Direct Potable Water Reuse Considered in West Basin

How would you feel about pouring yourself a glass of water that came directly out of a wastewater treatment plant and into your kitchen tap? Would you drink it down without a second thought?

Probably not … yet.

But, that’s just the concept being studied by the West Basin Municipal Water District in Los Angeles County, California.

Direct potable water reuse is just a concept, for now. Currently, even the most sophisticated water recycling plants in the world are using their water primarily for irrigation and industrial uses. When recycled water is returned to the potable system, it’s injected deep into wells where it percolates through the groundwater system for years before being treated for human consumption. But, is that really necessary?

Well, not technically, said Shivaji Deshmukh, West Basin assistant general manager, during a recent webinar hosted by Sustainable City Network. Deshmukh said today’s recycled water can be brought to nearly distilled quality, far exceeding existing quality standards for potable applications.

But, it’s the thought of it. That’s the bugger.

“There are some challenges associated with this that we feel we’ll have to look at in terms of outreach and research,” Deshmukh said, “and we plan to do that over the next 10 years working with our water reuse partners in California and throughout the nation.”

Once agencies like West Basin can show a solid history of providing consistently pure results, and with real-time sensor technology and automatic diversion of substandard water, Deshmukh believes the public will eventually come around.

“Ultimately, this could be a very reliable, high-quality supply of water,” he said.

The West Basin Municipal Water District, formed by the state of California in 1947, is a public provider of local, imported and recycled water serving about 1 million people in 17 cities along Los Angeles County’s Pacific Coast, from Malibu in the north to the Palos Verdes peninsula south of L.A. The district does not serve the larger cities of Santa Monica, Torrance, Long Beach and L.A. itself.

West Basin currently gets most of its water from the Metropolitan Water District of California, the largest water district in the U.S., which imports water primarily from the Sacramento-San Joaquin Bay Delta in northern California and the Colorado River.

Deshmukh said it was that reliance on imported water that kept his district’s leadership up at night, and was the main impetus for West Basin’s Water Reliability 2020 initiative, an ambitious program to cut the percentage of imported water in half by more than doubling the use of recycled water, doubling conservation efforts, increasing programs to educate youth about conservation, and beginning an ocean-water desalination program.

“What makes us unique is the fact that about 20 years ago, we looked at developing local supplies, so that we weren’t completely dependent on these imported supplies,” Deshmukh said.

West Basin’s small staff of 36 professionals works with United Water and other private-sector partners to design, build and maintain its treatment facilities. Brent McGovern is United Water's project manager responsible for the day-to-day operations of the main Edward C. Little Water Recycling Facility as well as three refinery satellite operations in the West Basin district, serving the Chevron, ExxonMobil and BP oil refineries. He is also responsible for West Basin’s Ocean Desalination Demonstration Project.

The water recycling operation produces five “designer” waters that range in quality from irrigation to near distilled quality water.

McGovern said California faces an interesting dynamic, in that two-thirds of its water is located in the northern portion of the state, while two-thirds of its people live in the southern half. As a result, the state has been struggling to import water to its growing southern population for many years, through such projects as the L.A. Aqueduct, the California Aqueduct, the Colorado River Aqueduct, and finally, the State Water Project, which began development in 1956 and continues expanding to this day.

Besides imported water supplies, McGovern said, southern California’s other options include local groundwater, stormwater, water transfers, desalination and recycled wastewater.

“The last two – ocean water desalination and water recycling – are the two that West Basin and United Water are focusing on further expanding,” he said. The primary reason: As California’s population continues to expand, the Sierra snowpack continues to melt, and the threat of drought looms larger than ever, imported water supplies are becoming less and less reliable, McGovern said.

“Also, there are serious issues with some of the state’s water transfer infrastructure,” he said. “All of these challenges point to the need for new water supplies to grow sustainable communities and provide for water reliability.”

In 1947, West Basin got all its water from local groundwater supplies. By 1990, it was importing nearly 80 percent. In 2008, it reduced that percentage to 66 percent through water conservation efforts and wastewater recycling. By, 2020, the district plans to diversify its water portfolio even more by importing only 33 percent, recycling 22 percent, pumping 20 percent out of the ground, conserving 15 percent and drawing 10 percent from ocean water, McGovern said.

Fully operational in 1995, the Edward C. Little Water Recycling Facility in El Segundo, Calif., is a state-of-the-art water recycling treatment facility that produces 30 million gallons of water per day, conserving enough drinking water to meet the needs of 60,000 households for a year. It is the largest water recycling facility of its kind in the United States, having recycled more than 130 billion gallons of water since 1992, McGovern said.

The feed water that serves as a source for the facility is treated secondary effluent from the Los Angeles Hyperion Wastewater Treatment Plant about two miles away. From this wastewater, the facility produces five types of “designer” water, which it sells to various industrial clients, or uses to recharge local groundwater reserves and prevent the intrusion of salt water from the Pacific Ocean. The highest quality water, which McGovern called “near-distilled quality,” is produced from treated sewer water in about 20 minutes.

