Advanced Process Water Recovery and Reuse Plant at Frito-Lay Casa Grande, AZ, 11 Years of Continuous Operations

Freshwater scarcity has become a serious global issue. The U.S. is experiencing water shortages in California, Arizona, Georgia and Texas, and water costs are increasing due to prolonged depletion of groundwater. Rising water/wastewater treatment costs and enforcement of new direct discharge limits are accelerating the need for evaluation and implementation of water recovery and reuse projects. Water reuse prevents the reduction of groundwater tables and protects freshwater resources for future generations.
Frito-Lay has a snack foods production plant in Casa Grande, AZ that produces corn and potato chips, including SunChips®. This plant was selected by Frito-Lay and parent company, PepsiCo, to implement a 'Net Zero' environmentally sustainable approach toward its management of water, energy and steam. This strategic decision lead to the installation of an advanced water recovery and reuse system, a large 5 MW solar system that generates sufficient power to sell back to the grid, and a biomass boiler that produces steam from wood chips waste at the facility. This paper will focus on one decade of operation and performance of this Process Water Recovery and Reuse Treatment Plant (PWRTP).
The project commenced in 2001 when Frito-Lay a division of PepsiCo evaluated many different technologies to treat their process water for direct reuse. Several technologies and solutions were identified and evaluated that could produce high quality reusable water. A pilot study comparing the selected technologies was performed on process water generated from the cooking of corn, fluming, and washing of potatoes, equipment cleaning, rinsing and sanitation, and general housekeeping activities. As the Casa Grande facility had no wastewater at the time, a site in New York was chosen since it had similar production lines, products, and wastewater characteristics. The pilot tests were performed over the course of several months and consisted of small scale MBR's followed by UV and nanofiltration. Based on the pilot testing results, Frio Lay started construction of a full scale PWRTP in 2008 at the Casa Grande facility. The plant was designed to treat 645,000 GPD of process water and achieve 75% water recovery and reuse. The PWRTP at Casa Grande site consists of the following processes: - Flow collection and pumping - Oil and Water Separators - Starch Recovery System - Rotary screening - Equalization - pH adjustment - Primary clarification - Activated sludge with nitrification and de-nitrification - MBR with ZeeWeed * ultrafiltration membranes - Activated Carbon Filters - UV disinfection - Low Pressure Reverse Osmosis (LPRO) - Water Stabilization System - Chlorination System - Water storage Tank - Sludge dewatering by dedicated centrifuges for primary solids to go to animal feed, and bio-solids go to the land application from WAS wasting. - Major control room, water quality lab, attractive-architecture, offices, and similar features. This paper will present key design criteria, daily operational parameters during last decade and solutions implemented to reduce annual O&M costs and improve operation including performance data from 11 years of consistent operation.
KEYWORDS: Full Scale Process Water Recovery and Reuse Treatment Plant (PWRTP), Food and Beverage, MBR, UV, GAC, LPRO, Water Stabilization * A trademark of SUEZ. May be registered in one or more countries.