Correct Answer: 22-24 hours
Explanation: The detention time in a septic tank is typically in the range of 22 to 24 hours. This allows sufficient time for the process of sedimentation and anaerobic digestion of organic matter.
Correct Answer: sedimentation + digestion (anaerobic)
Explanation: A septic tank is a watertight tank where sedimentation and anaerobic digestion of organic matter take place. The tank is designed to separate solids from wastewater and facilitate the decomposition of organic matter by anaerobic bacteria.
Correct Answer: scattered residences
Explanation: Septic tanks are best suited for scattered residences, particularly in areas where centralized sewage treatment may not be feasible. They provide on-site treatment of sewage for individual households.
Correct Answer: having fine organic solids with high BOD
Explanation: Septic tank effluent typically contains fine organic solids with a high Biochemical Oxygen Demand (BOD). It is not clear and sparkling, and it requires further treatment before being discharged.
Correct Answer: downward
Explanation: The inlet and outlet pipes of the septic tank are bent downward. This design helps prevent the disturbance of settled solids and scum during the inflow and outflow of wastewater.
Correct Answer: 3-4 minutes
Explanation: The detention time for the detritus tank is typically in the range of 3 to 4 minutes. This short detention time allows for the settling of heavier particles.
Correct Answer: ecosanitation
Explanation: Ecosanitation is a type of sanitation in which urine and solid waste are separated. It involves the separate collection and treatment of urine and feces to achieve sustainable and resource-efficient sanitation.
Correct Answer: inert matter of specific gravity > 2.65
Explanation: Grit is inert matter with a specific gravity greater than 2.65. It typically consists of sand, gravel, or other heavy particles that settle in wastewater treatment processes.
Correct Answer: 45 sec to 90 sec
Explanation: A grit chamber has a relatively short detention period, typically in the range of 45 seconds to 90 seconds. This allows for the settling of grit before the wastewater continues its flow.
Correct Answer: 15 to 45 cm/sec
Explanation: The velocity of flow through a grit chamber is typically in the range of 15 to 45 cm/sec. This velocity helps in the settling of heavier particles.
Correct Answer: as a substitute for sand
Explanation: Grit obtained in a grit chamber, often composed of sand and other heavy particles, can be used as a substitute for sand in construction activities.
Correct Answer: settling of a particle along with the neighboring particle
Explanation: ‘Mass action’ during sedimentation refers to the settling of a particle along with the neighboring particle. This property contributes to the formation of floc and settling in sedimentation tanks.
Correct Answer: both (a) and (b) of above
Explanation: The main differences between a septic tank and an Imhoff tank are that in an Imhoff tank, digestion takes place in a separate compartment, and it is suitable for serving a larger population.
Correct Answer: anaerobic in the lower and aerobic in the upper compartment
Explanation: The working conditions in Imhoff tanks involve anaerobic digestion in the lower compartment and aerobic conditions in the upper compartment. This allows for the separation and treatment of sludge and effluent.
Correct Answer: two-storey sedimentation tank
Explanation: An Imhoff tank is a two-storey sedimentation tank. It consists of an upper compartment for sedimentation and an lower compartment for anaerobic digestion of sludge.
Correct Answer: circular imhoff double storage tanks without bottom hoppers
Explanation: Clarigesters are circular imhoff double storage tanks without bottom hoppers. These tanks are designed for the separation and treatment of sewage, with an upper clarifying compartment and a lower sludge digestion compartment.
Correct Answer: the sludge digestion under optimum conditions
Explanation: Digesters are used for the anaerobic digestion of sludge under optimum conditions. This process helps in the stabilization and reduction of organic matter in the sludge.
Correct Answer: extraction of essence from waste
Explanation: Salvaging refers to the extraction of valuable or essential components from waste materials, contributing to recycling and resource recovery.
Correct Answer: waste pipe
Explanation: The pipe used to carry discharge from sanitary fittings like bathrooms and kitchens is called the waste pipe. It conveys wastewater to the sewage system.
Correct Answer: 30 minutes
Explanation: During the water test of a sewer, an allowance of 2 liters per centimeter of diameter per kilometer of sewer line may be allowed for a period of 30 minutes. This test checks for leakages in the sewer system.
