Optimizing ammonia volatilization by air stripping from aquatic solutions using response surface methodology (RSM)

Abstract

In the present work, ammonia removal by air stripping process is optimized using response surface methodology based on central composite design. The removal of ammonia was studied based on the obtained model. To determine the effect of the operating parameter on the rate of reaction, the kinetic was investigated. The most important parameters which can affect ammonia stripping such as ammonia concentration, pH, and temperature were optimized. The optimum ammonia concentration, pH, and temperature of air stripping process were obtained as 1,440 mg/L, 10.7, and 36°C, respectively. Under optimal conditions, effects of different flow rates were evaluated and the best volatilization was obtained using 3 L/min air flow rate. Maximum removal percentage was acquired as 84.11% at the end of 12 h of operating time. Analysis of Variance exhibited a reasonable correlation coefficient between the predicted and experimental values (R² = 0.97). Experimental results showed that the first-order kinetics with R² = 0.99 more fitted the removal data. According to the obtained results, correlation coefficient, volatilization rate, and half-life were obtained as 0.987, 0.1395/h, and 4.97 h, respectively.

Keywords:

• Ammonia
• Air stripping
• Kinetic
• Modeling
• RSM

Acknowledgments

The authors wish to acknowledge their gratitude for the financial support of Tarbiat Modares University and Northern Khorasan Water & Wastewater Company.