Biomining is a fascinating and environmentally friendly technique used to extract valuable metals from ores or waste materials through the use of microorganisms. Read here to learn more.
Biomining offers a sustainable alternative to traditional mining methods, often involving extensive drilling, blasting, and processing with harsh chemicals.
Biomining for solid waste management represents an innovative and eco-friendly approach to handling the increasing problem of waste accumulation, particularly in landfills.
This method leverages biological processes to recover valuable materials from solid waste, thereby reducing landfill mass, recovering resources, and minimizing the environmental impact of waste disposal.
Biomining for metal ores
Biomining relies on the natural abilities of certain bacteria and archaea, which can leach metals from ores.
These microorganisms produce chemicals, such as sulfuric acid, that dissolve metals, allowing them to be recovered from the solution.
The process can occur in two main forms:
- Bioleaching: This is the most common form of biomining and involves the extraction of metals from their ores by using living organisms. Bioleaching is particularly useful for extracting copper, gold, and other metals found in sulfide minerals. As the bacteria feed on the sulfide minerals, they convert them into soluble forms, allowing the metal to be leached from the ore.
- Biosorption or Bioremediation: In this method, microorganisms or their by-products bind to and concentrate metals from dilute solutions. This technique is often used to recover precious metals from wastewater or clean up heavy metal pollution.
Advantages of Biomining
- Environmental Benefits: It is considered more environmentally friendly than traditional mining methods. It reduces the ecological footprint by minimizing land disruption, water usage, and chemical pollution.
- Economic Efficiency: For low-grade ores, which are not economical to process using conventional methods, biomining offers a viable and cost-effective alternative.
- Energy Efficiency: It requires less energy compared to traditional smelting and refining processes, contributing to lower carbon emissions.
- Access to Difficult-to-Reach Ores: Microorganisms can extract metals from ores that are too deep underground or too poor in quality for conventional mining.
Challenges
- Rate of Metal Recovery: The process is generally slower than traditional mining methods, which can be a significant drawback for commercial operations.
- Control of Conditions: Maintaining the optimal conditions for microbial activity (such as temperature, pH, and nutrient supply) can be challenging, especially on a large scale.
- Metal Specificity: It is not suitable for all types of metals or ores. Research is ongoing to expand the range of metals that can be efficiently recovered through this method.
Biomining in Solid Waste Management

In the context of solid waste management, biomining involves using microorganisms to break down organic and inorganic components of waste.
- The process can help segregate and recover metals and other valuable materials from mixed solid wastes, including electronic waste (e-waste), municipal solid waste, and industrial by-products.
Key Processes in Biomining for Waste Management:
- Bioleaching: Similar to its application in metal ore processing, bioleaching in solid waste management involves using bacteria to dissolve metals from waste materials, making it easier to recover them. This process is particularly relevant for e-waste, which contains significant amounts of precious and base metals.
- Composting and Anaerobic Digestion: While not strictly biomining, these biological processes play a crucial role in the biodegradation of organic waste materials. They transform organic waste into stable, nutrient-rich compost or biogas, effectively reducing the waste volume and recovering energy resources.
- Biosorption: This process involves using dead or live microorganisms to adsorb and concentrate heavy metals from waste streams. It’s particularly useful in treating wastewater or remediating soils contaminated with heavy metals.
Advantages of Biomining in Solid Waste Management
- Resource Recovery: Biomining facilitates the recovery of metals and other valuable materials from waste, contributing to resource conservation and circular economy initiatives.
- Reduction of Landfill Space: By recovering materials and converting organic waste into compost or biogas, biomining reduces the volume of waste destined for landfills, extending landfill lifetimes.
- Environmental Protection: It decreases the leaching of heavy metals and other contaminants into the environment, reducing pollution and protecting ecosystems.
- Energy Production: Through processes like anaerobic digestion, biomining can convert organic waste into biogas, a renewable energy source.
Challenges
- Technological and Economic Hurdles: The initial setup cost for the facilities and the optimization of processes for specific types of waste can be significant. Economies of scale and technological advancements are critical for making biomining a cost-effective option.
- Regulatory and Social Acceptance: Implementing it on a large scale requires regulatory support and public acceptance. Concerns about potential odors, pollution, and the technology’s novelty need to be addressed.
- Research and Development: Continued research is necessary to enhance the efficiency of the processes, including the identification and engineering of microorganisms capable of processing a wider variety of wastes.
Biomining in India
According to the Central Pollution Control Board (CPCB) guidelines, “Biomining is the scientific process of excavation, treatment, segregation and gainful utilization of aged municipal solid waste lying in dumpsites typically referred to as legacy waste.”
- It comprises 4 steps: excavation of legacy waste, stabilizing the waste using bioremediation, segregation of excavated waste, and then sustainable management and its safe disposal.
- The Solid Waste Management Rules, 2016 now mandate bio-mine legacy waste instead of ‘capping’ which means covering the waste with soil.
- These rules focus on the segregation of waste at the source, the responsibility of the manufacturer to dispose of sanitary and packaging wastes, and user fees for collection, disposal, and processing from the bulk generator.
Why in the news?
The Municipal Corporation of Delhi (MCD) launched the biomining project to clear its three oversaturated landfill sites in July 2019 on the direction of the National Green Tribunal.
- The NGT had directed that legacy waste dumps are to be cleared within one year but substantial progress must be made and demonstrated within six months.
- But the ongoing biomining project at two of the Capital’s three landfill sites – Ghazipur and Bhalswa – are likely to miss the latest deadline of 2024 to clear the sites
Conclusion
Biomining offers a promising solution to the challenges of solid waste management by enabling the recovery of valuable materials, reducing landfill use, and mitigating environmental impacts.
As technology advances and societal attitudes toward waste and recycling evolve, biomining could play a pivotal role in sustainable waste management strategies worldwide.
Read: Legacy waste management
-Article by Swathi Satish
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