Inlet and Outlet Arrangement in Water Treatment
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Questions and Answers

What type of tanks keep water in complete rest for a certain period?

  • Rectangular tanks
  • Intermittent tanks (correct)
  • Continuous flow tanks
  • Circular tanks

    • Which type of settling basins are generally preferred due to their hydraulic stability?

  • Circular tanks with radial flow
  • Circular tanks with spiral flow
  • Long rectangular basins (correct)
  • Short rectangular basins

    • What is the function of the inlet zone in a long rectangular settling tank?

  • Facilitate sludge scraping
  • Collect settled material
  • Uniformly distribute the flow (correct)
  • Collect clarified effluent

    • What is the primary function of the sludge zone in a settling tank?

    <p>Collect settled material</p> Signup and view all the answers

    Why are long rectangular settling basins considered easier for flow control?

    <p>They are hydraulically more stable</p> Signup and view all the answers

    What distinguishes continuous flow type tanks from intermittent tanks?

    <p>Flow velocity is reduced</p> Signup and view all the answers

    What is the purpose of constructing a baffle close to the inlet in a settling basin?

    <p>To distribute water equally and at uniform velocities</p> Signup and view all the answers

    Why are peripheral weirs not acceptable in settling basins?

    <p>They cause excessive short-circuiting</p> Signup and view all the answers

    In circular settling basins, what is the path of particles as the flow moves radially towards the perimeter?

    <p>Parabola</p> Signup and view all the answers

    What is the formula for the vertical settling velocity of particles in a settling basin?

    <p>$vt = \frac{(ρp - ρ )gd^2}{18μ}$</p> Signup and view all the answers

    What is the surface area of the rectangular sedimentation tank designed to treat 2.4 million litres of raw water per day?

    <p>100 m2</p> Signup and view all the answers

    How is the horizontal velocity of water affected in a circular settling basin as the distance from the center increases?

    <p>Decreases</p> Signup and view all the answers

    What is the assumed depth of the rectangular sedimentation tank designed to treat 2.4 million litres of raw water per day?

    <p>3.0 m</p> Signup and view all the answers

    What is the determining factor for the size particle that can be completely removed in the settling zone?

    <p>$Q/As$</p> Signup and view all the answers

    What is the detention period recommended for coagulated sedimentation in settling basins?

    <p>2 to 2.5 hours</p> Signup and view all the answers

    What determines the magnitude of energy barrier that must be overcome before aggregation occurs in a colloidal dispersion?

    <p>Charge on the colloidal particles</p> Signup and view all the answers

    Which type of colloids are described as irreversible upon heating?

    <p>Lyophobic colloids</p> Signup and view all the answers

    What are the recommended tank dimensions for rectangular settling basins?

    <p>$L:B = 3:1$</p> Signup and view all the answers

    What process involves stimulation by mechanical means to agglomerate destabilized particles into compact, fast settleable flocs?

    <p>Flocculation</p> Signup and view all the answers

    What is the velocity of flow recommended for horizontal flow in settling basins?

    <p>&lt; 30 cm/min</p> Signup and view all the answers

    What is the term used for the motion of colloidal particles due to bombardment by molecules of the dispersion medium?

    <p><em>Brownian motion</em></p> Signup and view all the answers

    What is the surface overflow rate recommendation for thoroughly flocculated water in settling basins?

    <p>$24000$ to $30000$ L/d/m2 tank area</p> Signup and view all the answers

    Which step in the aggregation of colloidal particles involves particle transport to effect interparticle collision?

    <p><em>Flocculation</em></p> Signup and view all the answers

    What is responsible for providing bridges that lead to enmeshment in a precipitate and adsorption and interparticle bridging?

    <p><em>Providing bridges</em></p> Signup and view all the answers

    What effect occurs when colloidal particles pass through the pores of filtration media due to their small size?

    <p><em>Tyndall effect</em></p> Signup and view all the answers

    "The stability of colloids is mainly due to preferential adsorption of ions" reflects which property of colloids?

    <p><em>Electrical properties</em></p> Signup and view all the answers

    What is the purpose of reducing the stirring speed to 25 to 35 rpm in the jar testing apparatus?

    <p>To promote floc formation by enhancing particle collisions</p> Signup and view all the answers

    Which filtration mechanism is only important for particles with diameters less than 1 micron?

    <p>Brownian diffusion</p> Signup and view all the answers

    What is the term used to express the size of sand particles that will pass through a sieve?

    <p>Effective size</p> Signup and view all the answers

    Which material can sometimes be used as an alternative to sand as filter media?

    <p>Anthrafilt</p> Signup and view all the answers

    What does the sedimentation mechanism rely on to capture particles?

    <p>Gravity and settling velocity of particles</p> Signup and view all the answers

    What is the purpose of allowing the containers in the jar testing apparatus to settle for 30 to 45 minutes?

