If you think that making a silk purse out of a sow's ear sounds difficult, consider the task that lies before the staff of Willow Lake Wastewater Treatment Plant in Salem, Oregon. Over one hundred million gallons of sewage and agricultural waste water pour into the plant every day, and before it leaves, it must be clean enough to release into the Willamette River.
Supervisors Dave Robben and John Magee, two of the professional water alchemists at Willow Lake, walked us through the steps of filtering, digesting and chemical treatment. Once the incoming water has been through the "barscreen," which snags big debris, it goes to a primary clarifier where heavier solids are removed. The solids are recycled as "Biogro," which is used in agriculture. The next step for the water is a filter that mimics the natural cleaning action of a river. The water trickles over rocks, and green "zoogleal slime" further cleans the water through microbial action.
More microbes work on the water in the "reactor," where the temperature is just right for "activated sludge organisms" to feast sumptuously. After the protozoans have finished with it, the water heads for the secondary clarifier (pictured above). By this time, you'd have a hard time distinguishing the water from what what you'd find in a lake, but the cleaning process is not quite complete. Just to make sure that nothing unhealthful will be released into the river, the water passes though a contact basin where it is tested and disinfected with chlorine.
John showed us a sample of treated water. "Would you drink it?" we asked. "I'd drink it in a pinch," said Dave. "It's purer than most water in most rivers." We decided against the ultimate test, but marveled at the clarity of the water which only seventeen days before had been raw sewage. "You really are magicians," we said.
Willow Lake has other wonders. One is the "Enginator," a machine that turns the methane gas generated by the water treatment process into enough electricity to supply about 30% of the needs of the entire plant. Another is a stupendous rose garden that just won seven ribbons in the Salem Rose Show. The top wonder, however, is the staff of water wizards. These scientists and technicians are true unsung heroes.
If you're in the Salem area and would like to visit Willow Lake, call (503) 588-6380 or write Willow Lake Wastewater Treatment Plant, 5915 Windsor Island Road North, Salem, OR 97303.