Arsenic Treatment Demonstration
AdEdge Technologies installs a new 100-gpm Adsorption Package Unit arsenic treatment system at the Montezuma Haven well site in Rimrock, Ariz.
In mid-2003, AdEdge was selected to implement three full-scale arsenic treatment demonstration projects with the U.S. Environmental Protection Agency (EPA) using its granular ferric oxide technology. At the Rimrock, Ariz., location, implementation began in September 2003 including engineering submittals and permitting by the Arizona Department of Environmental Quality. Upon completing site preparations and construction in early March 2004, AdEdge Technologies installed a new 100-gpm Adsorption Package Unit (APU) arsenic treatment system at the Montezuma Haven well site. This system was AdEdge’s second installation for a public drinking water system in Arizona that utilized the granular ferric oxide technology. Historically, arsenic levels reported in the source well serving the community ranged from 50 to 55 parts per billion (ppb), more than five times the new EPA standard of 10 ppb. A complete water profile was obtained on the source water to assess the water chemistry and predict performance. Table 1 lists some of the more important water quality parameters. The project objectives included:
- Demonstrate the chosen technology at full-scale under EPA oversight;
- Gather additional cost/performance data on new promising commercial technologies for arsenic;
- Evaluate long product life before replacement;
- Provide a report documenting performance to assist other communities with selection process; and
- Provide a venue for other communities to visit and obtain first-hand informa tion on technology.
AdEdge and its local subcontractor installed an APU-100 designed for up to 100 gpm maximum flow in an outdoor location near the wellhead. The system was converted to a series flow configuration due to the lower than expected well pumping capacity. The system utilizes Bayoxide E33 granular ferric oxide adsorption media. The small footprint system features a twin vessel configuration with automatic controls, PLC, series flow configuration and a 100% backwash recycle system with zero discharge or loss of water. No pretreatment is necessary. For disinfection purposes, sodium hypochlorite is injected prior to the water entering the distribution system.
The AdEdge adsorption system requires no chemicals or regeneration, and does not generate liquid or hazardous waste. Media, when spent, will be discarded as a non-hazardous solid waste. Minimal operation, maintenance, or operator attention is required for this simple automated system. Instrumentation is provided on a control panel to measure critical operating parameters. Total gallon throughput and flow rate for each vessel is measured continuously with a dedicated flow totalizing meter.
The system was placed into operation in June 2004. Sustainable yield from the source well is approximately 35 to 38 gpm. The well runs 12 hours per day with the system treating approximately 25,000 gpd. Weekly sampling results during 65 weeks of run time indicate excellent arsenic removal performance—below 2 ppb in the lag vessel through 65,000 bed volumes. The system uptime has been greater than 99.9%, and the APU has run at very high treatment efficiencies despite arsenic in the raw water ranging from 45 to 80 ppb. EPA’s third-party contractor, Battelle, extended the one-year demonstration period to 18 months. Figure 1 provides treatment performance of the system during the 65 weeks of operation. wqp