Biofiltration of Ammonia Gas with Sponge Cubes Coated with Mixtures of Activated Carbon and Zeolite

Abstract

Removal of ammonia gas was investigated using a biofilter system packed with small cubes of polyurethane sponge that were coated with a powder mixture of activated carbon and natural zeolite. Experimental tests and measurements include removal efficiency, pH, metabolic products fo ammonia and kinetic analysis. A removal efficiency over 90% can be obtained with ammonia concentrations below 150 ppm and at contact times above 23 sec. The ammonia adsorbing power of the present biocarrier can protect the biofilter system from a high ammonia shock loading in the feed. The maximum removal rate, V_m, obtained from the kinetic analysis is 8.47 g N (kg carrier)⁻¹ day ⁻¹ and the saturation constant K_s is 59.36 ppm. Nitrite is produced dominantly during the entire experiments. The cell number of nitrifying bacteria is 1.58 × 10 ⁹ cell (g carrier)⁻¹. The present synthetic bio-carrier is considered to be one of the best among bio-carriers that have been used for the biofiltration of ammonia.

Keywords:

• Biofiltration
• Ammonia removal
• Polyurethane foam
• Activated carbon
• Zeolite