11
Apparatus for water supply and sanitary purposes; biological filtration, separation and artificial reef habitat media; waste treatment media for use in wastewater trickling filters, sewage treatment facilities and industrial waste treatment facilities; solid-liquid separation media; separation media for use in air scrubbing and stripping water towers; filters made of fiber for water filtration; fibrous filtering media for general industrial use; water filtering apparatus; water filtration installations; cooling tower equipment and components; cooling tower accessories in the nature of drift eliminators, inlet louvers and nozzles; wastewater equipment components, namely, cross-corrugated fills and vertical flow fills; tube settler components; trickling filters; surface media for use in evaporative heat exchangers
19
Drainage channels [not of metal]; drainage installations [non-metallic]; plastic pipe supports; non-metallic pipes; non-metal elbows for pipes; non-metal pipe collars; non-metal pipe couplings and joints; non-metal pipe fittings; non-metal tubing and tubing couplings for joining and terminating pipes; rigid pipes, not of metal; non-metallic sewer pipes; non-woven fabrics for land and soil drainage; erosion control fabric, mats and sheeting, not of metal; drainage apparatus of plastics or synthetic materials
37
Construction engineering and consultancy services; civil engineering relating to the prevention of inundation of land by flood water; civil engineering relating to water drainage and irrigation; installation of environmental engineering systems; advisory services relating to the repair, installation and maintenance of environmental control systems