Reaproveitamento de potássio de cascas de cacau por lixiviação de cinzas e produção de húmus de minhoca

Abstract

Cocoa is a fruit that has three subdivisions: husk, pulp and almonds. The raw material most targeted by the industries that use the fruit are the almonds, and for the extraction of one ton of them, about 6 to 8 tons of cocoa husks are generated, which do not have much use for the industry. These husks must also be removed from plantations, because, due to their high humidity, they become favorable environments for the development of pests. However, some studies indicate that cocoa husks have a large amount of potassium and because of that, try to reuse them in the plantations as fertilizer. Since Brazil is one of the largest cocoa producers outside Africa and does not have many reserves of potassium for the manufacture of fertilizers, a study was carried out on the reuse of this metal through the leaching of husk’s ashes and through the production of earthworm humus. For leaching extraction, the husks were dehydrated, calcined and then mixed with water. This mixture was taken to heat up to 90ºC and then it was filtered six times. The filtered liquid was diluted and analyzed in an atomic absorption spectrophotometer and obtained an average potassium concentration of 6.378g / L. This value was close to some commercial foliar fertilizers. For the humus, two earthworms were created with a proportion of [2: 2: 1] of black soil, red soil and sand. After that, the earth was humidified and the worms were deposited. One of the earthworms was used as a control and the earthworms received a varied diet of vegetables, while the other was fed only with cocoa husks and neutral organic matter. After 4 months of observation, the soils were analyzed using the same tests as for the leaching, but they did not show any statistical difference between them in relation to the potassium concentration, despite the fact that the cocoa husk soil had a higher pH than the control soil. Finally, it can be concluded that the extraction of potassium by leaching can be a good source of the metal for the production of fertilizers, and it’s left the suggestion of a study to create a plant that uses the organic matter for combustion and the extract as a fertilizer. For the humus, it can be seen that the husks were a good material for the maintenance of earthworms, but they did not produce soil with a different amount of potassium.