title: Influence of ultrasonication and Fenton oxidation pre-treatment on rheological characteristics of wastewater sludge.
abstract: The effect of ultrasonication and Fenton oxidation as physico-chemical pre-treatment processes on the change of rheology of wastewater sludge was investigated in this study. Pre-treated and raw sludges displayed non-Newtonian rheological behaviour with shear thinning as well as thixotropic properties for total solids ranging from 10 g/L to 40 g/L. The rheological models, namely, Bingham plastic, Casson law, NCA/CMA Casson, IPC Paste, and power law were also studied to characterize flow of raw and pre-treated sludges. Among all rheological models, the power law was more prominent in describing the rheology of the sludges. Pre-treatment processes resulted in a decrease in pseudoplasticity of sludge due to the decrease in consistency index K varying from 42.4 to 1188, 25.6 to 620.4 and 52.5 to 317.9; and increase in flow behaviour index n changing from 0.5 to 0.35, 0.62 to 0.55 and 0.63 to 0.58, for RS, UlS and FS, respectively at solids concentration 10-40 g/L. The correlation between improvement of biodegradability and dewaterability, decrease in viscosity, and change in particle size as a function of sludge pre-treatment process was also investigated. Fenton oxidation facilitated sludge filterability resulting in capillary suction time values which were approximately 50% of the raw sludges, whereas ultrasonication with high input energy deteriorated the filterability. Biodegradability was also enhanced by the pre-treatment processes and the maximum value was obtained (64%, 77% and 73% for raw, ultrasonicated and Fenton oxidized sludges, respectively) at total solids concentration of 25 g/L. Hence, pre-treatment of wastewater sludge modified the rheological properties so that: (1) the flowability of sludge was improved for transport through the treatment train (via pipes and pumps); (2) the dewaterability of wastewater sludge was enhanced for eventual disposal and; (3) the assimilation of nutrients by microorganisms for further value-addition was increased.
authors: INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec, Canada.
authors: T T H
authors: TT
authors: Pham
authors: S K
authors: SK
authors: Brar
authors: R D
authors: RD
authors: Tyagi
authors: R Y
authors: RY
authors: Surampalli
mesh_terms: D006861:Hydrogen Peroxide / Q000737:chemistry* / Q000528:radiation effects; D007220:Industrial Waste / Q000032:analysis* / Q000517:prevention & control; D007501:Iron / Q000737:chemistry* / Q000528:radiation effects; D008422:Materials Testing; D012722:Sewage / Q000032:analysis* / Q000737:chemistry*; D013010:Sonication / Q000379:methods*; D014783:Viscosity; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods
chemical_list: C045076:Fenton's reagent; D007220:Industrial Waste; D012722:Sewage; D014874:Water Pollutants, Chemical; D006861:Hydrogen Peroxide; D007501:Iron