Nitrogen removal from opto-electronic wastewater using the simultaneous partial nitrification, anaerobic ammonium oxidation and denitrification (SNAD) process in sequencing batch reactor

Abstract

Simultaneous partial nitrification, anaerobic ammonium oxidation and denitrification (SNAD) system was applied to treat the opto-electronic industrial wastewater in a 2.5L sequencing batch reactor. The characteristics of wastewater were low C/N ratio (∼0.2) with 100mg-COD/L and 567mgNH4+-N/L. The experiment was carried out over 8months in six different stages, where nitrogen loading rate was gradually increased from 16g-N/m3d in stage I to 230g-N/m3d in stage VI. The COD and nitrogen removal rates by the SNAD system reached to 28gCOD/m3d and 197gNH4+-N/m3d, respectively in stage VI. These results showed that the SNAD system is suitable to treat wastewater containing high nitrogen pollutants with low COD level. Presence of ammonium oxidizing bacteria and anammox bacteria were confirmed by polymerase chain reaction (PCR). PCR results also indicated that Candidatus Kuenenia stuttgartiensis may be one of the dominant species in the reactor.