Air stripping for removal of Trichloroethylene (TCE), Chloroform (CF) and Dichloromethane (DCM) from water were studied in a bubble column (0.073 m inside dia. and 1.08 m height with several sampling ports). The contaminated water was prepared from deionized water and VOCs. The presence of VOCs in feed solution was single, binary or ternary components. They were diluted to the concentrations ranged between 50 mg/l to 250 mg/l. The experiments were carried out in batch experiments which regard the bubble column as stirred tank and only gas was bubbled through stationary liquid. In this case transient measurements of VOC concentration in the liquid phase and the measured concentration profiles were modeled by bubble aeration model (BAM) to fit the experimental data fairly well. The results from batch experiments show that the removal efficiency of VOCs increases with increasing gas flow rate or gas holdup. It is found a pH=10 give the best removal rate, but all experiments were adjusted at pH=8 which allow to study other operating conditions. TCE is being removed faster than the other two components for all systems and a single component was removed faster than binary or ternary system. The KLa values were evaluated by fitting the BAM to the experimental data. It is found that KLa increased with increasing gas flow rate and TCE exhibits the highest KLa values.
Abstract
The study discussed three areas in strategic thinking, namely, (patterns elements, outcomes) , this study aimed to measure extent to which strategic leaders have the type or types of patterns of strategic thinking, and measure the extent of their use of the elements of strategic thinking, and measurement of strategic thinking outcomes for managers at various levels , And to know the relationship between the modes of strategic thinking, elements and outcomes in organizations. the study included five banks and four hospitals and four colleges and universities, has been a research sample consisted of 168 individuals, distributed in positions (Director General , Director of Directorate , Director of
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An efficient networks’ energy consumption and Quality of Services (QoS) are considered the most important issues, to evaluate the route quality of the designed routing protocol in Wireless Sensor Networks (WSNs). This study is presented an evaluation performance technique to evaluate two routing protocols: Secure for Mobile Sink Node location using Dynamic Routing Protocol (SMSNDRP) and routing protocol that used K-means algorithm to form Data Gathered Path (KM-DGP), on small and large network with Group of Mobile Sinks (GMSs). The propose technique is based on QoS and sensor nodes’ energy consumption parameters to assess route quality and networks’ energy usage. The evaluation technique is conducted on two routing protocols i
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تعد الانتخابات بمثابة الطريق المؤدي إلى الديمقراطية كونها النمط الأكثر شيوعاً لمشاركة المواطنين في الحياة السياسية للبلدان واختيار ممثليهم في المجالس التشريعية، حيث أن مطلب إجراء انتخابات حرة ونزيهة لم يعد مطلباً داخلياً فحسب بل مطلباً دولياً يصرّ المجتمع الدولي على الوفاء به وهذا يلقي على عاتق كل دولة أن تضع من الضمانات ما يكفل ممارسة هذه الانتخابات ب
... Show MoreAnaerobic digestion (AD) is the most common process for dealing with primary and secondary wastewater sludge. In the present work, four pre-treatment methods (ultrasonic, chemical, thermal, and thermo-chemical) are investigated in Al-Rustumya Wastewater Treatment plant in order to find their effect on biogas production and volatile solid removal efficiency during anaerobic digestion.
Two frequencies of ultrasonic wave were used 30 KHz and 50 KHz during the pre-treatment. Sodium hydroxide was added in different amounts to give three pH values of 9, 10 and 11 in chemical pre-treating processes. The sludge was heated at 60oC and 80oC through thermal pre-treatment experiment. Also, the sludge was treated thermo-chemically at 80 oC and pH