Tannery wastewater treatment coupled with bioenergy production in upflow microbial fuel cell under saline condition

Abstract

Tannery industry handling huge amount of leather materials release immense amount of saline organic content wastewater. The present research was focused on the treatment of tannery industrial wastewater in UMFC (upflow microbial fuel cell) under saline condition (4%). The UMFC reactor was operated at different organic load (OL) such as 0.6, 1.2, 1.8 and 2.4 gCOD/L respectively. Total chemical oxygen demand (TCOD) removal at 0.6, 1.2, 1.8 gCOD/L was 87 ± 1.2%, 91 ± 1.2% and 93 ± 1.8% respectively. Soluble chemical oxygen demand (SCOD) removal in UMFC at 0.6, 1.2, 1.8 gCOD/L was 85 ± 0.6%, 88 ± 1.2% and 91 ± 1.8% respectively. Total suspended solids (TSS) removal was 49%, 78%, 81% at 0.6, 1.2, 1.8 gCOD/L OL in UMFC. Further, raise in OL to 2.4 gCOD/L showed decrease in TCOD, SCOD (80% and 72%) and TSS (60%) removal. Maximal power production of 854 mV with corresponding PD (power density) of 462 mW/m² and CD (current density) of 523 mA/m² was registered at 1.8 gCOD/L OL in UMFC. Increase in OL to 2.4 gCOD/L revealed decline in energy production to 810 mV with PD (385 mW/m²) and CD (438 mA/m²) in UMFC. Maximal bioaccumulation of chromium (95%) was recorded at 1.8 gCOD/L OL. Among different OL used 1.8 gCOD/L OL was optimum for the treatment of tannery wastewater and energy production. Bacterial community analysis in anode of UMFC revealed the dominance of promising electrogenic halophilic strains such as Ochrobactrum, Marinobacter, Rhodococcus and Bacillus in all the OL. Thus, the research clearly revealed the efficacy of halophilic consortium to treat the saline tannery wastewater coupled with bioenergy production in UMFC.

Keywords: Bioenergy; Halophiles; Microbial fuel cell; Tannery wastewater.