Correct Answer: smoke test
Explanation: The smoke test is a common method for testing house sewers. It involves introducing smoke into the sewer system to detect any leaks or openings in the pipes.
Correct Answer: sewage is received in a wet well
Explanation: The odd statement is “sewage is received in a wet well” because wet wells are typically associated with pump stations in wastewater systems, not with the reception of raw sewage.
Correct Answer: carbon cycle, sulfur cycle, and nitrogen cycle
Explanation: The three cycles of decomposition of sewage are the carbon cycle, sulfur cycle, and nitrogen cycle. These cycles involve the transformation of organic and inorganic substances in sewage.
Correct Answer: storm sewer
Explanation: An inverted siphon is typically associated with storm sewers. It is designed to carry stormwater or wastewater across a depression or obstacle using a pipe that is lower in the middle than at the ends.
Correct Answer: three pipes
Explanation: An inverted siphon is made of three pipes. This configuration allows the conveyance of wastewater or stormwater across a low point while preventing siphonic action and maintaining flow.
Correct Answer: both of the above
Explanation: An inverted siphon is referred to as both a depressed sewer and a sag sewer. It is designed to allow the conveyance of flow through a depressed section or sag without creating a siphoning effect.
Correct Answer: places where garbage is kept
Explanation: A garbage dumping home is a place where garbage is kept temporarily before being further processed or disposed of. It is not necessarily the final disposal site.
Correct Answer: 5 days
Explanation: The standard Biological Oxygen Demand (BOD) at 20°C is expressed in terms of the oxygen consumed over a 5-day period. This parameter is commonly used to assess the organic strength of wastewater.
Correct Answer: landfill
Explanation: Letache refers to the settling and compaction of waste in a landfill. It is observed in landfill sites where solid waste undergoes natural processes of degradation and compaction over time.
Correct Answer: all of the above
Explanation: All of the abbreviations are correct
Correct Answer: all of the above
Explanation: During the decomposition of sewage, various gases are produced. Methane is the predominant gas, constituting around 65 to 70% of the gases produced. Carbon dioxide (CO2) is also generated, comprising about 30% of the gases. Nitrogen is present in smaller quantities, around 0.05%. Therefore, all the options (methane, CO2, and nitrogen) are correct.
Correct Answer: 12.1 Mld
Explanation: The capacity of Guheswari Sewage Treatment Plant (STP) is 12.1 Mld (Million Liters per Day). STPs are designed to treat and process sewage and wastewater.
Correct Answer: 2
Explanation: In the one-pipe system of plumbing, there are two vertical pipes. This system is a type of plumbing configuration used in buildings for the drainage of wastewater.
Correct Answer: 4
Explanation: In the two-pipe system of plumbing, there are four vertical pipes. This system is used for the separate conveyance of soil and waste pipes in plumbing installations.
Correct Answer: 1
Explanation: In the single-stack system of plumbing, there is one vertical pipe. This system is commonly used in buildings for the drainage of both soil and waste.
Correct Answer: 2
Explanation: In the partially ventilated single-stack system of plumbing, there are two vertical pipes. This system allows for separate ventilation of soil and waste pipes.
Correct Answer: cast iron
Explanation: A Nahni trap is typically made of cast iron. It is a type of trap used in plumbing to prevent foul gases from entering the building while allowing the flow of wastewater.
Correct Answer: blue
Explanation: The color of septic sewage is often described as blue. This color may result from the presence of certain chemicals or reactions during the decomposition of organic matter.
Correct Answer: water seal
Explanation: Any trap is intended to trap foul gases with the provision of a water seal. The water seal prevents the entry of foul gases from the sewer into the building by trapping water in the trap.
Correct Answer: interception trap
Explanation: The interception trap is the last trap provided in a house drainage system. It is designed to intercept and prevent the passage of solids and debris while allowing the flow of wastewater.
Correct Answer: S-Trap
Explanation: S-Traps have parallel legs. The configuration of the trap resembles the letter “S” with two vertical legs.
Correct Answer: P-Trap
Explanation: P-Traps have perpendicular legs. The configuration of the trap resembles the letter “P” with a horizontal inlet and a vertical outlet.
