Optimization and modeling of reduction of wastewater sludge water content and turbidity removal using magnetic iron oxide nanoparticles (MION)

Abstract

Economic and rapid reduction of sludge water content in sewage wastewater is difficult and requires special advanced treatment technologies. This study focused on optimizing and modeling decreased sludge water content (Y₁) and removing turbidity (Y₂) with magnetic iron oxide nanoparticles (Fe₃O₄, MION) using a central composite design (CCD) and response surface methodology (RSM). CCD and RSM were applied to evaluate and optimize the interactive effects of mixing time (X₁) and MION concentration (X₂) on chemical flocculent performance. The results show that the optimum conditions were 14.1 min and 22.1 mg L⁻¹ for response Y₁ and 16.8 min and 8.85 mg L⁻¹ for response Y₂, respectively. The two responses were obtained experimentally under this optimal scheme and fit the model predictions well (R² = 97.2% for Y₁ and R² = 96.9% for Y₂). A 90.8% decrease in sludge water content and turbidity removal of 29.4% were demonstrated. These results confirm that the statistical models were reliable, and that the magnetic flocculation conditions for decreasing sludge water content and removing turbidity from sewage wastewater were appropriate. The results reveal that MION are efficient for rapid separation and are a suitable alterative to sediment sludge during the wastewater treatment process.

Keywords:

• Magnetic iron oxide nanoparticles (MION)
• mixing time
• RSM
• sludge water content
• turbidity

Funding

This study was supported by the Korea Ministry of Environment “Global Top Project” (Project No.: GT-11-B-02-008-2).