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Tikrit Journal of Engineering Sciences (2013) 20(1) 15-29
Effect of Recycle Ratio and Hydraulic Retention Time on the Performance of Extended Aeration Activated Sludge
|Waleed M. Sh. Alabdraba||Masood Mihsen Hazaa|
|Environmental Eng. Dept., Tikrit University, Iraq|
Three laboratory scale units are designed and constructed in order to perform the present work. These units are capable of working under different hydraulic retention time (HRT) (16-32hrs), recycle ratio (0.25–1.5), and temperature (20 -35 ̊C). The results show that BOD5, COD, NO3-1, PO4-3 removal is increased with increasing HRT and recycle ratio under different temperatures. The maximum removal efficiency of COD and BOD5 is 97.16 % and 97.99 % respectively under 24 hrs retention time, 1.5 recycle ratio and 20 ̊C. However, the maximum removal efficiency of NO3-1 (83 %) was obtained under the same mentioned condition except temperature which was 35 ̊C. The maximum removal efficiency of PO4-3 (76.59 %) is obtained at 32hrs HRT, 1.25 recycle ratio, and 20 ̊C. It is obvious from the results of the present work that BOD5, COD, and NO3-1 removal increased with increasing temperature while; PO4-3 removal is decreased with increasing temperature.
Keywords: Recycle Ratio, Hydraulic Retention Time (HRT), Temperature, Domestic Wastewater.