26:I[70861,["/_next/static/immutable/chunks/1f5ikor90fo1s.js","/_next/static/immutable/chunks/34ess10yszfaa.js","/_next/static/immutable/chunks/2i9fpgum15wo3.js","/_next/static/immutable/chunks/1ibt5onceanwy.js","/_next/static/immutable/chunks/2a7_ugv-c84le.js","/_next/static/immutable/chunks/42v511g5vcq2f.js","/_next/static/immutable/chunks/1l3t_9rrw8w0i.js","/_next/static/immutable/chunks/1gbb60u7yuskl.js"],"PyqSectionNav"] 27:I[7212,["/_next/static/immutable/chunks/1f5ikor90fo1s.js","/_next/static/immutable/chunks/34ess10yszfaa.js","/_next/static/immutable/chunks/2i9fpgum15wo3.js","/_next/static/immutable/chunks/1ibt5onceanwy.js","/_next/static/immutable/chunks/2a7_ugv-c84le.js","/_next/static/immutable/chunks/42v511g5vcq2f.js","/_next/static/immutable/chunks/1l3t_9rrw8w0i.js","/_next/static/immutable/chunks/1gbb60u7yuskl.js"],"PyqArchiveNavigation"] 28:I[78838,["/_next/static/immutable/chunks/1f5ikor90fo1s.js","/_next/static/immutable/chunks/34ess10yszfaa.js","/_next/static/immutable/chunks/2i9fpgum15wo3.js","/_next/static/immutable/chunks/1ibt5onceanwy.js","/_next/static/immutable/chunks/2a7_ugv-c84le.js","/_next/static/immutable/chunks/42v511g5vcq2f.js","/_next/static/immutable/chunks/1l3t_9rrw8w0i.js","/_next/static/immutable/chunks/1gbb60u7yuskl.js"],"PyqFeedQuestionCard"] 29:T577,### Explanation Biological Oxygen Demand (BOD) is a standard criterion for **measuring organic pollution in water bodies**. It quantifies the amount of dissolved oxygen consumed by microorganisms during the decomposition of organic matter present in water. A higher BOD indicates a higher level of organic pollution, which can lead to oxygen depletion and harm aquatic life. ### Exam Pointers - **BOD Definition**: BOD is the amount of oxygen required by aerobic microorganisms to break down organic matter in water. It is expressed in milligrams of oxygen per liter (mg/L). - **Importance**: BOD is a key indicator of water quality, especially for assessing the impact of sewage and industrial effluents. High BOD levels can cause hypoxia, leading to fish kills and ecosystem degradation. - **Measurement**: The standard BOD test measures oxygen consumption over a 5-day incubation period at 20°C (BOD5). - **Related Parameters**: - **COD (Chemical Oxygen Demand)**: Measures oxygen equivalent of organic matter that can be oxidized chemically, often higher than BOD. - **DO (Dissolved Oxygen)**: The actual oxygen level in water; BOD is the demand that can reduce DO. - **Regulatory Use**: BOD is used in environmental regulations to set discharge limits for wastewater treatment plants. **Key Takeaway**: BOD is specifically about organic pollution, not hardness, acidity, or turbidity.2a:Te9e,### व्याख्या बायोलॉजिकल ऑक्सीजन डिमांड (BOD) **जल निकायों में कार्बनिक प्रदूषण को मापने** के लिए एक मानक मानदंड है। यह पानी में मौजूद कार्बनिक पदार्थों के अपघटन के दौरान सूक्ष्मजीवों द्वारा खपत की जाने वाली घुलित ऑक्सीजन की मात्रा को दर्शाता है। उच्च BOD कार्बनिक प्रदूषण के उच्च स्तर को इंगित करता है, जिससे ऑक्सीजन की कमी हो सकती है और जलीय जीवन को नुकसान पहुँच सकता है। ### परीक्षा के लिए महत्वपूर्ण बिंदु - **BOD की परिभाषा**: BOD पानी में कार्बनिक पदार्थों को तोड़ने के लिए एरोबिक (वायवीय) सूक्ष्मजीवों द्वारा आवश्यक ऑक्सीजन की मात्रा है। इसे प्रति लीटर ऑक्सीजन के मिलीग्राम (mg/L) में व्यक्त किया जाता है। - **महत्व**: BOD जल की गुणवत्ता का एक प्रमुख संकेतक है, विशेष रूप से सीवेज और औद्योगिक अपशिष्टों के प्रभाव का आकलन करने के लिए। उच्च BOD स्तर हाइपोक्सिया (ऑक्सीजन की कमी) का कारण बन सकता है, जिससे मछलियों की मृत्यु और पारिस्थितिकी तंत्र का क्षरण होता है। - **मापन**: मानक BOD परीक्षण 20°C (BOD5) पर 5 दिनों की ऊष्मायन अवधि (incubation period) में ऑक्सीजन की खपत को मापता है। - **संबंधित पैरामीटर**: - **COD (केमिकल ऑक्सीजन डिमांड)**: कार्बनिक पदार्थों के ऑक्सीजन समकक्ष को मापता है जिन्हें रासायनिक रूप से ऑक्सीकृत किया जा सकता है, यह अक्सर BOD से अधिक होता है। - **DO (घुलित ऑक्सीजन)**: पानी में ऑक्सीजन का वास्तविक स्तर; BOD वह मांग है जो DO को कम कर सकती है। - **नियामक उपयोग**: अपशिष्ट जल 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