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Hydrotech drumfilters (with or without addition of flocculant) are gravity-driven and self-cleaning units designed to achieve high performance with minimal footprint and low energy consumption.
The application studied in the frame of ETV verification is a primary treatment stage for raw municipal wastewater (after mechanical treatment, i.e. removal of sand, grit and grease) to enable removal of particulate matter.
Microscreen technology (drumfilter) employs woven cloth filter elements (100 microns in the studied case) installed on the periphery of the drum, and utilizes an inside-out flow pattern. The filter works with a few cm of water pressure gradient and is robustly designed with few moving parts to ensure long-life and low maintenance costs.
Water to be treated flows by gravity into the filter via the center drum. The media mounted on the partially-submerged drum separates solids from the water. The filtered water flows through the media into the collection tank. Once solids have accumulated, the media is cleaned by the counter-current backwash system. The filters are in continuous operation even during backwash and high solids events.
Flocculant can be added upstream the filter unit in order to improve the filterability of the particles. Such a feature allows for precise particle removal up to the values required by the user by careful control of the chemical dose.