Every question from this NCERT chapter, with a detailed explanation.
With reference to the composition of sewage, consider the following statements: 1. It is a liquid waste consisting entirely of dissolved impurities. 2. It contains nutrients such as phosphorus and nitrogen. 3. It is devoid of any saprophytic or disease-causing bacteria. Which of the statements given above is/are correct?
Consider the following statements regarding the impurities found in sewage: 1. Urea and pesticides are classified as organic impurities. 2. Nitrates and phosphates are classified as organic impurities. 3. Vegetable waste and animal waste are classified as organic impurities. Which of the statements given above is/are correct?
Consider the following statements regarding the physical treatment of wastewater: 1. Bar screens are used to remove large objects like rags and sticks. 2. The speed of wastewater is increased in the grit and sand removal tank to facilitate filtration. 3. Sedimentation tanks are designed to increase the flow speed to prevent settling of solids. Which of the statements given above is/are correct?
With reference to unit operations used in wastewater treatment, the role of a skimmer is to:
Consider the following statements regarding "Activated Sludge": 1. It consists of suspended microbes that settle at the bottom of the tank after aeration. 2. It contains a very low percentage of water, being mostly solid. 3. A part of it is pumped back into the aeration tank to serve as an inoculum. Which of the statements given above is/are correct?
With reference to the impact of oils and fats on the environment, consider the following statements: 1. In pipes, they can harden and cause blockages. 2. In open drains, they significantly increase the soil's porosity and filtration capacity. Which of the statements given above is/are correct?
Which tree species is often recommended for planting around sewage ponds to absorb excess wastewater via high transpiration?
With reference to sanitation and groundwater, consider the following statements: 1. Untreated human excreta causes soil pollution but does not affect groundwater quality. 2. Groundwater contamination is a common route for water-borne diseases like typhoid. 3. Septic tanks are primarily recommended for areas with extensive centralized sewerage systems. Which of the statements given above is/are correct?
Consider the following pairs regarding wastewater treatment stages and their functions: 1. Bar Screens : Removal of large objects like rags 2. Grit Tank : Removal of floatable oil and grease 3. Aeration Tank : Growth of aerobic bacteria 4. Clarifier : Settling of sludge How many of the above pairs are correctly matched?
Considering low-cost sanitation systems based on biological processing, the principal by-product of vermi-processing toilets is:
With reference to on-site sewage disposal systems, consider the following statements: 1. They are encouraged to improve sanitation in areas without sewerage. 2. In these systems, the excreta is chemically treated to strictly prevent biogas formation. 3. The biogas produced from sewage can be used as a source of energy. Which of the statements given above is/are correct?
Consider the following statements about the "Clarified Water" in a treatment plant: 1. It is the water obtained immediately after passing through bar screens. 2. It is water from which solids have settled and floatable impurities have been skimmed off. 3. It may still contain suspended impurities and requires further treatment. Which of the statements given above is/are correct?
Which chemicals are standardly used for the disinfection of water in public supply systems?
With reference to the "Swachh Bharat" mission, consider the following statements: 1. It was initiated in the year 2016. 2. It focuses on proper sewage disposal and providing toilets for everyone. 3. It strictly prohibits the use of vermi-processing toilets. Which of the statements given above is/are correct?
Consider the following statements regarding the role of bacteria in wastewater treatment: 1. Anaerobic bacteria are used to decompose sludge and produce biogas. 2. Aerobic bacteria are prevented from entering the aeration tanks. 3. Bacteria play a crucial role in consuming organic impurities during the treatment process. Which of the statements given above is/are correct?
In a wastewater treatment plant, what is the specific function of a "skimmer"?
In the context of urban sanitation and public health, why are open drains regarded as a serious hazard?
Consider the following statements regarding "Manholes" in a sewerage system: 1. They are typically located at intervals of 500 m to 600 m along the sewerage line. 2. They are placed at the junction of two or more sewers. 3. They are placed at points where there is a change in direction of the sewer line. Which of the statements given above is/are correct?
During the assessment of sewage impurities in treatment plants, which of the following is considered an inorganic contaminant?
With reference to the "Grit and Sand Removal Tank", consider the following statements: 1. It is a treatment step that typically follows the bar screens. 2. It relies on the principle of significantly increasing water speed to prevent sand from settling. Which of the statements given above is/are correct?
Which of the following pairs is correctly matched?
With reference to the "Aeration" process in wastewater treatment, consider the following statements: 1. It involves bubbling air through the wastewater. 2. It is a mechanical process designed to filter out fine dust particles. 3. It creates conditions that inhibit the growth of aerobic bacteria. Which of the statements given above is/are correct?
Which of the following diseases is primarily transmitted through contaminated water?
Consider the following statements regarding "Septic Tanks": 1. They are a type of low-cost onsite sewage disposal system. 2. They are strictly prohibited for use in residential clusters. 3. They function independently of the main city sewerage system. Which of the statements given above is/are correct?
In urban sanitation systems, solid household wastes such as cotton and tea leaves pose a problem when disposed of in sinks primarily because they:
Consider the following statements regarding the "Bar Screen": 1. It is a chemical filter used to neutralize acidic wastewater. 2. It removes large objects like plastic packets and napkins. 3. It is typically the first major step in a wastewater treatment plant. Which of the statements given above is/are correct?
Which of the following correctly pairs a water-borne disease with its causative agent?
