1. Amaresan, N., Kumar, M.S., Annapurna, K., Kumar, K., Narayanan, S., 2020. Beneficial Microbes in Agro-Ecology: Bacteria and Fungi. Academic Press, London, UK.
2. American Public Health Association (APHA), 2005. Standard Methods for Examination of Water and Wastewater. 21st ed., Washington, DC.
3. Principles and potential of the anaerobic digestion of waste-activated sludge;Appels;Prog. Energy Combust. Sci.,2008
4. Effects of ultrasonic pre-treatment on sludge characteristics and anaerobic digestion;Appels;Water Sci. Technol.,2012
5. Pretreatment methods to enhance anaerobic digestion of organic solid waste;Ariunbaatar;Appl. Energy,2014