The Loudoun County Sanitation Authority broke ground Thursday on a state-of-the-art water reclamation plant in Ashburn that the authority says will treat wastewater more effectively than the majority of plants in the region and across the country.

Plans for the $200 million Broad Run Water Reclamation Facility, near Loudoun County Parkway and Smith Switch Road, have been in the works for nearly 20 years. The plant is expected to begin operating in late 2007 and will eventually be able to treat 20 million gallons of water a day and remove particles as small as bacteria.

Water resource officials and scientists have lauded the planned facility, saying it will set new standards for wastewater treatment.

"The bottom line is it doesn't get any better," said Jeff Corbin, a scientist with the Chesapeake Bay Foundation who has reviewed the plans. "It's truly state of the art."

The plant marks a milestone for the sanitation authority, which serves nearly 130,000 people in eastern Loudoun. In the past, wastewater has been sent through transmission mains to a D.C. Water and Sewer Authority plant in Blue Plains to be treated. But that plant can treat only so much water, and the growth in eastern Loudoun means that eventually, the Blue Plains facility will not be able to meet the area's needs.

According to preliminary plans, the new plant will have a number of bells and whistles, including an "outdoor interpretive area" with 10 to 15 acres of pathways and waterways and museum-style kiosks where visitors can learn about water resources. An indoor education area with interactive exhibits is also planned. Sanitation authority officials said that, although a wastewater treatment plant is not a typical destination for most people, it can be an educational tool.

"They need to know because water, while it's recycled in nature, it's a finite resource," said Samantha Villegas, a spokeswoman for the authority. "It's something that everyone takes for granted until we've got a hurricane or a drought. This is, we hope, one way for people to understand water in the big picture."

Corbin said one virtue of the new plant is that it will discharge minimal amounts of nitrogen. Nitrogen from wastewater plants across the region flows into the Chesapeake Bay watershed and feeds algae blooms that deplete oxygen levels in the water. As a result, many species of fish, crabs and oysters cannot survive. Wastewater plants are one of the main sources of nitrogen pollution, scientists say.

Officials of the Broad Run plant say they aim to reduce its nitrogen level to three milligrams per liter. Discharge from plants in the area has an average nitrogen level of 18 milligrams per liter, Corbin said.

The technology to reduce pollution from the new plant makes use of, in part, synthetic materials with fine pores to filter wastewater. The sanitation authority says the technology is uncommon on the East Coast partly because facilities such as the one being constructed in Loudoun are expensive. But environmental officials say that, for the health of the Chesapeake Bay watershed, more are needed.

The sanitation authority said the costs of the new facility will not result in higher rates for consumers immediately. The authority has a long-term financial plan and is using money collected through connection fees to finance the project but could increase rates once the plant is fully operational.

During the groundbreaking ceremony, John Rocca, chairman of the sanitation authority's board, emphasized that the project was being carried out without taxpayer dollars. He credited a "brain trust of young engineers" for making it possible.

"This will be one of the finest plants that has ever been built," he said.

The plant is being built on a 340-acre site. During excavation for the project, archaeologists found hundreds of artifacts dating to prehistoric times. The sanitation authority said it would probably incorporate some of the artifacts into displays at the plant or in a new administration building.

The new wastewater treatment plant in Ashburn is expected to be completed by late 2007.