Correct Answer: Q-Trap
Explanation: Q-Traps have curved legs. The configuration of the trap resembles the letter “Q” with a curved outlet.
Correct Answer: 200 PPM
Explanation: The BOD (Biochemical Oxygen Demand) of the sewage is calculated based on the oxygen depletion after 5 days of incubation. If the depletion is 5 PPM, then the BOD is calculated as 5% of the initial concentration. Therefore, the BOD of the sewage is 200 PPM (5% of 2.5%).
Correct Answer: 96.86%
Explanation: The relative stability of sewage is calculated as the ratio of the remaining stability after incubation to the initial stability. If the period of incubation is 15 days, the relative stability is calculated as (15/15) x 100%, which is 100%.
Correct Answer: 99.9%
Explanation: The relative stability is calculated as the ratio of the remaining stability after incubation to the initial stability. If the period of incubation at 37°C is 15 days, the relative stability is (15/15) x 100%, which is 100%. Therefore, the correct answer is 99.9%, as there is a 0.1% reduction in stability.
Correct Answer: 25
Explanation: The dilution factor is calculated as the total volume of the diluted sample divided by the volume of the original sample. In this case, the dilution factor is 250 ml / 10 ml = 25.
Correct Answer: 250 PPM
Explanation: The Biochemical Oxygen Demand (BOD) is calculated as the difference between the initial and final dissolved oxygen concentrations. In this case, BOD = 9 PPM – 4 PPM = 5 PPM. Since the sample is diluted by a factor of 200 ml / 4 ppm = 50, the final BOD is 5 PPM x 50 = 250 PPM.
Correct Answer: 100 mg/l
Explanation: The BOD₅ is calculated as the difference between the initial and final dissolved oxygen concentrations in the diluted sample. BOD₅ = 9 mg/l – 5 mg/l = 4 mg/l.
Correct Answer: 10 mg/l
Explanation: The initial BOD (BOD₀) is calculated as the product of the dilution factor and the BOD₅. BOD₀ = 500 mg/l × (2 ml / 200 ml) = 5 mg/l. Since the D.O. content after 5 days is found to be 5 mg/l, the initial D.O. content of the diluted sample is 5 mg/l × 2 = 10 mg/l.
Correct Answer: 30 m
Explanation: The depth of a shallow tube well, considering economic factors, is typically recommended not to exceed 30 meters.
Correct Answer: acidity
Explanation: The presence of hydrogen sulfide in water can cause acidity. Hydrogen sulfide is a gas that can dissolve in water and contribute to its acidity.
Correct Answer: hydrogen
Explanation: pH is a measure of the acidity or alkalinity of a solution and is a symbol for the concentration of hydrogen ions (H⁺) in the solution.
Correct Answer: the entire arrangement from source to distribution
Explanation: A complete water supply system includes the entire arrangement from the source of water to its distribution to the end-users.
Correct Answer: aerobic bacteria
Explanation: Aerobic bacteria are microorganisms that require free oxygen for their survival and growth.
Correct Answer: GI
Explanation: GI (Galvanized Iron) pipes are commonly used in house plumbing for conveying water.
Correct Answer: 12 mm
Explanation: The diameter of pipes in bathrooms and lavatories in domestic water supply is typically around 12 mm.
Correct Answer: internal diameter
Explanation: The designation of GI pipes is based on their internal diameter.
Correct Answer: all of the above
Explanation: The time of concentration for a watershed depends on various factors, including the slope of the catchment, intensity of rainfall, and nature of the soil.
Correct Answer: hygienically safe
Explanation: Water for domestic consumption should be hygienically safe, ensuring it is free from contaminants and safe for human consumption.
Correct Answer: all of the above
Explanation: The factors to be considered for the source of water supply include the quantity and quality of available water, elevation of the water sources, and the general terrain of the area. All these factors play a crucial role in determining the feasibility and efficiency of a water supply source.
Correct Answer: 270 liters
Explanation: The daily per capita water demand is calculated by dividing the total water requirement by the population and then by the number of days in a year. For this city, the calculation would be: (19,710,000 cubic meters / 0.2 million people) / 365 days ≈ 270 liters.
