A poly-Al-Zn-Fe (PAZF) coagulant was prepared using a galvanized aluminum slag as main raw material, and was characterized by Scanning Electron Microscopy (SEM), Infrared Spectroscopy (IR) and X-ray Diffraction (XRD). Simultaneous removal efficiency and mechanism of nitrogen (as NH3-N) and organic matters (as CODCr) during coagulation process in treating simulated fountain water by PAZF were investigated compared to those by poly-aluminum-chloride (PAC). The results indicated that PAZF has better coagulation performance than PAC: PAZF gave the greatest NH3-N and CODCr removal of 82% and 89% over the whole dosage range, respectively, in comparison with 17% and 57% by PAC. PAZF has stronger adsorption than PAC: PAZF has a large surface area which consisted of series of cauliflower head structure having some pleated ditches with different width and depth, in comparison with an irregular mountain appearance of convex-concave structure of PAC having a small surface area. PAZF has greater capability of neutralization/destabilization for pollutants than PAC: the amount of positive charge carried by the hydrolysis products of PAZF was more than that of PAC because PAZF was composed of more crystalline and amorphous substances and was a co-polymer of three metals of Al, Zn and Fe. PAZF gave higher nitrogen removal than PAC: PAZF was a coagulant containing much zinc (w(Zn) = 30.25%), so one of its hydrolysis products of "zinc of hydroxide system" can react with NH4+ and NH3 to give "zinc-ammonia ion complexing system" positively charged. Nitrogen removal mechanism by PAZF was a comprehensive action of coagulation and chemical reaction. (C) 2012 Elsevier B.V. All rights reserved.