This treatment plant utilises a Sequential Batch Reactor (SBR) design. Many plants that serve communities with smaller populations use this design, but they are subject to foaming issues.
During the waste cycle, sludge moves from the bottom of the SBR basins into a waste basin where it undergoes aeration before being further processed. Due to the composition of this sludge, thick layers of foam sometimes develop within the waste basin during aeration.
As foam is made up of gas held in thin films of liquid, it is tough for traditional level measurement equipment to detect it. In this application, the customer only had a level transmitter capable of detecting water in the waste basin. The inability of this probe to detect foam posed a problem when confronted with a high foaming level situation.
There had been several instances, usually occurring when no one was on-site, where the foam would spill out of the basin without ever setting off a high-water level alarm. It would then seep into other areas of the plant, resulting in the need for a clean-up which would often take around 20 hours – a significant and costly disruption for the site. A solution was needed, and, following consultation with Hycontrol, the customer employed SmartFoam foam probes.
Site engineers installed two probes, each 150 cm long with a 20 mm diameter and EPDM sealing. SmartFoam utilises Hycontrol’s unique IMA® Sensing technology to detect contact with foam levels in the vessel and ignore any residue that may accrue on the probe.
A Site Instrument Technician picks up the story: “Ever since we have installed the Hycontrol foam probes in the waste basin, there has not been one instance of spillover. The probes connect to our SCADA system, which alarms during foam detection and signals the on-call operator. There have been several times when the probes have alarmed and prevented an over-foaming event. The savings from not having to spend 20 hours at a time cleaning up have covered the outlay for the foam control units and will on save future operating costs. The probes are easy to install and have been very reliable and accurate. I would not hesitate to purchase more if needed.”