Desalination of the power plant salty wastewater by use of an algae-based photosynthetic microbial desalination cell

Abstract

In this research the possibility of using a photosynthetic microbial desalination cell (PhMDC) is investigated for desalination of power plant salty wastewater (PPSWW), along with power generation and organic load removal. The PhMDC was operated with anaerobic sludge in the anode chamber, microalgae in the cathode chamber, and different conductivities of PPSWW (10, 20, 40, and 55 mS cm^-1) in the desalination chamber under different illumination modes (continuous light mode and light/dark mode). The highest power density (285.5 mW m^-2), desalination efficiency (60.9%), and COD removal (74.8%) was achieved at conductivity of 55 mS cm^-1 under continuous light mode. The highest algal growth (900 mg. L^-1) was also observed at this conductivity. The applied system demonstrated effective removal of different presented cations and anions in PPSWW with removal efficiencies of more than 58%. Dynamic shift of microbial community in the anode chamber showed notable increase in sulfate-reducing bacteria and some specific genera such as Desulfovibrio, Pseudomonas, Rhodobacter, Rhodopseudomonas, and Desulfuromonas due to their potential for electricity generation and adaptation to saline and acidic conditions.

Keywords: Algae; Desalination; Microbial community; Photosynthetic microbial desalination cell (PhMDC); Power plant salty wastewater (PPSWW).