Basin Water, Inc - Solutions

High Efficiency Ion Exchange Technology Brings Arsenic Compliance to Baldy Mesa Water District

Baldy Mesa Water District
Victorville, California
www.bmwd.net

"We are proud to have the first, permitted, full scale arsenic removal system in California."

By Guy Patterson, General Manager
Baldy Mesa Water District

On January 23, 2006, the maximum contaminant level (MCL) for arsenic in US drinking water supplies changed from 50 to 10 µg/L. The US Environmental Protection Agency (USEPA) estimates that 3,000 community water systems serving 11 million North Americans will need to take corrective action to lower the current levels of arsenic in their drinking water. Water systems that do not have existing resources, such as blending, developing new sources of supply, or importing water, must find arsenic treatment systems that are cost effective, readily available, and can be easily operated by their existing employees. The Baldy Mesa Water District (BMWD) is one such water system that is affected by the new Arsenic Rule.

BMWD is an independent, special district serving residents of the city of Victorville and county of San Bernardino, Calif. It was formed by vote in 1965 and encompasses approximately 27 sq mi within the Victor Valley. With approximately 7,000 customers and 21 employees, BMWD needed a treatment technology that would not be a great financial burden to its customers nor a drain on its existing staff. A recent study confirmed that at the current growth rate, its 7,000-customer base is poised to reach 65,000 during the next 25 years, which led BMWD to select a solution that was expandable, cost effective, and reliable.

FIRST LARGE ARSENIC REMOVAL SYSTEM TO BE PERMITTED IN CALIFORNIA

The BMWD has approximately 7,000 service connections and is currently 100% dependent on local groundwater. The groundwater is pumped to the system from eight wells that produce a combined 6,160 gpm. Additionally, the district has seven storage reservoirs with a total storage capacity of 14.4 mil gal. Because all eight wells in the system exceed the new USEPA standard for arsenic of 10 µg/L, the district was actively involved in evaluating various technologies for arsenic removal in 2003. Basin Water was selected to build a 1,000-gpm system to fully treat one of BWMD's eight contaminated wells for a trial period of one year. This article documents the successful completion of the long-term demonstration project - the first full-scale arsenic removal system permitted in California. In the fall of 2005, BMWD awarded Basin Water a contract for a 6,000-gpm arsenic removal system.

The Baldy Mesa Water District demonstration project team includes (L to R) Operations Manager Joe Ogg, Engineering Manager Doug Mathews, and General Manager Guy Patterson.

TRIAL BY WATER

With an average arsenic concentration in excess of 10 µg/L, BMWD needed a technology that consistently removed arsenic to nondetection levels. This would also allow the utility to meet future changes in the arsenic MCL.

On Aug. 14, 2003, BMWD received approval from the State of California Department of Health Services to operate Basin Water's 1,000-gpm ion exchange (BWIX) system at BMWD's well number 1. The unit was decommissioned as planned in the latter part of the fourth quarter of 2004. While in operation, the BWIX system treated 127 mil gal of drinking water.

The goal of this demonstration project was to establish the performance characteristics of the BWIX system. The following objectives were accomplished:

documenting the validity of the computer modeling software in predicting the performance of the system,
establishing the suitability of the system as a solution to BMWD's wellhead treatment needs,
benchmarking the reliability of the BWIX system for treatment,
verifying waste rates and establishing waste characteristics for the system.

The USEPA has designated IX as a best available technology for removing arsenic from drinking water. Arsenic is a divalent ion and is strongly attracted to strong base anion resins.

The USEPA and NSF International have issued an environmental technology verification to the patented BWIX system used at Baldy Mesa for its efficacy at removing arsenic from groundwater to below detectable levels. The ability to operate reliably at nondetection levels protects BMWD's investment for the long-term should MCL levels be reduced in the future. The system's flexibility provides the district with a long-term, highly-effective groundwater treatment solution.

