Most people don’t think about where wastewater goes once it leaves the house, but scientists at Kennedy Space Center (KSC) are doing that now as they evaluate methods to clean water containing human waste before it ever reaches local groundwater. The cost-effective technology could be a boon to coastal areas and other locations.
Dynamac Corporation is the KSC contractor responsible for life sciences support services and environmental and ecological monitoring of KSC’s premises, located on a national wildlife refuge. Their work in wastewater treatment is a natural extension of the research team’s efforts to develop closed, bioregenerative life support systems for long duration space missions.
In most residential areas without central sewerage systems, wastewater enters a leach field or drain field from a septic tank system. However, in areas with increased development and limited land, such as coastal areas with overly porous soil or impermeable rock strata, wastewater often finds its way into the groundwater and nearby surface water.
“It’s a widespread problem in Florida, where the soil is very porous,” said Dr. John Sager, a NASA scientist working at Kennedy and principle investigator on the wastewater research project. “That can lead to pollution, both in coastal areas and in the many freshwater lakes up the spine of the state.”
This problem is all too familiar to residents and health officials in areas such as the Florida Keys. As the Keys continue to grow in population, the amount of land becomes more and more limited, leading to the pollution of nearby seawater. As a result, beaches in more-developed areas are often closed due to wastewater intrusion until the pollution subsides.
The solution to this problem is to make sure wastewater is treated before it is released into the groundwater. Although there are some treatment methods currently used, they are complex, time-consuming and can be expensive.
In the method proposed by the NASA/KSC team, plants will use the phosphorus and nitrogen, or nutrients, in the wastewater for their own nutrition and growth. The pathogens will be held in the soil and ultimately deactivated. The remaining clean water will be released through the plants’ leaves in a process known as transpiration.
The work is being conducted at Hangar L, Cape Canaveral Air Force Station, the center of life sciences projects. Behind Hangar L, four large white boxes are topped by an attractive array of common Florida plants, including several varieties of palms and philodendrons. Each box acts as a contained drain field, receiving five gallons of simulated wastewater per day, or half the amount of wastewater created by one person.
Dynamac scientists Neil Yorio and Jay Garland pointed out that in a residential yard, the box would be buried, revealing only the thick stand of plants. The plants in use are salt-, flood- and drought-tolerant, making them well-suited for this tropical environment. A barrier hidden under a layer of mulch keeps rainwater from directly entering the soil.
Phase One of the three-phase project began in November 2001 and concluded in March 2002. After 105 days of testing, the plants thrived, showing no sign of toxicity to the high nutrient concentrations and bacteria in the water. Although the plants transpired less water during winter months than expected, this is not abnormal, especially when plants are still becoming established.
The team has seen a more rapid transpiration rate during the first three months of Phase Two, which began in April and will run for about a year. During Phase Three, the system will be tested in a real environment, although site selection is still in the planning stage.
“It’s exciting to use the expertise we have developed for NASA to address a terrestrial problem,” said Dr. Garland, a microbial ecologist. “The goal of developing sustainable human habitation systems is a transcendent challenge for Earth and space.”
NOTE: A NASA TV Video file will be shown with B-roll and interviews at 3 p.m. and 6 p.m. today.
