Waste Generation & Treatment – Quick Review

Definitions

• Waste: unwanted/unused materials; Basel: "substances/objects disposed of or intended/required to be disposed of by international law".
• Municipal, Hazardous, Bio-medical, Special Hazardous (radioactive, explosives, E-waste) – major legal groups.

Physical State Classification

• Solid: household garbage, cans, plastics, dead animals, industrial/hospital refuse.
• Liquid: sewage, industrial effluents, farm runoff, oil spills.
• Gaseous: exhaust emissions – CO2, CO, SOx, NOx, CH4, CFCs.

Biodegradable vs Non-biodegradable

• Biodegradable: organic plant/animal wastes; microbially decomposed → compost.
• Non-biodegradable: plastics, petroleum products, synthetic chemicals; persist, biomagnify, toxic.

Source-Based Categories

• Domestic – kitchen scraps, packaging, bottles.
• Industrial – chemicals (lead, mercury, arsenic), fly-ash, metals; sources: food, paper, textile, petroleum, chemical, metal, cement, nuclear.
• Agricultural – crop residues, husk, straw, manure; pesticide & fertilizer residues harmful.
• Construction – soil over-dumps, bricks, pipes, tiles, asbestos.
• Mining – tailings, slag, debris; vegetation loss, water contamination.
• Hazardous/Toxic – heavy metals, PCBs, dioxins; carcinogenic.
• Bio-medical – syringes, bandages, tissues; pathogen risk.
• E-waste – obsolete electronics; contains lead, Cd, Hg; non-biodegradable.
• Radioactive – from reactors, X-ray units, weapon tests; long-lived, genetic effects.

Impact of Accumulation

• Disease vectors & pathogens.
• Foul odour; aesthetic loss.
• Soil & water pollution; leachate; eutrophication; biomagnification.
• Respiratory diseases from particulates (asbestosis, silicosis).

Solid-Waste Treatment Methods

• Open Dumping – cheapest; odour, vectors, air/water pollution.
• Landfill – covered disposal; benefits: vector control, methane recovery; drawbacks: CH4 (global warming, 21\times CO2 potential), leachate, land unusable.
• Composting – aerobic biodegradation → humus; cheap, eco-friendly; unsuitable for non-biodegradables/hazardous.
• Incineration – high-temperature burn; handles toxic & biomedical waste; high cost, energy use, gaseous/ash pollution.
• Segregation – separate into biodegradable, recyclable, hazardous; lowers disposal load, enables 3R.

3R Approach

• Reduce – prevent generation (cloth bags, repair devices).
• Reuse – alternative use of items (jars as storage).
• Recycle – convert waste into new materials.

Waste-water Treatment

• Primary (physical): screening, sedimentation, flotation; removes suspended solids, oil, corrects pH.
• Secondary (biological): microbes degrade organics; activated-sludge/trickling filters; produces sludge.
• Tertiary (chemical): precipitation, filtration, disinfection (chlorine/UV) to remove remaining chemicals & pathogens.
• Activated Sludge: aeration tank + clarifier; microbes oxidize organics → settleable floc.

End-of-Pipe (EOP) Treatment

• Controls effluent just before discharge (filters, chemical treatment, chlorination, recycling).

Basel Convention (1989)

• Aims: minimize hazardous-waste generation; ensure environmentally sound management; regulate trans-boundary movement.
• Applies to >168 parties (including India).

Solid-Waste Management Challenges in India

• Poor segregation, irregular collection.
• Inadequate labour, transport, treatment facilities.
• Weak enforcement by pollution boards.
• Low public awareness & advocacy pressure.

Key Terms

• Leachate – polluted liquid percolating from landfill.
• Biomagnification – rise in toxin concentration along food chain.
• Eutrophication – O_2 depletion in water by nutrient enrichment.
• Humus – stable organic compost product.