The objective of this research is to study the effect of ambient temperature on the activity of aerobic bacteria in the activated sludge process and consequently, the efficiency of biological treatment of domestic sewage. The activated sludge process is one of the environment-friendly systems so as the progressive enhancement of the system is quite essential. In rural zones are military troops zones like Air-Force airports that are mostly located in rural zones where global sewerage system cannot be provided. Such situations need an optimized, integrated simple and potential treatment system for the sewage generated from the residents and personnel working over there. The target of optimizing the activated sludge is conducted intensively within this research via investigating the inter-relationships of temperature, dissolved oxygen as well as the efficiency of biological treatment process. All of these parameters are elaborated by measuring the decrease in (BOD5, COD and TSS). An experimental model scale system has been designed and built-up at El-Berkah Sewage
Treatment Plant site located to the north-east of Cairo, Egypt. The experimental system is fed with primary-treated sewage. The characteristics of experimented sewage have been varied widely over the experimental period that extended to more than one year. Samples of wastewater have been collected every week and analyzed for many parameters including (DO, TSS, BOD5, COD) as well as solid fractions. The experimental set up is scaled for temperature changes only in the range of (10-45oC) and dissolved oxygen (2-4) mg/l. All other operating parameters such as dissolved O2 and MLTSS are set constant all over the experimental period. The results of the experimental work reveal that the optimum operating temperature of the system is 25oC with respect to the removal of (TSS, BOD5) and COD (93, 97, and 95% respectively). Besides, it is shown that when the ambient temperature is in the range of 10-20oC, DO should be increased to raise removal ratio. On the other hand, when the temperature is raised more than 35oC, DO showed considerable decreases accompanied with indications of generation of filamentous bulking.