BENEFICIAL EFFECTS OF TREATING WASTE SECONDARY SLUDGE WITH THERMALLY ACTIVATED PERSULFATE

BACKGROUND The presence of numerous emerging contaminants including antimicrobials in waste activated sludge requires an effective treatment to reduce the risk of their dispersion in the environment in the case of land application. The potential ability of activated persulfate oxidation for organic contaminant destruction and sludge dewatering was subjected to detailed study to show the benefits of this process on sludge treatment. RESULTS Treatment of secondary waste sludge with persulfate thermally activated by microwave heating (S2O82−/MW), conventional heating (S2O82−/heat) and simultaneous conventional heating and ferrous iron (S2O82−/heat/Fe2+) were evaluated comparatively for both antimicrobial degradation and variation of sludge properties. Regardless of the activation type used in persulfate treatment, high degradations of model antimicrobials and shortened capillary suction time used to evaluate sludge dewaterability were obtained, with high destruction of tightly and loosely bound fractions of the extracellular polymeric substances. CONCLUSION While S2O82−/MW treatment required shorter treatment period at 140 °C S2O82−/heat/Fe2+ treatment with a two-fold lower dose of oxidant at 75 °C provided several other advantages including the minimization of adsorbable organic halogen species in the liquid phase of the sludge, enhancement of the overall metal solubilization, and precipitation of solubilized phosphorus. © 2016 Society of Chemical Industry