Although IX has superior technical qualities for the removal of arsenic, it is frequently dismissed because it produces excessive amounts of waste. Waste rates are measured by determining the amount of waste volume generated by a system divided by the total volume of raw water entering the system from the water provider's well. However, the BWIX used in this project produces less than one tenth the waste of a conventional IX system. As a result, BMWD can achieve a high yield of treated water with a correspondingly low amount of generated waste. This minimizes waste disposal costs, significantly reducing BMWD's operating costs and increasing the net amount of treated drinking water produced.

Early in the design process for the 1,000-gpm system, engineers used a state-of-the-art simulation program that rapidly designs and provides detailed data for each customer application. The data generated include assessments of cost, posttreatment contaminant levels, and waste rates. The software was developed by Gerald Guter, an expert on IX and other water treatment technologies. Modeling specified the number of bed volumes that can be processed before regeneration, specific to this well's water quality and flow rate. The predicted waste rate was 0.057% of the inlet flow or 190 gal/acre-ft (324,000 gal) of treated water. On the basis of data and measurements collected during the treatment process, the BWIX simulation program enabled the engineers to adjust the treatment process on a real-time basis for optimal operation. During the demonstration, roughly 127 mil gal were successfully processed, equating to 0.06% waste, or a water recovery rate of 99.94% during the 1.5-year time period.

THE SOLUTION

The district's BWIX system is a self-contained modular treatment system housed in a steel container. It uses multiple small cylindrical vessels to remove contaminants from well water. As the water passes through the beds, target contaminants are attracted and become attached to the resin. The system uses high-quality resins that have been NSF-certified as nontoxic, insoluble, and chemically and biologically stable. When the beds are filled with contaminants, they are regenerated with a 7% sodium chloride solution commonly called brine. NSF-certified sodium chloride is delivered in dry bulk form to the treatment system. No pretreatment or pH adjustment is needed, as is often the case with other technologies. In addition, no cartridges or media need to be discarded. All regeneration is handled within the system, and the resins have an estimated useful life of more than 20 years.

The first large arsenic removal system to be permitted in California was a 1,000-gpm system installed for the Baldy Mesa Water District by Basin Water.

The BWIX system has many key features and design concepts that make it an economically viable solution for removing arsenic.

Automatic control and monitoring of operations.

The instrumentation and control system automatically controls and monitors the operation of the BWIX system and ancillary devices. This includes a programmable logic controller (PLC), an operator-friendly graphical interface, automatic instrumentation (alarms, sensors, controllers, and analyzers), automatically controlled equipment (e.g., valves and pumps), and remote management via a phone line. The PLC automates and executes the entire regeneration, rinsing, and exhaustion process throughout the BWIX system. The production of treated water is uninterrupted because regeneration of the beds is performed while the system is on-line. The BWIX system is designed to operate unattended. This simplified operation means water purveyors' existing staff can learn to use the system within a day. In addition, the system has operational flexibilities such as the ability to operate from 0 to 100% of well capacity while accommodating the frequent starting and stopping of wells as needed.

Smaller-capacity beds.

The BWIX system uses multiple smaller-capacity beds operating in parallel to generate treated water . This is in contrast to conventional IX plants that use a low number of large-capacity beds and consequently experience significant variations in effluent water chemistry and quality. The use of multiple smaller-capacity beds minimizes the effect of an individual bed's effluent water chemistry on the overall system effluent water chemistry. Therefore, the effluent water quality remains predictable, consistent and relatively unchanged because the overall water quality will be the average of all online beds. Moreover, because of the multiple-bed design, the BWIX system has built-in redundancies to allow for continued operations without volume loss in the event of a mechanical problem or routine maintenance.

Minimal electrical power.

Many groundwater treatment solutions require significant amounts of electrical power to remove contaminants. The BWIX system uses the well pump's pressure to move water through the system for treatment, so it operates with minimal electrical power - significantly reducing its operational cost.

Brine-processing unit.

