Environmental Pollution and Waste Management — UPSC Environment Notes

1. Sources of Water Pollution

Point Sources: Discharge from a single identifiable outlet, such as a sewage drain, a factory effluent pipe or a tannery; easier to monitor and regulate.

Non-Point Sources: Diffuse runoff from farms (fertilisers, pesticides), urban streets and mining areas; hard to trace and the main driver of nutrient pollution.

Largest Source in India: Untreated or partly treated municipal sewage, followed by industrial effluents from sectors such as tanneries, distilleries, pulp and paper, and textiles.

2. Key Water Quality Indicators

Dissolved Oxygen (DO): Oxygen dissolved in water and available to aquatic life. Cold water holds more oxygen than warm water. Fish suffer when DO falls below about 4-5 mg/L.

Biochemical Oxygen Demand (BOD): Oxygen consumed by microbes to decompose the biodegradable organic matter in a sample, usually measured over 5 days at 20°C (BOD5). High BOD means heavy organic pollution and falling DO.

Chemical Oxygen Demand (COD): Oxygen needed to oxidise both biodegradable and non-biodegradable matter with a strong chemical oxidant (potassium dichromate). It takes about 3 hours, and COD is always equal to or higher than BOD.

Coliform Bacteria: Faecal coliforms (such as E. coli) indicate contamination by sewage and the likely presence of disease-causing organisms.

CPCB Bathing Water Criteria: DO at least 5 mg/L, BOD at most 3 mg/L, pH 6.5-8.5 and faecal coliform up to 2,500 MPN per 100 mL (500 desirable).

3. Eutrophication

Process: Excess nitrates and phosphates (from fertilisers, detergents and sewage) trigger algal blooms; the algae block sunlight, die and are decomposed by bacteria that use up oxygen, causing hypoxia, fish kills and 'dead zones'.

Natural vs Cultural: Natural eutrophication is a slow ageing of lakes over centuries; cultural (human-induced) eutrophication speeds it up to a few years.

Indian Examples: Water hyacinth choking lakes, frothing of Bengaluru's Bellandur lake from sewage and detergents, and algal blooms in Dal lake.

4. Groundwater Contaminants

Arsenic: Found in groundwater of the Ganga-Brahmaputra plains (West Bengal, Bihar, Uttar Pradesh, Assam); causes skin lesions (arsenicosis) and cancers.

Fluoride: Common in Rajasthan, Telangana, Andhra Pradesh and Gujarat; excess causes dental and skeletal fluorosis.

Nitrate: From fertilisers and sewage; causes methaemoglobinaemia or 'blue baby syndrome' in infants.

5. Laws, Treatment and Programmes

Water (Prevention and Control of Pollution) Act, 1974: India's first major pollution-control law; it created the Central and State Pollution Control Boards. The 2024 amendment replaced jail terms with penalties for many minor violations.

Sewage Treatment Stages: Primary (screening and settling of solids), secondary (biological treatment such as activated sludge) and tertiary (removal of nutrients and disinfection).

Namami Gange (2014): An integrated mission for the Ganga run by the National Mission for Clean Ganga (NMCG), covering sewage infrastructure, industrial effluent control, riverfronts, biodiversity, afforestation and public participation; many sewage plants are built under the Hybrid Annuity Model.

Governance: The National Ganga Council, chaired by the Prime Minister, oversees the river basin; NMCG is its implementing arm.

Practice

UPSC-style: 'A river stretch shows high COD but low BOD.' What does this suggest? (Answer: much of the pollution is non-biodegradable or toxic, such as industrial chemicals, rather than sewage.)

1. Causes of Soil Pollution

Agrochemicals: Overuse of urea and pesticides; skewed N-P-K use harms soil microbes and leaves residues that enter food chains.

Industrial and Mining Waste: Dumping of sludge, tailings and fly ash adds heavy metals such as lead, cadmium, chromium and mercury.

Urban Waste: Unscientific landfills and open dumps leak leachate (a toxic liquid) into soil and groundwater; microplastics accumulate in farmland.

