Investigation of carbon, nitrogen and phosphorus removal by advanced fixed biofilm activated sludge process

Conventional activated sludge systems have been used for over a century in the treatment of domestic wastewater. In recent years, in addition to carbon removal for the preservation of water resources, the removal of nitrogen and phosphorus has also become necessary, leading scientists to explore effective and sustainable methods. In this thesis, an advanced biofilm activated sludge system (IFAS) was applied in conjunction with a sequential batch reactor (SBR) that could be integrated into classical activated sludge processes. The IFAS-SBR system was operated with synthetic domestic wastewater for 5 study periods to investigate the removal of carbon (C), nitrogen (N), and phosphorus (P). Within the sequential batch reactor, mobile support media were filled at volumetric fill ratios of 20% and 40%, primarily for anaerobic (An)/aerobic (Ox)/anoxic (Ox) processes. The reactor operated with 2 and 3 cycles per day and hydraulic retention times (θH) of 24-36 hours, and sludge ages (θC) of 11.8-25.8 days were applied. During the study phases, the average removal rates were as follows: chemical oxygen demand (KOI) ranged from 92.7% to 96.2%, total nitrogen (TN) ranged from 60.2% to 95.5%, and phosphate phosphorus (PO4-P) removal ranged from 32.3% to 59.3%. The use of support media was observed to have a greater impact on tn removal, while no significant effect was observed on P removal. When the SBR reactor was used in conjunction with support media as IFAS-SBR, it was concluded that the fill ratios, loading conditions, cycle numbers, and phase sequences needed to be determined differently from those of classical SBR reactors. It was also determined that optimal operating conditions could be achieved to meet discharge standards. Although achieving a discharge water quality that meets the standards for phosphorus removal can be obtained through biological processes, it is suggested to consider alternative chemical removal of PO4-P.