What happens at a wastewater treatment plant?

“We make dirty water clean,” says Frank DiScuillo, wastewater systems director with the City of Lebanon Authority.

That’s the short version of what’s involved in treating wastewater — that is, anything that goes down a drain in any building in the authority’s service area.

It is a process that is simultaneously simple and complex.

It is simple because it is a natural process relying on bacteria for decomposition. It is complex because the natural processes are accelerated and concentrated so that the water can be cleaned for reuse in a short time.

Initially, liquids are separated from solids such as food, fecal matter, paper products and chemicals (DiScuillo said he once found three $20 bills that had entered the wastewater plant).

Then through a system of settling, chemicals or treatment with different bacteria, pollutants such as carbon, nitrates/nitrites and ammonia are removed or converted into solids and gas which can be separated from the water.  

Once the cleaned water has met federal standards, it leaves the plant and is discharged into the Quittapahilla Creek.

The remaining organic solids – byproducts of removing pollutants and chemically-treated phosphorous so it clumps together – are pumped to the digesters along with the multitudes of bacteria that have fed on the now removed pollutants.  

Twice a week the authority’s lab samples the biosolids in the digesters and checks total solids, alkalinity and volatile acids, said Cora Shenk, compliance and lab manager with the authority. Those analyses, combined with monitoring of gas production, are the key parameters in ensuring treatment processes are working efficiently.