Abstract: A system (10) comprising multiple units (40a-40h) and method for filtration of wastewater (20) is disclosed. Simultaneous denitrification of a single filter unit and normal filtration of the remaining filter units is provided for. Separate flow control systems (36) are described.

Abstract: A method for controlling the addition of liquid treatment chemicals by automatic dose control. The calculation of the amount of chemical to be dosed into the system combines signals from a liquid flow meter, an influent chemical concentration analyzer and/or an effluent chemical concentration analyzer. The signals are directed to a computerized chemical dose controller that analyzes and adjusts the data from the signals and generates an output signal that controls the chemical dosing mechanisms. For example, the automatic dose control method encompasses the ability to set maximum positive and negative limits of control action as well as the ability to automatically or manually control the reset period necessary to allow previous changes to propagate through the system and be displayed at the effluent sensor thereby improving the dosing of the chemical during treatment of a liquid, wastewater for example.