Four control systems for wastewater treatment

Each control system replaces the conventional PID control of one part of the treatment process. Each runs alongside the plant's existing SCADA system, uses instruments from any supplier, and leaves operators in charge: operators can override it at any time, and faulty readings are not acted on.

DO/Nmaster: aeration, dissolved oxygen and ammonia

Calculates the airflow, dissolved oxygen and valve-position setpoints for each aeration grid, with ammonia-based control where ammonia analyzers are installed. In service at the Pomona Water Reclamation Plant and the City of Chico; under contract at Metro Water Recovery, Denver.

SRTmaster: sludge age and waste sludge

Calculates the waste sludge flow continuously from on-line measurements to hold the sludge age on target. First installed in 1996; in service at the Pomona Water Reclamation Plant, and at the City of Chico since 2014.

BLANKETmaster: clarifier and thickener sludge blankets

Sets the return sludge flow of each clarifier from its own measured sludge blanket depth. Under contract for the secondary clarifiers at the Pomona Water Reclamation Plant since October 2026.

CLmaster: chlorine dosage

Controls sodium hypochlorite and aqueous ammonia doses together to hold the disinfection target (CT). Full-scale work began in October 2026 at Pomona, in The Water Research Foundation Project 5385.

Why the control systems are independent

Ekster & Associates sells no hardware, no automation platform and no service contract that places a vendor inside plant operations. Why independence matters