(a) A rotating biological contactor (RBC) system designed for five-day biochemical oxygen demand (BOD             5            ) removal and nitrification of domestic wastewater in a single system must include four stages and have a maximum overall organic loading rate of 1.6 pounds of BOD             5            per day per 1,000 square feet of media.     
      (b) A nitrifying RBC must be designed to allow chemical addition if the influent pH is below 7.0 standard units.     
      (c) The engineering report must justify the nitrification rate of a system using calculations.     
      (d) A nitrifying RBC system may be subject to the requirements of §217.7(b)(2) of this title (relating to Types of Plans and Specifications Approvals).     
     Source Note:        The provisions of this §217.186 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254