The aim of the project is a comprehensive comparison between two treatment trains to identify the most cost-effective alternative in the reduction of pollutants of concern in a reservoir with recreational uses and ecosystem-related services:

  1. ultrafiltration + reverse osmosis + UV disinfection, and;
  2. ozonation + granular activated carbon.

The Santa Margarita Water District – SMWD (Orange County, CA) is in the construction phase to substitute the current potable water refill of the Lake Mission Viejo with advanced treated water generated from tertiary treatment effluents.

Treatment sustainability and health safety will be thoroughly evaluated by means of physicochemical, biological and cost analyses. Quality control of the recycled water will be achieved by both conventional (chemical and microbiological) parameters, and with the removal, and activity assessment, of emerging contaminants of concern (ECC) and related modes of toxic action (genotoxic and estrogenic).

A detailed comparison between treatment trains will provide the required information for the assessment and identification of the most cost-effective alternative for the Lake Mission Viejo ecosystem and water use. Lake Mission Viejo (Mission Viejo, CA) recently implemented the aforementioned treatment train configuration (ultrafiltration + reverse osmosis + UV disinfection), which is expected to provide a reliable and high-quality input to the lake. However, the energy-intensity of this treatment may raise concerns on both environmental and economic sustainability. A suitable alternative achieving effluent quality for this lake and ecosystem may potentially be obtained by the use of less energy-intensive technologies. The proposed alternative, consisting in an ozonation process (O3) followed by granular activated carbon (GAC), will be, then, compared to the Reverse Osmosis (RO) configuration by means of the removal performance of the most representative pollutants of concern (conventional and emerging) during a 6-month monitoring period. Understanding the achievable effluent quality using different treatment together with the energy-demand of such processes will provide valuable information for future resource planning and reservoir management.