Biological contactor for treatment of sewage and drainage water; External ballast and bilge water filtering and absorbing device for use in a local containment area for removing aquatic nonindigenous species, oil and other contaminants from the effluent; External filtering device for use in a local containment area for removing oil and other contaminants from storm drain effluent as it exits storm water systems; Purification installations for sewage; Waste water purification apparatus, instal...