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Agricultural waste in southern Taiwan turned into ‘black gold’

Bat nuts not only delicious but economically valuable

Shells of water caltrops turned into biochar. 

Shells of water caltrops turned into biochar.  (CNA photo)

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.

Agricultural waste in southern Taiwan turned into ‘black gold’
Variety of merchandise made from bat nut shells. (CNA photo)

Updated : 2021-09-27 19:30 GMT+08:00