>>974892They may use a methane biogas digester instead. No waste at all them. Lots of methane for heat and electric plus lots of high nitrogen fertilizer from it. You can use any organic matter, human waste, manure, etc. Lots of farms are not converting their equipment to run off the biogas methane and making the biogas methane on the farm.
https://www.google.com/search?q=methane+biogas+digester 