Graduation project / internship project in rural Thailand
Project rural Thailand on improvement of production process and increase in use of Wood Vinegar
Introduction Wood Vinegar
In rural Thailand people get disabled because of use of toxic pesticides (pesticide poisoning). An alternative is to use wood vinegar as a pesticide. Unlike most synthetic pesticides, wood vinegar (or pyroligneous acid) is unharmful to humans. It has been proven to be an effective means to repel insects and snails from crops, while at the same time enriching the soil. Since wood vinegar is only mildly toxic to most soil organisms, its environmental risk is minimal. When added to stock feed, wood vinegar has also been proven to increase nutrient digestibility of pigs and increased production and quality of chicken eggs. All in all, there is ample evidence that wood vinegar has great potential in agriculture.
In 2016-2017 a group of five TU/e students with different technological backgrounds started this project to improve the production process of wood vinegar to make this solution even more beneficial to farmers. One of the teammembers of last years’ team visited relatives in rural Thailand two years ago and became inspired by the motivation of some of the rural farmers to change their mostly traditionally fed ways of doing things. He convinced some of his fellow students and they started this project as part of their Honors trajectory.
The currently used system uses a process of wood pyrolysis and distillation to arrive at a mixture of wood vinegar and tar. In about four months, the tar sinks to the bottom and the wood vinegar can be separated and diluted for use on the farm. A byproduct of the production process is biochar. This is used as well; for cooking and increasing soil fertility. The tar is used to prevent wood from rotting. The team of students assessed this installation which was already quite impressive but some improvements would be possible.
The main problem with the old design, which is similar to many wood vinegar distilleries in Thailand, is that a lot of the gas escapes the tubes uncondensed. Another issue is that running the installation takes an entire day, during which someone is required to constantly keep the fire going.
The preliminary design the students came up with is a compromise between efficiency, cost and ease of construction. The first main change is that a milk chug placed in a water basin functions as the condenser. Furthermore, the uncondensed gases are led through another oil barrel that is filled with wood for the next run. Heath from these gases is used for drying of the wood which can cut the run time of the system.
To test their design the students visited rural farmers in rural Thailand and built an improved installation. They ran this installation, built and tested the preliminary design and spoke to a lot of farmers. Also two wood vinegar schools were visited which teach people about these installations.
The new installation yielded 5 L wood vinegar for 70 kg of wood, a little more than the 3-4 L that is normally obtained. The yield could still become higher. The drying container did prove to be a success, as it caused about a 15% reduction in the wood’s mass. The exact influence of this on the runtime should still be measured.
The societal impact became clearer when meeting people who had suffered from pesticide poisoning and were forced to stop working.
Current research opportunities
Research opportunities can be found in additional optimization of the design, building different types of installations and experiment with those, meet up and team up with more organizations to spread knowledge in this field and enlarge the impact of improved installations and discuss in more detail with farmers and discover their motivation (survey and/or indepth interviews). Although the team of students that conducted this research will move to another topic in the next year, they are still available for information and questions (info@). Additionally, information can be found at their website (teamwoodvinegar.com). Also a movie is available on their results/project. TU/e supervisors of this project were Han van Kasteren and Mara Wijnker. teamwoodvinegar.com