Impact of Wastewater Concentration and Feed Frequency on Ammonia Inhibition in Microbial Fuel Cells

Abstract

Excessive amount of ammonia slows down exoelectrogenic bacteria activities in microbial fuel cells (MFCs). The aim of this study is to analyze the impact of wastewater concentration and feed frequency on the ability of exoelectrogenic bacteria to withstand against ammonia inhibition in MFCs, in particular, for total ammonium nitrogen (TAN) concentration ranging from 29 mgN$L^{-1}$ to 2000 mgN$L^{-1}$. MFCs were constructed to measure electric current and power density and tested in wastewater of selected TAN concentration samples. The MFCs frequently feed (2-days intervals) with full strength wastewater achieved a maximum power density between 0.8 mW$m^{-2}$ and 1.2 mW$m^{-2}$. The MFC less frequently feed (6-days feed intervals) with full strength wastewater and also the MFC frequently feed (2-days feed intervals) with low strength wastewater exhibited a relatively lower electricity generation. Increasing the concentration of total ammonium nitrogen resulted in a gradual decrease of chemical oxygen demand (COD) removal efficiency. Experimental results demonstrated that the frequency of feed and higher substrate concentration increase exoelectrogenic bacteria activities in generating electric current in MFCs.

Keywords:

• Total ammonium nitrogen (TAN)
• ammonia inhibition
• ammonia cytotoxicity
• wastewater