Infrastructure Series: Wastewater Treatment
Where does wastewater go and how is it treated?
Most people in America enjoy the luxury of washing waste down the drain or flushing it away in a toilet. But once it leaves the home, office or school, where does it go? What happens to it? In the latest installment of our infrastructure series, WAMC’s Jim Levulis explores the complex wastewater treatment industry.
The first stop for water flowing into the treatment plant in Menands, New York, is primary or preliminary treatment.
“We have bar screens where we’re pulling out any large debris,” explained Albany Water Purification District Executive Director Timothy Murphy. “Large debris can be just about anything in a combined system – we’ve seen tree branches.”
Murphy has been executive director for three years and has worked for the district for 37. He oversees the North Plant in Menands, just north of New York’s capital, which is designed to treat 35 million gallons of wastewater per day. The treated water is fed into the Hudson River. Full operation at the plant started in 1972.
“Prior to us, it just went to the river,” said Murphy.
The South Plant, in the Port of Albany, is permitted for 29 million gallons. In Menands, Murphy explains, once the wastewater has been screened it needs to be pumped up into the plant. The inflow enters 35 feet below the surface. Four large pumps sit at the bottom of a cavernous room to move the water. On this day, a dry, fall afternoon, only two pumps are running.
“So when it’s raining and when we have a hurricane, you’ll see them all running,” said Murphy.
The pumps move the water to the plant’s highest point. Gravity will help it the rest of the way.
“Here we’re slowing the flow down,” he said. “What we’re trying to do is we’re settling out grit material from the roads. Because we’re on a combined system, things that are on the road – dirt and stuff like that – through the combined communities will come in here. It’ll settle out and these rakes and buckets will take it off the bottom. Bring it back in, where it’ll drop on a conveyor, we’ll dewater it and take it to the landfill.”
Next, we walk between enormous tanks — sort of like standing in the middle of a bunch of in-ground swimming pools. Inside the tanks, the slow moving water is being agitated so nothing settles out. The flow is slowed so rotating flights can skim grease that floats to the top. The grease is decanted, solidified – to a point where it looks like dirt - and incinerated.