Section Env-Wq 714.03 - Rotating Biological Contactors (RBCs)(a) Rotating biological contactors (RBCs) shall only be used when the sewage is amenable to treatment by aerobic biological processes.(b) RBC units shall be housed or otherwise protected from winter conditions, freezing damage, and UV degradation.(c) Covers shall be designed to provide adequate ventilation and enclosed structures shall be protected from corrosion due to high humidity. Enclosures shall allow for the removal of one shaft without interfering with the WWTP operation.(d) Covers shall allow operator access to all parts of the RBCs for observation and maintenance.(e) RBCs shall be preceded by effective settling tanks equipped with scum collecting devices or other suitable pretreatment facilities in addition to those required in Env-Wq 711.01.(f) Multiple trains shall be furnished for flexible operation and stage bypassing.(g) Flow control to RBC tanks shall be by splitter boxes and weirs.(h) Buildings housing RBC processes shall have ventilation of at least 6 air changes per hour.(i) Electrical system components, panels, light fixtures, motors, and control centers shall be watertight and corrosion resistant.(j) Shafts and media shall be designed for an operational life of 20 years.(k) RBC units shall be sized in accordance with the following: (1) Organic loading to the first stage of the RBC system shall not exceed 6 to 8 pounds of BOD5/1,000 square feet/day or 2.5 to 4 pounds of soluble BOD5/1,000 cubic feet/day; and(2) Maximum bearing capacities for the shafts shall be specified based on the expected film thickness, the capacity to strip biofilm, and an adequate margin of safety. Load cells shall be provided for all shafts to monitor loadings.(l) Media shall be constructed to allow portions to be removed for cleaning and replacement without requiring the entire shaft assembly to be removed from the tanks.(m) Adequate flexibility in process operation shall be provided by including one or more of the following in the design: (1) Variable rotational speeds in the first and second stages, including speed reversal to remove excess biofilm;(2) Removable baffles between all stages in contoured basins to avoid dead spaces;(3) Positive influent flow control to each unit or flow train, including positively-controlled alternate flow distribution systems such as step feed;(4) Positive air flow metering and control to each shaft when supplemental air or motor driven units are used; or(5) Recirculation of secondary effluent.N.H. Code Admin. R. Env-Wq 714.03
(See Revision Note at chapter heading for Env-Wq 700) #8590, eff 3-25-06
Amended byVolume XXXIV Number 46, Filed November 13, 2014, Proposed by #10693, Effective 10/15/2014, Expires10/15/2024.