Bakersfield Well No. 26 in California was experiencing high arsenic levels in multiple groundwater wells when system owner Cal Water sought assistance to resolve the contaminant issue. Arsenic levels had reached 0.012 mg/L and were affecting drinking water for customers throughout the city. To bring the system into compliance and help Bakersfield Well No. 26 meet the arsenic maximum contaminant level (MCL) of 0.01 mg/L, AdEdge Water Technologies engineered, manufactured and commissioned a treatment system to resolve the high arsenic levels.
Arsenic Removal Through Adsorption
The duplex system consists of two 96-in.-diameter carbon steel epoxy-lined pressure vessels containing Bayoxide® E33 adsorption media for arsenic reduction. The system has a 500-gpm design flow—accounting for 50% of the well discharge—and 500-gpm bypass/blend, which helps increase the life of the adsorption media. An AdEdge AdIN CO2 gas injection system provides pretreatment, lowering the water’s pH for optimal treatment efficiency. The treatment system is designed to operate at a maximum flow of 700 gpm when bypass flow is reduced.
The star of the treatment system is the Bayoxide E33 adsorption media, a proven arsenic removal technology that has been used in thousands of applications over the past 20 years.
During the adsorption process, arsenic is adsorbed to the media within the pore structure as water passes through the media bed. This passive process is achieved by directing water through the pressure vessels at a specific rate to allow for proper contact time with the Bayoxide E33 media.
The Benefits of Design-Build
AdEdge’s progressive design-build delivery made the entire project process easier for the city. Working closely with Cal Water, the city of Bakersfield and MKN Engineering, AdEdge developed an efficient and cost-effective project timeline. This focus on schedule reduction led to faster completion of the design, manufacture and commissioning of the system—in fact, the entire project was completed in just 10 months from March 2017 to January 2018.
AdEdge’s approach also included providing a complete treatment solution to the city. It designed the arsenic removal system as a fully integrated solution that includes not only the pretreatment system and pressure vessels with Bayoxide E33 adsorption media, but also a programmable logic controller for automatic controls and monitoring, sample valves, and flow and pressure gauges.
As an additional benefit, the arsenic reduction system makes sustainability a priority. The treatment solution exhibits no negative impact on the environment and does not produce hazardous wastewater for discharge. The exhausted adsorption media is safely disposed of in a permitted land disposal facility, and it does not release arsenic above acceptable levels into the water supply based on standard leaching tests.