Mumbai: Compost from city waste is high in heavy metals

Compost from Mumbai’s municipal waste is so concentrated with heavy metals, which come from battery and paint waste that the natural fertiliser is likely to contaminate food and reduce soil fertility in farmlands where it is used. Snehal Rebello reports.

Compost from Mumbai’s municipal waste is so concentrated with heavy metals, which come from battery and paint waste that the natural fertiliser is likely to contaminate food and reduce soil fertility in farmlands where it is used.

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A five-city analysis by the Indian Institue of Soil Science, Bhopal and the Central Arid Zone Research Institute, Jodhpur, has revealed that the compost is also low in organic waste.

According to the study, heavy metal concentration of cadmium, chromium, copper, lead and zinc from electronic and electrical waste were almost three times the permissible limits set by the Fertiliser Control Order.

For instance, copper content was 1,098 parts per million (ppm) as against the permissible limit of less than 300ppm. Similarly, chromium content was 174ppm and lead was 169ppm as compared to limits of less than 50ppm and 100ppm, respectively.

“When compost with high heavy metal concentrations in fine fractions is used in fields, it can affect the food chain, pollute the sub-surface and contaminate ground water,” said professor Jayanta Saha, lead investigator. “Lack of segregation by the civic body at the landfills is the problem.”