| 摘要 |
<p>Liquid treatment apparatus has an underdrain assembly of conduits and strainers connected to a bottom port. The conduits are embedded in a liquid-impervious, inert, cast, flat-topped mass that fills the bottom of the apparatus around the port. The mass is made from an aggregate of macrobodies and microbodies coated and bour ?ogether by a cured thermosetting synthetic plastic resin. The cast mass may or may not be coated with a rubber lining. Strainers are attached to the conduits on top of the flat mass.</p> |
