Gas scrubbers; sewage treatment and sewage disposal plants; water purification units; water desalination plants; water purifying apparatus and machines; apparatus and machines for purifying air for industrial use; furnaces; separators for cleaning and purification of air; separators for cleaning and purification of gases; waste water purification units; water conditioning units; bioreactor for use in the treatment of sewage, wastewater, and waste; thickening and dewatering machines for use in...