Human waste key in cleaning our water

You are the Ottawa wastewater treatment plant.

In one of the ironies of sewage treatment, the -- uh, ah -- load you deposit before you shower dirties the water but also cleans it up.

Ottawa's $10 million wastewater plant, which began operation last year, uses natural bacteria that eat the gunk floating in wastewater.

Wastewater: that's the nice term for putrid-looking, foul-smelling raw sewage.

"All the bacteria we use comes from the intestines of warm-blooded mammals," Bob Hollon, superintendent of the Ottawa wastewater treatment plant, said. "That's you and me.

"Every time you flush the toilet, we're getting the bacteria we use."

With one exception, the plant uses no chemicals in the treatment process, he said. The only time a chemical is used is to strip away remaining sewage sludge from water that's being recirculated through the plant.

Indeed, the chemicals used to purify water for drinking purposes are themselves pollutants and must be stripped out of the water before it's dumped back into the Marais des Cygnes River, Hollon said.

Running downhill

And as much as possible, the city's sewer system uses gravity to move sewage through the city's network of pipes.

One of the characteristics of Ottawa's geography is that it's relatively flat, Hollon said.

"There's 7 feet of difference from south to north," Hollon said.

The city has nine "lift stations," which push sewage uphill with special pumps to the point where gravity takes over again, he said.

Hollon, who's dumped dye into the system to track the flow of sewage through the city's 61-mile network of lines, said that depending on if it's after the morning rush, at night or during a big televised event, it takes about five to seven hours for water flushed in a toilet from the southern-most part of Ottawa to reach the plant, which is on East First Street on the south bank of the river.

As cities go, that's not long for water to stay in the sewer pipes, he said.

"Some of the larger cities, like Wichita, it may take days and maybe even a month and the stuff builds up after being in the system so long," Hollon said. "It gives them a lot of trouble."

Keeping it clean

In past years, the city embarked on an effort to cut the amount of storm water and other water leaking, which will continue each year, Bradley.

Although the state and federal governments haven't required such efforts yet, it cuts the load placed on the wastewater plant, Bradley said.

Each year, a contractor "rebuilds" several lines by running special sleeves into older lines and then pumping hot water into them, which activates a special hardener, he said.

City crews clean nearly eight miles of sewer line each year, plus associated manholes, as well as running special underwater television cameras in about three miles of line each year, looking for obstructions and debris, he said.

The plant, designed to treat 2.68 million gallons a day, also depends mostly on gravity.

The new plant is one of the highest places in the city now, Hollon said.

When the city removed the Old Highway 50 overpass at 17th and Main several years ago, the dirt from the southern embankment was trucked to a spot next to the old sewer plant, Hollon said.

When construction began on the new plant, contractors poured a giant concrete pad and built the walls for the clarification and treatment basins. Then the dirt was piled 15 to 20 feet deep along those walls. Then the buildings were built on top of the new dirt mound, he said.

Powerful pumps push the effluent into the top story of the "headworks," the two-story building where the treatment process begins.

Once it's up there, everything is down hill, not counting the pumps needed to move water and effluent back and forth through certain steps of the treatment process.

In the headworks, mechanical grabbers take most solid and semi-solid items such as undigested clumps of toilet paper, tampons, condoms and other stuff out of the effluent.

"We've had some ladies call us and tell us to look out for their diamond rings they've dropped in the plumbing," Hollon said.

Operators often find children's toys, cruddy coins and severely tarnished jewelry in the  solids combed out of the effluent, he said.

"Of course, there's not much left after they've been in the system a few days," Hollon said.

A series of chambers, baffles and a pair of "racetracks" separate the solids from the water.

At each step, the biological organisms continue to break down and digest contaminants.

In many cases, some of the effluent is recirculated through the plant to extend the process, he said.

Depending on that day's temperatures, the Super Bowl and other TV or holiday extravaganzas or the time of day, it takes about eight hours for water to go through the plant, he said.

After the sludge

Hollon said he expects phosphorus emissions to be added to regulations in later years. The new plant was designed to meet those likely regulations, and probably already does, based on the numbers Hollon has heard proposed for such regulations.

Most of the "wet sludge" that's separated from the water goes to the Johnson County landfill where it's layered with the refuse buried at the landfill, he said.

Hollon said he's been told Johnson County landfill operators like the wet sludge, which still has some active bacteria, because its organisms help speed up the decomposition of the other refuse.

The remaining dried and other sludge is trucked to the Franklin County Transfer Station.

Once the sludge is separated and the water is cleaned and before it leaves the plant, the water is sterilized before it's discharged into the river, which ends the bacterial action. The water flows through a chamber lit up by banks of powerful ultraviolet lights that simulate sunlight, he said.

Sterilized water tumbles into the river down the man-made waterfall, a final cleaning step, behind the plant.

When the tumbling water falls into the Marais des Cygnes, it is cleaner than the water in the river, he said.

"You can stand along the river and see the plume of clean water as it mixes into the river," Hollon said. For years, the Marais des Cygnes has been listed as an "impaired river" rife with a variety of toxins and pollutants and the city was frequently at odds with the Kansas Department of Health and Environment and the Environmental Protection Agency concerning discharges from the old sewage treatment plant.

The KDHE hasn't released figures concerning pollution in the river since the city built the new plant, but both Hollon and the state are expecting the new figures to show an improvement -- especially downstream of the city's wastewater plant, he said.

"We're helping to clean up the river," he said.