As the water pollution by plastic waste was worsening, the importance of the treatment for microplastic is emphasized. The conventional water treatment process requires a lot of time to floc sedimentation, waiting for flocs to fall by gravity. And these collected flocs are contaminants that must be treated additionally for clean disposal. In this study, electrocoagulation-magnetic separation process which can form Fe₃O₄-PE floc, and can separate flocs instantly using the magnetism was proposed. The inhibition effect on photodegradation induced by Fe₃O₄ was observed. But, this effect was successfully removed by oxalic acid treatment. To recycle Fe₃O₄ to anode active material for lithium-ion battery, heat-treatment was conducted. Replacing a part of graphite to heat-treated floc, the capacity was increased from 249 mAh g-1 to 387 mAh g-1. The well-designed electrocoagulation-magnetic separation process can allow the treatment of microplastic from water in eco-friendly and zero-waste manner.