WATER TREATMENT METHOD AND WATER TREATMENT SYSTEM

摘要

One embodiment of the present invention provides a water treatment method. This water treatment method comprises: a process wherein a filtration assistant, which contains magnetic material primary particles or aggregates thereof and a coating material that covers the magnetic material primary particles or aggregates thereof and that has a critical surface tension (gammac) of 22 × 10-3 N/m or less, is prepared; a process wherein the filtration assistant is mixed with a dispersion medium, thereby forming a suspension in which the filtration assistant is dispersed in the dispersion medium; a process wherein the suspension is filtered through a filtration membrane so as to form a precoat layer containing the filtration assistant on the filtration membrane, and then water to be treated containing a solid content is caused to pass through the precoat layer and the filtration membrane so that the solid content is adsorbed and trapped by the filtration assistant in the precoat layer, thereby separating the solid content from the water to be treated; a process wherein water is poured onto the precoat layer so that the precoat layer is separated from the filtration membrane, thereby obtaining a mixture of the separated precoat layer, the solid content trapped in the precoat and the water poured in the precoat layer; and a process wherein the filtration assistant is magnetically separated from the mixture.