Enhanced COD and nutrient removal efficiency in a hybrid integrated fixed film activated sludge process



Nowadays, innovative processes especially processes with integrated growth (combined attached and suspended growth) such as moving bed biofilm reactor (MBBR) and integrated fixed film activated Sludge (IFAS) are being used successfully for new construction and upgrading existing wastewater treatment plants. Increasing the hydraulic capacity, COD and nutrients removal from the effluent are the two main targets of applying these processes. In this research the efficiency of a new version of IFAS reactor was studied at pilot plant scale in Ekbatan municipal WWTP in Tehran, Iran. In this new reactor (which is called H-IFAS reactor) aerobic, anoxic and anaerobic zones were designed in a single reactor and, as a result, the conditions of doing nitrification, denitrification, phosphorus removal and increasing BOD removal rate in the reactor were optimized in comparison with IFAS and MBBR. The media used in this reactor was Bee-Cell2000 with a total specific surface area of 650 m2/m3. In optimum conditions, the organic degradation rate of the anaerobic and aerobic zone with an average temperature of 23.48 °C OLR=22.5 kg COD/m3 day for the anaerobic zone and OLR 8.66 kgCOD/m3 day for the aerobic zone, was equal to 3.56 and 6.22 kgCOD/m3 day respectively. Nitrification and denitrification rate of media with an average temperature of 23.48 °C, HRT=1.26 hr was equal to 532.77, 723.42 and 168.4 gN/m3 day respectively. Biological phosphorus removal rate of the reactor at the best operational conditions with a phosphorous loading rate of 243 g P-PO4 /m3 day, an average temperature of  23.48 °C, and HRT 27 min was  equal to 168.4 g P-PO4 /m3 day