Quick lime modification and coagulation performance of nano-inorganic polymer coagulants from oil shale ash

The nano-inorganic polymer coagulant, poly-ferric-aluminum-silicate-sulfate (PFASS) modified by quick lime were prepared from oil shale ash, which were evaluated by treating sewage. The following results are discovered: The samples contain (CaO)(x)SiO2 center dot zH(2)O, Fe-2(SO4)(2)(OH)center dot 5(H2O), NaAl(SO4)(2)center dot(H2O)(6) and other crystal; PFASS are complicated compounds by iron, aluminum, silicon and other ions rather than simple mixtures of raw materials. The optimal coagulant dosage is about 80-100 mg/L for the turbidity removal, and the range of the suitable dose is wider for COD removal, the optimal dose of quick lime is 2.5 g for turbidity removal and 3 g for COD removal.