Population growth have led to producing more solid waste from wastewater treatment plants (WWTPs), increasing both energy and cost for treatment and disposal of waste-activated sludge (WAS). If not treated properly, WAS poses serious threats to human health and the environment. The annual production of WAS reached 2 billion tons in 2011 worldwide and it is expected that this number will grow to 9.5 billion tons per year by 2050 [1]. Conversion of solid waste to value added chemicals and fuels could address environmental concerns imposed by the growing of WAS.

To confront these challenges, Botte’s research group is working in the electrochemical valorization of WAS to chemicals [2]. In this talk, we will describe recent findings in the electrocatalysis of sludge using transition metals for the synthesis of ammonia and short-chain fatty acids production. Short-chain fatty acids (e.g., acetic acid, propionic acid, butyric acid, etc.) are the intermediate chemicals in anaerobic digestion. The global market demand for short-chain fatty acids in 2020 was 18,500 kt and it is expected to increase annually by 3% per year over the next three years [3].

[1] Lemar, M.; De Fontaine, A., Energy Data Management Manual for the Wastewater Treatment Sector. Technical Report ORNL/SPR-2018/14 2017, United States. https://doi.org/10.2172/1432164

[2] Jafari, M.; Botte, G. G., Electrochemical treatment of sewage sludge and pathogen inactivation. Journal of Applied Electrochemistry 2021, 51 (1), 119-130.

[3] Ramos-Suarez, M.; Zhang, Y.; Outram, V., Current perspectives on acidogenic fermentation to produce volatile fatty acids from waste. Reviews in Environmental Science and Bio/Technology 2021, 20 (2), 439-478.