BharatNotes What is Bioremediation?
Bioremediation is a clean-up technology that harnesses living organisms—bacteria, fungi, algae, and plants—or their enzymes to break down, immobilise, or remove contaminants from polluted soil, groundwater, sediment, and air. The pollutants are metabolised into harmless or less toxic products; for hydrocarbon contamination, the end-products are typically carbon dioxide and water. The US EPA describes it as a process that enhances naturally occurring biological degradation of contamination in soil, sediment, and groundwater.
Key Types and Approaches
Bioremediation is classified by where treatment occurs and by the biological agent used.
| Basis | Type | What it involves |
|---|---|---|
| Site | In situ | Treatment of contaminated media in place, without excavation |
| Site | Ex situ | Contaminated media excavated and treated in an engineered system |
| Agent | Phytoremediation | Plants extract, stabilise, or transform pollutants (phytoextraction, phytostabilisation, rhizofiltration, etc.) |
| Agent | Mycoremediation | Fungi degrade contaminants |
| Strategy | Bioaugmentation | Adding (wild or engineered) microbes to a site |
| Strategy | Biostimulation / natural attenuation | Nurturing microbes already present by supplying nutrients/oxygen |
Compared with physico-chemical methods, bioremediation is generally cheaper, more sustainable, and eco-friendly, though it is slower and sensitive to temperature, pH, oxygen, and nutrient conditions.
Significance for India
India deploys bioremediation across several flagship efforts:
- Oilzapper — Developed by The Energy and Resources Institute (TERI) over several years of research with support from the Department of Biotechnology, Oilzapper is a carrier-based consortium of five bacterial strains (immobilised on powdered corncob) that degrade aliphatic, aromatic, asphaltene, and NSO (nitrogen-sulphur-oxygen) fractions of oil. The technology was commercialised through ONGC TERI Biotech Ltd (OTBL), a joint venture formed in March 2007. Per OTBL, more than 1.3 million tonnes of contaminated soil have been treated using Oilzapper (as of March 2025).
- Namami Gange Programme (approved June 2014) — Microbial bioremediation and phytoremediation are used as interim measures to treat drains and "nallas" discharging into the Ganga before sewage treatment plants become operational, as recommended by the National Green Tribunal.
- Heavy-metal and industrial pollution — Phytoremediation offers a cost-effective alternative to excavating and dumping contaminated material.
UPSC Angle
For Prelims, focus on distinguishing the techniques—phytoremediation versus bioaugmentation, in situ versus ex situ—and on indigenous developments such as Oilzapper and its developer (TERI). For Mains GS3, bioremediation is best deployed as a concrete mitigation measure in answers on river pollution, oil-spill management, soil contamination, and clean technology, paired with its limitations (slow pace, site-specific efficacy). It is a foundational concept that underpins the broader question family of pollution control and ecological restoration rather than a stand-alone PYQ topic.
Cross-link: For current developments on river rejuvenation and pollution policy, see related coverage on Ujiyari.com.
