Great variations

Auma Actuators explain how the company helped ITT Sanitaire enhance the ICEAS SBR system


Sequencing batch reactors (SBR) made their mark as an effective alternative to conventional activated sludge systems at WwTWs during the late 1950s and early 1960s. Over the last 50 years, the SBR's fill-and-draw system of treating and discharging undesirable components from wastewater has been widely adopted by utilities.

ITT Sanitaire's recent development, a variant on the SBR, is based on the intermittent cycle extended aeration system (ICEAS), where influent wastewater continually flows into the reactor. ITT Sanitaire's advancement has seen them using Auma Sipos actuators to meet the variable speed requirements of SBR decant operations at WwTWs.

Internalised intelligence
The ABJ SBR decanter upgrade incorporates Auma Sipos Flash 5 actuators and moves away from external componentry to integrate intelligent functions within the actuator. Among the technology enhancements provided is advanced data feedback with increased detail of decanter functionality.

Reliability and safety are key benefits of the system; advance warning is given regarding potential problems. Variable decanter movement is also provided, so as to give superior flow control for the SBR's fill-and-draw wastewater treatment activated sludge system.
ITT Sanitaire's SBR decanters used to use a metric screw jack mechanism driven by a separate variable-speed drive located in the motor control centre. The introduction of an integral actuator inverter means variable frequency drive-starters are no longer required and cabling costs are reduced.

Auma's Ian Sully explains, "ITT Sanitaire's ICEAS SBRs work on a time principle to treat the effluent they contain. Having been filled with effluent, air is blown from the bottom of the SBR to activate the sludge. The ICEAS SBR then rests so particles can fall to the bottom before the clean, treated liquid is decanted from the top of the SBR.

"Auma SIPOS technology was chosen to address the challenges of operating the decant arm, which performs continually throughout a 24-hour period.

"Unlike valves, the decant arm is required to lower very slowly onto the top of the water over a period of 70 minutes. Once at the decanting point, it remains at this position for a period of two minutes to allow the treated water to be drawn off. Having completed this process, the decant arm is required to raise to its top (parked) position for a period of twenty minutes.

"Based on this requirement it was clear that a standard actuator could not be used, due to fixed speed constraints. The Auma Sipos actuator, operating via an internal frequency converter, offers total and continual variation in speed.
"Other key benefits include integral controls and self-monitoring functionality. The actuator also contains torque and position-sensing to accurately feed back the position of the decant arm at any given time. Additionally, the motor temperature is monitored throughout the decant arm travel and a warning is sent to the control system if this temperature becomes excessive. It doesn't require the use of an external control system, as all required technology is incorporated within the actuator and units can be supplied with the latest digital two-wire control technology, for instance Profibus DP."

ITT Sanitaire's ICEAS SBR solution has been installed at four key utility sites in the UK and Hungary, while the seaside town of Charmouth in west Dorset was the location of the first treatment works to install the Auma Sipos Flash 5 actuators. Forming part
of a £4.5M programme by Wessex Water to upgrade the WwTW, the solution met the variable speed requirements of the works' decant operations. Various treatment options were considered to determine how best to re-develop the existing site and ITT Sanitaire's solution was selected on the basis of lowest cost and space efficiency.

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