11 Water purification installations, apparatus, machines, units, filters and tanks; regulating accessories for water apparatus and pipes, namely, anti-backpressure valves, check valves, flow check devices; air filtering and purification apparatus and machines; environmental control apparatus, namely, drying apparatus for wastewater treatment equipment, desulfurization apparatus for wastewater treatment equipment, particle activators for use in drinking water treatment and municipal and industrial waste water treatment; UV-lamps for water purification installations