Treatment method for eutrophic water and device

The invention discloses a treatment method for eutrophic water. By utilization of the characteristic that the magnetic graphite powder reacts with pollutants with high efficiency and at a high speed, pollution factors such as resolvable COD, UV254, chromophoric substances, total nitrogen and total phosphorus in bio-chemical effluents are effectively removed. Alga in water is quickly separated according to the self-polymerization sedimentation of the magnetic graphite powder, and adsorption saturation magnetic carbon powder and alga mud flocs after alga is flocculated are regenerated and activated by a regeneration system, so that the magnetic graphite powder is recycled repeatedly. The invention further discloses a device for achieving the method. The treated effluents are clear, the alga and water separation efficiency and the treatment cost are far superior to those in the prior art, 300 to 10,000 kg of alga mud with larger than 10% of solid content can be obtained every hour, and a better effect on the quality of various eutrophic water is achieved.