Viewfinder: Tour the Wastewater Treatment Plant

Go inside the bowels of the place, so to speak

Mike Didato says that he and the rest of the folks who work at the wastewater treatment plant on Pink Row are really just bug farmers.

The bugs are the ones that are doing the work, cleaning the pollutants and the goo out of everything that flows into the treatment plant.


THE PLANT AT 83 PINK ROW is cleaner and shinier inside than most houses, and is surprisingly odor-free. Here and there, there’s an earthy smell, and that’s about the most of it. To Didato, who is the superintendent of the plant, and to Tom McNally, assistant superintendent, that eathy smell is the smell of success.

Many of the changes that have helped clear the air and the water in Montville, Didato says, have come from the Mohegan Tribe. In 2002, the tribe helped install a whole load of new equipment.

“They did things right,” Didato says. “I used to go home and I used to stink.” That’s no longer the case.

The most recent upgrade to the plant cost about $20 million. The tribe, Didato says, “really cares about what’s going on. They’ve really been a good neighbor. The tribe changed my life,” he says.

Not only is there new equipment, and enough of it, but “morale is way up. This,” he gestures, “is now home.”


THERE ARE TWO DISTINCT DEPARTMENTS in the Water Pollution Control Authority. One is to potable water to customers – 1,800 of them, with 500 connections – and the other is to clean the sewage and wastewater that returns to the plant. There are 5,000 sewer connections.

All the flow of wastewater and sewage goes through the main pump, except for what comes from Rand-Whitney. That company has its own system that links up with the town’s at a certain point.


THE PUMP ROOM is a gigantic place, with a floor that is deep underground.

The three pumps currently lift about 2 million gallons a day, and have a capacity of about 3,000 gallons a minute. They speed up and slow down, according to demand, and while they’re loud, they’re not deafening.

Throughout the system, redundancies are built in. Not only are there several pumps, and a number of large replacement parts, but there are also portable pumps that can be taken to the scene of a pipe break, if something like that should occur.

The main pumps take wastewater from the wet well. After the wet well, the flow goes through preliminary treatment in the grit chamber.  This is where solids are pulled from the liquid. Didato and McNally warn that the wet well and the grit chamber are the stinkiest parts of the process. In all honesty, the area doesn’t smell as bad as an average outhouse.

It is sort of an icky process, though, removing wet and dank solids from the liquid. The solids - rags, rocks, twigs - are captured by a sort of moving chain, and taken to another part of the processing plant.

At this point, the odors are removed in a large chamber called the scrubber. In this silo-like building, a mixture of sodium hypochlorite and sodium hydroxide – a caustic substance, plus bleach, plus water – is sprayed over whiffle-ball like devices inside the giant tank. The scrubbers take the stink out. 


THE PLANT HAS TWO types of water treatment tanks. They work somewhat similarly, using the right kind and density of “bugs” – bacteria – to clear the bad stuff from the water.

In the giant tanks where this process takes place, there is also an area of constant aeration, which moves the water around and provides a vital component for the bugs’ health.

The SBRs, sequencing batch reactors, use an incredibly fine aeration system. In each tank 2,080 fine bubble diffusers send tiny bubbles of air constantly into the wastewater. The bubbles and the bacteria in the tanks help the heavier, dirtier solids separate from the lighter, thinner liquid.

The plant has six SBRs; the newest two were purchased with the aid of the Mohegan Tribe. The SBRs are highly complex, heavily computerized systems.  Each is 20 feet deep, and holds 1.2 million gallons of wastewater.


THE MATERIAL IN THE TANKS is aerated for two hours. It’s allowed to settle for an hour and a half. Then, an open trough-like device at one end of the tank sinks gently into the liquid and siphons the cleaned liquid away from the solids. The liquid goes in one direction, and the solids in another.

The solids - which at this point smell just sort of wet - end up in the Gravity Belt Thickener. The GBT is an amazing machine, which presses the solids into a very fine mesh, pulling the liquids from them.

The remaining sludge – the solids without the liquids - is shipped off to a plant in Hartford. Montville pays for the shipping by the truckload, and Didato says that there are usually three or four tanker trucks a day. So the effort of pulling the remaining water from the solids and condensing those solids is financially advantageous to the town.

 The remaining cleaned water goes back into the river, with a portion going to Rand-Whitney


THIS IS TRULY A THUMBNAIL VERSION of the process. It is far more complex than what’s been outlined in this story, and the addition of Rand-Whitney, with its own system that links into the town’s just before the SBRs, makes it even more complicated.

Computers are running and measuring at every step in the process. Operators check the computers and the measurements constantly, intervening and balancing chemicals and flows when needed.

The wastewater treatment system maintains all sorts of trucks, generators, lifters and other machines that are necessary either for the running of the system, or as backups and redundancies, should some part of the system fail.


DIDATO, McNALLY AND THE OTHERS who work at the plant have earned a variety of licenses and certificates. For a person to obtain a Wastewater Operator Class 4 License,  Didato says, “one needs to acquire three years of higher education that the DEP finds directly related to wastewater treatment, with at least three years as a responsible in charge of a class four system and lastly, pass the state class four exam.”

Didato says the job involves electronics, electrical work, hydraulics, financial work, and biological and chemical work, as well. In addition to the treatment facility, the Water Pollution Control staff manages more than 75 miles of underground pipe in the collection system, and 22 pump stations with a combined total of 123 pumps, 219 motors, and 17 generators.

“You have to know all of it,” Didato says. “That’s why I like it.”





Georgene July 26, 2011 at 01:55 PM
great article shedding light on the inner workings of such an important aspect of our daily lives
Jean St. Denis July 26, 2011 at 02:05 PM
Well written article about the wastewater treatment process. We are lucky to have such a well run facility.


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