See Milorganite: https://en.wikipedia.org/wiki/Milorganite https://en.wikipedia.org/wiki/Milorganite At scale, in Milwaukee. There have been concerns about c

See Milorganite: https://en.wikipedia.org/wiki/Milorganite https://en.wikipedia.org/wiki/Milorganite At scale, in Milwaukee. There have been concerns about contaminants though. Still production and sales have been ongoing since 1926.