Q.1) Chlorine demand of water is equal to _____.
A) residual chlorine
B) applied chlorine
C) applied + residual chlorine
D) Applied – residual chlorine
Q.2) The water which is not chemically pure but does not contain anything harmful to human health is called –
A) Wholesome water
B) Pure water
C) Drinking water
D) Distilled water
Wholesome water : Water that has been not chemically processed but doen not contain any harmful particles.
Pure water: Water that has been processed to remove all contaminants and impurities, such as minerals, bacteria, and pollutants.
Drinking water: Water that has been treated with chemicals, such as chlorine, to make it safe for human consumption.
Distilled water: Water that has been boiled and the vapor condensed back into liquid form to remove any dissolved solids and contaminants.
Fluorine < 1 ppm (dental cavity)
Fluorine > 1.5 ppm (mottling of teeth)
Permissible Fluorine Content = 1 to 1.5 ppm.
Q.4) Blue Baby disease is caused due to the presence of the excess amount of _______.
Presence of excess Nitrate in water causes blue baby disease scientifically called as “Methemoglobinemia“.
Nitrate ≤ 45 ppm.
Q.5) Aeration of water is done to remove _____.
Aeration is the process of adding air to a liquid or solid to raise the oxygen content, lower the odour, or enhance the quality of the water. The procedure aids in the breakdown of contaminants and the reduction of suspended solids, improving the clarity and safety of the water.
Aeration also encourages the growth of advantageous bacteria, which can aid in lowering the concentration of hazardous substances in the water.
Q.6) Flocculation agent is added to the raw water in the treatment plant to remove the _____.
A) fine suspended particles
B) floating particles
C) dissolved chemicals
D) heavy metals
Chemicals called flocculation agents are added to raw water to cause contaminants to cluster together as flocs. This procedure aids in the elimination of colloids, suspended particles, and other impurities that may cause the water to seem turbid.
The flocs that are created can therefore be more easily removed throughout the treatment process, enhancing the water’s general quality. The type of flocculant used and the conditions under which it is administered can have an impact on flocculation effectiveness, therefore these parameters must be carefully selected and controlled.
Q.7) The desirable limit of chlorine content as per BIS standards in water for domestic supplies should not exceed ________.
A) 200 ppm
B) 350 ppm
C) 250 ppm
D) 450 ppm
Q.8) Which of these is an indirect method for the determination of stream flow?
A) Ultrasonic method
B) Dilution techniques
C) Slope area method
D) Area velocity method
Ultrasonic Method : The ultrasonic method measures the speed of fluid in a conduit using sound waves. This technique is based on the Doppler effect, in which sound waves hit moving objects and change frequency. The frequency shift can be used to determine the fluid’s velocity. When using corrosive or unclean fluids, for example, or when typical flow monitoring techniques are impractical or impossible, the ultrasonic approach is frequently used.
Dilution Techniques: Dilution techniques measures the flow rate by introducing a known volume of tracer into the flow and then measuring the concentration of the tracer downstream. The flow rate can be calculated by using the concentration and volume of the tracer, and the time it takes to move through the flow. This method is often used in applications where other flow measurement techniques are not possible or practical, such as with low-velocity or complex flows.
Slope Area Method : The flow metre, a device used to gauge a fluid’s flow rate, is utilised in the slope area approach. The apparatus comprises of a curved plate with a predetermined shape that is put in the fluid pipe. A pressure drop related to the flow rate of the fluid across the plate occurs. The flow rate can be determined by monitoring the pressure drop and knowing the form of the plate. This technique is frequently utilised in situations where other flow monitoring techniques are impractical or impossible, for as when dealing with highly viscous fluids or poorly known flow patterns.
Area Velocity Method: The area velocity method is a flow measurement technique that uses a device to determine the flow rate of a fluid by measuring the cross-sectional area of the flow and the velocity of the fluid. The device typically consists of a calibrated weir or flume that is installed in the pipe carrying the fluid. By measuring the height of the fluid over the weir or flume and the velocity of the fluid, the flow rate can be calculated. This method is often used in applications where other flow measurement techniques are not possible or practical, such as with low-velocity or irregular flows.
Q.9) The treatment of water with only chlorine is known as ___________.
