ASSESSING THE PERFORMANCE OF IFAS SYSTEMS TO RAISE THE CAPACITY OF EXISTING WWTP

Ola D.S. EL- monayeri, Abul-abbas E. Galal

Abstract


This paper focuses on using the Integrated Fixed-film Activated Sludge (IFAS) technology to retrofit wastewater treatment plants (WWTPs) specially those who are apt to receiving high fluctuations in organic loads. A model was constructed at the WWTP in the city of Zenien, Giza, Egypt, to study three flowrates: 1.013 m3/d, 3.04 m3/d, and 6.08 m3/d with hydraulic retention times (HRTs): 18, 6, and 3 hours, respectively to be implemented for extended aeration system (EAS) IFAS technology.Field-obtained results were validated using computer modeling; GPS_X which is a vital tool in the evaluation of operating treatment plants. Results show that the EAS performs well with a HRT of 18 hours where the removal efficiency ranges from 85 to 92 % for BOD5, COD, and TSS, which complies with literature except for TKN which is about 77%. However the system fails to target the acceptable removal efficiency when the HRT decreases to 6 and 3 hours, the efficiency being in the range of 57 to 72 % for the 6 hr HRT and in the range of 34 to 66 % for the 3 hour HRT. This indicates that the extended aeration process cannot resist high variations in organic loads or incoming flowrate. For the IFAS system used in this study, much better removal efficiencies are achieved. For HRT 18 hr, the removal ratio is 92% for BOD, COD and TSS and 80% for TKN, which is a higher level of performance compared to the extended aeration process. Furthermore, for the 6 hour HRT, the ratio ranges from 90 to 92 % for BOD, COD, and TSS and 80 % as well for TKN and, similarly, for the 3 hour HRT except that the removal of TKN decreases to about 75 %. Despite these promising results, further efforts would be recommended to identify reliable and profound design criteria for the IFAS technology as is the case with existing conventional and extended activated sludge systems

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