Treatment of pharmaceutical effluent using novel heterogeneous fly ash activated persulfate system

In this work, a novel heterogeneous fly ash activated persulfate oxidation was proposed for the degradation of pharmaceutical effluent. The results showed that, inexpensive and difficult to degrade waste material-fly ash has the potential to degrade and mineralize the effluent effectively. In this work, two different fly ashes, one with high iron content (FA1) and another with less iron (FA2) were employed as activator. The effect of reaction time, temperature, initial pH, dose of fly ash and agitation rate on COD and TOC reduction was analyzed for both FA1 and FA2. At lower temperatures, FA1 catalyzed persulfate oxidation effectively due to the presence of high % of iron. On the other hand, at higher temperatures, both FA1 and FA2 performed in similar way as heat was acted as activator in persulfate oxidation. Maximum degradation was achieved at highly acidic conditions and the degradation decreases with increase in pH till 7.0 beyond which little increase in degradation was observed. Increase in fly ash dose enhanced the degradation. Presence of un-burnt carbon, alumina, silica and other metallic oxides on fly ash produced better adsorption. The activation energy of degradation process was found to be significantly less (23.32 kJ/mol) during the use of FA1 in comparison with FA2 (47.64 kJ/mol). The degradation process was found to follow pseudo first order kinetic model. The effluent treated using FA1 produced less toxic wastewaters than FA2. This study clearly illustrates the efficacy of fly ash on persulfate oxidative degradation of industrial effluent.