Worm composts are not just for kitchen waste, since the bugs also happen to be good at absorbing heavy metals, according to a study by the International Journal of Environment and Waste Management.
An earthworm vermicompost is effective at removing heavy metals, like lead, zinc, cadmium, copper and manganese, from urban waste.
The authors of the study, Swati Pattnaik and M. Vikram Reddy both from Pondicherry University, found substantial reductions in heavy metals when the worms had at the garbage.
Concentrations of zinc, cadmium and copper were 36.1%, 50.9% and 70.2% higher in municipal solid waste than waste that had not been processed by the worms.
The worms' digestive tract is able to absorb heavy metal ions, and the dead worms could then be separated from the waste.