Ammonia recovery via direct contact membrane distillation: Modeling and performance optimization

Area of Science:

• Environmental Science
• Chemical Engineering
• Water Treatment Technologies

Background:

• Ammonia recovery from wastewater prevents eutrophication and reduces energy use.
• Membrane distillation offers excellent separation for volatile substances like ammonia.
• Global optimization of direct contact membrane distillation (DCMD) parameters for ammonia recovery efficiency (ARE) was previously unattempted.

Purpose of the Study:

• To globally optimize DCMD operating parameters for maximizing ammonia recovery efficiency (ARE).
• To identify and model key factors influencing ammonia recovery via DCMD.

Main Methods:

• Plackett-Burman Design (PBD) identified feed ammonia concentration, feed pH, and DCMD running time as significant factors.
• Response Surface Methodology (RSM) with Box-Behnken design (BBD) modeled and optimized these parameters.
• Analysis of Variance (ANOVA) statistically verified the model's significance.

Main Results:

• The developed model showed a high coefficient of determination (R² = 0.99).
• Feed ammonia concentration and feed pH interaction significantly impacted ARE.
• Optimal parameters: 0.46 g/L NH₄Cl, pH 10.6, 11.3 h DCMD time, predicting 98.46% ARE.
• Experimental validation achieved 98.72% ARE, confirming model reliability.

Conclusions:

• The study successfully optimized DCMD parameters for ammonia recovery.
• The validated model provides a reliable tool for maximizing ARE in DCMD processes.
• Achieved high ARE demonstrates the effectiveness of optimized DCMD for wastewater nutrient management.