Question

Read the conversation given below and answer the question that follow.

The next time you take printouts unnecessarily or you throw a paper in to the bin, think for a minute as to how many trees have been felled to manufacture it and how much wastewater generated in the process for something you use so often every day. Can you take out some time from your everyday routine and devote it to starting a simple recycling program at your school or your neighbourhood? Not only you would save our planet from the torture of felling greenery, but you would also reduce generation and dumping of waste into the environment.

Which three indicators of water quality should be checked? What is their significance if you want to recycle wastewater generated in the case above?

Answer 1

Indicators of water quality:

B.O.D, C.O.D, pH, D.O, Electrical conductivity, Turbidity, Temperature, Nitrates, Sulphates, and Faecal waste in water.

Significance:

1. B.O.D: Biochemical oxygen demand or B.O.D is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific period of time. Higher BOD value suggests more polluted water.
2. C.O.D: Chemical oxygen demand or C.O.D test is commonly used to indirectly measure the number of organic compounds of water. Most applications of COD determine the number of organic pollutants found in surface water e.g. lakes and rivers or wastewater. High COD means polluted water.
3. pH: It indicates the acidity, alkalinity or H+ ion concentration. It depends on the surrounding land, water inputs, or type of minerals in contact with water. It affects the solubility of organic matter, minerals and metals. It affects both biological and chemical processes. Change in pH level may increase the toxicity of water. The pH range from 5.5 to 8 is acceptable. More or less pH than the above suggest water is polluted.
4. Dissolved pollutants: More the dissolved pollutants, poor is the quality of water.
5. Physical Indicators: Indicators such as maggots’ larvae and other plant or animal species also suggest poor quality of water.
6. Turbidity: it is a measure of light transmission through water. The greater suspended particles greater is the turbidity, which indicates polluted water.
7. Electrical Conductivity: The greater the concentration of ions in water higher will be the conductivity which means contaminated water. Salinity of water is the measure of its conductivity. It affects the aquatic biota; it also affects the quality of water used for irrigation and drinking purpose.it can also indicate any seepage or sewage leak in the ground water.
8. Temperature: It is an important measure of the health of water. High temperature reduces the solubility of dissolved oxygen. BOD and COD rises. Spawning of fish, photosynthesis is affected. Extreme temperature may prove to be fatal. It may lead to mass death of fish also.