Transformation of a waste product
Because mikania vine propagates so prolifically, a new plant may spring up wherever a stem node is left touching the soil. Hence special care is needed in its eradication. Lü Kunwang explains the standard operating procedure for removing mikania vine: Follow the stem of the plant to the roots and then dig it out with the roots still attached. You should remember not to pull too hard, to make sure that broken stems do not fall on the ground and regrow. During Mikania Vine Control Month, branches of FANCA bring uprooted plants to a central location for disposal, either by packing them in garbage bags and burying them, or by incineration. At other times, people can simply roll up the vines and hang them on trees, where they will wither and die.
During Mikania Vine Control Month in 2022, the Hualien Branch alone cleared away a full metric ton of the vine. Unfortunately, handling such an enormous amount of waste material requires a great deal of manpower and money and increases carbon emissions.
“This got us thinking about whether it might be possible to turn this waste into something useful,” says Chiu Huang-sheng, chief of the operations planning section at FANCA’s Hualien Branch. With this in mind, the Hualien Branch then asked Zantan Studio, located in Fenglin, which specializes in making bamboo charcoal, to adapt their method for producing bamboo vinegar and wood vinegar and try to develop mikania vine vinegar. This would make a Cinderella story out of this waste product.
What is wood vinegar? Huang Ying-pin, manager of the Biomass Materials Technology Department at the Central Region Campus of the Industrial Technology Research Institute (ITRI), leads a team that has done many years of research into such vinegars. Huang tosses some mikania vine gathered from the roadside into a simple pyrolysis kiln, and as the biomass is decomposed by the heat, smoke and vapor curls up into the air. Huang explains that this is the basic process for making wood vinegar (a.k.a. pyroligneous acid).
During pyrolysis (thermal decomposition) of organic material, smoke and vapor are given off. To make wood vinegar, the smoke and vapor are collected and condensed into liquid, which is stored for about six months, during which time the liquid settles into layers according to weight. The upper layer consists of an oily liquid, the bottom layer is tar oil, and the middle layer is the vinegar.
As the names “wood vinegar” or “bamboo vinegar” suggest, these liquids include acetic acid. They have the aroma of smoked plums or monk fruit, and because they are rich in organic chemical compounds like phenols and alcohols, they can act as antibacterials and odor removers. It was the Japanese who first began to pay attention to the uses of such vinegars, adding them to cleaning products to reduce pungent odors such as ammonia and sprinkling them on farmland to revitalize the soil.
In order to ensure the quality and safety of mikania vine vinegar, FANCA Hualien Branch sent samples to the certification companies SuperLab and SGS to verify that it contains no heavy metal residues. They also went a step further and mediated the founding of a line of cleaning products made with wood vinegar, produced by the brand Dawoko.
Dawoko, whose ideal is to implement the circular economy, emphasizes that their main raw material for making wood vinegar is waste wood from the pruning of longan trees. “This residual wood material and uprooted mikania vine both make excellent raw materials,” says Hung Wei-lin, production manager at Dawoko.
In complete agreement with the idea of circular use of forest resources, Dawoko gladly agreed to work with FANCA Hualien Branch and further distilled their mikania vine vinegar before adding it to seven products including shampoo, hand lotion, and liquid mosquito repellent. In their first batch they produced 5,000 bottles of product, and consumers responded well, rapidly buying up the entire stock.
Huang Ying-pin uses a simple pyrolysis kiln to explain the extraction process for wood vinegars.
The brick-built kilns at Zantan Studio are small, making it easier to control temperatures and ensure the quality of the extracted wood vinegar.
The Hualien Branch of FANCA has worked with the wood vinegar maker Dawoko to develop seven home cleaning products made with mikania vine vinegar.