biology-class-12-unit-10-chapter-01-biologyin-human-welfare-microbesin-human-welfare-lecture-1-2-uqcmkw8xwtw

<h3 id="successsecondarybiological-treatmentsuccess"><Success>Secondary/biological treatment</Success></h3>
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<p>Primary effluent is passed into large aeration tanks</p>
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<p>Mechanical agitation and pumping of air allows vigorous growth of useful microbes into flocs</p>
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<p>Flocs are masses of bacteria associated with fungal filaments to form mesh like structures</p>
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<p>Majority of organic matter in the effluent is consumed by these microbes</p>
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<p>This reduces the Biological oxygen demand (Answerwer)</p>
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<p>BOD refers to the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria</p>
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<p>Greater the BOD, more is the pollution in water</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-01-biologyin-human-welfare-microbesin-human-welfare-lecture-1_2-uqcmkw8xwtw-06.jpg"></p>
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<h3 id="successbiological-treatment-success"><Success>Biological treatment </Success></h3>
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<p>Once there is a significant reduction in BOD, the bacterial flock are allowed to sediment</p>
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<p>This sediment is called “Activated sludge which can again be used as inoculum (a small part) when pumped back into the aeration tank</p>
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<p>Remaining major part is pumped into large tanks called anaerobic sludge digestors</p>
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<p>The anaerobic bacteria present in it further digest the bacteria and fungi in the sludge producing a mixture of gases known as “Biogas”</p>
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<p>The effluent is further treated with disinfectants before releasing into rivers and streams</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-01-biologyin-human-welfare-microbesin-human-welfare-lecture-1_2-uqcmkw8xwtw-076-1900.8.jpg"></p>
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<h3 id="successganga-action-plansuccess"><Success>Ganga action plan</Success></h3>
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<p><strong>Ganga’s sorrow</strong></p>
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<p>Nearly <strong>40,000</strong> long km drains not cleaned for over <strong>50 years falling</strong> into the river at different points. They also carry urban and chemical discharge</p>
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<p>Varanasi alone discharges <strong>200 million litres</strong> of untreated human sewage into the river causing <strong>Faecal Coliform Bacteria</strong> (FCB). Official standards state 500 ml faecal coliforms per 100 ml is safe for bathing in Varanasi it is 120 times high <strong>60,000 FCB</strong></p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-01-biologyin-human-welfare-microbesin-human-welfare-lecture-1_2-uqcmkw8xwtw-077-2122.8.jpg"></p>
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<h3 id="successlets-discuss-textbook-questionssuccess"><Success>Let’s discuss textbook questions!</Success></h3>
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<p><strong>Question 1.</strong> Bacteria can not be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample, which sample would you take and why?</p>
<p><strong>Answer.</strong> Curd contains <em>Lactobacillus</em> and is most common household product</p>
<p><strong>Question 2.</strong> Give examples to prove that microbes release gases during metabolism</p>
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<p>Puffed up appearance of bread, dosa, idli etc</p>
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<p>Large holes in Swiss Cheese</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-01-biologyin-human-welfare-microbesin-human-welfare-lecture-1_2-uqcmkw8xwtw-10.jpg"></p>
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<h3 id="successlets-discuss-textbook-questionssuccess-3"><Success>Let’s discuss textbook questions!</Success></h3>
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<p><strong>Question 7.</strong> What is sewage? In which way can sewage be harmful to us?</p>
<p><strong>Answer.</strong> All the domestic and industrial wastewater is the sewage. Its harmful effects are<br>
• Spread of water borne diseases<br>
• Reduced Disolved oxygen content may kill aquatic life</p>
<p><strong>Question 8.</strong> What is the key difference between primary and secondary sewage treatments!</p>
<p><strong>Answer.</strong> Primary treatment is physical or mechanical while Secondary treatment is biological due to microbial activity</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-01-biologyin-human-welfare-microbesin-human-welfare-lecture-1_2-uqcmkw8xwtw-13.jpg"></p>
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<h3 id="successlets-reflectsuccess"><Success>Let’s reflect</Success></h3>
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<p><strong>Question 1.</strong> Critically analyze the role of microrganisms in sustaining of our ecosystem</p>
<p><strong>Question 2.</strong> What according to you is the most distinguishing feature of microorganisms that enables them to be used for commercial production?</p>
<p><strong>Question 3.</strong> Find out from magazines or newspapers about any latest research on beneficial aspects of microbes</p>
<p><strong>Question 4.</strong> Can you suggest some examples in nature where microbes have proved to be beneficial</p>
<p><strong>Questoin 5.</strong> Some of the archaeabacteria are extremophiles. How are they able to survive in such extreme conditions?</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-01-biologyin-human-welfare-microbesin-human-welfare-lecture-1_2-uqcmkw8xwtw-14.jpg">