Crab cooker wastewater contains high concentrations of chemical oxygen demand (COD), total suspended solids (TSS), and total Kjeldahl nitrogen (TKN). Biological treatment of the wastewater releases high concentrations of ammonia. In this study, UASB treatment of crab cooker wastewater was evaluated, in terms of COD and TSS reduction, and compared with previous anaerobic treatment efforts. Additionally, UASB and UBF treatment of crab cooker wastewater was demonstrated with pilot-scale treatment units. The potential for air stripping to remove ammonia from biologically treated wastewater was evaluated. When treating unamended crab cooker wastewater, UASB performance appeared similar to UPF and UBF reactor performances reported by Diz and Boardman (1994). When treating unamended wastewater at a 0.25 day⁻¹ F/M ratio, a UASB reactor’s effluent soluble COD fluctuated and increased to above 6,000 mg/L. Batch toxicity assays indicated that unionized ammonia limited anaerobic treatment performance. Unionized ammonia concentrations of 41 and 120 mg/L (as nitrogen) caused 50 and 80 percent inhibition, respectively, of acetate utilizing methanogens. Acidification of the feed wastewater greatly enhanced UASB treatment performance by reducing reactor pH and wastewater feed suspended solids concentrations. When fed acidified wastewater at a 0.3 day⁻¹ F/M ratio, a UASB reactor’s effluent soluble COD was 1,220 mg/L. The wastewater feed TSS was reduced from 910 mg/L, prior to acidification, to 249 mg/L in the reactor’s effluent. An air stripping tower’s ammonia removal efficiency increased from 50 to 72 percent as the air flowrate increased from 9 to 21 m³/min. The average liquid loading rate and liquid temperature were 25 L/m²/min and 14° C, respectively. / Master of Science