Baylor Faculty and Students to Present Research FindingsMarch 5, 2007
State Wastewater Treatment Research Council to Meet in Waco to Hear Results
With approximately 25 percent of the homes in the United States utilizing a septic tank system for on-site wastewater treatment, finding better ways to protect the surrounding environment is essential. A Baylor University researcher will present new research findings on Tuesday, March 6, on an alternative treatment system that could be a significant addition to what is currently available for residential use. The "system" is a submerged-bed wetland, which mirrors the pollutant removal ability of nature by relying on gravel and plants to remove contaminants.
The wetland is located on the Waco Metropolitan Area Regional Sewage System's (WMARSS) property. Wastewater from WMARSS was pumped three times a day to a 1,500-gallon septic tank, which then feeds into the 1000-gallon wetland.
Dr. Joe C. Yelderman Jr., a geology professor at Baylor, and his research team spent the past year evaluating the submerged wetland against the National Sanitation Foundation's "STANDARD 40" protocol, a widely accepted set of requirements used to evaluate and certify individual on-site aerobic treatment systems. Two back-to-back six-month studies mark the first time a submerged-bed wetland has been tested against the STANDARD 40. The results were very promising, according to Yelderman.
Baylor researchers found:
Overall, the wetland consistently produced effluent that was above the normal requirements. In some cases, the wetland produced better levels than what some larger municipal treatment centers can achieve.
In the first evaluation, it took two months before the wetland met the required effluent levels. After the first two months, the wetland produced effluent that was above the normal requirements. The delay could have been caused by a number of factors ranging from the cold weather to a lack of bacteria on the rocks.
In both the first and second study the wetland continued to function properly during stress tests. These tests included a vacation stress in July where the wetland did not receive any wastewater for eight days during which time the temperature exceeded 100 degrees Fahrenheit each day. In the second study the wetland performed well during several days of freezing weather and it continued to function well through the winter even though the plants died back due to the freezes.
The wetland did not reduce nutrients like nitrogen and phosphorous to wanted levels. However these nutrients are not currently regulated but they may be regulated in the future.
In the second study, which started in September, the wetland met the effluent standards immediately and continued to function well throughout the study period.
"I think these results will change attitudes by people in regulatory areas about submerged wetlands," Yelderman said. "Residents can put in these wetlands now, but they have to get approval on a case-by-case basis. Our study could provide the base for a uniform certification process that manufacturers and regulators could abide by."
Once effluent leaves a septic tank, it normally flows into a drain field, which is an arrangement of perforated pipes that carry the effluent into the soil. The submerged gravel wetland would not replace the septic tank or drain field, but rather supplement the system and allow the drain field to be modified.
"If you want to build a home in a place where shallow soil is over hard limestone, like west of Waco, you can't put in a traditional treatment system like a septic tank with a drain field. You have to install a non-traditional system, which can be expensive," Yelderman said. "This would allow you to put in a traditional septic tank with a wetland, and a modified drain field which might be less expensive."
Yelderman will present his findings to the Texas On-Site Wastewater Treatment Research Council, who funded the project, at 4:45 p.m., Tuesday, March 6. The council, which usually meets in Austin, is holding its quarterly meeting and two day conference at the Waco Convention Center.
A Baylor graduate student also will present research findings and two other Baylor professors are expected to submit up to four proposals for additional research projects.
Research at Baylor has long been an important part of the academic life of the University. In 2006, the Carnegie Foundation reclassified Baylor as a "research university" with high research activity. The faculty's standing commitment to excellent teaching, scholarship and research continues to produce outstanding graduates at both the undergraduate and graduate level. Baylor 2012, the university's 10-year vision, articulates Baylor's aspiration to develop into one of America's leading Christian research universities. With that in mind, Baylor now has more than 25 research institutes and centers with many leading to discovery in emerging areas of science.
For more information, contact Frank Raczkiewicz at (254) 710-1964.