Microbes play a dual role when used for sewage treatment as they not only help in retrieve usable water but also generate fuel. Write in points how this happens?

Microbial fuel cells are considered a source of sustainable energy. Why? 1. They use living organisms as catalysts to generate electricity from certain substrates. 2. They use a variety of inorganic materials as sub strates. 3. They can be installed in waste water treatment plants to cleanse water and produce electricity. Which of the Statements given above is/are correct? (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3

Large quantities of sewage is generated everyday in cities and towns, which is treated in Sewage Treatment Plants (STPs) to make it less polluted. Given below is the flow diagram of one of the stages of STP. Observe the given flow diagram and answer the questions accordingly (a) Why primary effluent is passed into large aeration tanks? (b) Write the technical term used for the sediment formed? Mention its significance (c) Explain the final step that results in the formation of biogas in the large tank before the treated effluent is released into water bodies.

Read the given passage and answer the questions that follow. Pollution befouls the air and poisons water. Pollution induces the release of toxicants into the biosphere which makes the air unsuitable for breathing,harms the quality of water and soil, and causes the emission of substances that may cause damagae to humans, plants and animals. To cater to the needs of an increasing population, agriculturre has been intensified through the use of a wide spectrum of fertizilers and pesticides. Diverse industries have been set up to produce chemicals including those that pose a danger to all life forms. Rapid industrialisation has led to deterioration in the quality of air. Widespread use of coal and fossil fuels in industries and petroleum fuel in motor vehicles has aggravated the air pollution problem. Our atmosphere seems to have become a waste basket into which dust, noxious fumes, toxic gases and other pollutants are callously thrown. The intensity of air pollution in Indian cities is increasing primarily due to our vintage vehicles and their poor performance. Water pollution, too has increased with the growth of our pollution and also that of our industries. Water pollution has acquired dangerous dimensions ever since sewage and industrial effluents have started being disposed of into the rivers. Once considered sacred, the rivers are now turning murky and stink.It is sad that almost three-fourths of our fellow citizens have no choice but to drink filthy water. The severely polluted rivers due to mindless dumping of sewage and industrial wastes are a cause for concern not only to us humans but also to myriads of life forms that exist in water. On the French and italian rivieras we can no longer see the sparkling blue waters. The Mediterranean Sea is reported to be turning grey. Rivers and canals pour sewage, detergents and industrial waste into the sea, tankers flush their contents near the river or sea, bottles. rotting garbage and oil slicks are washed into the beaches. The phosphates and nitrates applied to farmlands as inorganic fertilizers, concentrate in lakes and estuaries causing algal blooms due to which wide expanses of water get choked, plants rot, oxygen is used up and fish die. Since when has water pollution acquired dangerous dimensions?