Electronic Thesis and Dissertation Repository


Master of Engineering Science


Civil and Environmental Engineering


Dr. Jason I. Gerhard


Managing biosolids, the major by-product from wastewater treatment plants (WWTPs), persists as a major global challenge that often constitutes the majority of WWTP operating costs. Self-sustained smouldering is a new approach for organic waste treatment, in which the waste (i.e., the fuel) is destroyed in an energy efficient manner after mixing it with sand. Smouldering has never been applied to biosolids. Column experiments, using biosolids obtained from a WWTP, were employed to identify if - and under what conditions - smouldering could be used for treating biosolids. The parameter space in which smouldering was self-sustaining was mapped as a function of key system metrics: (1) sand/biosolids mass fraction, (2) biosolids moisture content, and (3) forced air flux. It was found that a self-sustaining reaction is achievable using biosolids with water content as high as 80% (with a biosolids lower heating value greater than 1.6 MJ/kg). Moreover, results suggest that operator-controlled air flux can assist in keeping the reaction self-sustaining in response to fluctuations in biosolids properties. An economic analysis suggests that smouldering could be a cost-effective management approach for WWTP biosolids in a number of scenarios by providing on site destruction with minimal energy input and limited preliminary dewatering.