B) Post chlorination
C) Pre chlorination
De-chlorination: It is the process of removing chlorine from water after it has been treated with chlorine. This is typically done to reduce the taste and odor of the water, to prevent damage to equipment or the environment, or to meet regulatory requirements for discharge. De-chlorination can be achieved through physical methods such as aeration or through chemical methods such as adding a de-chlorinating chemical.
Post Chlorination : The process of adding chlorine to water after its initial treatment, known as post chlorination, is typically done to keep a residual chlorine content in the water’s distribution system, which guarantees that the water won’t carry any harmful pathogens. To maintain an efficient level of disinfection, the residual concentration is typically checked and changed as necessary.
Pre-chlorination : Pre-chlorination is the process of adding chlorine to water before it receives any other kind of treatment. This is typically done to get rid of dangerous microorganisms and reduce organic matter. Pre chlorination is frequently utilised in the treatment of surface water to offer a more reliable and efficient level of disinfection.
Chlorination : Chlorination is the process of disinfecting water by introducing chlorine to it in order to eradicate any dangerous pathogens that may be present. One of the most popular techniques for disinfecting water is chlorination, which is frequently employed in both industrial and municipal water treatment procedures. To suit certain disinfection requirements, the chlorine addition amount and contact duration with the water can be changed.
Q.10) The removal of taste and odour from water is accomplished best by _____.
Coagulation : It is a process of removing suspended particles, colloids, and other impurities from water by destabilize the negatively charged particles in the water, causing them to form larger particles called flocs. These flocs can then be removed from the water more easily by sedimentation or filtration. This is achieved by adding a coagulant agent such as aluminum sulfate (alum) or ferric chloride. The coagulant neutralizes the negative charges on the particles and causes them to clump together and form flocs.
Q.11) The colour in water is generally due to –
A) Dissolved impurities
B) Colloidal impurities
C) Suspended impurities
D) None of the above
Colour in water is generally due to dissolved organic matter from decaying vegetation or some inorganic material such as coloured soil etc.
Colour matching technique (tintometer) is done to measure colour. The results are expressed in TCU or Hazen unit true colour where 1TCU = colour produced by 1 mg/lit of platinum in the form of chloroplatinum ion.
Q.12) Zeolite process is used to _______.
A) remove bacteria
B) remove permanent hardness
C) remove zinc
D) None of the above
The term “zeolite process” describes the process of purifying water by using zeolites as an adsorbent material. This method is frequently used to remove radioactive materials like cesium and strontium as well as heavy metals like lead and cadmium from contaminated water.
Q.13) The suitable layout of a distribution system for irregular growing town is –
A) Radial system
B) Dead end system
C) Ring system
D) Grid iron system
Radial System : A network of pipelines that branch off from a main water source, like a treatment plant, and travel in one direction to serve a sizable area is known as a radial system of water distribution. Like the spokes of a wheel, the pipes in a radial system are arranged in a series of straight lines that radiate from the central source. This kind of system is frequently employed in rural locations when there is minimal water demand and a significant amount of distance between customers.
Dead-end system: A dead-end system of water distribution is a network of pipelines that run in a single direction and terminate at a dead end. This type of system is commonly used in urban areas where the demand for water is high and the distances between users are short. The dead-end system is characterized by high water pressures at the end of the pipes and low water pressures at the beginning of the pipes.
Ring System : A network of pipelines that forms a closed loop and allows water to flow in both directions is known as a ring distribution system. Water flows from high-pressure locations to low-pressure areas to keep the system balanced, resulting in roughly constant water pressures across the network. This kind of system is frequently employed in metropolitan settings where there is a high demand for water and close proximity between consumers.
Grid System : A network of pipelines constructed in a grid-like layout, with water flowing in various directions, is a grid system of water distribution. High water pressures at the pipeline intersections and low water pressures in the centre of the grid define the grid system. This kind of system is frequently employed in metropolitan settings where there is a high demand for water and close proximity between consumers.