Correct Answer: suspended solids
Explanation: The sedimentation process in water treatment is primarily effective in removing suspended solids. It allows these particles to settle down, resulting in clearer water.
Correct Answer: 2/3 full
Explanation: A sanitary sewer is designed to operate at approximately 2/3 full under normal conditions. This ensures that there is enough capacity to handle peak flows without causing sewer overflows.
Correct Answer: Pathogens
Explanation: Harmful bacteria that can cause diseases are commonly referred to as pathogens. These include various disease-causing microorganisms.
Correct Answer: All of the above
Explanation: Physical characteristics of sewage include turbidity (cloudiness), color, and odor. These factors are important indicators of the quality and composition of sewage.
Correct Answer: 3.0-4.0 litres
Explanation: The quantity of flushing water required for a pour-flush water seal latrine typically ranges from 3.0 to 4.0 litres.
Correct Answer: Maximum flow
Explanation: Sewers are designed for the self-cleaning velocity, which is usually associated with the maximum flow conditions. This helps prevent sediment deposition in the sewer.
Correct Answer: Honeycomb inner wall
Explanation: The baffle wall in a septic tank is a honeycomb inner wall that helps in directing the flow and improving the efficiency of the treatment process.
Correct Answer: Cesspool
Explanation: A cesspool is an underground structure in the form of a tank that admits sewerage from an intercepting chamber for temporary storage or treatment.
Correct Answer: 24 hrs
Explanation: A water supply system is considered continuous when it provides water for 24 hours. This ensures uninterrupted access to water for the consumers.
Correct Answer: All of the above
Explanation: The intermittent water supply system has advantages such as the ability to carry out repairs during non-supply hours, reduced chances of water wastage, and the use of a lesser quantity of water.
Correct Answer: Oxygen-free sedimentation cum disposal under anaerobic conditions
Explanation: A septic tank is designed for the oxygen-free sedimentation and disposal of sewage under anaerobic conditions. It facilitates the separation and digestion of solids in the absence of oxygen.
Correct Answer: Release the pressure generated in the pipe
Explanation: A break pressure tank in a water supply system is incorporated to release the pressure generated in the pipe. It helps regulate and manage the pressure within the system.
Correct Answer: HDPE pipes
Explanation: High-Density Polyethylene (HDPE) pipes are widely used for rural water supply in Nepal. These pipes are known for their durability and flexibility, making them suitable for various applications in water supply systems.
Correct Answer: Solar disinfection
Explanation: The SODIS method, or Solar Water Disinfection, is a process of using solar energy to disinfect water. It involves exposing water-filled transparent containers to sunlight, which helps in deactivating pathogenic microorganisms.
Correct Answer: Bir Dhara scheme
Explanation: Bir Dhara scheme is the oldest waterworks in Nepal. It has historical significance in providing water supply.
Correct Answer: Union
Explanation: A union is a fitting used to join GI pipes coming from both sides. It allows for easy disconnection of pipes for maintenance or repairs.
Correct Answer: For quality water storage and uses for different purposes
Explanation: A water security plan is prepared to ensure the quality of water storage and its varied uses for different purposes. It involves strategies for long-term risk minimization and community participation.
Correct Answer: Anaerobic bacterial environment that develops in the tank
Explanation: The term “septic” refers to the anaerobic bacterial environment that develops in a septic tank during the treatment of sewage.
Correct Answer: The motor will ultimately burn-out
Explanation: Running an induction motor pump under significantly low voltage continually can lead to overheating and damage, eventually causing the motor to burn out.
Correct Answer: 5.00-7.00
Explanation: The peak water consumption hours, as recommended by the Department of Water Supply and Sewerage (DWSS), are typically from 5.00-7.00 hours when water demand is high.
Correct Answer: 99%
Explanation: Slow sand filters are efficient in removing bacteria from raw water, and their effectiveness can be up to 99% in removing bacterial contaminants.
Correct Answer: Water related
Explanation: Dengue is considered a water-related disease as it is primarily transmitted by Aedes mosquitoes breeding in stagnant water.
Correct Answer: Alum
Explanation: Alum is the most commonly used coagulant in water treatment processes to promote the aggregation and settling of impurities.
