Soda Concentration Snail

Aerial view of the soda concentration snail

The soda concentration snail , also Caracol ( Spanish for snail), is a 19 kilometer long canal spiral north of the former Texcoco Lake in the agglomeration of Mexico City . It produced soda ( sodium carbonate ) and the cyanobacterium spirulina . However, the quality of the spirulina sold as a dietary (supplement) product was very poor, due to air and groundwater pollution in Mexico City. After the USA stopped imports because of this, production had to be stopped.

Explanation of the formation of soda

Spirulina thrive particularly well in alkaline salt lakes with pH values between 9 and 11, such as B. the Texcoco Lake, and precipitate lime . This reacts with sodium sulfide from volcanic rock in the water to form calcium sulfide and soda:

${\displaystyle \mathrm {CaCO_{3}\ +Na_{2}S\ \longrightarrow \ Na_{2}CO_{3}\ +\ CaS} }$

The resulting calcium sulphide reacts with water to decompose (e.g. to hydrogen sulphide ).

history

The soda concentration screw is the only system of its kind and was built from 1936. However, the construction is related to the drainage system to the northeast, which was completed around 1900. The operator was Sosa Texcoco, based in Mexico City.

Web links

Commons : El Caracol (Ecatepec)  - collection of images, videos and audio files

• The soda concentration snail
• How spirulina is ecologically grown ( Memento from January 6, 2012 in the Internet Archive )
• History of Spirulina

Coordinates: 19 ° 34'12 "  N , 99 ° 0'7"  W.