The book titled Rubbish! The Archaeology of Garbage by William Rathje and Cullen Murphy was a very interesting read.  Created in 1973, the archaeology of garbage was a program primarily created as an exercise in archeology for students at the University of Arizona Tucson.  The most fascinating aspect of the book is the discoveries of what our garbage tells about us as a society.  It was interesting the amount of detailed behavior that can be discovered by going through trash.  For example, in times of product scarcity our garbage shows that we waste more of the scarce product. Another major fact Dr. Rathje’s team discovered is that our landfills are not filling up from disposable diapers which is taking up about 1% of a landfills mass.

There have been some in the PLA (corn plastics) industry who use quotes from Dr. Rathje’s book to support an argument that composting biodegradable plastics is better for the environment than landfilling them.  Their argument takes some of the data out on context by looking at the hundred year old “poor” environmental designs of landfills.  The printing of “RUBBISH!” was in 1991 with most data provided in the book ending in 1988.  Most of the data in the book is over 20 years old.  As with many things from our past we eventually discover better and more environmentally sound solutions.  Yes, it is absolutely true that traditional dry-tomb landfilling is not the best solution for dealing with our garbage.  As a society we have made significant improvements to the methods we use for disposing of garbage.  Since the writing of the book we have implemented hundreds of recycling programs as well as the EPA requiring methane from the anaerobic biodegradation process happening in landfills to be captured and burned or used to create clean energy.  The EPA in the last 5 years has also changed laws with recirculating leachate through a landfill so to accelerate biodegradation by up to 10x.

Dr. Rathje does briefly address composting as a solution to some of our organic garbage.  He points out that composting is expensive  and the issues is that most compost becomes tainted with hazardous elements, such as the heavy metals used in inks and pigments as well as yard waste containing traces of pesticides and herbicides.  Another issue with composting biodegradable plastics is that the corn used in fermenting the lactic acid is Genetically Modified corn, because of this, if PLA plastics are composted that compost cannot be labeled “organic”.  For many composting facilities this would severely impact the marketability of the compost material.

What Dr. William Rathje, and those using the book to bash biodegradable plastics neglect to mention is that over the last few years we have made significant improvements to the way we handle our trash.  One of these improvements is called landfill bioreactors, which is not discussed at all in the book.  These types of landfills are designed in the beginning to better control the anaerobic biodegradation process by circulating the leachate back through the garbage.  This not only helps to accelerate anaerobic biodegradation by adding moisture but it has also been discovered to improve the quality of the leachate.  These bioreactors are built with collection systems for collecting not only the leachate but also the methane.  So from the beginning of the bioreactor landfill life the methane is being captured and typically used to create clean inexpensive energy.  In fact, energy from methane captured from landfills is the least expensive form of “green” energy we can create today.  It is less costly than solar, wind, or hydro.  In April 2004, the EPA finalized a rule permitting the transformation of landfills into bioreactors.  Landfill bioreactors produce MUCH more gas than traditional landfills, about 10 times the amount and are at concentrations of up to 50%.  Bioreactors with their advanced LFG collection systems are able to collect more than 90% of the methane gasses.

Another benefit of bioreactor landfills is that the life of the landfill is extended by as much as 25 years.  This means that the same physical space of land that would traditionally have been filled up and capped can now be used for another 25 years longer before needing additional bioreactor landfill cells.  There is some discussion that a bioreactor landfill could later on be dug up to use the soil for fertilizer and then reuse the landfill space again, but this is yet to be a reality.

The key to utilizing anaerobic biodegradation with organic garbage is that it creates a greater value proposition over composting.  With composting, the organic material is artificially processed to accelerate aerobic biodegradation resulting in compost material which makes a great rich soil.  What is off gassed is CO2 which is released into the atmosphere as a GHG.  Some would argue that this would be a zero sum game but it really depends on the organic material and the life cycle of that material.

Markets for compost material are very specific to the geographical location of that composting facility.  In many cases today, there are not enough markets available to utilize the compost material and a lot of it ends up as soil cover in landfills.  With utilizing anaerobic biodegradation either in anaerobic digesters or bioreactor landfills we can capture the methane and use it for cleans energy.  Once the methane is burned to create that energy the CH4 is converted into CO2 which now we are right back to where we were with composting but now we created clean energy which reduces our reliance on fossil fuels.  The soil that remains from anaerobic biodegradation can also be used as fertilizer.  The additional value proposition of creating CH4 vs. CO2 has much more value and results in a better environmental solution.

According to the EPA as of April 2009, there are approximately 480 operational LFG energy projects in the United States. In addition, about 130 projects are currently under construction or are exploring development options and opportunities. These are landfills that convert the LFG to clean, inexpensive energy.  New Jersey’s Governor Jon S. Corzine’s Energy Master Plan touts landfill methane gas as one of the key renewable energy sources that the state hopes will combine to supply 30 percent of New Jersey’s electricity by 2020. http://www.huffingtonpost.com/2008/10/27/new-jersey-landfills-capt_n_138076.html

There is much we can learn about our past, present and how to better design our future from both a social and environmental perspective.  It is in the nature of archaeology to look at the past but it is in the best interest for the human race to stay focused on the future.

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By Danny Clark
ENSO Bottles, LLC