IAS Gyan

Daily News Analysis


21st March, 2024 Science and Technology


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  • The biomining project initiated by the Municipal Corporation of Delhi (MCD) aimed to clear the oversaturated landfill sites at Ghazipur and Bhalswa.
  • Despite efforts, the project is likely to miss the latest deadline of 2024 due to various challenges.


  • Biomining involves separating various components of legacy waste such as plastic, paper, cloth, sand, and bricks using trommel machines.
  • MCD launched the biomining project in July 2019 following the National Green Tribunal's directive to clear legacy waste dumps within a specified timeframe.
  • The ongoing dumping of fresh waste and adverse weather conditions, especially during the monsoons, have slowed down the biomining process.
  • Disposal issues related to inert material and plastic derived from the biomining process also contributed to delays.
  • Multiple revisions and extensions of deadlines were necessary due to these challenges.


  • Biomining, also known as phytomining, is a method of extracting metals from ores and solid materials using prokaryotes, fungi, or plants.
  • Microorganisms such as bacteria and archaea secrete organic compounds that chelate metals from the environment, making them accessible for extraction.


  • Biomining dates back to the discovery in 1950 that Acidithiobacillus ferrooxidans thrives in iron-, copper-, and magnesium-rich environments.
  • Subsequent research revealed the potential of microorganisms, including fungi, in leaching metals from their environment.
  • Biomining has evolved into an environmentally friendly alternative to traditional mining, with applications in extracting iron, copper, zinc, gold, uranium, and thorium.

Mechanisms of Biomining

  • Biomining primarily involves biooxidation and bioleaching processes.
  • Biooxidation utilizes iron- and sulfur-oxidizing microorganisms to release occluded metals from mineral sulfides.
  • Bioleaching involves the use of organic acids produced by microbial metabolism to dissolve metal ions from ores.

Types of Biomining

  • There are two primary types of biomining: heap leaching and stirred tank reactor (STR) bioleaching.
  • Heap leaching involves piling ores in heaps and irrigating them with microbial solutions, while STR bioleaching uses bioreactors for controlled microbial activity.
  • Biomining can target various metals, including copper, gold, uranium, and rare earth elements, depending on the microbial consortium and ore composition.

Industrial Applications

  • Biomining processes target various metals, including copper, gold, uranium, and rare earth elements.
  • Large-scale biomining operations utilize chemostats of microbes to leach metals from ores, offering a sustainable and eco-friendly alternative to traditional mining methods.

Microbial Processes in Biomining

  • Microorganisms such as Acidithiobacillus ferrooxidans facilitate the leaching of copper from mine tailings.
  • Thermophilic archaea like Sulfolobus metallicus and Metallosphaera sedula are efficient in extracting metals from sulfide ores, particularly copper.

Environmental and Economic Benefits

  • Biomining reduces energy consumption, water usage, and carbon emissions compared to traditional mining methods.
  • It permits extraction from low-grade ores, contributing to resource recovery and waste remediation.
  • Biomining has become economically viable, with approximately 25% of all copper mined worldwide now obtained from leaching processes.

About Waste Treatment

  • Waste treatment encompasses various processes aimed at managing and reducing the environmental impact of waste materials.
  • It involves the conversion, neutralization, or disposal of waste to minimize pollution and promote environmental sustainability.

Types of Waste

  • Solid Waste: Includes household garbage, industrial waste, and municipal solid waste.
  • Liquid Waste: Consists of wastewater from households, industries, and agriculture.
  • Gaseous Waste: Includes emissions from industrial processes, vehicles, and combustion.

Waste Treatment Processes

A)Physical Processes

  • Screening and Sorting: Separates waste materials based on size, density, and composition.
  • Shredding and Grinding: Breaks down large solid waste into smaller particles for further processing.
  • Compaction: Reduces the volume of waste through compression, making it easier to handle and transport.
  • Incineration: Thermal treatment of waste at high temperatures to convert it into ash, gases, and heat energy.

B) Chemical Processes

  • Neutralization: Adjusts the pH of acidic or alkaline waste to make it less harmful.
  • Oxidation: Converts organic waste into simpler, less harmful compounds through chemical reactions.
  • Precipitation: Forms insoluble precipitates by adding chemicals to wastewater, facilitating the removal of contaminants.

C) Biological Processes

  • Composting: Decomposes organic waste using microorganisms to produce nutrient-rich compost for soil enrichment.
  • Anaerobic Digestion: Breaks down organic waste in the absence of oxygen, producing biogas (methane) and organic fertilizer.
  • Bioremediation: Uses microorganisms to degrade or detoxify hazardous substances in soil, water, or air.

D) Advanced Treatment Technologies

  • Membrane Filtration: Removes suspended solids, bacteria, and contaminants from wastewater using membrane filters.
  • Activated Carbon Adsorption: Absorbs organic pollutants and odors from liquid and gaseous waste streams.
  • Reverse Osmosis: Purifies water by removing dissolved salts and contaminants through a semipermeable membrane.
  • Ultraviolet (UV) Disinfection: Inactivates pathogens and microorganisms in water and wastewater using UV light

Waste Disposal Methods

  • Landfilling: Burying waste in designated landfills with protective liners to prevent groundwater contamination.
  • Incineration: Burning waste at high temperatures to reduce its volume and generate energy.
  • Recycling: Collecting and processing waste materials to produce new products or raw materials.
  • Hazardous Waste Treatment: Specialized processes for handling and disposing of hazardous materials, such as chemical incineration and detoxification.

Environmental Impact and Sustainability

  • Effective waste treatment reduces pollution, conserves resources, and protects ecosystems and human health.
  • Sustainable waste management practices promote the reuse, recycling, and recovery of valuable materials from waste streams.
  • Public awareness, government regulations, and technological innovations play key roles in promoting environmentally responsible waste treatment practices.


Q.  By employing a combination of physical, chemical, and biological techniques, waste treatment facilities can minimize pollution and maximize resource recovery. Illustrate with examples. (250 Words)