Talk:Sludge incineration

Number of plants in the US
I've moved this statement from the article to the talk page because I couldn't figure out what kind of reference this was - we need to know the year!? It seems to be copied out of some book?:

There are approximately 170 sewage sludge incineration plants in operation in the United States. EMsmile (talk) 20:39, 7 June 2017 (UTC)