Rural Water - Quarter 1, 2008 - (Page 24)

From Sewage, Added Water for Drinking BY RANDAL C. ARCHIBOLD IT USED TO be so final: Flush the toilet, and waste, be gone. But on Nov. 30, for millions of people in Orange County, Calif., pulling the lever was the start of a long, intense process to purify the sewage into drinking water — after a hard scrubbing with filters, screens, chemicals and ultraviolet light and the passage of time underground. On that Friday, the Orange County Water District turned on what industry experts say is the world’s largest plant devoted to purifying sewer water to increase drinking water supplies. They and others hope it ser ves as a model for authorities worldwide facing persistent drought, predicted water shortages and projected growth. The process, called “indirect potable water reuse” by proponents and “toilet to tap” by the wary, is getting a close look in several cities. The San Diego City Council approved a pilot plan in October to bolster a drinking water reservoir with recycled sewer water. The mayor vetoed the proposal, saying it was costly and unlikely to win public acceptance, but the council will consider overriding the veto in early December. Water officials in the San Jose area announced a study of the issue in September, water managers in South Florida approved a plan in November calling for abundant use of recycled wastewater in the coming years, in part to help restock drinking water supplies, and planners in Texas are giving it serious consideration. “These types of projects you will see springing up all over the place where there are severe water shortages,” said Michael R. Markus, general manager of the Orange County district, whose plant, which processes 70 million gallons a day, has already been visited by water managers from across the globe. 24 • First Quarter 2008 The finished product, which district managers say exceeds drinking water standards, does not flow directly into kitchen and bathroom taps; state regulations forbid that. Instead, it is injected underground, with half of it helping to form a barrier against seawater intruding on groundwater sources and the other half gradually filtering into aquifers that supply 2.3 million people, about three-quarters of the county. The recycling project produces much more potable water and at a higher quality than did the mid-1970s-era plant it replaces. The Groundwater Replenishment System, as the $481 million plant here is known, is a labyrinth of tubing and tanks that sucks in treated sewer water the color of dark beer from a sanitation plant next door and first runs it through microfilters to remove solids. The water then undergoes reverse osmosis, forcing it through thin, porous membranes at high pressure, before it is further cleansed with peroxide and ultraviolet light to break down any remaining pharmaceuticals and carcinogens. The result, Markus said, “is as pure as distilled water” and about the same cost as buying water from wholesalers. Recycled water, also called reclaimed or gray water, has been used for decades in agriculture, landscaping and by industrial plants. And for years, treated sewage, known as effluent, has been discharged into oceans and rivers, including the Mississippi and the Colorado, which supply drinking water for millions. But only about a dozen water agencies in the United States and several more abroad recycle treated sewage to replenish drinking water supplies, though none here steer the water directly into household taps. They typically spray or inject the water into the ground and allow it to percolate down to aquifers. Namibia’s capital, Windhoek, among the most arid places in Africa, is believed to be the only place in the world that practices “direct potable reuse” on a large scale, with recycled

Table of Contents for the Digital Edition of Rural Water - Quarter 1, 2008

Rural Water - Quarter 1, 2008
From the President
Afterburn: Nexters' Impact in the Workplace
Retirement Will Have to Wait
From Sewage, Added Water for Drinking
Rural Water and the Farm Bill
Fiduciary Responsibility: It's All About Trust
Water Industry Supports International Rural Water Association
Regulatory Update
The Rural Water Washington Rally in April
Throwing My Loop
A Precious Thing Called Water
Index to Advertisers
From the CEO

Rural Water - Quarter 1, 2008