Salinity and Waterlogging: Excess canal irrigation without drainage raises the water table and brings salts to the surface, creating saline and alkaline (usar/reh) soils in Punjab, Haryana and Uttar Pradesh.

Oil Spills and E-waste: Leaks from pipelines and informal e-waste recycling (acid baths, open burning) contaminate soil in clusters such as Delhi's Seelampur.

2. Effects

Loss of Fertility: Decline of soil organic carbon and of earthworms and microbes reduces productivity.

Food Chain Contamination: Crops take up heavy metals (for example cadmium in rice), which then move up the food chain.

Groundwater Pollution: Nitrates and pesticides leach through soil into aquifers.

3. Bioremediation

Meaning: The use of living organisms, mainly bacteria, fungi and plants, to degrade, remove or immobilise pollutants.

In-situ: Treatment at the site itself, for example bioventing (supplying air to stimulate microbes), biosparging (injecting air below the water table) and bioaugmentation (adding selected microbes).

Ex-situ: Contaminated soil is dug out and treated elsewhere, for example in landfarming, biopiles, composting or bioreactors.

Phytoremediation: Plants clean soil: phytoextraction (taking up metals into shoots, as Indian mustard does with lead), phytostabilisation (locking pollutants in roots), rhizofiltration (roots filtering water) and phytovolatilisation (releasing pollutants as vapour).

Mycoremediation: Fungi (such as white-rot fungi) break down complex compounds, including some pesticides and dyes.

Oil Spills: Oil-eating bacteria are used to clean spills; India's TERI developed 'Oilzapper', a bacterial consortium used to clean oily sludge and contaminated land.

Limits: Bioremediation is slow, works best for biodegradable pollutants and depends on temperature, moisture and nutrients; metals can only be concentrated or immobilised, not destroyed.

4. Policy Response

Soil Health Card Scheme (2015): Gives farmers nutrient status and crop-wise fertiliser advice to curb overuse.

Natural and Organic Farming: Schemes such as Paramparagat Krishi Vikas Yojana and the National Mission on Natural Farming promote chemical-free cultivation.

Hazardous Waste Rules, 2016: Govern storage, treatment and disposal of hazardous waste and the remediation of contaminated sites.

Practice

UPSC-style: Which technique uses plants to accumulate heavy metals from soil in their harvestable parts? (Answer: phytoextraction, a form of phytoremediation.)

1. Key Terms

Bioaccumulation: Gradual build-up of a substance in an organism's tissues because it is absorbed faster than it is broken down or excreted.

Bioconcentration: Uptake of a chemical directly from the surrounding water (for example through fish gills), a part of bioaccumulation.

Biomagnification: Increase in the concentration of a pollutant at each successive trophic level of a food chain, so that top predators carry the highest load.

2. Conditions for Biomagnification

Persistent: The substance must resist breakdown by biological and chemical processes.

Fat-soluble (lipophilic): It dissolves in fat rather than water, so it is stored in fatty tissue instead of being excreted.

Biologically active and mobile: It must be taken up by organisms and passed on through feeding.

Why Water-Soluble Pollutants Do Not: Substances like nitrates are excreted easily, so they cause other problems (such as eutrophication) but do not magnify.

3. Classic Examples

DDT: In a well-known US estuary study, DDT rose from about 0.003 ppb in water to about 25 ppm in fish-eating birds, a million-fold increase. In birds, DDT disturbs calcium metabolism, causing thin eggshells that break, which drove declines of eagles, ospreys and peregrine falcons.

Mercury: Bacteria convert mercury into methylmercury, which magnifies in fish; it caused Minamata disease in Japan (1950s), a nervous disorder.

Cadmium: Contaminated rice irrigation water caused itai-itai disease (bone softening) in Japan.

PCBs and Arctic Wildlife: Polar bears, seals and Arctic peoples carry high POP loads although these chemicals were never used there, because POPs travel long distances through air and ocean currents (the 'grasshopper effect').

Diclofenac and Vultures: A related case of secondary poisoning: the veterinary drug in cattle carcasses killed vultures in India (see the vulture topic).

