Abstract: To provide a new technique for efficiently recovering microplastics from water to be treated, in which problems of conventional techniques such as large energy consumption are solved. A method for recovering microplastics from water to be treated containing the microplastics, the method comprising a step of allowing algae having microplastic adsorption and recovery ability to be present in the water to be treated, in which the algae are algae that secrete a sticky substance, and an amount of a sticky substance secreted by the algae is such that a volume of a sticky substance secreted to an outside of cells is 0.25 times or more and 100 times or less compared to a cell volume.

Abstract: Provided is a technique capable of efficiently removing nitrogen contained in water to be treated and efficiently recovering microplastics from the water to be treated. An aspect of the present invention is a water treatment system 10 including an aquaculture tank 20 and a water treatment tank 30. Aquatic organisms are cultivated in the aquaculture tank 20. In the water treatment tank 30, algae having a microplastic adsorption and recovery ability grow in the water to be treated introduced from the aquaculture tank 20. The microplastics contained in the water to be treated are recovered, and the nitrogen compounds contained in the water to be treated are removed, by the algae.

Abstract: To provide a new technique for efficiently recovering microplastics from water to be treated, in which problems of conventional techniques such as large energy consumption are solved. A method for recovering microplastics from water to be treated containing the microplastics, the method comprising a step of allowing algae having microplastic adsorption and recovery ability to be present in the water to be treated, in which the algae are algae that secrete a sticky substance, and an amount of a sticky substance secreted by the algae is such that a volume of a sticky substance secreted to an outside of cells is 0.25 times or more and 100 times or less compared to a cell volume.