Cost of reclaimed municipal wastewater for applications in seasonally stressed semi-arid regions

The effectiveness and the cost of wastewater treatment options appropriate for different uses of reclaimed water in seasonally stressed regions are evaluated. Data are for applications in locales of the semi-arid regions of the Mediterranean rim and islands. These regions experience water demand stresses mainly from seasonally intense tourism and agriculture. With precipitation-derived resources fixed, recycled treated wastewater is a non-traditional, potentially cost-effective alternative water source that can be secured to meet certain demands. Different levels of wastewater treatment have been studied, T_i, satisfying effluent quality standards corresponding to four final effluent destinations: T₁, for a sea outfall or surface waters (zero-alternative, for comparison); T₂, for irrigation (USEPA guidelines); T₃, for aquifer recharge by infiltration from spreading fields (guidelines of the California Department of Health Services) and T₄, for aquifer recharge by direct injection (USA Drinking Water Standards). The result is a set of cost functions for investment I and for operation and maintenance O&M developed based on the technical design and the cost estimation of the unit processes and operations of the studied wastewater treatment plant (WWTP).