Interest in water reuse has picked up momentum in the past several years, especially in the areas where drought has become a long-lasting issue (think California and Texas) or where environmental regulations are forcing changes (think Florida).
Brown and Caldwell is a water reuse leader who works with water agencies nationally. But Wendy Broley, in Brown and Caldwell’s San Diego, CA, office, admits most of her work is centered in California. Ninety percent of water reuse occurs in California, Arizona, Texas, and Florida, she says. While water scarcity is the primary driver in the first three states, the driving forces in Florida are sensitive environmental conditions and policy requirements.
Broley observes that water agencies throughout the west are thinking about indirect and direct potable reuse, providing Brown and Caldwell strong business opportunities, even though specifications are only at the thought stage. Broley says, “We can no longer afford to manage our water supplies in silos. We can’t close the water cycle if we’re not reaching across groups.”
The WateReuse Association reports that across the country 19 agencies are planning or have constructed indirect potable reuse facilities. Another five are planning, constructing, or operating direct potable reuse facilities. Two of the five are profiled here, along with two indirect potable reuse facilities.
There is a difference between the two technologies. Indirect potable reused or reclaimed water is treated to a level matching purified water, then injected into groundwater or surface spreading reservoirs. After a period of time, it is piped to water treatment plants along with raw water and into the drinking water system.
Direct potable reuse on the other hand, after following relatively identical treatment, skips the environmental buffer created by the reservoir and is piped directly to the water treatment plant where it is treated again with raw water and distributed as drinking water.
Interest in water reuse has picked up momentum in the past several years, especially in the areas where drought has become a long-lasting issue (think California and Texas) or where environmental regulations are forcing changes (think Florida). Brown and Caldwell is a water reuse leader who works with water agencies nationally. But Wendy Broley, in Brown and Caldwell's San Diego, CA, office, admits most of her work is centered in California. Ninety percent of water reuse occurs in California, Arizona, Texas, and Florida, she says. While water scarcity is the primary driver in the first three states, the driving forces in Florida are sensitive environmental conditions and policy requirements. Broley observes that water agencies throughout the west are thinking about indirect and direct potable reuse, providing Brown and Caldwell strong business opportunities, even though specifications are only at the thought stage. Broley says, "We can no longer afford to manage our water supplies in silos. We can't close the water cycle if we're not reaching across groups." The WateReuse Association reports that across the country 19 agencies are planning or have constructed indirect potable reuse facilities. Another five are planning, constructing, or operating direct potable reuse facilities. Two of the five are profiled here, along with two indirect potable reuse facilities. There is a difference between the two technologies. Indirect potable reused or reclaimed water is treated to a level matching purified water, then injected into groundwater or surface spreading reservoirs. After a period of time, it is piped to water treatment plants along with raw water and into the drinking water system. Direct potable reuse on the other hand, after following relatively identical treatment, skips the environmental buffer created by the reservoir and is piped directly to the water treatment plant where it is treated again with raw water and distributed as drinking water. [text_ad] Public acceptance of direct potable reuse, the holy grail of water reuse, is still the worry of agencies working it. At the town hall plenary session featuring industry and agency representatives held during the WateReuse–California Conference in March in Los Angeles, the consensus was that the technology is well developed but that public acceptance still needs work. Felicia Marcus, chairwoman of the State Water Resources Control Board, says, "Demographic shifts will make direct potable reuse more acceptable, easier, and less of a yuck factor because [the young] accept technology." On the other hand, Daniel Nix, the utility operations manager with the Wichita Falls, Texas Public Works Department, also speaking at the plenary session, says, "We truly believed we would have difficulty with public acceptance" with their new direct potable reuse facility which adds 500 gallons/day to the water supply. However, "the media sold the public on the project, including print, TV, and radio that all ran positive stories on the drought, conservation, and reuse. We couldn't have done this without the media," he says. The plant has been operating since July 2014. The Orange County Water District (OCWD) in California built a groundwater replenishment system in 2008 and brought an expansion online in June. This system has become an inspiration and model for water districts struggling with diminishing water supplies. Managers interviewed for the four projects highlighted here cited the OCWD's successful experience with indirect potable reuse as the reason for moving their projects ahead. The First in New Mexico Cloudcroft, NM, is a 110-year old mountain resort community in the southeast corner of