4. Global and Indian Response

Stockholm Convention on POPs (adopted 2001, in force 2004): Aims to eliminate or restrict persistent organic pollutants; it began with the 'dirty dozen' (including DDT, aldrin, dieldrin and PCBs) and has added more chemicals since. India ratified it in 2006.

Minamata Convention on Mercury (2013, in force 2017): Controls the mining, use, trade and emissions of mercury; India is a Party.

DDT in India: Banned in agriculture, but allowed in limited quantities for vector (mosquito) control under the Stockholm Convention's public-health exemption.

Rotterdam and Basel Links: The Rotterdam Convention requires prior informed consent for trade in hazardous chemicals, and the Basel Convention controls cross-border movement of hazardous waste.

Practice

UPSC-style: Why do top carnivores show the highest concentration of DDT although they never consume it directly? (Answer: DDT is persistent and fat-soluble, so it biomagnifies at each trophic level.)

1. Solid Waste Management Rules, 2016

Scope: Extended beyond municipal areas to census towns, urban agglomerations, industrial townships, railways, airports and places of pilgrimage (the rules are being revised by MoEFCC).

Segregation at Source: Every household must separate waste into three streams: wet (biodegradable), dry and domestic hazardous.

Bulk Generators and User Fees: Local bodies may levy user fees and spot fines; bulk generators must process wet waste on site where possible.

Waste Hierarchy: Only non-recyclable, non-combustible residue should go to sanitary landfills; high-calorific waste (1,500 kcal/kg or more) should go to energy recovery, refuse-derived fuel or co-processing in cement kilns.

Informal Sector: Rag-pickers and waste-pickers are to be integrated into the formal system.

Swachh Bharat Mission-Urban 2.0 (2021): Aims at 'garbage-free cities', including remediation of legacy dumpsites.

2. E-Waste (Management) Rules, 2022

In Force: From 1 April 2023, replacing the 2016 rules.

EPR Regime: Producers must meet annual recycling targets by buying EPR certificates from registered recyclers on a CPCB online portal; collection-centre based compliance was replaced by this market system.

Wider Coverage: 106 items of electrical and electronic equipment are covered, and solar photovoltaic panels and cells were brought in for the first time.

Other Features: Environmental compensation for non-compliance, and a restriction on hazardous substances (RoHS) such as lead, mercury and cadmium in new equipment.

3. Battery Waste Management Rules, 2022

Coverage: All batteries, including electric-vehicle, portable, automotive and industrial batteries, regardless of chemistry (replacing the 2001 lead-acid battery rules).

Circular Economy: EPR with collection and recycling targets, minimum material recovery from waste batteries and mandatory use of a share of recycled material in new batteries.

4. Bio-Medical Waste Management Rules, 2016

Colour Coding: Yellow (anatomical, soiled and chemical waste, for incineration), Red (contaminated recyclable plastics such as tubing and gloves), White translucent (sharps such as needles) and Blue (glassware and metallic implants).

Key Rules: Pre-treatment of laboratory and highly infectious waste on site, phase-out of chlorinated plastic bags and gloves, bar-coding of waste bags, and treatment at Common Bio-medical Waste Treatment Facilities.

5. Plastics (Link)

Plastic Waste Management Rules: Ban on identified single-use plastics from 1 July 2022 and EPR for plastic packaging; see the topic on plastic waste for details.

Practice

UPSC-style: Under the E-Waste (Management) Rules, 2022, which new item was brought under EPR? (Answer: solar photovoltaic modules, panels and cells.)

1. Controlling Particulate Matter

Electrostatic Precipitator (ESP): Gives particles an electric charge and collects them on oppositely charged plates; removes over 99% of particulates and is standard in thermal power plants and cement units.

Bag (Fabric) Filters: Flue gas passes through fabric bags that trap fine dust; very efficient for small particles.

Cyclone Separators: Spin the gas so that heavier particles are thrown out by centrifugal force; cheap but effective only for coarse dust.

