Treatment system solves camp’s variable wastewater flows issue
Fed up with a wastewater treatment system poorly equipped to deal with variable flow conditions, one retreat and camp facility found a more effective and operator-friendly solution.
The Bishop Hodges Pastoral Center is a year-round West Virginia recreational facility known for hosting camps, business meetings and other social events. From week to week, or even day to day, the number of people on the property can vary significantly.
“We can go from 10 to 250 [people] in the blink of an eye … and then back to 10 on a moment’s notice,” said Jon DiStefano, maintenance supervisor for the Bishop Hodges Pastoral Center.
Replacing an Aging System
The camp previously utilized a conventional biological system that was aging and poorly equipped to deal with these variable flow conditions. Its biological bacteria were wholly mixed into the liquid, so they were susceptible to dying off during low-flow periods and washing out during high-flow periods. According to DiStefano, the system required frequent sludge management and other operations and maintenance, but still produced only average effluent quality that barely met permit requirements.
“They were probably as hard to operate with low population as they were with high population; they did not react well to that,” DiStefano said.
Bishop Hodges began exploring treatment system options that would better meet its needs. With the help of engineering firm MR2, camp staff conducted more than a year of research and traveled to see different types of plants in operation and talk to operators about the pros and cons of each.
Due to its design and experience in variable flow applications, the group selected the FAST wastewater treatment system by Smith & Loveless. This customizable system was equipped with the following four components as specified by Bishop Hodges: An EQ basin; an aeration chamber with 1,300 sq ft of FAST media; a clarifier; and a post-aeration tank. The system was designed for a range of flows between 0 and 20,000 gpd and was installed in early 2010. It has since provided five years of dependable service in the face of rapidly changing flows.
“It’s pretty amazing how well it actually deals with population bounces,” DiStefano said. “It has adapted to the changes without any problem.”
Unlike the previous system, the FAST unit does not require sludge management or other frequent, time-consuming maintenance tasks like cleaning and skimming. DiStefano conducts minor weekly maintenance and a simple backwash every three to six weeks, but this is far less onerous than the maintenance requirements associated with the previous system. Fewer maintenance requirements enable DiStefano to focus on maintaining the rest of the 1,300-plus-acre property, a windfall from which Bishop Hodges has greatly benefitted.
“It doesn’t seem to require so much fine tuning whenever populations are changing,” DiStefano said. “It’s a lot easier than taking care of the old [plant].”
The FAST process utilizes a fixed-film media that provides the necessary environment for robust bacterial growth and retention during periods of low flow and shock loads. While conventional systems use suspended biological processes that are susceptible to bacterial loss in variable flow conditions, the FAST system is designed so that bacteria grow not only in suspension in the liquid, but also on the fully submerged media and inside the liquid circulating through the media.
The result is a self-regulating biological process that adapts well to variable flow conditions. When surface bacteria are lost, the FAST media provides oxygen-activated subsurface bacteria that assume the role of primary treatment. The system is able to operate for periods of up to two weeks with zero flow. No sludge management or other daily operation is required.
Operational benefits aside, however, the primary job of a wastewater treatment system is still to treat wastewater. This was certainly the case with Bishop Hodges, where effluent is discharged into a local trout stream. Permitting requirements set biochemical oxygen demand (BOD)/total suspended solids (TSS) limits at 30 mg/L and fecal count limits at 200.
“We actually have tested nondetectable for TSS and BOD for three out of four quarters [in the past year],” DiStefano said. “We were confident that the FAST unit was going to meet our permit parameters, but we didn’t think it would meet them so well.”
Overall, Bishop Hodges is pleased with the system and its ability to deal with variable flow conditions. Treatment quality is better than ever, operations and maintenance requirements are at a minimum and the system has provided dependable service in the face of frequent population changes. That leaves a lot more time for DiStefano and the rest of the Bishop Hodges staff to focus on the camp’s visitors.
“The FAST unit far exceeded our expectations,” DiStefano said. “This was the best decision we could have made.”