Infrastructure Series: Wastewater Treatment

Dec 17, 2017

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. 

“So we’ve done three phases of treatment: we’ve screened it, we’ve removed grit and we’ve sent it through primary clarification where we use gravity and buoyancy to remove more impurities,” Murphy explained. “So from what you saw from in our inflow pumps to what we've done so far, you can see a noticeable change in the [water] quality. And we haven’t removed organics yet.”

The next part of the wastewater treatment process might seem counterintuitive.

“They want to keep all the bacteria in the system,” said Murphy.

And here’s where Murphy addresses the question that’s likely been stuck in your mind and frankly my own since hearing the word “wastewater.”

"If you smell that, it smells nice and earthy,” Murphy pointed out. “A lot of wastewater treatment, our operators walk around smelling the plant for these different smells. If it smells septic, you got a problem. If it smells nice and earthy like this, it means you got a good, healthy bacteria in your system.”

He’s right. It smells like a damp cellar in an older home. Murphy explains that an air compressor, what he calls the lungs of the plant, provides the organisms with oxygen to keep them alive. The compressed air is mixed with the wastewater via discs about the size of your hand strewn across the bottom of the tanks. More than 300 discs line each of the four tanks fed by a quarter inch hole of air. Calculations are run daily to determine how much bacteria it takes to treat the material coming in and to adjust the detention time – how long the water is in the system.

“The bacteria have done their job,” he said. “I like to say this is like Thanksgiving dinner. Everybody comes to dinner and they eat and feast in the aeration tanks. Now they all make their way over to couch and settle out to watch the game. That’s what we are doing here. These are called clarifiers. We’re introducing the bacteria now and they’re all fed and happy.”

From here the water flows to circular pools to remove the bacteria.

“We have these huge rotating arms, there’s two of them, that keep moving around at about once an hour they make a revolution. They’re scooping the bacteria back off the couch to send them either back for dessert or if they take the wrong turn in the pipe, they go over to sludge holding tank, they mix with that primary sludge to become combined sludge and they don’t eat another day, we get rid of them. So what you’re seeing here through these weirs, that’s our final effluent. And look at how clear that is compared to what you first saw coming in.” 

“Now we come to the final stage with the water and it’s our disinfection,” Murphy said. “At this plant we use hypochlorite and then sodium bisulfite to dechlorinate.”

After the chemical is removed, the water runs down a flume into the Hudson River.

“That’s clean water going out,” explains Murphy.

While highly technical and energy-intensive, the plant appeared to be operating smoothly when Murphy showed me around. But, during a storm, it’s a different story.

“We saw flows for [Hurricane] Irene – I think we recorded like 110 million [gallons],” said Murphy.

Again, the North Plant is designed to treat 35 million gallons per day. It’s required by permit to put 2 and a half times that, or 88 million gallons, through preliminary and primary treatment and disinfection. Storm flows cause a chain reaction throughout the plant starting at the inflow point, again 35 feet below the surface.

“If you remember Hurricane Floyd and Hurricane Irene, this is where the water level came up to,” Murphy said as he points to markings on the wall two staiwells up. “So when the water enters plant it’s about 35 feet below surface. The intensity was so great and so fast, that these are the levels that the water rose here and that’s with every pump we have running. Everything was underwater.”

The words Floyd and Irene are written on the stairwell wall, marking the water levels of the storms in 1999 and 2011, respectively.

In order to prevent treatment plants from being overwhelmed, many cities have combined sewer overflows. Combined sewers mean storm water and material from sanitary systems run through the same pipe. In Albany’s case, there is also an interceptor.

“The dry weather flow from the combined sewers goes into that interceptor sewer and then to a wastewater treatment plant,” said William Simcoe, deputy commissioner for the city of Albany’s water department.  “If there’s too much water for the interceptor to take that’s the point of overflow. Wastewater treatment plant is only designed for dry weather flows and the wet weather flows there would be a discharge to the river.”

Simcoe’s involved in a 15-year, roughly $150 million combined sewer overflow control plan for six communities along the Hudson River.

“This is happening all over the country,” said Martin Daley, an environmental planner with the Capital District Regional Planning Commission, which is leading the long-term control plan. “So New York City, Seattle, Chicago, Boston, a lot of the older cities, mostly in the Northeast, but several across the West are also doing programs like these. Some of them much more expensive and expansive given the amount of flow they’re contributing. Washington D.C.’s program is about a billion dollars.”

