Question

Laundry engaged in washing clothes has been pouring waste water directly into the river. Over a period of time, it was found that large numbers of fish were dying in the river.
Answer the following questions based on the above information:
a) Mention the reasons for the dying of fish
b) Is there any way it can be avoided?
c) Mention values associated with above information.

Answer 1

The anionic surfactants (detergent) have the ability to bind to bioactive macromolecules like enzymes, DNA, peptides etc. and the nonionic surfactants can bind to proteins and phospholipid membranes. This can result in serious damage to cells or even cell death.

Complete answer:
a) A detergent is a surfactant or a mixture of surfactants that has cleaning properties in dilute solution with water. They are usually alkyl benzene sulfonates and are amphiphilic in nature i.e. have both hydrophobic and hydrophilic regions. They are used for cleaning like dishwashing and laundry and also as fuel additives and biological reagents.
The phosphate present in detergents inhibits the biodegradation of organic substances and non-biodegradable substances cannot be removed by public or private wastewater treatment. The phosphate-based detergents cause water to become choked with algae and other plants. Due to this eutrophication, water becomes deprived of oxygen and causes the death of other organisms. Eutrophication is the process by which a water body becomes enriched with minerals and nutrients and induces excessive growth of algae. This causes a lack of oxygen and many fishes and marine mammals die and the whole food chain is affected.
When the detergent concentration is 5ppm, it kills the fish eggs and when it reaches 15 parts per million, most fishes die. It can also decrease the breeding ability of aquatic organisms.

b) There are some methods to avoid or control them: the chemicals can be disposed of separately to prevent ecosystem damage, using phosphate-free detergents to prevent eutrophication, treating the wastewater properly before releasing it into the environment, phytoremediation of wastewater, using adsorbents to remove surfactants, etc.

c)With the above information, one can be aware of the various effects of the detergent that is a part of our daily life. Others can be made aware through us, one can find methods to reduce the chemical effects caused by this. It will cause a person to reason scientifically and will raise the concern for the environment.

Note: The chemicals released by soaps and detergents go inside the body of fishes and when humans, birds or any other animal consume this fish it affects their health.