tamarind seed kernel powder, discarded as agricultural waste, is an effective agent to make turbid municipal and industrial wastewater clear. The present practice is to use aluminium salt to treat such water. It has been found that alum increases toxic metals and ions in treated water and could cause diseases like the Alzheimer's.
"Kernel powder, compared to alum, is not-toxic and biodegradable," says Sampa Chakrabarti, lead researcher from the department of chemical engineering of Calcutta University. "It is cost-effective compared to alum and other synthetic polymers as it is an agricultural waste and can be procured at a throwaway price," she says.
For the study, four flocculants (chemicals that cause colloids and other suspended particles in liquids to aggregate, forming a floc) namely tamarind seed kernel powder, mix of the powder and starch, starch, and potash alum were used. Flocculants with slurries were prepared by mixing measured amounts of clay and water. The results showed aggregation of the powder and suspended particles were more porous and allowed water to ooze out and become compact more easily. According to Chakrabarti, this led to a more compact sediment and larger volume of clear water. Starch-flocs on the other hand were found to be light weight and less porous and therefore didn't allow water to pass through it easily.
"The study establishes the powder's potential as an economic flocculant with performance close to more established flocculants such as potash alum," says Sunando Das Gupta of iit, Kharagpur. The findings of the study will be published in a forthcoming issue of Bioresource Technology.