Water Pollution by Detergents

News: Water pollution caused by detergents has become a big concern in the global context. The per capita (per person) detergent consumption in India is around 2.7 kilogram per year. It is around 3.7 kg in the Philippines and Malaysia and 10 kg in the United States of America.

Detergents:

  • A detergent is a surfactant or mixture of surfactants that has cleaning properties in dilute solution with water. A detergent is similar to soap.
  • Surfactant, also called surface-active agent, substance such as a detergent that, when added to a liquid, reduces its surface tension, thereby increasing its spreading and wetting properties. Surface Tension is the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules.
  • They tend to be more soluble in hard water than soap because the sulfonate of detergent doesn’t bind calcium and other ions in hard water as easily as the carboxylate in soap does.

Pollution due to Detergents:

  • Nonylphenol, a hazardous chemical present in detergents, is known to enter water bodies and the food chains. It bio-accumulates and can pose serious environmental and health risks. It has been detected in human breast milk, blood and urine, and is associated with reproductive and developmental effects in rodents.
  • Many laundry detergents contain approximately 35 to 75% phosphate salts. Phosphates can cause a variety of water pollution problems. For example, phosphate tends to inhibit the biodegradation of organic substances. Non-biodegradable substances cannot be eliminated by public or private wastewater treatment.
  • Biodegradation is the process by which organic substances are broken down into smaller compounds by living microbial organisms. Some phosphate-based detergents can also cause eutrophication. Phosphate-enrichment can cause the water body to become choked with algae and other plants.
  • In Belgium, phosphates have been restricted for use in household detergents since 2003.
  • Detergents also contain oxygen-reducing substances (ie, a chemical compound that readily transfers oxygen atoms) that may cause severe damage to the fishes and other marine animals.
  • Detergents are capable of destroying the external mucus layers that protect the fish from bacteria and parasites, causing severe damage to the gills. Mostly fish die when detergent concentrations are near 15 parts per million (ppm); however, detergent concentrations as low as 5 ppm will kill fish eggs.
  • A few more harmful components of detergents which are anthropogenic components such as herbicides, pesticides and heavy metal concentrations (like zinc, cadmium and lead) can cause the water to grow dark. This blocks out light and disrupts the growth of plants.
  • Turbidity also clogs the respiratory system of some species of fishes. Pathogens from these toxic water bodies cause diseases, some fatal, in human or animal hosts diseases.
  • The detergents contain suspected carcinogens, and ingredients that do not fully biodegrade.
  • A carcinogen is an agent with the capacity to cause cancer in humans.