Biosolids combat poisoning
soil poisoned by lead can be easily decontaminated with the help of composted biosolids (organic residuals produced during wastewater treatment). Over the years the problem has become acute, especially in the case of children determined to taste 'delicious' mud while playing. The soil is contaminated by peeling chips of lead-based paints and exhaust from vehicles that use leaded gasoline.
During an experiment, researchers from the University of Washington, usa, added biosolids rich in iron, manganese and organic matter to a garden in Baltimore. The garden's soil is similar to that of potentially hundreds of thousands of backyards contaminated with lead. The researchers tested seven different biosolids by adding three inches of each to different areas of the garden. They found that bioavailability (amount of a chemical that can enter the bloodstream) of lead was reduced by 20-38 per cent. The best biosolids were ones that contained high levels of iron and manganese.
The researchers assert that biosolids are the most economically viable option to decontaminate soil. They will now find out for how long the affects of biosolids last and if similar results can be obtained using compost that does not come from biosolids.
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