Influence of ultrasonication and Fenton oxidation pre-treatment on rheological characteristics of wastewater sludge

• Published in: Ultrasonics sonochemistry Vol. 17; no. 1; pp. 38 - 45
• Main Authors: Pham, T.T.H., Brar, S.K., Tyagi, R.D., Surampalli, R.Y.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 2010; Elsevier
• Subjects: Biodegradability; Chemistry; Exact sciences and technology; Fenton oxidation; Filterability; General and physical chemistry; Hydrogen Peroxide - chemistry; Hydrogen Peroxide - radiation effects; Industrial Waste - analysis; Industrial Waste - prevention & control; Iron - chemistry; Iron - radiation effects; Materials Testing; Particle size; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Rheology; Sewage - analysis; Sewage - chemistry; Sonication - methods; Ultrasonic chemistry; Ultrasonication; Viscosity; Wastewater sludge; Water Pollutants, Chemical; Water Purification - methods; Ultrasonication; Particle size; Biodegradability; Rheology; Fenton oxidation; Filterability; Wastewater sludge; Viscosity; Correlation; Rheological model; Shear; Sonochemistry; Pump; Solid; Waste water; Thinning; Energy; Chemical treatment; Oxidation; Microorganism; Pretreatment; Transport; Ultrasound; Rheological properties
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2009.06.007

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.