by Staff Writers
Zurich, Switzerland (SPX) Dec 04, 2014
Plastic waste is one of today's major environmental concerns. Most types of plastic do not biodegrade but break up into ever smaller pieces while remaining a polymer. Also, most types are made from oil, a rapidly dwindling resource. But there are promising alternatives, and one of them is polylactic acid (PLA): it is biodegradable and made from renewable resources.
Manufacturers use PLA for disposable cups, bags and other sorts of packaging. The demand for PLA is constantly rising and has been estimated to reach about one megaton per year by 2020.
The research groups of ETH professors Konrad Hungerbuhler and Javier Perez-Ramirez at the Institute for Chemical and Bioengineering are now introducing a new method to produce lactic acid.
The process is more productive, cost-effective and climate-friendly than sugar fermentation, which is the technology currently used to produce lactic acid. The new method's greatest advantage is that it makes use of a waste feedstock: glycerol.
Waste product of biofuel manufacturing
This waste substance is becoming more and more abundant, with 3 megatons in 2014 expected to increase to over 4 megatons by 2020. Because of its impurity, glycerol is not suitable for the chemical or pharmaceutical industry. Moreover, it does not burn well and is thus not a good energy source.
"Normally, it should go through waste water treatment, but to save money and because it is not very toxic, some companies dispose of it in rivers or feed it to livestock. But there are concerns about how this affects the animals."
Making use of this waste feedstock by converting it into lactic acid already constitutes an advantage that makes the new method more eco-friendly. In this procedure, glycerol is first converted enzymatically to an intermediate called dihydroxyacetone, which is further processed to produce lactic acid by means of a heterogeneous catalyst.
"Without the assessment and comparison with the conventional method, we might have been happy with an initial catalyst design used for our study, which turned out to be less eco-friendly than fermentation", explains Pierre Dapsens, a PhD student in the Perez-Ramirez group. By improving several aspects of the catalyst design, the researchers were finally able to surpass sugar fermentation both from an environmental and an economic point of view.
Industrial processes are often turned "sustainable" simply by switching to a renewable resource.
"However, taking the whole process into account - from the source of the feedstock to the final product and including waste management - you will often find that a supposedly sustainable production method is not necessarily more sustainable than the conventional one", adds Cecilia Mondelli, a senior scientist in the Advanced Catalysis Engineering group who is also involved in the study.
A third less CO2
"Our calculations are even rather conservative", says Morales. "We assumed a glycerol feedstock of relatively good quality. But it also works with low-quality glycerol, which is even cheaper." Thus, manufacturers could increase their profit even further.
"Although today's major bioplastic companies are based in the US, the process is relatively simple and could be implemented in other countries that produce biofuel and the by-product glycerol", concludes Dapsens.
Space Technology News - Applications and Research
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|