    <p>To remove impurities still further</p> Signup and view all the answers

    What is the role of gravel in the filtration process?

    <p>Support the layers of sand</p> Signup and view all the answers

    Which type of filter consists of fine sand supported by gravel?

    <p>Slow sand filter</p> Signup and view all the answers

    What is the mechanism responsible for capturing large particles that follow streamlines close to the media surface?

    <p>Interception</p> Signup and view all the answers

    What does Brownian diffusion mechanism rely on for particle movement?

    <p>Thermal gradients</p> Signup and view all the answers

    What is the purpose of rapid or flash mixing in the water treatment process?

    <p>To form the nucleus for floc formation</p> Signup and view all the answers

    In perikinetic flocculation, how do colloidal particles come into contact for floc formation?

    <p>Through Brownian motion of colloidal particles</p> Signup and view all the answers

    Which parameter is utilized to estimate the velocity gradient in a system involving orthokinetic flocculation?

    <p>$P$ (Power)</p> Signup and view all the answers

    How do Al(III) and Fe(III) salts accomplish destabilization in water treatment?

    <p>By absorption and charge neutralization</p> Signup and view all the answers

    What is the key factor that controls the precipitation of amorphous metal hydroxides during coagulation?

    <p>$ ext{pH}$ (Hydrogen ion concentration)</p> Signup and view all the answers

    What is the primary function of a jar test in water or wastewater treatment?

    <p>To predict large-scale treatment operation outcomes</p> Signup and view all the answers

    Which type of flocculation involves contacts or collisions of colloidal particles due to Brownian motion?

    <p><strong>Perikinetic</strong></p> Signup and view all the answers

    What is the purpose of mechanical flocculation in water treatment?

    <p><strong>To create contacts between colloidal particles</strong></p> Signup and view all the answers

    ${Al(H_2O)_3^+}$ and ${Fe(HO)_3^+}$ are examples of what in water treatment?

    <p><strong>Soluble species</strong></p> Signup and view all the answers

    ${Alum}$ reacts with natural alkalinity in water to produce what compound?

    <p>${Al(OH)_3(s)}$</p> Signup and view all the answers

    What is the base material size range in Rapid Sand Filters?

    <p>3 to 40 mm</p> Signup and view all the answers

    Which process helps slow sand filters remove impurities mainly during the first few days?

    <p>Sedimentation</p> Signup and view all the answers

    How is a slow sand filter's rate of filtration compared to a rapid sand filter?

    <p>Smaller</p> Signup and view all the answers

    What is the effective size range of filter sand in Rapid Sand Filters?

    <p>0.35 to 0.55 mm</p> Signup and view all the answers

    Which method is used for cleaning Rapid Sand Filters?

    <p>Agitating and backwashing</p> Signup and view all the answers

    What does the 'Schmutzdecke' refer to in slow sand filtration?

    <p>Living quarters of micro-organisms</p> Signup and view all the answers

    What type of water is obtained directly from Slow Sand Filters?

    <p>'Almost' pure water</p> Signup and view all the answers

    How does the loss of head compare between Slow Sand Filters and Rapid Sand Filters?

    <p>Initial loss is higher in SSF</p> Signup and view all the answers

    'Schmutzdecke' becomes living quarters for micro-organisms that break down organic material and convert it into what products?

    <p>'Water, carbon dioxide, and other oxides'</p> Signup and view all the answers

    'Multimedia filters' consist of how many layers of different granular materials?

    <p>$3$ layers</p> Signup and view all the answers

    What is the formula for head loss in the Carman-Kozeny equation?

    <p>h = f (1 - n) Lvs^2 Φ n^3 dg</p> Signup and view all the answers

    What does the porosity 'n' represent in the Carman-Kozeny equation?

    <p>Particle shape factor</p> Signup and view all the answers

    Why is it not recommended for filters to run for longer periods without backwashing?

    <p>To avoid packing down of filter media</p> Signup and view all the answers

    What is the condition that indicates the need for backwashing a filter according to the text?

    <p>High turbidity in filter effluent</p> Signup and view all the answers

    What issue arises when the frictional resistance exceeds the static head of water in a newly commissioned filter?

    <p>Air binding</p> Signup and view all the answers

    What is the phenomenon known as when air binds to the sand grains in a filter?

    <p>Air binding</p> Signup and view all the answers

    Why does the bottom sand layer act like a vacuum in a filter experiencing air binding?

    <p>To aid water filtration</p> Signup and view all the answers

    What is done to prevent shrinkage cracks in a filter bed according to the text?

    <p>Washing with caustic soda solution</p> Signup and view all the answers

    What is generally used to clean filters that have mud balls formed on them?

    <p>Caustic soda</p> Signup and view all the answers

    What is recommended to be not less than 60 times its diameter in a Rapid Sand Filter?

    <p>Lateral length</p> Signup and view all the answers

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