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| Although the Escalator Fine Screen is new to North America, it is widely used in Europe. Over 600 such screens have been installed in the UK. |
Not glamorous but unique to North America
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| Although the Escalator Fine Screen is new to North America, it is widely used in Europe. Over 600 such screens have been installed in the UK. |
The Greater Napanee Water Supply and Pollution Control Board in Ontario has recently put on stream its new head-works treatment process the first such system in North America. It comprises a Mectan® Vortex Grit Chamber, a Sam® Dewatering Screw, a Rotopac® Washing Compactor and, for the first time in North America, an Escalator® Fine Screen replaces manually cleaned horizontal grit chambers and a comminutor.
The Escalator gives continuous fine screening for channel type applications with very few moving parts below the water level. Perforated stainless steel screen panels are carried on heavy-duty chains and incorporate holes of 1/4 inch (6 mm) diameter, giving fine screening in any direction. The screen panels are specially formed to create steps, which remove larger solids, and increase the effective screening area.
Both, board manager Max Christie and Todd Harvey, operations manager, are convinced the system will pay for itself in the reduction of manual labour in cleaning downstream pumps and process tanks, as well as wear and tear on other mechanical equipment.
"Some areas of the process, including a digester recirculation pump and tank weirs, would require cleaning two or three times per day," said Todd Harvey. "The new system, which has been up and running for the last few months, has already made a difference in the downstream processes. Rather than manually removing the debris which is now removed by the headworks, operators' time can be spent in more productive ways," he added.
The Escalator, when coupled with a washer compactor, also breaks up larger biodegradable materials, returning them to the liquid process stream where they are more optimally treated in the secondary treatment process. Wastes from the Escalator are expelled as a relatively dry, compact plug, suitable for disposal as solid waste.
R.V. Anderson and Associates assisted Napanee with the headworks equipment selection. A major problem formerly experienced at the Napanee plant was plastics and other floatable inert substances passing directly into the downstream systems.
Lifestyle changes, especially the greater use of plastics, have resulted in a wider variety of objects entering the wastewater stream. The system filters out those objects society generally doesn't think twice about flushing down the drain, either knowingly or inadvertently. Besides plastics, rags, and other larger objects, the Escalator Fine Screen is also removing a significant amount of hair. The net effect is not only reduced equipment maintenance but also the anaerobic digester cleaning frequency will be significantly reduced.
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