Agricultural waste like rice husk, fruits and vegetables peels can be helpful to eliminate the heavy metals
Due to tremendous increase in industrialization and release of untreated chemical effluents into the water, there is a great decline of fresh water level in past few decades.
Many industries release untreated water into the water bodies thereby causing illness to people and animals and even sometimes death. Increase in the population, expansion of industries, use of chemical fertilizers are the main causes of sewage and water pollution.
The removal of metals, non-metals or tiny particulates from the water by the means of any biological component is known as biosorption. Agricultural waste like rice husk, fruits and vegetables peels can be helpful to eliminate the heavy metals. Bio-adsorbents like fruits and vegetables peels are most common organic waste and major by-product of the food -processing industries, can be used to treat wastewater.
Polluted water contains toxic metals like Lead, Copper, Chromium, Zinc and many more which is harmful to human beings and animals. Banana peels have the clumping property in it and contain negatively charged ions which attract positively charged metals in polluted water. Due to this property they are known as binding agents.
They clump up all the toxic metals and make water less polluted. Study reveals peels have antimicrobial activity against the harmful microorganisms like Klebsiella pnuemoniae, Escherichia coli, Salmonella typhi, Staphylococcus aureus. This property is due to presence of some chemical components such phenols, tannins, saponins, alkaloids, flavonoids and carbohydrates. It also contains nitrogen, sulphur and carboxylic acids which are responsible for the binding ability with the toxic metals. Banana peels shows good adsorption property against Lead and Copper.
It contains lignocellulosic compounds (cellulose, hemicellulose and lignin) which have functional groups like carboxyl, hydroxyl, ester, etc. due to this it acts as a bio-adsorbent. Because of its high cellulose content, it is selected as a successful agricultural product in terms of eliminating toxic metals from the water. Studies proved that pumpkin peels can remove 85% of Lead and 40% of Chromium. It is the best alternative of activated carbon.
Apart from these many other agricultural wastes can be used as a bio-adsorbents like rice husk, saw dust, tea and coffee waste, orange peels, peanut shells and neem bark. Pumpkin peels, banana peels and chicken egg shell are the best combination in waste water treatment as all are cheap, easily available and a very effective absorbent.
Different peels are collected and washed with tap water. To removes moisture, peels are sun dry for two days. Peels are blended in a blending machine. After getting homogenous mixture it can be directly used for the treatment. Many plants are also used to eliminate toxic metals like water hyacinth, water lettuce, azolla, water lily, reed, etc as they all have the capabilities to accumulate and degrade components of contaminants present in water.
The treatment of wastewater by bio-adsorbents and agricultural waste is very economic and effective. It requires less man power and gives efficient results. Agricultural waste and by products of food processing industries can be recycled and reuse for the benefit of environment.
Rashmi Chauhan, Quality Control Officer, Indore Biotech Inputs & Research Pvt Ltd, Indore, MP