Biofilm development and ammonia removal in the nitrification of a saline wastewater

The present work investigated biofilm development and process parameters in the nitrification of a synthetic saline wastewater (50 g l−1 NaCl) in reactors known as ‘submerged aerated biological filters’. The support used for biofilm development was made of PVC wrinkled plates with large specific area (138 m2 m−3) and high porosity (> 95%). Biofilm development on the support was investigated by cultivating the mixed culture batchwise. In the first week of operation, a brown biofilm was macroscopically evident on the support surface. After 10 days the biofilm activity became stable, an ammonia removal rate of 2 g NH3 m−3 h−1 was observed and the attached biomass reached a maximum value of 172 μg cm−2. When the system was operated continuously, with a hydraulic retention time of 15 h, the removal efficiency observed was 94% in the absence of NaCl and 48% in the presence of 50 g l−1 NaCl.