Using natural systems for wastewater treatment at Egyptian coastal resorts

Reuse of treated wastewater to develop landscape areas in touristic sites is a maJor consideration in any site development plan. There is a need, however to identify an alternative method of treating wastewater at these sites other than compact units which depend on mechanical and chemical processes that adversely affect the cost of development. Often overlooked is the idea that compact units also negatively impact the architectural layout in that they must be placed in a hidden location with no relation to the guest area for aesthetic reasons. The increasing use of natural treatment systems 111 various municipal and industrial applications makes them a logical candidate as an alternative design for tow-istic sites. These natural systems depend on the stimulation of natural (eg., biological) processes to produce a suitable yet flexible environment for treating wastewater. There are two major categories of natural treatment systems: terrestrial and aquatic including constructed wetlands. Therefore, a methodology is needed to determine the most appropriate natural system for a specific application. In this work, it is proposed to base the selection of the particular natural system on at least four criteria: (1) Size and occupation of the site, including subsequent wastewater flows; (2) wastewater quality characteristics and the treatment effectiveness required; (3) the anticipated appearance of the system and aesthetic compatibility with the overall architectural design; (4) odor control. Applying these criteria to the specific case of Egyptian coastal resorts, the constructed wetland system was selected. Moreover, experimental application of this system in Egypt has proven a capability for achieving effluent of sufficient quality for landscape irrigation. Actual design of a constructed wetland required the implementation of model equations incorporating the design wastewater flow, influent biochemical oxygen demand, required effluent B.O.D concentration, and the geometry of the wetlands basins. The proposed system utilizes two stages of treatment; the first is a subsurface flow system followed by free water flow. Once a conect sizing of physical/hydraulic elements of the design is completed, an architectural landscape model is proposed that makes full benefit of suitable plant selection and arrangement to achieve an aesthetic landscape pattern compatible with the function and objectives of Egyptian coastal touristic villages. Finally, this system represents a genuine environmental care of these sites and an example of rural development with maximum consideration of nature