TAIPEI (Taiwan News) — Waste from the water caltrop has been transformed into a high added-value product in the city of Tainan, where the aquatic plant is grown in large quantities.
Also known as water chestnuts, or bat nuts, the black-shelled fruit is a specialty in Tainan’s Guantian District, which grows 70% of the country’s water caltrop crop. However, the discarded shells, which amount to a thousand tons each year, have become a source of environmental woes and a burden to local incinerators.
To solve the issue, the district office has joined hands with Kun Shan University to establish a community cooperative promoting recycling of bat nut shells, which are then turned into a kind of biochar through a process that involves combustion at 1,000 degrees Celsius, wrote CNA.
Touted as “black gold,” the waste-turned-charcoal can be used to absorb odors, purify water, and improve the quality of soil. These attributes have made it a material for a variety of merchandise, boosting its economic value in a successful example of circular economy.
Guantian Black Gold is now a brand offering a wide array of products ranging from room deodorizers to soaps and masks. Water caltrop-derived applications and items can also be found at a museum dedicated to the "black gold" in the district, adding to Tainan's appeal as a tourist attraction.
Variety of merchandise made from bat nut shells. (CNA photo)