Composition and method of use for tannin based environmentally benign polymeric coagulants are disclosed. Tannin based coagulants are copolymers of naturally occurring tannins and a cationic monomer. One embodiment of the present invention provides for a composition of a tannin based polymeric coagulant which is comprised of N,N-(dimethylaminoethyl)methacrylate (MADAME) polymerized using t-butylhydroperoxide and sodium metabisulfite. The resulting polyMADAME is converted to hydrochloride and then blended/reacted in an aqueous medium with tannin to obtain a homogenous poly(MADAME)-Tannin composition.The method of use comprises adding an amount of the composition effective for the purpose of clarifying oily wastewater from food and beverage, steel, automotive, transportation, refinery, pharmaceutical, metals, paper and pulp, chemical processing and hydrocarbon processing industries.