Wet Scrubbers: Spray water or a chemical solution to wash out both particles and soluble gases.

2. Controlling Gaseous Pollutants

Flue Gas Desulphurisation (FGD): Removes sulphur dioxide, usually by reacting flue gas with limestone slurry; the by-product is gypsum, which can be used in cement and wallboard.

NOx Control: Low-NOx burners, and selective catalytic or non-catalytic reduction (SCR/SNCR), which use ammonia or urea to turn NOx into nitrogen and water.

Catalytic Converter: Platinum, palladium and rhodium catalysts in vehicle exhausts convert CO, unburnt hydrocarbons and NOx into CO2, water and nitrogen; lead in petrol poisons the catalyst, so unleaded fuel is required.

3. Norms for Industry and Vehicles

Thermal Power Plant Norms (December 2015): MoEFCC set limits for PM, SO2, NOx and mercury from coal plants; deadlines for installing FGD have been extended several times and compliance has been slow, keeping the issue in the news.

Vehicles: India leapfrogged from BS-IV to BS-VI on 1 April 2020; electric mobility is supported through schemes such as FAME and PM E-DRIVE, and old vehicles through the Vehicle Scrapping Policy (2021).

Clean Cooking: PM Ujjwala Yojana (2016) gives LPG connections to poor households, reducing indoor air pollution from solid fuels.

4. Stubble Burning

Why Farmers Burn: In the rice-wheat system of Punjab and Haryana, combine harvesters leave tall stubble and only 2-3 weeks remain before wheat sowing; laws that delay paddy transplanting to save groundwater (such as Punjab's 2009 subsoil water law) push the harvest closer to winter.

Effects: Smoke adds to PM2.5 over the Indo-Gangetic plain in October-November, when low winds and temperature inversion trap pollutants; burning also destroys soil nutrients and friendly microbes.

In-situ Solutions: Machines such as the Happy Seeder and Super Seeder sow wheat directly into the residue; the Pusa bio-decomposer (developed by IARI) is a microbial spray that speeds up decomposition of stubble.

Ex-situ Solutions: Using residue for biomass power, compressed biogas, 2G ethanol and co-firing biomass pellets in coal power plants; crop diversification away from water-intensive paddy addresses the root cause.

5. Delhi-NCR: GRAP

Graded Response Action Plan: Enforced by the Commission for Air Quality Management (CAQM) in four stages linked to AQI: Stage I 'Poor' (201-300), Stage II 'Very Poor' (301-400), Stage III 'Severe' (401-450) and Stage IV 'Severe+' (above 450), with curbs ranging from dust control to bans on construction and on entry of certain trucks.

Quick Fixes vs Structural Fixes: Smog towers and anti-smog guns have only local and short-lived effects; lasting gains come from cutting emissions at source across the whole airshed.

Practice

UPSC-style: Which device in a coal power plant removes SO2, and what is its useful by-product? (Answer: flue gas desulphurisation unit; gypsum.)

A. Noise Pollution

Measurement: Sound is measured on the logarithmic decibel scale; an increase of 10 dB means ten times the sound intensity. Continuous exposure above about 85 dB can damage hearing.

Sources: Road and air traffic, construction, industry, loudspeakers, firecrackers and generators.

Health Effects: Hearing loss, sleep disturbance, stress, high blood pressure and heart disease, reduced concentration in children; it also disturbs wildlife communication and breeding, including whales affected by ship noise.

Legal Basis: The Air Act was amended in 1987 to include noise as an air pollutant; the Noise Pollution (Regulation and Control) Rules, 2000 were framed under the Environment (Protection) Act, 1986.

Zones: Four categories (industrial, commercial, residential and silence zones) with separate day (6 am-10 pm) and night (10 pm-6 am) limits; a silence zone covers at least 100 metres around hospitals, educational institutions and courts.

Loudspeakers: Not allowed between 10 pm and 6 am except in closed premises; states may relax this up to midnight on a limited number of festival days in a year.

Firecrackers: Supreme Court orders have restricted their timing and promoted 'green crackers' developed by CSIR-NEERI with lower emissions.

