organic waste to bioenergy in various forms, to desalinate salty water. If MDCs were applied to the production of hydrogen peroxide, which is an important green oxidant, less energy-intensive and eco-friendly hydrogen peroxide production can be achieved during desalination. Here, we examined MDCs for concurrent hydrogen peroxide and desalination by varying an applied voltage, initial sodium chloride concentration, electrode materials, oxygen concentration, catholyte pH and catholyte concentration. The hydrogen peroxide production rate and salt removal rate (SR) increased by 0·033 kg (H2O2/m3)/h and 197·5 mg/(L·h) with increasing applied voltage. Carbon felt showed the highest hydrogen peroxide production (0·197 kg H2O2/m3) but the lowest SR (119·0 mg/(L·h)). Compared with air supply, pure oxygen supply dramatically improved hydrogen peroxide production (100%), but the SR only slightly improved (10%). With increasing sodium chloride concentration from 5 to 30 g/L, the hydrogen peroxide production and the SR increased, reaching 0·261 kg H2O2/m3 at 30 g/L and 236 mg/(L·h) at 20 g/L, respectively. The highest hydrogen peroxide production was achieved at catholyte pH 4, but the highest SR was achieved at pH 7. With increasing catholyte concentration from 5 to 100 mM, the hydrogen peroxide production and the SR increased.