Optimization of coagulation-flocculation process for pulp and paper mill effluent by response surface methodological...

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Chemical Engineering

Background:

• Coagulation-flocculation is an established method for treating wastewater laden with high concentrations of suspended solids.
• Pulp and paper mill wastewater presents unique challenges due to its high suspended solids content.
• Optimizing process variables is crucial for maximizing efficiency and achieving desired treatment outcomes.

Purpose of the Study:

• To optimize the coagulation-flocculation process for pulp and paper mill wastewater.
• To determine the ideal coagulant dosage and pH for enhanced total suspended solids (TSS) removal, reduced sludge volume index (SVI), and increased water recovery.
• To develop predictive models for treatment efficiency based on operating parameters.

Main Methods:

• Application of central composite face-centered design (CCFD) and response surface methodology (RSM).
• Systematic variation of coagulant dosage and pH as key operating variables.
• Statistical analysis including Analysis of Variance (ANOVA) to develop quadratic models and assess variable interactions.

Main Results:

• Significant interactions between coagulant dosage and pH were observed for TSS removal and SVI.
• No significant interaction was found between coagulant dosage and water recovery.
• Developed quadratic models with a high coefficient of determination (R(2) > 0.99) for TSS removal, SVI, and water recovery.
• Identified optimal conditions: 1045 mg/L coagulant dosage and pH 6.75.
• Achieved 99% TSS removal, an SVI of 37 mL/g, and 82% water recovery under optimal conditions.

Conclusions:

• The study successfully optimized the coagulation-flocculation process for pulp and paper wastewater.
• The developed models accurately predict treatment performance, enabling efficient process control.
• Optimal conditions provide a viable solution for high-efficiency wastewater treatment, resource recovery, and sludge management in the pulp and paper industry.