October 26, 2013 11:27:16 PM
Nathan Gregory - [email protected]
■ EDITORS NOTE: There are few infrastructure systems as critical to a community's health and prosperity as a city's water supply. Beginning today, the Dispatch takes a closer look at three critical elements in that system in a three-part series that begins with a look at the wastewater system.
The Reynolds R. Ridgley Wastewater Treatment Plant in Columbus has the capacity to treat 10 million gallons of wastewater a day. It typically sees 6-8 million gallons on a daily basis.
Consecutive heavy rains sustained early this summer might have presented a challenge for the plant if there weren't two massive storm lagoons totaling 80 acres just outside the entrance gate. If more than 10 million gallons come through the two main city wastewater pumping stations, the capability is there to bypass the plant and store it in the lagoons until the incoming volume decreases to control flow and minimize discharge amounts.
Plant operator Darren Buckhalter said that gives Columbus a leg up on most Mississippi municipalities.
"It's something we have that most stations don't," Buckhalter said. "We can easily bypass our flow and get what we want into the area of the flow and then later we can either just let it run through the cycle and take it back out to the river or we can bring it back through the plant and let it cycle through the mechanical part of it."
The mechanical part of treating wastewater is a seven-step process, Buckhalter said. The first step is when gravity flow transfers waste from households and businesses to either of the pumping stations -- one on 22nd Street or the other at the plant -- depending on location. The water then comes to the plant through those stations into a long, narrow tank known as the grit chamber.
A grit chamber slows the water down and picks up any sediments. Anything that escapes the chamber is ground into tiny pieces by what Buckhalter calls a muffin monster.
The water is then introduced to air to reduce pollutants through four aeration tanks before it moves on to clarifiers. Semi-solid material known as sludge is separated from the water at this stage and transferred to a digester and sludge thickener before being pumped to one of three 5-acre sludge lagoons on the plant site.
Meanwhile, the separated water enters chlorine contact chambers, or disinfection tanks that add chlorine to kill pathogens and bacteria. Then sulfur dioxide is added to neutralize the chlorine before the finished product is discharged into streams.
Columbus Light & Water general manager Todd Gale said the amount of dissolved oxygen, bitrates, phosphates and ammonia determines the strength of how wastewater is measured. As for recent improvements to the plant, there hasn't been an immediate need to upgrade the facility to have more flow capacity, but Buckhalter said modifications were done to the clarifiers five years ago to improve their functionality.
Such a well-oiled machine is the plant that the few employed there mainly ensure it keeps running. Four people man the plant 7 a.m.-3 p.m. during the week. Otherwise, one person runs the show during an eight-hour shift. Someone is there 24 hours a day, seven days a week, overseeing the operation and doing necessary maintenance to any of the pumps. Buckhalter makes sure the buildings housing the pumps are kept in order, while maintenance workers, including Austin Cooke, keep up the grounds.
"First thing when we get here is we check everything, the buildings and the pumps." Cooke said. "We grease pumps every three months as a preventative maintenance. If we've got something torn up, we tear it down and fix it or take it to get fixed. Day to day, there's no set routine -- just whatever comes about.
"The most grueling thing is probably having to pull a pump or drain one of these tanks and clear it out or do some repairs," Cooke added. "It's hot and nasty in there."
■ Coming Monday: Water supply and delivery
■ Coming Tuesday: Drainage system
Nathan Gregory covers city and county government for The Dispatch.