Monday, April 06, 2015

The Dirty Little Secret of Agricultural Plastics

You may have seen this story entitled either as "The Biggest Source of Plastic Trash You've Never Heard Of" or "How can agriculture solve its $5.87 billion plastic problem?". It came out late last week and is making the rounds different sites. The article provides a high level overview of how plastic films are extensively used in agriculture for a number of reasons such as water retention and warming the soil so as to extend growing seasons. People have recognized the waste and potential for is use for years (since at least 2003), so it isn't quite as new of a concern as the headlines may have you believe. Much of this plastic is never recycled, but the article really downplays why.

It's the dirt.
"Another big issue in recycling agricultural plastics is dirt and debris."
Another big issue? How about it being the biggest issue. I was at a plastics recycling conference a few years ago and all the speakers kept talking about was the dirt. Dirt is going to contaminate the plastic and discolor it (unless it is already black). Consumers are all in favor of companies using recycled plastics and some are even willing to pay a little more for it, but no one is willing to give up on appearance. White plastic with dark brown specks, line and swirls? Not too likely.

At that conference, one of the speakers showed prototypes how using the unwashed plastic could generate tiles for use in plastic sidewalks. The appearance was nice, as the nonuniform discoloration provided visual interest, much like slate, marble, granite and other natural materials do. I've not heard much about that application since, but it was mentioned in passing in this article. Sadly, there aren't too many applications like that that can take in the plastic "as is" and run with it. The plastic can be washed, but then you have to dry it afterwards. Water and molten plastics just don't get along.

Previous Years

April 6, 2012 - Chemophobia - from a grant reviewer?

April 6, 2011 - Plastics to the Rescue in Japan

April 6, 2010 - Wind Power Problems

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