New Mexico about 200 miles from Albuquerque and 90 miles from El Paso. It normally has 850 residents that grow to 2,000 during holidays, says Scott Powell, the water and wastewater plant's operator. Powell explains the village has limited rainfall with a lot of fluctuations. The National Guard had to bring in water in the early 2000s, which precipitated their interest in potable reuse, says Eddie Livingston, the project principal with Livingston Consultants and consulting engineer for Cloudcroft. Planning for direct potable reuse began immediately, says Powell, and initial construction began in 2005, but issues with contracting stalled the project by 2007. Now back on track, construction bids were released in June to build the membrane bioreactor (MBR) and upgrade the existing wastewater treatment plant. Construction on a new treatment plant will begin in 2016 and take about two years to complete, according to Livingston. Livingston says currently the 1970s era wastewater treatment facility uses a trickling filter process before the wastewater is discharged down the local dry canyon riverbed. Livingston described what the new wastewater reclamation facility will do. As wastewater flows from the current wastewater treatment plant, it will go through the MBR and be disinfected with chloramines. It will be stored, then 100,000 gallons will be sent through reverse osmosis (RO) and advanced oxidation, including ultraviolet disinfection combined with hydrogen peroxide. The treated water will first be stored in a one-million gallon reservoir, then 80,000 gallons will be blended with 80,000 gallons of groundwater and again treated with ultrafiltration, UV disinfection, and then granular activated carbon (GAC). Finally, it will be chlorinated and pumped into the distribution system, says Livingston. Xylem is supplying the RO and ultrafiltration technologies and Trojan is providing the UV and disinfection technology. After blending with the groundwater supply, 160,000 million gallons/day (mgd) will be available for distribution, says Livingston. On average, village water usage is between 160,000 and 180,000 mgd. The remaining 20,000 gallons of reclaimed wastewater not blended will be used for forest firefighting,construction, and road maintenance, says Livingston. Cloudcroft's direct potable reuse project will be the first in New Mexico and second in the US, says Livingston. The New Mexico Environment Department is now formulating guidelines and has highlighted the project on its website as a model for other communities. Says Livingston, "Once this project starts to supply Cloudcroft, it secures a water supply for its citizens and serves as a model. It demonstrates that wastewater is a resource, and is a great example of how to take advantage of the resource." [caption id="attachment_24115" align="alignright" width="300"]
Public acceptance of direct potable reuse, the holy grail of water reuse, is still the worry of agencies working it. At the town hall plenary session featuring industry and agency representatives held during the WateReuse–California Conference in March in Los Angeles, the consensus was that the technology is well developed but that public acceptance still needs work.
Felicia Marcus, chairwoman of the State Water Resources Control Board, says, “Demographic shifts will make direct potable reuse more acceptable, easier, and less of a yuck factor because [the young] accept technology.”
On the other hand, Daniel Nix, the utility operations manager with the Wichita Falls, Texas Public Works Department, also speaking at the plenary session, says, “We truly believed we would have difficulty with public acceptance” with their new direct potable reuse facility which adds 500 gallons/day to the water supply. However, “the media sold the public on the project, including print, TV, and radio that all ran positive stories on the drought, conservation, and reuse. We couldn’t have done this without the media,” he says. The plant has been operating since July 2014.
The Orange County Water District (OCWD) in California built a groundwater replenishment system in 2008 and brought an expansion online in June. This system has become an inspiration and model for water districts struggling with diminishing water supplies. Managers interviewed for the four projects highlighted here cited the OCWD’s successful experience with indirect potable reuse as the reason for moving their projects ahead.
The First in New Mexico
Cloudcroft, NM, is a 110-year old mountain resort community in the southeast corner of New Mexico about 200 miles from Albuquerque and 90 miles from El Paso. It normally has 850 residents that grow to 2,000 during holidays, says Scott Powell, the water and wastewater plant’s operator.
Powell explains the village has limited rainfall with a lot of fluctuations. The National Guard had to bring in water in the early 2000s, which precipitated their interest in potable reuse, says Eddie Livingston, the project principal with Livingston Consultants and consulting engineer for Cloudcroft.
Planning for direct potable reuse began immediately, says Powell, and initial construction began in 2005, but issues with contracting stalled the project by 2007. Now back on track, construction bids were released in June to build the membrane bioreactor (MBR) and upgrade the existing wastewater treatment plant. Construction on a new treatment plant will begin in 2016 and take about two years to complete, according to Livingston.
Livingston says currently the 1970s era wastewater treatment facility uses a trickling filter process before the wastewater is discharged down the local dry canyon riverbed.
