Thursday, March 05, 2009

The living landfill

It's our lucky week: the Economist has dedicated its Special Report section to the waste management industry. There's a lot to blog about, but for now, I'll focus on Waste Management's new "bioreactor" landfills.

For years, landfills have been carefully sequestered and sealed from the outside world: if nothing could get in, the thinking went, then none of the waste's toxic chemicals could leak out into surrounding groundwater. This theory has worked so well for modern landfills that the garbage inside has become more or less mummified: archaeologists have unearthed deep layers of late-20th-century dumps and discovered more or less intact scraps of food wrapped in legible, decades-old newspapers.

Of course, it's expensive to mummify garbage. For one thing, many dumps are trying to make a business out of harvesting methane (a.k.a. natural gas), which only gets produced underground if the garbage decomposes. For another, landfill real estate is expensive: landfill owners would appreciate it if produce from the disco era could rot away and make room for iPods and Miley Cyrus merchandise.

So instead of thinking of landfills as inert, unchanging piles, Waste Management, one of the nation's largest garbage collection and disposal corporations, has begun experiments to turn some of their landfills into "bioreactors." From Waste Management's website:
What is a bioreactor landfill? Simply put, it is a waste treatment landfill with technology that accelerates the decomposition of organic wastes in a landfill. This is accomplished by controlling the addition and removal of moisture from the waste mass, the collection and extraction of landfill gas, and in some instances the addition of air.
The landfill's hive of bacteria digests its waste, farts into a power plant, and opens its maw for more. The landfill is alive.

What really tickles me, though, is the fact that the bioreactor has particular tastes. Quoting from the Economist article:
Waste Management has tried pumping different mixtures through landfills to achieve the desired effect, and found that injections of out-of-date beer and soft drinks work better than water.
The results: Waste Management's bioreactors produce natural gas at four times the rate of other landfills and reduce the volume of garbage up to 35%, according to the Economist's report. The concept seems to be catching on: after the success of a pilot bioreactor in Florida, officials are applying the same techniques to four additional landfills.

Here's where you can read more about bioreactors:
US EPA: Bioreactors


Benjamin said...
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Benjamin said...

Cool idea. I read this post right as I was reading an article on Newark's Waste Management history which seemed to fit.

The city got very excited about "energy recovery"- burning garbage in order to generate electricity, as well as processing it for Refuse Derived Fuel- and contracted out to a private company to build a facility, paying a price based on an optimistic estimation of how much garbage would be available, and the profits it would generate.

But when it went online, there wasn't enough garbage! This caused a lower than anticipated burn temperature, which created illegal emissions and lots of ash, and the need for more garbage also created a disincentive for any sort of waste reduction. So the incinerator never made the profit expected, and eventually closed, leaving Newark with a major garbage problem.

The point I keep coming back to is what happens when people try to solve an ecological problem by some means that will also be economically profitable, the economic goals tend to take over and trump environmental concerns. It seems inevitable that companies will developing ways to capture the emitted gas for resale (which they have for the other new technology mentioned in the economist article, gasification). And while clearly this is a good thing, because it accelerates construction of these nice new landfills, and provides some energy from a non-CO2 producing source, I just wonder how the resulting economic pressure to maintain production of the gas will affect the running of the reactors- maybe causing a quota on certain types of waste, or something. It's certainly still frustrating to see new technological developments for dealing with waste to be put forward without any companion effort at any sort of waste reduction...

Anonymous said...

ben how about stiil controling the gas that leak out of the reactor,i live in michigan this one is a monster wanting to get out they cant control it. thanks larry