VDM El Monayeri, O: Enhancement of DO Using Stepped Cascade Aera

Stream restoration has been a vital area of investigation over the past decade due to the huge quantities of untreated wastewater and pollutants being disposed by man depleting the levels of DO; thus affecting the performance of anaerobic bacteria that feeds on organic matter. Stepped cascade has proven to be an effective low cost simple technique that could enhance the quality of water. Various cascade heights, flowrates and organic loads were examined to test their effect on the performance of stepped cascade to enhance DO levels in wastewater. This has been accomplished via three phases presented in seven chapters; experimental work (field & laboratory), mathematical modeling (including Gameson, WRL, Nakasone, adjusted Nakasone) and computer modeling (Qual2k). The results in this work have proven the significance of considering the combined effect of flowrate and organic loads in the adjusted model to design optimum dimensions for a stepped cascade. Consequently, maximum possible level of aeration to rehabilitate stream water, wastewater, and hence protect the aquatic organisms and the surrounding environment could be attained.