Landfill mining -- reducing environmental impact

Terra Daily: Retrieving material for composting from open dumps across the developing world could reduce the environmental impact of growing mountains of waste, according to researchers in India, writing today in the Inderscience publication, International Journal of Environmental Technology and Management. These days we in the developing world are encouraged to compost our garden and kitchen waste.

However, not everyone has a compost bin and not all of us are willing or able to separate waste into compostable and non-compostable materials. In the developing world, the problems are very different. Open dumps are prevalent and have a poor environmental record, according to environmental engineer Kurian Joseph and colleagues at Anna University, in Chennai, India.

Joseph and his team have considered the possibility of landfill mining as a viable means of rehabilitating open dumps. An earlier analysis of decomposed waste from the Deonar dumpsite, in Mumbai, India, revealed that almost a third of the mass is organic matter, while moisture accounts for 14 percent of the sieved material and inert matter the same again. Soft plastics, textiles, glass, ceramics, metals, rubber, leather, and other substances account for the remainder of the sieved mass.

"Landfill mining can recover recyclable materials, landfill space, and compost," explains Joseph. He suggests that mining of compost from open stabilized dumpsites and the application of the bioreactor landfill concept across the developing world could make dumps much more sustainable and reduce their environmental impact. The current study as part of the "Asian Regional Research Program on Sustainable Landfill Management in Asia" funded by the Swedish International Development cooperation Agency (Sida) indicates that up to half of material dumped at such sites could be recovered and re-used as compost for non-edible plants or as daily cover material for landfills.

Over the last two decades, experimental testing and field pilot studies have been conducted to develop and improve landfill techniques and designs with the aim of reducing their negative impact on the environment. The researchers suggest that by encouraging microbial degradation of solid waste in landfill bioreactors it should be possible to improve the overall efficiency of the landfill mining process. This, they explain, needs to be demonstrated at the pilot scale to complement the ongoing research in this area.