Purification installations for sewage; Separators for the cleaning and purification of liquids; Septic tanks; Sewage disposal plants; Sewage purification apparatus; Sewage purification installations; Sewage treatment plants; Slurry treatment units for stabilizing and sanitizing slurry; Thickening and dewatering machines for use in treatment of liquids including water, industrial effluent and sewage; Waste processing machines using heat and chemical breakdown processes; Waste water purificatio...