Here in the US, tea is essentially a niche product, falling way behind coffee in terms of popularity. But in places like the Middle East, Europe, and Asia, tea far surpasses coffee as a national past time. In 2008 alone, the world production of black tea was more than 3.8 million tons.
Typically, all those spent tea leaves and remaining liquid are tossed out with the trash, but now two Pakistani researchers have decided to tackle what they perceived as a waste of resources, and have figured out how to completely recycle the leftover tea and tea leaves into biodiesel, ethanol, methane, propane, fertilizer and even chemical spill absorbent.
Pretty ingenious if you ask me.
Tariq Mahmood and Syed Tajammul Hussain are researchers for the Nano Science and Catalysis Division at the Pakistani National Centre for Physics in Islamabad. Their experiment tackled two separate methods to convert the spent tea into something useful.
In the first method, they used a process known as gasification — essentially the “cooking” of organic material at really high temperatures in the absence of oxygen — to convert the waste tea leaves into gases, liquids and charcoal. The gases produced in this method were all hydrocarbons (methane, propane, methanol, ethene, and propyne), which can all be used in their own right in either chemical or fuel applications. The resulting liquid from the gasification was subsequently turned into biodiesel, glycerol and soap through a process known as transesterification. The charcoal left from gasification can also be used as a garden fertilizer or as an agent to clean up chemical spills.
Gasification is certainly not a new process, but the Pakistani scientists made it much less energy intensive by using nano particles of cobalt as a catalyst. Usually gasification requires temperatures of around 1000 degrees Celsius (1,832 degrees Fahrenheit) to work. By adding the nano particles of cobalt to the mix, they were able to reduce that temperature to 300 degrees Celsius (572 degrees Fahrenheit). Not only that, the Cobalt catalyst is completely recovered in the process, so it can be reused over and over again.
In the second method, the researchers used a well-known microbe, Aspergillus niger, to ferment the spent tea leaves directly into ethanol, which resulted in almost 60% of the spent tea and tea leaves being turned into ethanol. Given that tea drinkers tend to put quite a bit of sugar in their tea, the microbes were extra happy to ferment the waste. As it turns out, ethanol is also a required addition to making biodiesel in their first method, so the two methods have some potential to work quite well together.
At this point, the two major sticking points I see are; 1) how to get all that spent tea to central processing facilities, and 2) figuring out if the energy required to do all the conversion through gasification isn’t more than you get out. Certainly those are not overcome-able barriers, but the first one I see as a real logistical nightmare. Anyway, it’s promising research and represents some creative thinking on how to deal with waste.
If you’re so inclined, you can read the whole scientific paper on the next page.
Source: African Journal of Biotechnology (via Biofuels Digest)
Image Credit: allaboutgeorge’s Flickr photostream. Used under a Creative Commons License.
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