Desalination of diluted seawater and bioelectricity generation by microbial desalination cell using sewage as substrate and source of microorganisms

Abstract

Shortage of freshwater has led mankind to develop technologies to make seawater usable. The present day desalination technologies are uneconomical for developing countries as these are energy intensive. In the present study, a simple, economical, laboratory scale microbial desalination cell was set up and operated without the input of energy, by using sewage as a source of substrate and microorganisms. In addition to achieving desalination, it also resulted in production of power, though insignificant. On operating the MDC using 0.5% NaCl and diluted seawater separately, the reduction in Na+ was 45% and 22.5% respectively and reduction in Cl- was 53% and 7.9% respectively within the first 24 hrs of operation with no further decrease thereafter. The maximum potential difference recorded was 13.1 mV (0.026 mA) with 0.5% NaCl solution, at 24 hrs. Preliminary studies of the microbial community developing on the anodic surface using Scanning Electron Microscopy revealed the presence of slightly curved rod shaped bacteria with thread like appendages. In light of the numerous technical innovations in this area, the present study documents the use of simple basic environment friendly MDC using sewage as a substrate and source of microorganisms to drive the desalination process.