Performance of the unified clarifier packed with filter media (UC-FM) as a preliminary water treatment step

AbstractThe unified clarifier packed with filter media (UC-FM) is composed of three treatment tanks connected in series, and each tank is packed with porous filter media. As the downflow of untreated surface water is fed into the central cylinder of the tank, uniform upflow current in the outer area of the cylinder is concurrently made throughout the tank. The UC-FM system showed 80–90% removal in normal turbidity and above 90% removal in high turbidity. The average algae and COD removal by the system over 303 days operation were 80% and more than 90%, respectively. Precoagulation prior to the system improved the removal efficiency of the dissolved and particulate contaminants up to 99% without sand filtration or other consecutive treatment. The UC-FM system was operated any additional energy except for the intake of the raw water into the first tank. A negligible head loss was observed after almost 100 days operation and backwashing was not required.