When we think of waste, we don’t usually think utility. Yet, as we face droughts, limited landfill space, and depleting natural resources, we’ve been forced to reconsider our castoffs, with interesting results. These five case studies show that with innovation and a little planning, our dumps, sewers, and piles of manure are not necessarily the end of the line. Instead, they’re just the beginning.
Sewage into Showers
Last summer, while the rest of the southwest was grappling with one of the most severe droughts in recorded history, a county in Georgia was sitting high on the water table. Twenty years ago, Clayton County recognized that growth and limited rainfall would make a water shortage inevitable, so they built a unique water treatment center to ensure reservoirs would remain full even in a drought. The center incorporates a 4,000-acre wetland, where treated wastewater runs through a serious of graded pools surrounded by thick vegetation to help filter out any leftover toxins. Clean water then runs into reservoirs for future use. With this system, the county is able to reclaim ten million of the twenty-six million gallons of water used annually. Although the treatment center requires a significant amount of open space, it’s cheaper than building a regular treatment plant and doubles as a nature preserve.
If one person’s trash is another’s treasure, then our collective trash may be worth its weight in gold—or at least oil. That’s because when trash decomposes in landfills, it releases methane, a polluting gas that is traditionally dealt with by incineration or allowed to escape. Instead of letting this gas escape and pollute the air, some waste management companies are employing a capture and purification system that allows them to convert the landfill gas (LFG) into energy.
In California, LFG is fueling over 300 of the same garbage trucks that collect the trash. At an East Kentucky Power Cooperative, they use landfill gas to generate enough power to fuel 7,500–8,000 homes. And the University of New Hampshire is planning on getting 80 to 85 percent of its total energy from a nearby landfill.
According to the EPA, there were approximately 445 operational LFG projects in the United States in 2007.
If we can generate energy from a dump, then it only seems logical that we can generate energy from the ultimate waste product—poop. Manure is the fifth largest contributor to methane emissions in the U.S., but the waste product doesn’t have to be a nuisance; instead, it can be converted into energy rich biogas and useful byproducts. At the AA Dairy in New York, for instance, manure and animal bedding (newspaper, hay) are scraped from the barn into a digester where the methane is collected and processed, ultimately generating enough power to run the farm with some leftover to sell. The solid waste is composted and sold, providing a dual financial incentive. And farms aren’t the only industries to benefit from manure methane. Long-Trail Brewing Company, located in cow dense Vermont, will soon be getting all of its energy from dairy farm manure, while the farm gets a waste product from the brewery—mash, a mixture of barley and water, which is used as cow feed.
There are approximately 114 farm-scale biogas systems in operation.Cut Back on Grass
In 1994, Montgomery County, Alabama imposed a ban on the disposal of yard trimmings, which accounted for 18 percent of the solid waste heading to a landfill. However, their composting facility couldn’t handle the influx of new material, so they instead promoted source reduction with grasscycling (leaving trimmings on lawn instead of bagging for pick-up), backyard composting, and mulching. Instead of throwing away a rich source of nutrients, residents and businesses were encouraged to incorporate them back into their yards. In addition to yard waste, they also implemented a separate program for food scraps, which included using worm composting as a teaching tool at school cafeterias. The program resulted in more than 50,000 tons of waste being grasscycled or composted in 1994. By reducing and reusing waste, the county saved close to one million dollars in processing costs and avoided having to do a 2.5 million dollar expansion of existing facilities.
Much of the oil, grease, and fat used for frying and cooking in restaurants is discarded in a landfill, or worse, sent down the drain. However, used cooking oil (not to be confused with biofuels, like ethanol, which are made from pure vegetable oil) can be used to fuel cars and other machinery. A 2004 report by the International Energy Agency estimates that the U.S. could make 500 million gallons of biodiesel a year from its waste grease. Used cooking oil is so in demand that it has even spurred a rash of yellow grease thieves, who steal old oil from restaurants. Even the gunk known as brown grease has utility—a company in Philadelphia, Fry-O-Diesel, has figured out how to make biodiesel from sewer grease traps.
Numerous other examples abound—household greywater systems turning used shower water into backyard irrigation; old tires turned into a source of fuel; clothing, bottles, benches, etc., made of recycled plastics. For those that strive for resource efficiency, these types of programs are inherently attractive, both from a financial and logical perspective. Yet, except for traditional recycling, many of these waste reuse programs are remarkable because they are not widespread. But with new technology and an eye on making money from what would otherwise be waste, we’ll likely be seeing our refuse used in entirely new ways.