title: Application of self-sustaining smouldering combustion for the destruction of wastewater biosolids.
abstract: Managing biosolids, the major by-product from wastewater treatment plants (WWTPs), persists as a widespread challenge that often constitutes the majority of WWTP operating costs. Self-sustained smouldering combustion is a new approach for organic waste treatment, in which the waste - the combustion 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 kJ/g). Moreover, results suggest that operator-controlled air flux can assist in keeping the reaction self-sustaining in response to fluctuations in biosolids properties. This proof-of-concept demonstrates the potential for smouldering as a new energy efficient biosolids disposal method for very wet (i.e., minimally processed) biosolids that may offer WWTPs significant operating cost savings. This study emphasizes smouldering's usefulness as a novel waste management technique.
authors.affiliation: Department of Civil and Environmental Engineering, University of Western Ontario, N6A 5B9 London, ON, Canada.
authors.forename: Tarek L
authors.initials: TL
authors.lastname: Rashwan
authors.affiliation: Department of Civil and Environmental Engineering, University of Western Ontario, N6A 5B9 London, ON, Canada. Electronic address: jgerhard@uwo.ca.
authors.forename: Jason I
authors.initials: JI
authors.lastname: Gerhard
authors.affiliation: Department of Civil and Environmental Engineering, University of Western Ontario, N6A 5B9 London, ON, Canada; Savron, 130 Stone Road West, N1G 3Z2 Guelph, ON, Canada.
authors.forename: Gavin P
authors.initials: GP
authors.lastname: Grant
mesh_terms: D012722:Sewage / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D014865:Waste Disposal, Fluid / Q000379:methods*; D018505:Waste Management
chemical_list: D012722:Sewage; D012989:Soil Pollutants
keywords: Biosolids; Self-sustaining; Sludge; Smouldering combustion; Waste management; Wastewater treatment