Livingston described what the new wastewater reclamation facility will do. As wastewater flows from the current wastewater treatment plant, it will go through the MBR and be disinfected with chloramines. It will be stored, then 100,000 gallons will be sent through reverse osmosis (RO) and advanced oxidation, including ultraviolet disinfection combined with hydrogen peroxide.
The treated water will first be stored in a one-million gallon reservoir, then 80,000 gallons will be blended with 80,000 gallons of groundwater and again treated with ultrafiltration, UV disinfection, and then granular activated carbon (GAC). Finally, it will be chlorinated and pumped into the distribution system, says Livingston.
Xylem is supplying the RO and ultrafiltration technologies and Trojan is providing the UV and disinfection technology.
After blending with the groundwater supply, 160,000 million gallons/day (mgd) will be available for distribution, says Livingston. On average, village water usage is between 160,000 and 180,000 mgd. The remaining 20,000 gallons of reclaimed wastewater not blended will be used for forest firefighting,construction, and road maintenance, says Livingston.
Cloudcroft’s direct potable reuse project will be the first in New Mexico and second in the US, says Livingston. The New Mexico Environment Department is now formulating guidelines and has highlighted the project on its website as a model for other communities.
Says Livingston, “Once this project starts to supply Cloudcroft, it secures a water supply for its citizens and serves as a model. It demonstrates that wastewater is a resource, and is a great example of how to take advantage of the resource.”
San Diego’s Advanced Water Purification Facility, with the reverse osmosis technology on the right. The facility produces
purified water, which is being used to reduce salt content in recycled water, and is shown during public education tours.
Pure Water San Diego
San Diego is at the end of California’s water distribution pipelines coming from northern California and from the Colorado River. The cost of this imported untreated water will continue to rise and, according to the city’s Water Recycling Study completed in 2012, the conveyance system delivering imported water to the region’s water treatment plants will need to be improved. New local supplies will cost less, the study concluded.
San Diego began studying water purification in 1993 and following planning, regulatory reviews, and preliminary design of the project, the topic became a political issue in several closely contested political campaigns. In response, the city council canceled the project in 1999.
The city began a new effort in 2005 by undertaking a Water Reuse Study after it had signed a settlement agreement with environmental groups who were pushing for improved ocean monitoring and increased water reuse among other issues.
In October 2007, the San Diego City Council approved moving ahead with a water purification demonstration project. A Recycled Water Study was approved by the city council in July 2012 and a report summarizing the results from the project was adopted in April 2013, according to Marsi Steirer, formerDeputy Director, now retired, in San Diego’s Public Utilities Department in a February 2014 webcast sponsored by American Water Works Association. The new program became known as Pure Water San Diego.
After analyzing a number of alternatives, two types of indirect potable reuse were considered: reservoir augmentation and groundwater recharge. The final concepts concluded that nonpotable recycled water projects at the North City and South Bay reclamation plants should continue, and purified potable water was to be directed to the San Vicente Reservoir and the Otay Lakes.
The City has been producing reclaimed water treated at the tertiary level since 1997 at its North City Water Reclamation Plant, and since 2002 at its South Bay Water Reclamation plant. The recycled water is distributed to surrounding communities for irrigation and industrial uses. Two other recycling facilities in the eastern portion of the county have been operating since 1967 and 1988, respectively. The oldest one, the Padre Dam Water Recycling Facility, in conjunction with Helix Water District, is evaluating the potential to expand its Ray Stoyer Water Recycling Facility as part of an indirect potable reuse project.
As part of the Water Purification Demonstration Project the City constructed the 1-mgd Advanced Water Purification Facility at the North City Plant. It was completed in 2011 and is producing purified water for testing, public tours, and salt reduction in recycled water. The Council adopted the final report on the operation of the demonstration project in April 2013.
Bill Pearce, senior engineer in San Diego’s Public Utilities Department, following his presentation at the WateReuse California Annual Conference in Los Angeles in March, reports that the water being treated in the Advanced Water Purification Facility cannot go directly into either the water treatment plant or to the San Vicente Reservoir because regulations for both indirect and direct potable reuse are being written by the California Division of Drinking Water. Once the indirect potable reuse regulations are set after 2016, the city will be able to apply for permits to begin building a new treatment plant.
Separately the San Vicente Reservoir is being expanded (called a dam raise) and this will increase the potential to integrate potable water. A study of the San Vicente Reservoir determined that it would provide an environmental barrier that satisfies anticipated regulatory requirements, and that purified water will be diluted at least 100:1 under all anticipated reservoir operations. Further, reservoir expansion will improve water quality and purified water will not substantially change this.
