The 20-day biochemical oxygen demand (BOD) measurement is commonly designated as_______________?
Show answer Hide answer
Answer: D. All of these
Explanation
The twenty-day biochemical oxygen demand test measures the oxygen consumed by carbonaceous matter oxidation. This prolonged test period represents the initial stage of biological decomposition in wastewater samples. All the listed terms accurately describe different facets of this same standard oxygen demand measurement. Biochemical oxygen demand quantifies the amount of dissolved oxygen needed by aerobic biological organisms. Carbonaceous demand reflects the oxidation of organic carbon compounds in water. First stage demand precedes nitrogenous biochemical oxygen demand in wastewater decomposition.
Environmental engineers use biochemical oxygen demand tests to design municipal wastewater treatment plants. Monitoring effluent oxygen demand protects natural water bodies from severe ecological deoxygenation. Wastewater discharge permits enforce strict limits based on standardized oxygen demand measurements. Option A correctly identifies initial demand but ignores other valid descriptive terms listed. Option B correctly describes first stage demand but is not the exclusive accurate label. Option C correctly names carbonaceous demand but overlooks the other valid classification titles.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. At points where multiple sewers intersect___________________?
Show answer Hide answer
Answer: D. None of these
Standard sewer intersection design guidelines match hydraulic energy line grades or crown levels. None of the listed options accurately describe standard hydraulic matching criteria for intersecting sewers. Correct inter...
Q2. Standing baffle walls incorporate lower 15 cm × 15 cm openings designed to________________?
Show answer Hide answer
Answer: B. 22.5 cm c/c
Standing baffle wall openings are spaced at specific standard intervals to ensure proper flow distribution in sedimentation tanks. The correct center-to-center spacing measurement ensures hydraulic efficiency and prevent...
Q3. The apportionment of an initial capital asset cost via periodic operational charges (such as depreciation) or debt retirement through scheduled payments is termed ___________________?
Show answer Hide answer
Answer: B. Amortization
Amortization is the financial process of spreading capital asset costs or loan repayments over time. It accounts for periodic operational charges or structured debt retirement through scheduled payments. This financial m...
Q4. After 24 hours of immersion in cold water, premium first-class bricks should absorb no more than______________?
Show answer Hide answer
Answer: B. 20%
High-quality first-class bricks must possess low porosity to ensure structural durability and strength. Standard building specifications limit water absorption for premium bricks to twenty percent of dry weight. Exceedin...
Q5. Identify which of the listed properties represents a scalar quantity ?
Show answer Hide answer
Answer: A. energy
Energy is a scalar quantity because it possesses magnitude only without any associated directional component in space. Scalar quantities can be completely described by a single numerical value accompanied by appropriate...
Q6. Per IS specifications, ordinary portland cement must exhibit a three-day compressive strength of at least________________?
Show answer Hide answer
Answer: C. 16 MPa
Standard material specifications set strict mechanical performance benchmarks for ordinary Portland cement. Compressive strength testing at three days is a primary quality control check for cement batches. Ordinary Portl...