The Challenge of Making Wastewater Treatment Plants Composed by Anaerobic Reactors Capable of Removing Nitrogen

Both domestic and industrial effluent treatments contain or produce nitrogen loading during the treatment process. It is important to seek the removal of nitrogen while maintaining the design of existing systems, which are usually composed by the association of anaerobic and aerobic reactors. Thus, in this research, an anaerobic filter (AF) and an upflow anaerobic sludge blanket (UASB) reactors were fed with synthetic effluent enriched with nitrate to compare how these reactors would behave if they became denitrifying reactors. With the application of 100.0 mg NO3--NL-1, the AF presented better efficiency. With respect to the biogas production, the composition was significantly altered: from CH4 and CO2 concentrations close to 70% and 13% without NO3N addition to N-2 concentration higher than 85% with addition of 100.0 mg NO3--NL-1. The UASB hydrodynamic profile was modified due to an increase in the mixing behavior along the denitrification stages by biogas production. This was not observed in the AF due to the presence of the support media, which was also responsible for ensuring a greater capacity to withstand denitrification without organic matter being carried out of the system.