About the Site...

The Ariyamangalam Dumpyard (10°48'13.02"N, 78°43'33.02"E), located in the Tiruchirappalli district of Tamil Nadu, India, is owned by Tiruchirappalli Municipal Corporation (TMC). The site spreads over an area of 47.7 acres, fully designated for the disposal of MSW, with an average height of 5.6 m. The LFM project at the Ariyamangalam Dumpyard was initiated in 2019 by the Tiruchirappalli City Corporation (TCC) in compliance with the Solid Waste Management (SWM) Rules of 2016. The Ariyamangalam Dumpyard is divided into four zones and equipped with three waste processing plants. Phase I of the biomining process was initiated in January 2020 and concluded in September 2022, resulting in the recovery of approximately 0.75 million cubic meters of legacy waste. Subsequently, Phase II commenced in October 2022 and was completed in April 2024, facilitating the recovery of an additional 0.33 million cubic meters of legacy waste from the landfill.

Landfill Mining (LFM)

Biomining or landfill mining (LFM) is the process of segregation of legacy waste with the view to recover valuable land locked in old dumpsites. Enhanced landfill mining (ELFM) includes the recovery of both materials (waste to material) and energy (waste to energy) without  compromising sustainability. LFM aims to conserve and minimize landfill area, eliminate contaminants sources, mitigate existing contaminants, recycle material, recover energy and reduce management costs for landfills. Revenue can also be generated by the utilisation of land and material recovered from legacy waste. A landfill needs to be at least 15 years old before choosing the biomining option.

Various steps involved in the biomining process are excavation of legacy waste, bioremediation (i.e., stabilisation of waste using bio-cultures to ensure no further production of heat, landfill gas and leachate), screening of different fractions, storage and transportation based on application. The separation scheme involves the use of mechanical methods such as sieving, magnetic and eddy current separation, density separation by airflow and water-based density separation. 

Landfill Mined Fraction

Different fractions of LFM include Soil-Like Material (SLM) or bio-earth, Refuse-Derived Fuel (RDF) or Combustibles, Recyclables or Incombustibles and Inerts. The RDF contains mainly of paper, plastic, textiles, leather and rubber. The recyclables constitutes glass, ceramics, metals etc. Screen sizes available are 150 to 4 mm, varying based on the application of product material.

Soil-Like Material

The finest fraction, which contains humus-rich substances mixed with soil or sand, is called bio earth or SLM as per Central Pollution Control Board. Based on the results of various studies, SLM constitutes about 40 to 70% of the total mined waste and depends on the age of the landfill and particle size. The sources for SLM are the daily landfill cover, disposal of street sweeping, silt from drains, biodegradable organic waste and C&D wastes. SLM obtained from LFM is heterogeneous in nature. SLM is nonplastic and classified as silty sand. SLM is rich in plant nutrients such as nitrogen and phosphorus because of degraded organic matter. 

Potential of the Legacy Waste Fractions for WtM and WtE 

(Guidelines for Disposal of Legacy Waste CPCB, 2019)