(a) For a wastewater treatment facility designed to provide advanced nutrient removal, the engineering report must specify the process units needed to achieve the effluent limits established in the wastewater treatment facility's wastewater permit.     
      (b) Biological nutrient removal using an activated sludge process, membrane filtration, sand filtration, or a combination of these processes may be used for advanced nutrient removal without applying for the executive director's approval under the innovative or non-conforming technology criteria in §217.7(b)(2) of this title (relating to Types of Plans and Specifications Approvals). A biological nutrient removal process that involves fixed-film treatment is subject to the executive director's determination under §217.7(b)(2) of this title.     
      (c) If a biological nutrient removal unit is proposed, the engineering report must include the:      
        (1) anticipated food to microorganism ratio in both the anoxic and anaerobic zones;       
        (2) volatile fatty acid recycle ratio; and       
        (3) design of a foaming control system.       
      (d) If a chemical addition unit is proposed, it must comply with the chemical containment requirements in Subchapter K of this chapter (relating to Chemical Disinfection). Chemical addition may only be used if approved in writing by the executive director.     
     Source Note:        The provisions of this §217.163 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254