Use of Air Stripping Technology to Remove Ammonia from Biologically Treated Blue Crab Processing Wastewater

Abstract

Crab cooker wastewater contains high concentrations of chemical oxygen demand (COD), total suspended solids (TSS), and total Kjeldahl nitrogen (TKN). Anaerobic biological treatment of the wastewater releases high concentrations of ammonia. In this study, the potential for air stripping to remove ammonia from wastewater which was treated biologically under anaerobic conditions was evaluated. An air stripping tower's ammonia removal efficiency increased from 50 to 72 percent as the air flowrate was increased from 9 to 21 m3/min. The average liquid loading rate and liquid temperature were 25 L/m2/min and 14GC, respectively. Ammonia stripping efficiency increased as the stripping factor was increased from one to three; however, under the conditions of this study (2,3 inch LanPac packing and countercurrent tower), stripping factors from two to three were only possible at low liquid loading rates (less than 41 m-Vm2/min) due to pressure drop considerations. At liquid loading rates less than 41 m-Vm2/min, the product of the overall mass transfer coefficient (KL) and the specific interfacial area (a) increased with increasing liquid loading rate, probably because more of the packing surface was wetted at higher liquid loading rates.