NOVELTY - A waste water treatment agent comprises coagulative precipitation reagent and neutralization absorbent.    USE - A wastewater treatment agent for processing potato starch.    ADVANTAGE - The agent converts waste to usable substance thus reducing pollutants.    DETAILED DESCRIPTION - A waste water treatment agent comprises coagulative precipitation reagent and neutralization absorbent. The coagulative precipitation reagent is pickling solution produced in the implementation of ZL01144627.7 Crystal Processing Waste Oil Sand Comprehensive Treatment Method and 200410034004.8 Crystal Processing Waste Sand Treatment Method to remove silicon oxide; having a pH value of 1-4; and containing 10-30% ferric chloride, 30-10% ferrous chloride, and 2-5% hydrochloric acid. The neutralization absorbent is an alkali wash in implementation of ZL01144627.7 Crystal Processing Waste Oil Sand Comprehensive Treatment Method and 200410034004.8 Crystal Processing Waste Sand Treatment Method to remove silicon dioxide; having a pH of 10-14; and containing 10-30% sodium silicate, 1-3% sodium hydroxide and 1-5% silicon oxide. An INDEPENDENT CLAIM is included for a wastewater treatment method for treating potato starch comprising:    (A) adding 3-5% coagulative precipitation reagent to discharged wastewater to acidify the wastewater;    (B) coagulating, precipitating, stratifying and clarifying dissolved sugar, potato resin, protein and fiber in the wastewater to obtain brown flocculent sludge and transparent light green supernatant liquid having 60-80% reduced chemical oxygen demand and biological Oxygen;    (C) transporting the supernatant liquid to neutralization pond;    (D) adding neutralization absorbent (same quantity with reagent);    (E) mixing and reacting neutralization absorbent and coagulative precipitation reagent to generate absorptive and active silicone gel, salt and ferric oxide;    (F) coagulating, precipitating, stratifying and clarifying the treated water to further remove sugar and pigment to obtain brown flocculent sludge, and colorless and tasteless supernatant liquid; and    (G) recycling part of the obtained supernatant liquid to sweet potato slurry for producing starch, and transporting remaining part to water purifying pond before discharging.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic view of a wastewater treatment method for treating potato starch.