Giant Archimedes screw for sewage treatment.
Fullsize image: https://diqn32j8nouaz.cloudfront.net...w_fullsize.jpg
https://diqn32j8nouaz.cloudfront.net...edes_screw.jpg
Previously:
https://www.homemadetools.net/forum/...400#post116801
https://www.homemadetools.net/forum/...3198#post77628