The California Department of Public Health approved San Diego’s proposal for the San Vicente Reservoir Augmentation concept in September 2012. (Since then, the California Division of Drinking Water at the State Water Resources Control Board has taken over this responsibility.)
Pearce says a 25-mile pipeline needs to be built to send the purified water to the reservoir where it will be held before going to a final water treatment plant. Given the expense of transporting the purified water, direct potable reuse will probably be less expensive, but the potential for that is less certain, given the regulatory requirements, he says.
Pearce says the value of the reservoir as an environmental buffer is that purified water can be held longer if it is ever off its specified water quality. Online continuous monitoring of treatment processes is intended to identify and divert any off-specification water before it leaves the Advanced Water Purification Facility.
City Evaluating DPR
San Diego is evaluating direct potable reuse where the purified water would be sent directly to the water treatment plant. Pearce explained that the concept reduces response time, so additional process monitoring and/or additional treatment processes are needed to decrease the likelihood of a water quality excursion, a pollutant concentration exceeding criteria values beyond the designated duration.
The City Council in 2013 directed San Diego city staff to continue with the education and outreach program and it has been extensive. The city’s Speakers Bureau made 200 public presentations, there have been 61 community events and 319 facility tours. There has also been extensive publicity on social media as well as in the national consumer press. Public opposition has declined from 45% in 2004 to 11% in 2012.
Victor Occiano, a vice president with Brown and Caldwell, has been involved with San Diego’s work on water reuse since 2002, and Brown and Caldwell was responsible for the Water Recycling Study. He says the success of Orange County’s groundwater replenishment study, in addition to California’s four-year drought, influenced and encouraged San Diego city managers to plunge ahead with the study’s conclusion to augment the city’s two main reservoirs with purified water.
Brown and Caldwell, with teaming partner, MWH Global, will help the city mange the 20-year Pure Water San Diego program.
Occiano says a new treatment plant must be built in addition to the 25-mile pipeline to the San Vicente Reservoir before potable water can be transferred to the reservoirs. He says current plans call for 83 mgd to be produced, with 68 mgd going to San Vicente to be blended with the untreated water there, and 15 mgd to go to the Otay Reservoir. A total of 18 mgd of new recycled nonpotable water will be added to the current recycled water program for irrigation of city properties.
Occiano says deliveries of potable water to the reservoirs is scheduled to begin in 2023. Why so far in the future? He says design and construction plans have to be completed and both programmatic and specific environmental impact reports (EIRs) have to be developed. The EIRs will be required to apply for the permits to be issued by state and federal resource agencies.
San Diego Public Utilities managers have calculated that water reuse costs are projected to be more economical than future water costs and are comparable to 2011 untreated imported water delivery costs of $904/acre-foot.
San Diego will need a permit from the California Division of Drinking Water before the city is ready to deliver potable water to the reservoirs. The California legislature passed a law in September 2010 authorizing the Department of Public Health to adopt regulations for surface water augmentation (indirect potable reuse) by December 31, 2016. It is also required to “investigate the feasibility of developing direct potable reuse and to provide a final report to the legislature” by the same date.
Since then the State Water Resource Control Board has been given responsibility for drinking water, including recycled water, which is regulated by Title 22. The Board issues recycling permits and the Division of Drinking Water reviews and comments on draft permits.
Constructed Wetlands Cleanse Water
Clayton County, GA, is prone to drought, says Chris Hamilton, Water Reclamation Manager for the Clayton County Water Authority, which has operated an indirect potable reuse facility since 2004. The county is divided by the subcontinental divide and lies in the upper part of the Flint River Basin which flows to the Gulf of Mexico and the Ocmulgee River Basin which flows to the Atlantic Ocean. The county has no large rivers or impoundments to draw water from. The groundwater quantity and quality is highly variable because of the predominance of dense bedrock that holds very little water. The county is also highly populated, being home to approximately 270,000 residents.
The Clayton County Water Authority had been spraying its treated wastewater on land, called a land application system, since the 1970s and operated the system for almost 30 years. But it was reaching the end of its life cycle, says Hamilton.
During the development of CCWA’s 2000 Master Plan, “we decided reclamation and constructed wetlands was the better solution,” says Hamilton. It requires much less land, energy, and maintenance than the land application system, he explains.
With the help of CH2M HILL, its selected design firm, the Authority upgraded two of its three wastewater treatment plants in 2002 to advanced treatment standards and to transform the land application system into constructed wetlands requiring only 15 acres to treat one million gallons of treated plant effluent.
