|(a) A rotating biological contactor (RBC) may be used
in conjunction with other treatment as a dual treatment system.
(b) An RBC may be used as aroughing unit, as described
in §217.182(b)(1) of this title (relating to Trickling Filters--General
Requirements, regarding trickling filter classifications), in series
with an activated sludge system.
(c) The engineering report must include supporting
data, calculations, process descriptions, and vendor information to
describe how a proposed RBC system will meet the permitted effluent
(d) Combined systems may be subject to the requirements
of §217.7(b)(2) of this title (relating to Types of Plans and