Hydrous aluminum oxide particles precipitated from simulated wastewater were dispersed on mica substrates and examined using atomic force microscopy, adhesion force measurements, interfacial force microscopy (IFM), and zeta potential methods in order to understand their structural and coating properties. Results on IFM of the mica substrate are also reported. Three types of particles were examined: aluminum oxides coprecipitated by adding alum in the presence of a solution of phosphates and tannic acid; postprecipitated particles formed by adding phosphates and tannic acid to already formed aluminum oxides; a control case consisting of particles precipitated in the absence of either phosphate or organic component. In all cases, the particles all had similar values for the reduced modulus of the tip-sample system, although in the case of the postprecipitated particles there was evidence for the presence of a compliant organic coating. The adhesive force and zeta potential measurements were also consistent with this observation. The results are discussed in the context of the relative effectiveness of these aluminum oxides in removing phosphates and other contaminants from aqueous systems.