The waste brine produced by the system is treated by a brine-processing unit (BPU). The BPU removes heavy metals from brine wastes generated by the system. The process uses a coprecipitation technology that removes arsenic, chromium, and other contaminants from wastewaters. The precipitation process enables the separation of waste effluent into two categories of waste: solids (sludge) and liquid. The sludge and liquid are separated through a decanting and filtering process. The treated waste brine was characterized as nonhazardous in accordance with 40 Code of Federal Regulations (CFR) 261 and California Title 22. The sludge was characterized as nonhazardous in accordance to 40 CFR 261, but was California-regulated as a result of its exceeding the total threshold limit concentration testing for arsenic. The solid waste was minimal and was stored in drums for appropriate disposal by a certified waste-handling company. All waste characterization, transportation, and disposal were prearranged by Basin Water. Over the course of this entire demonstration period, a total of only nine 55-gal drums of waste was produced.

BMWD evaluated several technologies and selected the BWIX, high-efficiency arsenic removal system because of its low capital cost, ease of operation, low maintenance and operating costs, and low waste production. The BWIX system also included a contractual guarantee of compliance with the 2006 arsenic MCL so that BMWD will only pay for treated water that complies with the federal arsenic standard.

A CLEARER, CLEANER FUTURE

On the basis of the demonstration period, BMWD concluded that the BWIX system exceeded the arsenic treatment goal by consistently lowering arsenic to nondetectable levels. Over 127 mil gal were successfully processed. On the basis of the system's performance, BMWD signed a contract to construct a larger 6,000-gpm (8.6 mgd) arsenic removal system to treat five of the districts's wells simultaneously. Because of the unique business model used - long-term contracted outsourcing - not only does the district spend less capital up front, but it also saves the "hidden costs" of operations and maintenance, both of which are provided by the Basin Water, the IX system manufacturer. The end result is that BMWD only pays for water that is delivered (per acre-ft) to the required specifications and a minimal amount of operations and maintenance costs.

Thanks to the cooperative efforts of BMWD and Basin Water, the residents of the city of Victorville and San Bernardino County can be assured that their water supply will be reliable and safe for decades to come.

Guy Patterson is the general manager at Baldy Mesa Water District, 10313 Duncan Rd., Victorville, CA 92392 and can be reached at (760) 949-0332.


