Operators keep authority over the plant
Ekster & Associates' control systems adjust aeration, sludge wasting, return sludge and chlorine dosing automatically and continuously. They assist operators; they do not replace them.
What operators control
- Targets and limits. Operators set the setpoints and the limits within which the system operates, through the operator interface.
- Override at any time. Operators can override any control loop at any time.
- The existing equipment. The system sends setpoints to your SCADA system. Your PLCs continue to run the blowers, valves and pumps.
- If the control system stops. If the control system or its communication link stops, the plant's own control system (PLCs or SCADA) responds according to the fallback logic programmed for that plant.
What happens when an instrument gives a faulty reading
- Every reading is checked before it is used: spikes, frozen values, values out of range and changes faster than the process can physically produce.
- Faulty readings are detected and not acted on, and operators are alerted.
- In the twenty years to 2016, at SRTmaster installations, there is no recorded incident of the controller acting on an erroneous instrument signal (WEFTEC 2016).
Less routine work
- Fewer laboratory tests. With on-line sludge age control, laboratory suspended solids tests for process control were reduced by as much as 90% (WEFTEC 2016).
- Less frequent calibration. With automatic detection of sensor drift, suspended solids meter calibration was reduced to one to three times a month (WEFTEC 2016).
- No daily wasting calculation. SRTmaster calculates the sludge age from on-line measurements and sets the waste flow automatically.
- Fewer settling and foaming problems. Stable sludge age reduced Nocardia foaming at Sacramento Regional and at other plants, and improved sludge settling (WEFTEC 2016).
Outside staffed hours
At the City of Chico, the plant is staffed 8 hours a day and the activated sludge system operates unattended for the rest of the day. SRTmaster has been in service there since 2014, and DO/Nmaster since 2018.
From a plant manager
"The performance of these systems has been exceptional, and they substantially helped the City increase performance and reliability of the Plant while reducing long term costs and maintaining regulatory compliance." James Carr, Plant Manager, City of Chico
Speak with plant staff who use it
Plant staff at Chico and Pomona are available to speak with other utilities.