In the late '80s Albany International Airport (ALB) was threatenedwith being shut down because of the pollution caused by stormwaterrunoff. Immediately the airport sought action to clean up its recoveryand recycling efforts, which include on-airport treatment with microbes.Since then, the airport has received awards and accolades from the Environmental Protection Agency and other airports for its efforts.
At the time says Stephen Iachetta, airport planner, Shaker Creek, which flows through airport property, had reached propylene glycol (deicing fluid) concentrations of some 13 percent, or 130,000 parts per million. “That's what you'd see typically in many drainage swales or streams flowing though airports.”
In 1989 the airport began its containment and collection program, in which the stormwater was transported to a wastewater treatment facility. Iachetta explains that this method lacked efficiency and was expensive. Additionally, he says, “public sanitary plants really are not built to handle the high loading of deicing stormwater. So they’re really not adapted or well-suited and it can be very costly.”
Beginning in the early ‘90s, airport officials were researching on-airport biological treatment of the spent glycol and runoff water. Iachetta, whose education includes regulation of toxic substances, was aware that the fluid used to deice aircraft, propylene glycol, was a certified safe food additive and used this knowledge to experiment with on-airport treatment.
The experiments involved putting dried brewer’s yeast microbes into the storage lagoon, which yielded tremendous results, says Iachetta, “Total removal in just a few days.”
Working with the New York State Energy Research and Development Authority, along with faculty and students at several universities, the airport conducted a pilot project to “set up basically wetlands in a bottle,” says Iachetta. “So what comes down as winter rain and snow can go right back on the airfield in the most direct and lowest cost manner possible.”
The airport’s award winning biological treatment system has been visited by engineering teams from major airports around the world, the Department of Defense, as well as the Environmental Protection Agency.
Iachetta says the cost savings and environmental benefits are significant. “Every year we’ve been very pleased with the overall cost reduction of 75 percent.”
The Solution: Streamlined Efficiency
The airport is the primary permit holder, covering all tenants. Iachetta explains some airports “pass the buck to their tenants” and require each tenant to acquire its own permit. “But that’s not streamlined efficiency.”
Albany invested in a dual system (two systems operated side by side that can be run in parallel or in series) with what Iachetta calls all the “bells and whistles” at a cost of some $3.4 million. He adds that the process can be replicated on a smaller scale at a cost of $1.5 million to $2 million.
The airport has storage for some 11 million gallons of stormwater, which includes a 2-1/2 million gallon storage tank and two lagoons that will be converted into storage tanks in the next few years.
“I would recommend to anyone considering on-airport treatment to consider establishing storage tanks as opposed to lagoons, unless you have a remote area in which odors would not be an issue,” says Iachetta. “Because if you’re collecting and storing deicing stormwater in any warm periods, you will have difficulty controlling the odors.” Iachetta says when natural degradation of deicing storm water in a pond occurs it tends to go septic on its own, causing a sweet, pungent smell that can be quite offensive.
Lagoons also tend to be shallow, collect a lot of rainwater, are difficult to maintain, and need to be cleaned. “They’re really not an optimal or efficient design for deicing stormwater storage.”
The Collection Process
Collection occurs from 56 acres of impervious surface, says Iachetta. The runoff goes into the treatment system, comprised of two vessels filled with activated carbon, which also contain the microbes. The vessels stand 30 feet high and are 15 feet wide. The wastewater cycles through the system at a rate of 150 gallons per minute.
If soil temperatures are above 50 degrees Fahrenheit, explains Iachetta, the recycled water can be discharged onto the airfield, which is generally what is done from late April through June. During the winter months, the water, which has been processed into Class A drinking water, is discharged into Shaker Creek, which is a Class C stream. “We’re actually improving the water quality in Shaker Creek,” says Iachetta.
The airport was able to reduce the solids in the water from the primary treatment plant from 50 parts per million to non-detectable levels of suspended solids.
A Fuel Byproduct
“One of the best benefits of this system,” says Iachetta “is that it’s a net energy producer. It creates more energy than it uses.” The microbes that ingest the propylene glycol give off methane which is then used to heat two buildings as well as up to 45 millions of deicing stormwater each year, as microbes prefer their food heated. According to Iachetta, the gas is 85 percent pure methane and 15 percent carbon dioxide. “That’s better than the natural gas you get from your utility company, which is only about 60 to 65 percent pure.”
According to Doug Myers, director of public affairs, on a full day of operation the methane that is produced equates to some 500 gallons of number two heating oil, which sold for $1.50 per gallon last year. “If we were heating those buildings with heating oil,” says Meyers, “we’d be paying $1.50 a gallon.”
Myers adds that often there is an excess of fuel. What is not used is currently burned off, but the airport is looking into ways of recapturing the excess to heat snow that is piled on a melting pad. Last year, says Myers, 70 feet of snow lingered into July. The addition of heat under the pad, much like a stove burner, would speed up the process considerably, he says.
Feeding the Help
The microbes, similar to those used in brewer’s yeast, feed off of the propylene glycol during months of operation. When the food runs out, typically some time in July or August, the recycling plant is shut down, the bugs grow a shell and go to sleep, explains Iachetta. However, when the food supply is turned back on by means of deicing fluids in the system, the microbes will be back at full production within 72 hours. “They’re really resilient, truly remarkable little animals,” says Iachetta.
The bugs can also handle a number of different contaminants such as small amounts of fuel spillage and firefighting foam. Also, they can adapt to various organic food sources, including soda syrup which the airport is currently testing. A neighboring Pepsi-Cola bottling plant has soda syrup that can no longer be used for its products. So, the airport is putting it through the system during the off-season and the bugs seem to like it, says Myers.
Stephen Iachetta, airport planner, Albany InternationalAirport, says only a few facilities still use ethylene-basedproducts for deicing fluids, but ethylene glycol (EG) and propyleneglycol (PG) are often confused.
There are several differences between PG and EG, one being
that PG is used in many foods, food coloring, and medicines. “Only
PG is the certified safe food additive,” explains Iachetta. “Ethylene
is an alcohol and will affect your liver and other organs as
any other alcohol.”
Iachetta says the use of EG was more of an issue a decade ago, but the military and other airports, particularly those with water quality sensitivities, led the transition during the 1990s from ethylene to propylene. The biological treatment that occurs at ALB will completely remove any type of glycol, as well as other contaminants.
“There’s no difference between EG and PG to the bugs,” says Iachetta. “They don’t care about certification for food or beverage safety. They’ll eat all kinds of things.” However, ALB requires that tenants use only propylene-based deicing fluids.