Evaluation of pH, alkalinity and temperature during air stripping process for ammonia removal from landfill leachate

Abstract

The objective of this research was to evaluate the air stripping technology for the removal of ammonia from landfill leachates. In this process, pH, temperature, airflow rate and operation time were investigated. Furthermore, the relationship between the leachate alkalinity and the ammonia removal efficiency during the process was studied. The leachate used in the tests was generated in the Gramacho Municipal Solid Waste Landfill (Rio de Janeiro State, Brazil). The best results were obtained with a temperature of 60^oC, and they were independent of the pH value for 7 h of operation (the ammonia nitrogen removal was greater than 95%). A strong influence of the leachate alkalinity on the ammonia nitrogen removal was observed; as the alkalinity decreased, the ammonia concentration also decreased because of prior CO₂ removal, which increased the pH and consequently favored the NH₃ stripping. The air flow rate, in the values evaluated (73, 96 and 120 L air.h⁻¹. L⁻¹ of leachate), did not influence the results.

Keywords:

• Ammonia stripping
• carbon dioxide stripping
• Henry constant
• landfill leachate

Acknowledgments

The authors thank FAPERJ and CNPq for the financial support, and the COMLURB (Urban Clean Company of Rio de Janeiro Municipality) for the sample shipment.