Constructed wetlands treatment is a natural process involving plants, soils, and bacteria that naturally occur within the aquatic ecosystem and all play a part in removing residual nutrients. Wetland plants were selected based on the ability to prosper in the local climate. After the wastewater is treated at the Water Reclamation Facility, the reclaimed water is pumped about five miles to the wetlands where it remains for five days before flowing into the Shamrock and Blalock reservoirs.
“The constructed wetlands gave us the opportunity to keep water in the watershed and shield ourselves in droughts,” says Hamilton. During Georgia’s second worst drought in 2007, three years after the water reuse system began operating, Clayton County’s raw water reserves remained at 77% of capacity. According to Hamilton, the new water reclamation system drew a lot of industry attention.
Energy savings was an additional benefit. Electricity use was reduced by 5.3 GWh annually after moving from land application to water reclamation.
The W.B. Casey Water Reclamation Facility is the largest of CCWF’s water reclamation facilities and has a capacity of 24 mgd of treated effluent that is eventually sent to the E.L. Huie constructed wetlands. This water is constantly being tested and monitored. Hamilton says the reclaimed water is piped from the wetlands to an area where it flows over rocks that provide aeration before flowing naturally into the raw water reservoirs from which the drinking water is drawn and destined for the water treatment plant, which prepares it for distribution to residents.
Originally built in 1958, the W.B. Casey facility has been expanded and upgraded several times over the years. The most recent upgrade came online July 1, 2004. It uses chemical, biological, and mechanical methods to clean the wastewater, says Hamilton.
Clayton County Water Authority’s reclaimed water is pumped to constructed wetlands where it remains for about five days
before flowing into two reservoirs from which raw drinking water is drawn.
Solids Into Fertilizer
The W.B. Casey Facility first sends wastewater through preliminary treatment screens and removes grit, debris, and sand, which are disposed of in a landfill. The wastewater then flows through primary clarification treatment where the solids are allowed to settle out. It then flows to the Biological Reactor basins where billions of common bacteria and microorganisms stabilize the waste materials in the water. This activated sludge process can operate in the Modified Ludzak Ettinger (MLE) process mode or the A20 (Anoxic/Anaerobic) mode depending on treatment objectives.
The next stage is secondary clarification where the wastewater is clarified in three 160-foot-diameter circular basins. Solid materials are separated from the liquid and the majority are returned to the biological treatment process to keep the microorganisms in the process to feed on or oxidize the incoming wastewater flowing from the primary clarification process. The clarified effluent flows to the next treatment process called disinfection to kill any remaining pathogens using sodium hypocloride. Then the treated water flows to the Huie constructed wetland.
The solids that settle out in the primary and secondary clarification processes are pumped to a holding tank awaiting dewatering and are thermally dried to create a fertilizer product called Agri-Plus 650. About 5,000 tons of pellets are produced annually and sold for $15.00/dry ton.
The smaller Shoal Creek Water Reclamation Facility which first began service in 1982 was upgraded in 2002 and can now treat up to 4.4 mgd. The treatment process is similar to the W.B. Casey WRF but it has no primary clarification. The biological process used, called a continuously sequencing reaction (CSR) process, is patented by Schreiber. After final clarification the water is sent through ultraviolet light, a Trojan UV technology, for disinfection and pathogen destruction, then pumped over to the Panhandle Road Wetlands at the south end of the county. It remains there for five days as a polishing step before flowing into the Shoal Creek reservoir. The solids which were removed are trucked to another facility and turned into compost which is sold as Earth Products.
The third plant, called the Northeast Water Reclamation Facility, has a treatment capacity of 10 mgd. It uses the activated sludge process for biological treatment and utilizes secondary clarification or the solids/liquid separation process and UV for disinfection and pathogen destruction. It discharges the wastewater to a stream called Panther Creek after going through mechanical filters.
Hamilton says there is no discussion of going to potable reuse.
First DPR in Nation
The Colorado Municipal Water District supplies water to its member cities of Big Spring, Snyder, and Odessa and to several customer cities including Midland in West Texas. The Permian Basin, where these cities are located, has suffered drought for many years and prompted the water district to explore reusing the City of Big Spring’s wastewater, according to the November 2011 issue of Texas WET magazine.
The feasibility study completed in 2005 by Freese and Nichols, headquartered in Fort Worth, TX, determined the proposed plan for direct potable reuse could be completed safely, with proven technology, and be cost competitive with other available supply options. The study concluded wastewater could be treated to a standard that allows it to be re-introduced directly into the raw water supply for the treatment plants of Big Springs and its member and customer cities.
