Disclosed is a multi-step method for producing an algae product from waste water treatment including: a waste consumption step including, combining, in a first vessel, organic waste products and phagotrophic-algae-consumable microorganisms capable of consuming said organic waste products, and allowing said phagotropic-algae-consumable microorganisms to consume said organic waste products to thereby grow said phagotrophic-algae-consumable microorganisms； and transferring said phagotrophic-algae-consumable microorganisms to a second vessel； and a phagotrophic-algae-consumable microorganism consumption step carried out after said waste consumption step, said phagotrophic-algae-consumable microorganism step including: adding phagotrophic algae to said second vessel, allowing said phagotrophic algae to consume said phagotrophic-algae-consumable microorganisms and thereby grow said phagotrophic algae； collecting a desired algae product from said phagotrophic algae.
