Worms Clean Toxic Metals from Indian Soil | Source: Ben Barber, Huffington Post | Oct 8, 2012
Worms, those squishy animals sought after by fishermen for bait and early birds for nutrition, have not got a new occupation — treating thousands of tons of toxic sludge left in farms and fields by Indian factories as industrial growth skyrocketed in recent years.
They key to success has been that the worms burrow up to five feet deep into the contaminated soil, soak up heavy metals and other toxins, and then come to the surface without releasing the toxins.
The worms then are allowed to wander off into nearby land, dispersing and diluting the toxins so they no longer pose a threat to people or the environment. Otherwise, the worms may be transported to a secure, long term dump site or burned in an incinerator.
Assessment of the performance of a novel, on-site, worm based sanitation system for peri-urbanvenvironments, 2012.
F. F. Kassam
This study evaluates how effective a worm based sanitation system is in reducing the rate at which solid waste accumulates and at how worms can improve the quality of effluent by reducing pathogen levels and the concentrations of harmful chemicals. Both pilot scale laboratory reactors and a prototype Tiger Toilet were fed with human faeces on a daily basis and the accumulated solid wastes in the systems were weighed. Every week microbiological and chemical analysis was carried out on the effluents of the systems, as well as of a control reactor without worms, which provided a point of comparison.
Over the course of the investigation, the worms processed the waste and reduced the total accumulated solids by 90% in the laboratory reactor and by 70% in the prototype reactor. Pathogen levels were reduced by an average of 99.79% and 95.45% in the laboratory reactor and the prototype reactor respectively, over this period. There was a reduction in the levels of harmful chemicals, such as COD, which reduced by around 94% in both reactors. This investigation verified that the Tiger Toilet technology provides an effective, low cost, low tech solution to less economically developed countries’ sanitation problems.