Consider the following statements regarding "Biogas" produced in a wastewater treatment plant: 1. It is produced during the aeration phase of treatment. 2. It is a product of anaerobic decomposition of sludge. 3. It cannot be used to generate electricity due to its low calorific value. Which of the statements given above is/are correct?
In wastewater engineering, controlled flow velocity in grit chambers is essential mainly to ensure that:
With reference to "Eucalyptus trees" and wastewater, consider the following statements: 1. They absorb surplus wastewater rapidly. 2. They retain all absorbed water and do not release any vapour into the atmosphere. 3. They are often planted near sewage ponds to absorb surplus wastewater. Which of the statements given above is/are correct?
Consider the following statements regarding the "Skimmer": 1. It is used exclusively in the grit removal tank. 2. It is designed to remove floatable impurities like oil and grease. 3. It operates on the surface of the water in the clarifier. Which of the statements given above is/are correct?
Which of the following pairs is correctly matched regarding sewage impurities?
With reference to "Sanitation at Public Places", consider the following statements: 1. Large amounts of waste are generated at public places like railway stations. 2. Scattered litter has no impact on the spread of diseases. 3. If no dustbin is available, one should leave the litter in a corner. Which of the statements given above is/are correct?
In the context of human infectious diseases, Vibrio cholerae belongs to which major group of microorganisms?
Consider the following statements regarding the "Aerator" in a wastewater treatment plant: 1. It is used to mechanically stir the wastewater. 2. It removes oxygen to support anaerobic bacteria. 3. It is typically used before the water enters the secondary clarifier. Which of the statements given above is/are correct?
What is the primary environmental consequence of discharging untreated sewage into river systems?
With reference to "Chemical Toilets", consider the following statements: 1. They require a direct connection to a centralized treatment plant. 2. They are suitable for places with no sewerage system. Which of the statements given above is/are correct?
Consider the following statements regarding "Groundwater": 1. It is never used as a source for wells or tubewells. 2. It can be polluted by surface sanitation issues. 3. It is a common route for water-borne diseases if contaminated. Which of the statements given above is/are correct?
Consider the following statements regarding "Scarcity of Freshwater": 1. Population growth is a contributing factor to water scarcity. 2. Industrial development has no impact on the scarcity of freshwater. 3. Mismanagement of water resources increases the availability of freshwater. Which of the statements given above is/are correct?
With reference to "Ozone" in water treatment, consider the following statements: 1. It is used to disinfect water. 2. It is essential for the breathing of aquatic animals in the treatment tank. 3. It is an allotrope of oxygen that can absorb ultraviolet rays. Which of the statements given above is/are correct?
Consider the following statements regarding "Sewage": 1. It consists exclusively of industrial effluents. 2. It includes rainwater that washes off roads. 3. It is a complex mixture of solids, organic and inorganic impurities. Which of the statements given above is/are correct?
With reference to "Composting Pits", consider the following statements: 1. They are a type of onsite sewage disposal system. 2. They contribute to high-cost sanitation solutions. 3. They are only permitted in areas with a centralized sewerage system. Which of the statements given above is/are correct?
Consider the following statements regarding the "Bar Screen" function: 1. It is a physical barrier placed at the inlet of the treatment plant. 2. It allows large objects like cans and plastic packets to pass through. 3. It helps prevent damage to pumps by removing large solids. Which of the statements given above is/are correct?
With reference to "Sanitation and Disease", consider the following statements: 1. Poor sanitation has no correlation with the quality of drinking water. 2. A large fraction of people defecate in the open, which is a health hazard. 3. Untreated human excreta is a cause of both soil and water pollution. Which of the statements given above is/are correct?
Consider the following statements regarding "Aerobic Bacteria": 1. They function effectively in the absence of oxygen. 2. They consume soaps and food waste left in clarified water. 3. They remain permanently suspended in the water and never settle. Which of the statements given above is/are correct?
Which of the following components of sewage is classified as a "nutrient" pollutant?
With reference to "Biogas", consider the following statements: 1. It is produced from the decomposition of sludge. 2. It consumes energy rather than producing it. 3. It is produced by anaerobic bacteria. Which of the statements given above is/are correct?
Consider the following statements regarding "Sewage Disposal": 1. Low-cost onsite systems are banned where sewerage is unavailable. 2. Septic tanks and vermi-processing toilets are examples of onsite systems. 3. Open drains are a breeding ground for mosquitoes. Which of the statements given above is/are correct?
With reference to "Water Pollution", consider the following statements: 1. It is caused by the discharge of untreated sewage. 2. It prevents the spread of diseases like cholera. 3. It affects only surface water and not groundwater. Which of the statements given above is/are correct?
Consider the following statements regarding "Vermi-cakes": 1. They are a byproduct of vermi-processing toilets. 2. They are hazardous waste that must be incinerated. 3. They are a resource needed for soil. Which of the statements given above is/are correct?
With reference to "Activated Sludge", consider the following statements: 1. It is completely dry and contains no water. 2. The water from it is removed by sand drying beds. 3. It can be used as manure. Which of the statements given above is/are correct?
With reference to the by-products generated during sewage treatment, the dried sludge obtained after treatment is generally used as:
Which method is typically used to remove or process activated sludge in a treatment plant?
What is the primary role of anaerobic bacteria in the context of sewage treatment?