“Designer waters are produced to meet the specific needs of the end user,” McGovern said. “So, it’s specifically designed to meet certain water quality parameters.” The five types of designer water produced at the facility include:

1. Tertiary Water (Title 22) for a wide variety of industrial and irrigation uses;

2. Nitrified Water for industrial cooling towers;

3. Softened Reverse Osmosis Water: Secondary treated wastewater purified by micro-filtration (MF), followed by reverse osmosis (RO), and disinfection for groundwater recharge;

4. Pure Reverse Osmosis Water for refinery low-pressure boiler feed water; and

5. Ultra-Pure Reverse Osmosis Water for refinery high-pressure boiler feed water.

The softened reverse osmosis water is injected into 153 wells along the coastline to serve as a seawater barrier to prevent the ocean from contaminating local groundwater.

“This water does not directly get reused, however, over a period of a number of years it will flow through the aquifer and make its way to a customer’s tap at some point in the future,” McGovern said.

West Basin sells its designer water for between $0.84 and $1.58 per cubic meter, depending on the quality. The weighted average price is $1.33 per cubic meter.

McGovern said West Basin has invested $520 million over 14 years, building 120 kilometers of pipeline. Its fourth plant expansion is about 60 percent complete and by 2013, the district expects that 100 percent of the local seawater barrier will be supplied by recycled water from the expanded plant. After the expansion, the facility will increase production from 30 million gallons to 70 million gallons per day.

Along with its water recycling efforts, West Basin is also investing in energy conservation. It currently gets 10 percent of its peak energy use from solar panels installed on site.

Some of the challenges West Basin is facing include changes in the volume and quality of the source water, delivery and distribution issues, regulatory requirements and public perceptions of recycled water, McGovern said.

In a counter-intuitive twist, he said, water conservation has actually caused some of the problems.

“When you consider all the efforts and improvements that have been made with respect to conservation – like using low-flow or high-efficiency toilets, low-flow shower heads, high-efficiency washing machines – this has all contributed to a reduction in the amount of water going to the wastewater treatment facility, therefore increasing the concentration of the waste that has to be treated,” he said.

But, Deshmukh said that despite the challenges conservation creates on the treatment side of the operation, it remains a high priority and a key ingredient of the 2020 plan.

“Educating the public and implementing conservation devices really helps us reduce water waste and allows us to provide more water reliability to our service area,” Deshmukh said. He said one of West Basin’s key focus areas is on the reduction of outdoor irrigation water usage, with a goal of reducing usage by 20 gallons per person each day. The district promotes re-landscaping with “California friendly” plants that require less water through its “Ocean Friendly Garden Classes” and rebates/savings offers to industrial and residential customers for updating to more efficient systems.

The district uses partnerships with local commercial and non-profit groups to provide conservation education and incentives, including toilet distributions, landscape surveys, smart controllers, sprinkler nozzles, restroom and kitchen retrofits and green street medians, among others. Deshmukh said the agency uses local, state and federal grants to finance 75 percent of the costs.

Desalination is another major effort. Deshmukh said the district is investigating and testing the latest cost-efficient and environmentally friendly technologies to remove salt from ocean water. Since desalination uses 10 percent more energy than importing water, he said West Basin is committed to making its desalination operation carbon neutral by using low-energy membranes, energy recovery systems, high-efficiency pumps and renewable energy.

“So, we currently have an Ocean Water Desalination Demonstration Project that we’re operating in conjunction with United Water, and we’re testing many of these things so we can only move forward if we have the confidence that we’re having a minimal impact on the ocean,” Deshmukh said. He said the ultimate decision will come down to how the technologies affect the environment, how energy efficient they can be, how the public reacts to the program, and how the economics work.

“All these things have to be met before we can move forward with planning a larger-scale project,” he said.

Some of the technologies being tested include advanced intake screens that protect marine life in and around the source waters.

“We even installed an underwater camera so we could provide the public a real-time showing of the screen and its impact on the marine life,” Deshmukh said. He said the district is also working with marine biologists to analyze the impact that high-salinity effluents will have on life in the discharge area to determine the amount of salt that can safely be discharged.

While West Basin is currently planning to produce only 10 percent of its water supply with desalination, Deshmukh said the agency is investigating whether other area districts would be willing to help pay for a larger facility to reduce the overall cost per gallon. Depending on the size of the facility, the unit cost of desalinated water will be just under or just over that of recycled water, he said.

Deshmukh said the costs of desalination have come down considerably since it was first introduced in 1947. At that time, desalinated water cost 30 times that of imported water. By 2000, it was about twice the cost of imported water, and by 2015 it is expected to be about 1.5 times as expensive as imported water, he said.

A recording of the water recycling webinar can be downloaded at http://scitynetwork.com/store.