In 2007, the Albany Pool Communities started developing the plan to study the river’s health and look at ways to improve it.

“DEC informed us something was wrong and we knew back then that we were not meeting water quality standards,” Daley said. “We had to make a diagnosis and then come up with the treatment plan.”

The plan, being administered under a consent order with New York state’s Department of Environmental Conservation, calls for green infrastructure improvements with projects like porous pavement, bio-retention and tree plantings to allow rainwater to go into the soil rather than the sewers. Simcoe says new treatment and disinfection facilities are also planned.

“At six of our regulating chambers in 2018 we’re going to have new screening facilities to remove floatables so that overflows that occur will actually be screened and the screening materials will be returned back to sewer district so they won’t be contributing to the bad water quality in the Hudson River,” said Simcoe. 

Across the six communities, there are 92 combined sewer overflow points into the Hudson. Daley says the plan makes the most of the funding by addressing the CSOs with the highest volumes. About 30 of the $150 million plan’s 53 projects are completed.

“We’ve gotten a significant amount of projects done,” Daley said. “We’ve invested a significant amount. The district projects are done for the most part. They have about $30 million of projects that they’ve completed, several of those were grant funded. We have roughly $25 million of community projects that are completed. A lot of those were grant funded as well. To date, I’m going back to 2007 when we’ve completed the plan, we’ve leveraged about $25 million in grant funding between plan development and implementing our projects.”

“Right now, across the country, municipalities and the local systems like the Albany County [Water] Purification District, they’re shouldering 97 percent of the funding load for clean water in our country through rates and municipal bonds,” said Adam Krantz, the CEO of the National Association of Clean Water Agencies. “Three percent of the money is coming from the federal government through a program called the [Clean Water] State Revolving Loan Fund program. It’s $2 or $3 billion a year, compared to $100 billion a year being spent by municipalities, which goes to the states and the states can then loan that money out to the municipalities. So it’s not even a real grant system in the sense that the wastewater treatment plants, the clean water agencies, still have to pay that money back.”

The National Association of Clean Water Agencies lobbies on behalf of the roughly 55,000 drinking water utilities and more than 16,000 wastewater treatment facilities nationwide. He says wastewater treatment plants across the country are raising their rates at double the rate of inflation to pay for what the federal Environmental Protection Agency estimates is a nearly trillion dollar need over the next 20 years — about $600 billion for infrastructure upgrades and roughly $300 billion to comply with regulatory requirements.

“What’s happening is there’s becoming an affordability problem,” Krantz said. “I would call that the third leg of the troubled stool. Increasingly? low-income folks, rural or urban, can’t afford the payments at the rates that are being charged. What that does is create a political problem because the utilities are public agencies beholden to their communities and it starts to develop some political difficulty in getting the kind of rate increases they really need.”

Krantz says water crises in Flint, Michigan, Toledo, Ohio and Puerto Rico have moved water systems upgrades into Washington’s national infrastructure conversation. He also says what is now being called water purification instead of sewage treatment is becoming a revenue stream through energy production.

“Right now by burning bio-solids we are generating 312 kilowatts,” explained Murphy.

Back at the North Plant of the Albany Water Purification District, Executive Director Timothy Murphy says the district hopes to generate enough power to cover a good portion of its secondary treatment.

“So we’re taking the hot gas off the top of the incinerator and passing it through something very similar to a radiator on a car,” Murphy said. “In that radiator is thermal oil that we’re trying to heat up. That heated oil we are then pumping over where we’re bringing it into contact with a synthetic oil. The synthetic oil has a very low boiling point and it goes to a vapor. That gas is what’s spinning our turbine. The turbine is spinning the generator and we’re generating power.”

Murphy says the district has had a fairly level budget over the past 15 years, with more than $35 million invested in its own infrastructure. So have the long-term control plan and the improvements at the existing treatment facilities improved the Hudson River’s water quality? Daley, of the Capital District Regional Planning Commission, says we’ll have to wait and see.

“We have seen some improvement, but we’ve been doing our sampling program for two years,” Daley said. “Two years is a snapshot; we want three years of data to be able to illustrate a trend and compare what’s happening now to our data that we collected in 2007 to 2009.”