As businesses and governments around the world are increasingly turning to waste as a source of chemicals, materials, energy and fuel, the team of Clean Nature Solutions rises to the challenge of producing technology that can up-cycle complex bio-wastes into the high value chemicals and materials that are normally sourced from petrochemicals. “Enhanced landfill mining” (ELFM) is a newer, more advanced technique that aims to maximize valorization of the excavated waste materials that have been stored in the landfill. The potential of landfill mining depends on many variables and is therefore site dependent. Factors such as the age, type and location of a landfill might have an impact on the type and condition of materials stored in the landfill and their valorization potential.
Landfill mining is a more recent and limited activity practiced throughout the World. The primary factors that this activity is undertaken include (1) extraction of energy resources such as diesel, oil, methane gas and other byproducts; glass, metal and other recyclables and compost byproducts which can be sold as a side benefit, (2) to address groundwater contamination problems posed by wastes in old unlined landfills by removing the source of pollution, (3) to create new capacity for future land-filling activities, and (4) to reduce closure costs by reducing the footprint of the landfill. The extraction of energy resources is an undertaking made possible only recently by a new technology called Pyrolysis, a renewable resource process which holds great promise and further promotes a new way of addressing the undesirable footprints of the MSW landfill problems around the world.
There are different kinds of landfills to be mined, municipal landfills, bioreactor landfills, electronic scrap, as found on gigantic land sites in developing countries such as India and Africa, mostly shipped there from the West. Landfill mining is also a very effective way of remediating hazardous waste to keep further toxins from seeping into the ground. Big excavators dig up the waste and transport it to moving conveyor belts that transport the wastes toward a mobile Pyrolysis plant. Before entering the plants, the waste can be dried and pre-separated for further processing. The resources to be recovered from mixed and hazardous waste can be oil, fuels, Diesel, kerosene, asphalt and precious metals.
The amount of combustibles in the excavated waste is expected to vary between 17 and 53% (w/w) with a calorific value of around 18 MJ/kg dw and confirm the large potential of waste-to-energy for landfill mining. We also expect most waste samples to contain a large amount (40 up to 70% (w/w)) of a fine grained (<10 mm) mainly mineral and/or soil waste material. Especially for industrial waste, the fines contained high concentrations of heavy metals (Cu, Cr, Ni and Zn) and offer opportunities for metal extraction and recovery. The fine grained and heterogeneous nature of such fines poses large challenges for effective material recovery by physical and chemical methods. A characterization study of fines present in any samples of the excavation tests will need to be performed. Significant differences between the compositions of MSW and IW fines will help determine the necessity for diverse recycling approaches for these two types of material. In addition to traditional technology such as milling, pelletizing and macerating, it can offer fiber expansion and CO2 extraction as well as novel technologies including low temperature microwave Pyrolysis and spinning cone distillation facilities.
Social sustainability is as important as economic and environmental sustainability. Development of bio-refineries, where fuels, chemicals and materials are manufactured from locally grown raw materials, produces clusters of businesses and support industries, revitalizing rural economies. Using grains and oilseeds for food and bio-wastes for renewable chemical and fuel production reduces competition for agricultural resources. CNS is seeking to do this by harnessing the chemical potential of food supply chain waste using green chemical and composting technologies and use nature's own functionalities to obtain sought-after properties in everyday products.