Q.14) Pump commonly used for lifting water in water supply mains is –
A) Axial flow pump
B) Centrifugal pump
C) Reciprocating pump
D) Rotary Type pump
Q.15) The minimum velocity of flow in a sewer should be ideally –
A) Less than self-cleansing velocity
B) Equal to self-cleansing velocity
C) Equal to non-scouring velocity
D) Less than non-scouring velocity
The minimal flow rate necessary to prevent the accumulation of sediment and other material in a pipeline is referred to as self-cleansing velocity. A pipeline stays clear and free of clogs when water is moving through it at a self-cleansing velocity because the flow is powerful enough to carry away any possible silt.
The flow rate below the self-cleansing velocity is referred to as non-scouring velocity. When water moves through a pipeline at a non-scouring velocity, the flow is insufficient to flush out sediment, which can build up inside the pipeline and cause clogs and reduced flow.
Q.16) Eutrophication of water bodies is caused by –
A) Excessive discharge of chlorides
B) Discharge of toxic substances
C) Excessive discharge of suspended solids
D) Excessive discharge of nutrients
Eutrophication is the natural process under water bodies ge infested with algae and silt up gradually to become shallower and more productive through the entry of cycling nutrients like carbon, nitrogen and phosphorus.
Eutrophication can also occur by human activities, such as the release of wastewater and agricultural runoff into waterways. These sources of nutrients can cause an overgrowth of algae, which can then die and decompose, using up dissolved oxygen in the water and creating low-oxygen (or hypoxic) conditions. This can lead to the death of fish and other aquatic life and can have significant impacts on the ecosystem as a whole.
Eutrophication can also cause changes in the water chemistry and quality, leading to decreased water clarity, increased turbidity, and altered pH levels. These changes can have negative impacts on recreational activities, such as fishing and swimming, and can reduce the value of the waterbody as a habitat for wildlife.
In order to reduce eutrophication, it is important to reduce the inputs of nutrients into waterways, through measures such as wastewater treatment, fertilizer management, and stormwater management.
Q.17) The liquid that collects at the bottom of a landfill is known as –
Leachate: It is a liquid that has percolated or leached through solid waste in a landfill, and that contains dissolved and suspended materials. Leachate can contain a wide range of pollutants, including chemicals, heavy metals, and pathogens, and can pose a threat to the environment and human health if it is not properly managed.
Sludge: It is a semi-solid material that is generated during the treatment of wastewater. It is composed of organic matter, such as food waste and sewage, and inorganic matter, such as sand and grit, that settle to the bottom of a treatment tank.
Sediment: It is solid material, such as dirt, sand, and clay, that has been suspended in water and deposited on the bottom of a body of water or a pipeline. Sediment can accumulate in water bodies and pipelines, reducing flow and causing damage to the infrastructure.
Floc: It is a clump of particles, such as algae, dirt, and bacteria, that have become attached to each other. Floc forms as a result of chemical reactions in water, such as the addition of coagulants, and can aid in the removal of pollutants from water.
Q.18) A 2% solution of a sewage sample is incubated for 3 days at 270C and the depletion of oxygen was found to be 4 mg/L. What is thee BOD 3 @ 270 C of the sample?
A) 200 mg/L
B) 400 mg/L
C) 120 mg/L
D) 50 mg/L
Q.19) Which one of the following methods can be employed for plastic and rubber waste disposal?
D) Sanitary landfill
Incineration: The process of combustion of waste at high temperatures to convert it into ash, gases, and heat is called Incineration.
Composting: Composting is a biological process in which organic waste, such as food waste and yard waste, is decomposed by microorganisms into a nutrient-rich soil amendment.
Pyrolysis: Pyrolysis is a process of thermal degradation that involves the heating of waste in the absence of oxygen to convert it into gases, liquids, and solids.
Sanitary Landfill: An engineered waste disposal facility called a sanitary landfill is created to contain and isolate trash from the environment. To stop the discharge of leachate and gases into the environment, sanitary landfills are built with numerous layers of barriers, such as a bottom liner and a cover. To limit the volume of the waste and the amount of space required for disposal, it is layered and compacted before being dumped in the landfill. Sanitary landfills are observed to make sure they are operating properly and protecting the environment.
Q.20) Trickling filter removes BOD5 upto –
A) 60 to 70%
B) 50 to 60%
C) 70 to 80%
D) 80 to 90%