Inhibition of Volatile Fatty Acid Production in Granular Sludge from a UASB Reactor

Abstract

Inhibition of volatile fatty acids (VFA), namely acetate, butyrate, and propionate, on the activity of acetoclastic methanogens within a full-scale upflow anaerobic sludge blanket (UASB) reactor was investigated using specific methanogenic activity (SMA) test. SMA tests were carried out at acetate concentrations in a range of 1000–25,000 mg l⁻¹, butyrate concentrations in a range of 3000–25,000 mg l⁻¹ and propionate concentrations between 500–10,000 mg l⁻¹. Maximum potential methane production (PMP) rates were obtained as 389 ml CH₄ gTVS⁻¹ .d⁻¹ at 3000 mg l⁻¹ acetate concentration, 432 ml CH₄gTVS⁻¹.d⁻¹ at butyrate concentration of 5000 mg l⁻¹, and 162 mlCH₄gTVS⁻¹.d⁻¹ at 1000 mg l⁻¹ propionate concentration. App. 50% and 100% inhibition occurred at acetate concentrations of 13,000 mg l⁻¹ and 25,000 mg l⁻¹, butyrate concentrations of 15,000 mg l⁻¹ and 25,000 mg l⁻¹, and propionate concentrations of 3500 mg l⁻¹ and 5000 mg l⁻¹, respectively.

Keywords:

• Specific methanogenic activity test
• Acetate
• Butyrate
• Propionate
• Anaerobic sludge
• VFA inhibition

ACKNOWLEDGMENTS

Author Bahar Kasapgil Ince would like to acknowledge the project coded 01S101 of the Research Fund of Bogazici University. Author Orhan Ince would also like to acknowledge the project coded 844 of the Research Fund of Istanbul Technical University.

Notes

* Unitless.