Solutions
Case Studies > Arizona Water > Avondale > Baldy Mesa > Cal Water > Coachella Valley > East Valley > Hi-Desert > Pomona > SoCal Water Browse Solutions > By Contaminant > By Region > By Customer High Efficiency Ion Exchange Technology Brings Arsenic Compliance to Baldy Mesa Water District Click to view PDF Baldy Mesa Water District Victorville, California www.bmwd.net "We are proud to have the first, permitted, full scale arsenic removal system in California." Reprinted from Journal AWWA, (March 2006) by permission. Copyright © 2005, American Water Works Association By Guy Patterson, General Manager Baldy Mesa Water District On January 23, 2006, the maximum contaminant level (MCL) for arsenic in US drinking water supplies changed from 50 to 10 µg/L. The US Environmental Protection Agency (USEPA) estimates that 3,000 community water systems serving 11 million North Americans will need to take corrective action to lower the current levels of arsenic in their drinking water. Water systems that do not have existing resources, such as blending, developing new sources of supply, or importing water, must find arsenic treatment systems that are cost effective, readily available, and can be easily operated by their existing employees. The Baldy Mesa Water District (BMWD) is one such water system that is affected by the new Arsenic Rule. BMWD is an independent, special district serving residents of the city of Victorville and county of San Bernardino, Calif. It was formed by vote in 1965 and encompasses approximately 27 sq mi within the Victor Valley. With approximately 7,000 customers and 21 employees, BMWD needed a treatment technology that would not be a great financial burden to its customers nor a drain on its existing staff. A recent study confirmed that at the current growth rate, its 7,000-customer base is poised to reach 65,000 during the next 25 years, which led BMWD to select a solution that was expandable, cost effective, and reliable. FIRST LARGE ARSENIC REMOVAL SYSTEM TO BE PERMITTED IN CALIFORNIA The BMWD has approximately 7,000 service connections and is currently 100% dependent on local groundwater. The groundwater is pumped to the system from eight wells that produce a combined 6,160 gpm. Additionally, the district has seven storage reservoirs with a total storage capacity of 14.4 mil gal. Because all eight wells in the system exceed the new USEPA standard for arsenic of 10 µg/L, the district was actively involved in evaluating various technologies for arsenic removal in 2003. Basin Water was selected to build a 1,000-gpm system to fully treat one of BWMD's eight contaminated wells for a trial period of one year. This article documents the successful completion of the long-term demonstration project - the first full-scale arsenic removal system permitted in California. In the fall of 2005, BMWD awarded Basin Water a contract for a 6,000-gpm arsenic removal system. The Baldy Mesa Water District demonstration project team includes (L to R) Operations Manager Joe Ogg, Engineering Manager Doug Mathews, and General Manager Guy Patterson. TRIAL BY WATER With an average arsenic concentration in excess of 10 µg/L, BMWD needed a technology that consistently removed arsenic to nondetection levels. This would also allow the utility to meet future changes in the arsenic MCL. On Aug. 14, 2003, BMWD received approval from the State of California Department of Health Services to operate Basin Water's 1,000-gpm ion exchange (BWIX) system at BMWD's well number 1. The unit was decommissioned as planned in the latter part of the fourth quarter of 2004. While in operation, the BWIX system treated 127 mil gal of drinking water. The goal of this demonstration project was to establish the performance characteristics of the BWIX system. The following objectives were accomplished: documenting the validity of the computer modeling software in predicting the performance of the system, establishing the suitability of the system as a solution to BMWD's wellhead treatment needs, benchmarking the reliability of the BWIX system for treatment, verifying waste rates and establishing waste characteristics for the system. The USEPA has designated IX as a best available technology for removing arsenic from drinking water. Arsenic is a divalent ion and is strongly attracted to strong base anion resins. The USEPA and NSF International have issued an environmental technology verification to the patented BWIX system used at Baldy Mesa for its efficacy at removing arsenic from groundwater to below detectable levels. The ability to operate reliably at nondetection levels protects BMWD's investment for the long-term should MCL levels be reduced in the future. The system's flexibility provides the district with a long-term, highly-effective groundwater treatment solution. Although IX has superior technical qualities for the removal of arsenic, it is frequently dismissed because it produces excessive amounts of waste. Waste rates are measured by determining the amount of waste volume generated by a system divided by the total volume of raw water entering the system from the water provider's well. However, the BWIX used in this project produces less than one tenth the waste of a conventional IX system. As a result, BMWD can achieve a high yield of treated water with a correspondingly low amount of generated waste. This minimizes waste disposal costs, significantly reducing BMWD's operating costs and increasing the net amount of treated drinking water produced. Early in the design process for the 1,000-gpm system, engineers used a state-of-the-art simulation program that rapidly designs and provides detailed data for each customer application. The data generated include assessments of cost, posttreatment contaminant levels, and waste rates. The software was developed by Gerald Guter, an expert on IX and other water treatment technologies. Modeling specified the number of bed volumes that can be processed before regeneration, specific to this well's water quality and flow rate. The predicted waste rate was 0.057% of the inlet flow or 190 gal/acre-ft (324,000 gal) of treated water. On the basis of data and measurements collected during the treatment process, the BWIX simulation program enabled the engineers to adjust the treatment process on a real-time basis for optimal operation. During