Correct Answer: Calcium bicarbonate
Explanation: Boiling water can remove hardness if it is due to calcium bicarbonate. The heat causes the bicarbonate to decompose, precipitating the hardness minerals.
Correct Answer: Darcy’s
Explanation: Darcy’s law is the most commonly used non-empirical formula to determine the velocity of the flow of underground water.
Correct Answer: 0.25 lps
Explanation: The minimum water flow in a tap stand is typically 0.25 liters per second (lps) to ensure an adequate supply for users.
Correct Answer: At all intersections, changes in grade, size, alignment
Explanation: Manholes in a sewer system should be installed at all intersections, changes in grade, size, and alignment to facilitate maintenance and inspection.
Correct Answer: Privy pit
Explanation: The most suitable excreta disposal unit for human excreta is a privy pit, which provides a simple and sanitary means of waste disposal.
Correct Answer: Night
Explanation: The flow in sewers is typically minimum during the night when water use is reduced.
Correct Answer: 1 in 100
Explanation: For a sewer with a diameter of 150 mm, a gradient of 1 in 100 is generally required to generate a self-cleaning velocity.
Correct Answer: High-level alarm
Explanation: A high-level alarm is a device that warns when the liquid in a system is above the pump level, helping to prevent overflow and potential damage.
Correct Answer: Pressure
Explanation: The sewage in an inverted siphon will flow under pressure conditions. The design of the inverted siphon allows sewage to be transported under an elevated obstacle using pressure.
Correct Answer: Top of PWC
Explanation: An anti-siphonage pipe is connected to the top of a PWC (Public Water Closet) to prevent backflow and siphonage of contaminated water into the water supply system.
FAQs on Water Supply & Sanitation Engineering MCQs for Civil Engineers
▸ What are the key topics covered in Water Supply & Sanitation Engineering for Civil Engineers?
Key topics include water distribution systems, wastewater treatment processes, stormwater management, and sanitation practices. For comprehensive MCQs and detailed explanations on these topics, visit GK Aim.
▸ Where can I find MCQs on Water Supply & Sanitation Engineering for Civil Engineers?
You can find MCQs on Water Supply & Sanitation Engineering specifically designed for Civil Engineers at GK Aim. The website provides a range of questions to test your knowledge.
▸ How can I use MCQs to prepare for Water Supply & Sanitation Engineering exams?
Utilizing MCQs can help you assess your understanding of Water Supply & Sanitation Engineering concepts. Regular practice with MCQs from sources like GK Aim can enhance your exam preparation.
▸ What resources are recommended for studying Water Supply & Sanitation Engineering?
Recommended resources include textbooks on water supply and sanitation engineering and online platforms that offer MCQs and quizzes. GK Aim provides a valuable collection of MCQs for in-depth study and practice.
▸ How are MCQs organized on GK Aim for Water Supply & Sanitation Engineering?
On GK Aim, MCQs on Water Supply & Sanitation Engineering are organized into manageable sections. Each section focuses on different aspects of the subject, allowing you to practice systematically.
▸ Are there mock tests available for Water Supply & Sanitation Engineering on GK Aim?
Yes, GK Aim offers mock tests for Water Supply & Sanitation Engineering. These tests are designed to help you evaluate your preparation and improve your performance.
▸ How can I access the MCQs for Water Supply & Sanitation Engineering on GK Aim?
To access MCQs for Water Supply & Sanitation Engineering, visit GK Aim. The site provides organized and easy-to-navigate content for effective study.
▸ What is the importance of practicing MCQs in Water Supply & Sanitation Engineering?
Practicing MCQs is crucial for reinforcing your knowledge and improving problem-solving skills in Water Supply & Sanitation Engineering. Regular practice with resources like GK Aim can greatly aid your understanding and exam readiness.
▸ Can I get detailed solutions for the MCQs on GK Aim?
Yes, GK Aim provides detailed solutions and explanations for MCQs on Water Supply & Sanitation Engineering, helping you understand the concepts thoroughly.
▸ What are the benefits of using GK Aim for Water Supply & Sanitation Engineering MCQs?
Using GK Aim for Water Supply & Sanitation Engineering MCQs offers benefits such as a wide range of questions, detailed explanations, and organized content. This helps in comprehensive preparation and better understanding of the subject.