Reduction of Heavy Metals during Composting- A Review

Ajay S. Kalamdhad; Jiwan Singh
Composting is becoming a more acceptable and economical method for treating sewage sludge, municipal solid waste, tannery waste, pig manure, poultry manure, etc.. The application of compost formed by above waste material to land can be used as soil fertilizer/conditioner due to presence of nitrogen, phosphorus, potassium and other nutrients. However, presence of heavy metals in the compost restricts its use as soil conditioner. Heavy metals uptake by plants from the soil and successive accumulation in human tissues and biomagnifications through the food chain causes both human health and environment concerns. Heavy metals from the compost can be reduced by addition of some chemicals (natural zeolite, red mud, lime, sodium sulfide, bamboo charcoal and bamboo vinegar, etc.) and biological agents during composting process. Biological agents such as Phanerochaete chrysosporium that is a fungus has been used to remove Lead (Pb) from the compost and earthworm can accumulate the high concentration of heavy metals in the non-toxic forms and be capable of reducing possible toxic effects of unessential heavy metals by utilizing them for physiological metabolism. The principal advantage claimed for biological process over the use of chemicals during composting is the low capital cost. Therefore, the present study gives an overview of the various heavy metal reduction techniques from the composting of various wastes materials carried out by different mode of operation.
Composting; Heavy Metals; Soil Contamination; Reduction
Download | Back to Issue| Archive