Effect of C/N ratio, temperature, and pH on the removal of ammonia-nitrogen from wastewater using inverse fluidized bed biofilm reactor

Abstract

Experiments have been carried out in an inverse fluidized bed biofilm reactor (IFBBR) to study the effects of carbon to nitrogen (C/N) ratio, temperature (T), and pH on the removal of ammonia-nitrogen (NH₄⁺-N) from wastewater using mixed microbial-culture. IFBBR is operated at settled bed volume to reactor volume ratio (V_b/V_r) of 0.380, superficial gas velocity (U_g) of 0.0085 m/s, and liquid recirculation velocity (U_l) of 0.0021 m/s. Three initial NH₄⁺-N concentrations (40, 100, and 200 mg/L) are considered here. Effects of different parameters are studied for wastewater treatment by varying C/N ratio from 0.0 to 2.5, T from 26 to 34°C, and pH from 7.5 to 9.0. Maximum NH₄⁺-N removal is observed at C/N ratio of 0.0, T of 30°C, and pH of 8.3. NH₄⁺-N removal is found to decrease with increase in C/N ratio. Both NO₃^--N formation and nitrification percentage are found to decrease with increase in C/N ratio and initial NH₄⁺-N concentration. Fractional Factorial Design analysis is used to predict the NH₄⁺-N removal. Average absolute percent deviation is found to be 11.75 implying the proposed correlation is in good agreement with experimental values. Kinetic constants are found to be higher than the values reported in literatures.