Fixed-film system solves camp's variable wastewater problems
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.
The camp utilized a conventional biological system that was aging and poorly equipped to deal with these variable flow conditions. As the plant’s operator, DiStefano said the system required frequent sludge management and other maintenance, but it 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,” said DiStefano.
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 plants in operation and talk to operators. The group selected the FAST wastewater treatment system by Smith & Loveless due to its design and experience in variable flow applications. The system was designed for a range of flows between 0 and 20,000 gpd (75.7 cmd), and it 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,” said DiStefano. “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 such as cleaning and skimming. DiStefano conducts minor weekly maintenance and a simple backwash every 3 to 6 weeks, but that is all. This allows him to focus on maintaining the rest of the more-than-1,300-acre property, a windfall from which Bishop Hodges has benefitted greatly.
“It doesn’t seem to require so much fine-tuning whenever populations are changing,” said DiStefano. “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 utilize 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. 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 at Bishop Hodges, where effluent is discharged into a local trout stream. Permitting requirements set biological oxygen demand (BOD)/total suspended solids limits at 30 mg/L and fecal count limits at 200.
“We actually have tested non-detectable for total suspended solids and BOD for three out of four quarters [in the past year],” said DiStefano. “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 more than pleased with the FAST 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 staff is freed up to focus on the camp’s number one priority: its visitors.
“The FAST unit far exceeded our expectations,” said DiStefano. “This was the best decision we could have made.”