As the reclaimed water leaves the wetlands, it flows through pipes, then over rocks that provide aeration, before flowing naturally into the reservoirs.
Pilot testing was completed in October 2009 following member city negotiations, permitting, and preliminary engineering design. The water district provided a pre-pilot protocol for review to the Texas Commission of Environmental Quality (TCEQ) prior to beginning the pilot testing and submitted the pilot study report for review once it was completed. The report was approved in 2010 by TCEQ allowing construction to commence.
Freese and Nichols designed and provided construction and startup services for the Big Spring Raw Water Production Facility. The district awarded a contract for the microfiltration and reverse osmosis membrane systems to Pall Corp. Trojan provided the UV-oxidation equipment. Construction started in late 2011 and operations began in April 2013.
Raw water from the Colorado River is captured in the E.V. Spence Reservoir, then pumped uphill and treated at the Big Spring water treatment plant, which can treat up to 16 mgd of water. It is then ready to be delivered to member and customer cities of the Colorado River Municipal Water District.
Up to 2.5 mgd of filtered secondary effluent is drawn from the Big Spring Wastewater Treatment Plant and treated to near-bottled-water quality in the Raw Water Production Facility. The wastewater is treated with membrane filtration, reverse osmosis, and advanced oxidation then blended with raw surface water in the District’s raw water E.V. Spence Reservoir. From there a portion of the combined water is transported through a transmission pipeline to Big Spring’s water treatment plant for further cleansing. The remainder is conveyed at a junction just outside Big Spring, through a raw cross-country pipeline system to water treatment plants at the water district’s member and customer cities.
According to David Sloan, a senior process engineer with Freese & Nichols and the project manager for the Raw Water Production Facility, water in the system is fairly salty already, and more so as wastewater effluent. Thus, the wastewater is also desalinated in the RO process. This process is used at the Orange County, CA Water District Groundwater Replenishment System and in Singapore’s NEWater reclamation plants and was deemed to be necessary for large-scale reclamation, says Sloan. Furthermore, with the use of full-stream reverse osmosis the reuse circle could be shortened, he adds.
Pilot testing of the membrane filtration and reverse osmosis processes confirmed that the treated water was superior to the current raw water in most respects. It will make up about 15% of the blended water in the pipeline during low demand periods, and as low as 5% during summertime high demand periods. As they pump more water from the reservoir to meet demand, the rate of withdrawal from the reclaimed tank remains the same so the percentage drops, says Sloan.
The RO process produces two liquid streams: the desalinated water and a second stream, called brine or concentrate, which contains the salts and other contaminants. To dispose of the brine, it is diverted to an off-channel reservoir the district many years ago constructed, along with a channel dam to divert and store the flow from Beals Creek, a naturally brackish stream in the Colorado basin, to improve the water quality in the District’s reservoirs on the Colorado River. The stored water is either sold to oil interests for secondary recovery of oil from mature fields or is allowed to evaporate.
Texas Regulators Supportive
The TCEQ provided guidance to assure that the finished water conveyed to consumers will meet TCEQ’s primary drinking water standards. The TCEQ was generally supportive of the project but did impose specific regulatory actions. The City of Big Spring had to obtain authorization from TCEQ to transfer water to the Colorado River Municipal Water District. And the district had to get an industrial discharge permit to discharge the concentrate or brine into Beal Creek.
The water district also had to obtain an industrial pretreatment permit from the City of Big Spring to return the membrane filtration backwash waste to the city’s wastewater treatment plant.
All three of the treatment processes are energy-intensive, using about 3.55 kWh per 1,000 gallons of product water produced. Estimated UV oxidation operation adds about 0.39 kWh/1,000 gallons and pumping to and from the reclamation facility will increase the total to about 5.34 kWh/1,000 gallons reclaimed.
By comparison, lifting water from Lake Spence to Big Spring requires about 4.2 kWh/1,000 gallons under normal conditions. All in all, it was estimated 5.04 kWh of energy per 1,000 gallons of reclaimed water is avoided, comparable to the energy requirement for the total reclamation process.
Public education has continued since the feasibility study was completed. The district has used radio interviews, newspaper articles, Internet sites, and public meetings to simultaneously convey the severity of water supply limitations and to describe the proposed reclamation concept in a straightforward way. Public reaction has been muted and generally positive or at least neutral.
