Onsite installers can choose from a wide array of aerobic treatment units with varied processes and modes of operation. Jason Birdsong, owner of J & T Service Co. in Claremore, Oklahoma, since 2006, relies on NuWater ATUs from Enviro-Flo.

He chose the NuWater series for his more than 50 ATU installations per year because he prefers its mechanical componentry and a two-tier alarm system that helps him and homeowners determine when an alarm does and does not call for an emergency service visit.

“It’s a two-light alarm system,” says Birdsong. “There are two lights on the control box — a yellow light for air problems and a red light for the high-water alarm. Many aerobic systems have just one red light.

“When my customers call at 10 o’clock at night and say they have an alarm, I can ask them what color light is on. If they tell me they have a yellow light, I know that’s an air problem. I tell them it’s no big deal and I can put them on the schedule for the next day. That saves them the expense of an emergency call.

“On the other hand, if somebody calls and the system has just one red light and it’s on, I can’t tell what’s wrong. It could be an air problem, or it could be that they have a high-water situation and are moments away from the system backing up into the house.” And that means he has to respond right away.

Birdsong also prefers systems that do not rely too much on electronic componentry, which he feels can be sensitive to the damp and dirty environment of a treatment unit. The aerator is the only electrical component.

“In the NuWater system, everything is mechanical,” he says. “It uses floats for water level control, and it has a mechanical timer. I have found that it operates for long periods without problems.”

The NuWater system uses extended aeration, a modification of the activated sludge process in which microorganisms are allowed to remain in the treatment process for long periods. A large inventory of biological solids provides a buffer for shock loading of organic matter. The long aeration period also allows organisms in the system to consume themselves, reducing the total solids produced.

Wastewater enters a pretreatment chamber and then passes into the aeration chamber through an opening below the flow line. Aeration is provided by a diffused air system at the chamber bottom that operates on a continuous cycle. The aeration chamber provides a retention time of 22 hours at design flow.

Settling is accomplished in a clarification chamber. The bottom of this chamber is sloped to help direct settled solids back toward the opening between the two chambers. The hydraulic roll created by the air system in the aeration chamber helps draw the settled solids from the bottom of the clarifier back into the aeration chamber. Treated wastewater exits through a multi-directional outlet tee.

According to NuWater, the units can produce effluent containing less than 2 mg/L CBOD5 and TSS. Systems are available in capacities from 500 to 1,500 gpd.

Read more about Jason Birdsong and his company here.