Control: Noise barriers and green belts along highways, quieter vehicle and generator standards, land-use planning and real-time noise monitoring (CPCB's network).

B. Radioactive Pollution

Ionising Radiation: Alpha particles (stopped by paper but very harmful if inhaled or swallowed), beta particles (stopped by thin metal) and gamma rays (need thick lead or concrete).

Natural Sources: Cosmic rays, radon gas from rocks and soil, and radioactive minerals such as thorium-rich monazite sands on the Kerala coast, which give some areas high natural background radiation.

Human Sources: Nuclear power plants and fuel-cycle facilities, uranium mining, medical X-rays and radiotherapy, nuclear weapons tests and accidents.

Units: Becquerel (activity of a source), Gray (absorbed dose) and Sievert (effective dose, which accounts for biological harm).

Effects: Somatic effects in the exposed person (burns, radiation sickness, cancers such as leukaemia and thyroid cancer) and genetic effects passed to offspring; radioactive iodine-131 concentrates in the thyroid and strontium-90 in bones.

Major Accidents: Three Mile Island (USA, 1979), Chernobyl (then USSR, 1986) and Fukushima (Japan, 2011, after an earthquake and tsunami); Chernobyl and Fukushima are rated level 7, the highest on the International Nuclear Event Scale.

Nuclear Waste: Classified as low, intermediate and high level; India follows a closed fuel cycle, reprocessing spent fuel and immobilising high-level waste in glass (vitrification) for long-term storage.

Regulation in India: The Atomic Energy Regulatory Board (AERB, 1983) licenses and inspects nuclear and radiation facilities, including X-ray machines; India's nuclear liability law dates from 2010.

Practice

UPSC-style: Which unit expresses the biological effect of a radiation dose? (Answer: the Sievert.)

1. Pollution from Coal Power

Air: Particulates, sulphur dioxide, nitrogen oxides and mercury; SO2 and NOx also form secondary PM2.5 and acid rain.

Climate: Coal power is India's largest single source of CO2 emissions.

Water: Large withdrawals for cooling, and thermal pollution when warm water is discharged into rivers, lowering dissolved oxygen.

Land: Ash ponds occupy large areas; breaches of ash dykes (for example in Singrauli in 2019-2020) have flooded farmland and villages with slurry.

2. What is Fly Ash?

Formation: The fine, powdery residue carried up with flue gases when pulverised coal is burnt; it is captured by electrostatic precipitators. The heavier ash that falls to the furnace bottom is bottom ash, and ash mixed with water in ponds is pond ash.

Composition: Mainly silica, alumina and iron oxides, with some calcium and traces of heavy metals such as arsenic, lead and mercury.

Why India Has So Much: Indian coal typically has a high ash content (often 30-45%) but low sulphur, so ash volumes are far higher than in countries burning imported coal.

Hazards: Airborne ash causes respiratory illness; heavy metals can leach into groundwater from unlined ponds.

3. Uses of Fly Ash

Cement and Concrete: Used in Portland Pozzolana Cement (PPC) and as a partial cement substitute, cutting the CO2 footprint of construction.

Bricks and Blocks: Fly ash bricks save fertile topsoil that clay-brick kilns would otherwise remove.

Roads, Embankments and Mines: Used in road and flyover embankments and to refill abandoned mines.

Agriculture: In controlled doses it can improve the texture and water-holding capacity of some soils.

4. Regulation

Fly Ash Notification (1999, revised 2021): The December 2021 notification, under the Environment (Protection) Act, requires coal and lignite plants to ensure 100% use of the ash they generate, assessed over three-year cycles, and to use up legacy ash over a longer period; unused ash attracts environmental compensation on the polluter-pays principle.

Cleaner Generation: Supercritical and ultra-supercritical boilers burn less coal per unit of power; biomass pellets are co-fired with coal; and FGD and other controls are required under the 2015 emission norms.

Practice

UPSC-style: Fly ash is used in which of the following: (1) bricks (2) cement (3) road embankments (4) mine filling? (Answer: all four.)