Simultaneous nitrification and denitrification of real domestic wastewater using novel biodegradable Cocos Nucifera fibre as biofilter media and carbon source: performances and microbial community composition

Abstract

The simultaneous nitrification and denitrification (SND) performances in biofiltration system are largely governed by the filter media material and also the operating conditions. Moreover, a significant gap exists regarding the influence of different operating conditions on the SND performances in using plant-based waste materials as the biofilter media. Thus, in this study, long-term SND and organic pollutants removal were investigated in a continuous-flow biofiltration system filled with novel biodegradable Cocos nucifera fibre media operating under different dissolved oxygen (DO) concentrations, HRT and backwash intensity. Under best operating conditions of DO 1.5 mg/L, HRT 16.0 h, and airflow and water flow rate of 1.0 L/m2/s, the biofiltration system was able to remove an average of 70.7 % of NH3-N, 98.5 % of NO2-N, 90.3 % of COD, 86.9 % of soluble COD (sCOD), 98.7 % of TSS, 70.4 % of TN and achieved 94.3 % of SND efficiencies. The coexistence of enriched functional microorganisms such as nitrifiers (Nitrosomonas, Nitrospira) and denitrifiers (Dechloromonas, Zoogloea, Acidovorax) were believed to be responsible for the efficient performance of the system working under best operating conditions.