the demonstration, roughly 127 mil gal were successfully processed, equating to 0.06% waste, or a water recovery rate of 99.94% during the 1.5-year time period. THE SOLUTION The district's BWIX system is a self-contained modular treatment system housed in a steel container. It uses multiple small cylindrical vessels to remove contaminants from well water. As the water passes through the beds, target contaminants are attracted and become attached to the resin. The system uses high-quality resins that have been NSF-certified as nontoxic, insoluble, and chemically and biologically stable. When the beds are filled with contaminants, they are regenerated with a 7% sodium chloride solution commonly called brine. NSF-certified sodium chloride is delivered in dry bulk form to the treatment system. No pretreatment or pH adjustment is needed, as is often the case with other technologies. In addition, no cartridges or media need to be discarded. All regeneration is handled within the system, and the resins have an estimated useful life of more than 20 years. The first large arsenic removal system to be permitted in California was a 1,000-gpm system installed for the Baldy Mesa Water District by Basin Water. The BWIX system has many key features and design concepts that make it an economically viable solution for removing arsenic. Automatic control and monitoring of operations. The instrumentation and control system automatically controls and monitors the operation of the BWIX system and ancillary devices. This includes a programmable logic controller (PLC), an operator-friendly graphical interface, automatic instrumentation (alarms, sensors, controllers, and analyzers), automatically controlled equipment (e.g., valves and pumps), and remote management via a phone line. The PLC automates and executes the entire regeneration, rinsing, and exhaustion process throughout the BWIX system. The production of treated water is uninterrupted because regeneration of the beds is performed while the system is on-line. The BWIX system is designed to operate unattended. This simplified operation means water purveyors' existing staff can learn to use the system within a day. In addition, the system has operational flexibilities such as the ability to operate from 0 to 100% of well capacity while accommodating the frequent starting and stopping of wells as needed. Smaller-capacity beds. The BWIX system uses multiple smaller-capacity beds operating in parallel to generate treated water . This is in contrast to conventional IX plants that use a low number of large-capacity beds and consequently experience significant variations in effluent water chemistry and quality. The use of multiple smaller-capacity beds minimizes the effect of an individual bed's effluent water chemistry on the overall system effluent water chemistry. Therefore, the effluent water quality remains predictable, consistent and relatively unchanged because the overall water quality will be the average of all online beds. Moreover, because of the multiple-bed design, the BWIX system has built-in redundancies to allow for continued operations without volume loss in the event of a mechanical problem or routine maintenance. Minimal electrical power. Many groundwater treatment solutions require significant amounts of electrical power to remove contaminants. The BWIX system uses the well pump's pressure to move water through the system for treatment, so it operates with minimal electrical power - significantly reducing its operational cost. Brine-processing unit. The waste brine produced by the system is treated by a brine-processing unit (BPU). The BPU removes heavy metals from brine wastes generated by the system. The process uses a coprecipitation technology that removes arsenic, chromium, and other contaminants from wastewaters. The precipitation process enables the separation of waste effluent into two categories of waste: solids (sludge) and liquid. The sludge and liquid are separated through a decanting and filtering process. The treated waste brine was characterized as nonhazardous in accordance with 40 Code of Federal Regulations (CFR) 261 and California Title 22. The sludge was characterized as nonhazardous in accordance to 40 CFR 261, but was California-regulated as a result of its exceeding the total threshold limit concentration testing for arsenic. The solid waste was minimal and was stored in drums for appropriate disposal by a certified waste-handling company. All waste characterization, transportation, and disposal were prearranged by Basin Water. Over the course of this entire demonstration period, a total of only nine 55-gal drums of waste was produced. BMWD evaluated several technologies and selected the BWIX, high-efficiency arsenic removal system because of its low capital cost, ease of operation, low maintenance and operating costs, and low waste production. The BWIX system also included a contractual guarantee of compliance with the 2006 arsenic MCL so that BMWD will only pay for treated water that complies with the federal arsenic standard. A CLEARER, CLEANER FUTURE On the basis of the demonstration period, BMWD concluded that the BWIX system exceeded the arsenic treatment goal by consistently lowering arsenic to nondetectable levels. Over 127 mil gal were successfully processed. On the basis of the system's performance, BMWD signed a contract to construct a larger 6,000-gpm (8.6 mgd) arsenic removal system to treat five of the districts's wells simultaneously. Because of the unique business model used - long-term contracted outsourcing - not only does the district spend less capital up front, but it also saves the "hidden costs" of operations and maintenance, both of which are provided by the Basin Water, the IX system manufacturer. The end result is that BMWD only pays for water that is delivered (per acre-ft) to the required specifications and a minimal amount of operations and maintenance costs. Thanks to the cooperative efforts of BMWD and Basin Water, the residents of the city of Victorville and San Bernardino County can be assured that their water supply will be reliable and safe for decades to come. Guy Patterson is the general manager at Baldy Mesa Water District, 10313 Duncan Rd., Victorville, CA 92392 and can be reached at (760) 949-0332.
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