ROBERTSDALE, Ala. — Almost every Robertsdale city council meeting has some mention of the “clarifiers” being built at the city’s wastewater treatment plant on County Road 52.

But what are clarifiers, and why are they important?

“The clarifier makes solids settle out,” said city engineer Greg Smith. The solids in the wastewater are transferred to sludge ponds and beneficial (aerobic bacteria, which are organisms that live in an oxygen environment is used to break down the solids before the water is returned to the clarifier. The solid-free water from the clarifier is sanitized using ultraviolet light before being released, almost bacteria free, into Rock Creek.

According to Robertsdale Mayor Charles Murphy, the original ponds for the sewer facility were built in 1995, and the current system went on-line in 2007.

The clarifiers under construction at the Robertsdale plant are deep concrete tanks. Waste water flows into the bottom of the tank and compressed air forces the cleaner water to the top. A boom pushes any floating solid material to drains that feed into the sludge pond. The ponds are lined to minimize the chance of untreated water escaping the system.

“This is a lot more aggressive system than we had in 1995,” said Smith.

The facility is licensed to treat .95 million gallons per day, and should a new industry come to Robertsdale, ordinances and regulations require that the plant using more that a set rate of water will have to have their own treatment facility. That’s good for the city plant — the bacteria that decompose the waste are sensitive to toxins and will die if a poison is released into the system. Normal household applications won’t hurt the plant, but wastewater from industry does have to be treated before coming to the plant.

The first new clarifier (the city already has one) will come on-line in December of this year, Murphy says.

“The second (clarifier) requires an upgrade to our permit,” said Murphy. The additional clarifier, Murphy says is being built to add some redundancy to the system. That way, if a malfunction occurs in one of the existing clarifiers, there is a spare on hand ready to use.

“We started this in 2006, and we were under so much pressure because of growth,” Murphy said. “We will use the third basin for future expansion.”

Spills and other mishaps at the plant are reported to the Alabama Department of Environmental Management, Murphy says.

“We report,” Murphy said. “The worst thing you can do is not tell them or give false information.”

The city is also working on a system to separate wood and wood products from the waste that is hauled to a dump.

The water will be “chipped,” or cut into small pieces that will be useful for a garden or composting.

The process has saved the city, Murphy estimates, about $55,000.

“The real savings is in the tipping fees and that we are saving about an hour a day for two people to make that trip.”