Vermi-remediation of Heavy Metal-Contaminated Soil
2013
Suneet V. Dabke, PhD
Background. Rapid development in India has lead to pollution around industrial facilities. Earthworms are tolerant of many contaminants, and some are reported to remove heavy metals and pesticides from soil via tissue accumulation. Earthworm activity also increases levels of beneficial microbes. Objectives. Test vermi-remediation as a low-cost, on-site method of remediating heavy metal soil contamination. Methods. Soil was assessed for heavy metal contamination. Existing worm population was estimated via sampling, then the soil supplemented with beneficial bacteria, compost and a proprietary earthworm growth accelerator. Site was seeded with grass and maize, and Eisenia fetida worms introduced. Earthworm population was studied and soil contamination and accumulation in maize roots analyzed at the end of the project. Discussion. Worms were expected to remove heavy metals via bio-accumulation and also stimulate microbial remediation by increasing soil micro-organisms. Conclusions. The study showed positive results, with a reduction in chromium and survival of introduced earthworms, which reproduced after soil treatment, indicating improved conditions. Chromium concentrations were reduced to as low as 4.54mg/kg from a high of 194.17 mg/kg. There was variation in iron content and a controlled reduction in cadmium and lead. Due to limited funding, further study of the soil’s final nutrient balance and earthworm analysis was not possible. Further study is necessary. Competing Interests. The author owns Concept Biotech.
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