In this study, the conditions for coagulation and filtration to gain high phosphorus removal efficiency were investigated with a coagulation-filtration phosphorus removal system and its practicability was confirmed. Sand of 0.6 mm in diameter, anthracite of 1.2 mm in diameter and a mixture of both were examined as a filter media, and the dual filter bed proved to be superior in the aspects of pressure drop and breakthrough. This system can be operated continuously for over 20 hours. A blocked filter bed can be recovered by backwashing. Over 80% phosphorus removal efficiency is achieved at an LV of under 5.0 m·hr−1. when the PAC dose is controlled so that the A1/P mole ratio would be 3.0 for the first period, and then subsequently around 2.0. Flocs caught in the filter further adsorb the soluble phosphorus in the wastewater, thus the chemical requirement can be reduced compared to the chemical precipitation method.

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