Water Pollution Practice Questions

Contamination of water bodies by harmful substances degrading water quality.

Untreated sewage, industrial effluents, agricultural runoff.

Oxygen required by microbes to decompose organic matter; high BOD indicates pollution.

High organic pollution, low dissolved oxygen.

Oxygen needed to chemically oxidize organics, higher than BOD.

Nitrates and phosphates from fertilizers and sewage cause algal blooms.

Oxygen depletion, fish kills, dead zones.

Yamuna stretch in Delhi, also Ganga at Kanpur-Varanasi, high BOD and coliform.

1986 to reduce pollution in Ganga.

2014 as integrated conservation mission.

Fecal contamination from sewage.

Zero per 100 ml as per BIS/WHO.

West Bengal and Bihar Gangetic plains.

Dental and skeletal fluorosis.

Rajasthan, Gujarat, Andhra Pradesh, Telangana.

Mercury discharged into Minamata Bay, Japan.

Cadmium from mining into Jinzu River.

Marine ecosystems, coating birds, blocking light.

Power plants discharging hot water reducing dissolved oxygen.

Below 5 mg/L stressful, below 2 mg/L lethal for many.

Fertilizers and septic tanks.

Nitrate in drinking water converting to nitrite, causing methemoglobinemia.

1974, established CPCB and SPCBs.

Water Act 1974 and EPA 1986.

Large solids and suspended matter by screening and sedimentation.

Biological processes (activated sludge) to remove organics.

Nutrients (N,P) and pathogens.

Chromium, especially hexavalent chromium.

Tanneries discharging into Ganga.

No liquid waste discharged, water recycled.

Great Pacific Garbage Patch and microplastics.

Ingestion by plankton and fish.

Bellandur Lake Bengaluru (foam, fire), Dal Lake, Hussain Sagar.

Siltation, aquaculture, pollution, but also Ramsar site.

Below 5.6, often 4-5.

Adsorption, coagulation, reverse osmosis.

Cholera, typhoid, dysentery, hepatitis A.

Five classes A-E for designated best use.

Drinking without conventional treatment.

Nutrient runoff leading to hypoxia, e.g., Gulf of Mexico.

Textile dyeing, pulp-paper, sugar, distilleries.

Reducing BOD and coliform.

Natural filtration by plants and microbes.

BOD and COD.

Total Dissolved Solids.

Freshwater but generates brine waste.

Yamuna Delhi stretch BOD >30 mg/L.

Treat sewage, enforce industry norms, reduce fertilizer use, watershed management.

Only ~30-40% treated, rest discharged untreated.

World Water Day, March 22.