| 摘要 |
PROBLEM TO BE SOLVED: To make the contact with water to be treated with powdery active carbon longer and utilize the powdery active carbon effectively by providing the device with a biological filtration tank and a powdery active carbon treatment tank for injecting powdery active carbon into water to be treated, and returning a part of the water to be returned which has been treated with powdery active carbon to the biological filtration tank. SOLUTION: Water to be treated fed into a filtration tank main body 1 of a biological contact filtration tank (a) through an inflow pipe 2 is biologically treated, and then passed through a communication valve 16 and fed into a storage tank 17. Powdery active carbon is injected into water to be treated fed from the storage tank 17 into a powdery active carbon treatment tank (b) constituted of a tank main body 5 and a powdery active carbon injector 13 disposed in a tank positioned on the most upstream side out of a plurality of tanks. Chromaticity, odorous substances, trihalomethane precursor substances of biological hard-to-decompose properties, agricultural chemicals, surface active agents and the like in the water to be treated are removed by the powdery active carbon treatment, and then a part of the water to be treated is introduced into a following process, and residual water to be treated is returned to the biological filtration tank (a) through a return pipe 8. |
