Environmental Protection and Pollution Control

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Questions and Answers

What is the primary purpose of the 'Minimal National Standards' (MINAS) for industries?

  • To ensure that industries take anti-pollution measures within their techno-economic capability (correct)
  • To provide a relaxation in pollution standards for industries
  • To impose stricter pollution standards on industries without considering their capabilities
  • To set unattainable standards for industries

Under what circumstances can MINAS be relaxed?

  • When the industry is willing to pay a fine
  • When the recipient environment demands stricter quality of the effluent
  • When the industry is unable to meet the standards
  • Under no circumstances (correct)

Who is empowered to prescribe standards stricter than MINAS?

  • The Central Pollution Control Board (CPCB)
  • The Ministry of Environment
  • The State Pollution Control Boards (correct)
  • The Industry Regulatory Body

What is the concept developed by the Central Pollution Control Board (CPCB) to designate water bodies?

<p>Designated best use (D)</p> Signup and view all the answers

How many 'designated best uses' has the CPCB identified?

<p>5 (A)</p> Signup and view all the answers

What is the primary purpose of the 'designated best use' concept?

<p>To determine the quality of water required for a specific use (D)</p> Signup and view all the answers

What is the importance of environmental education in the context of pollution?

<p>It plays a crucial role in negating the adverse impacts of pollution (D)</p> Signup and view all the answers

What is the main challenge in addressing environmental degradation?

<p>Complexity of environmental problems (B)</p> Signup and view all the answers

What is the recommended maximum particle size of suspended solids for inland surface water?

<p>850 microns (A)</p> Signup and view all the answers

What is the purpose of implementing environmental laws?

<p>To take proactive steps to prevent environmental degradation (C)</p> Signup and view all the answers

What is the maximum permitted suspended solids in marine/coastal areas for process wastewater?

<p>100 mg/L (D)</p> Signup and view all the answers

What is the significance of having a firm hand in implementing environmental protection laws?

<p>To ensure effective implementation of laws (C)</p> Signup and view all the answers

What is the hindered settling velocity represented by?

<p>uH (C), us (D)</p> Signup and view all the answers

What is the value of n in Stoke's law region?

<p>4.6 (D)</p> Signup and view all the answers

What is the formula for bulk density?

<p>ρb = ρs(1 - ε) + ρfε (C)</p> Signup and view all the answers

What is the assumption in the ideal sedimentation basin about the distribution of flow?

<p>Uniform horizontal velocity entering the settling zone (D)</p> Signup and view all the answers

What happens to particles that enter the sludge zone?

<p>They remain in the sludge zone (C)</p> Signup and view all the answers

What is the characteristic of the upflow clarifier?

<p>The velocity of the rising water is greater than the settling velocity of the particle (A)</p> Signup and view all the answers

What happens to the area through which the water passes as it rises in the upflow clarifier?

<p>It increases (C)</p> Signup and view all the answers

What is the purpose of the settling zone in the sedimentation basin?

<p>To remove particles from the water (D)</p> Signup and view all the answers

What is the condition for particles to be completely removed from a horizontal flow sedimentation tank?

<p>ut ≥ vo (A)</p> Signup and view all the answers

What is the typical flow velocity range used when piping flocculated water to the settling tank?

<p>0.15 to 0.6 m/s (C)</p> Signup and view all the answers

What is the percentage of particles removed (P) with a settling velocity of vt in a horizontal flow sedimentation tank designed with an overflow rate of v0?

<p>$\frac{vt}{vo} * 100$ (A)</p> Signup and view all the answers

What is the maximum horizontal velocity through the tank that does not allow resuspension of settled particles?

<p>Scour velocity (VH) (C)</p> Signup and view all the answers

What is the purpose of the diffuser wall in the settling tank?

<p>To reduce the flow velocity and spread the flow evenly (B)</p> Signup and view all the answers

What is the recommended head loss through the holes in the diffuser wall?

<p>4 to 5 times the velocity head (D)</p> Signup and view all the answers

What is the value of the cohesion constant (k) for sticky interlocking matter?

<p>0.6 (D)</p> Signup and view all the answers

What is the typical diameter of the holes in the diffuser wall?

<p>0.10 to 0.20 m (A)</p> Signup and view all the answers

What is the expression for the scour velocity (VH) in a horizontal flow sedimentation tank?

<p>$\frac{8k \rho_p - \rho_f}{gD_p}f$ (B)</p> Signup and view all the answers

What is the purpose of controlling horizontal flow velocities in the settling zone?

<p>To reduce turbulence and scour particles (A)</p> Signup and view all the answers

What is the condition for the ratio of length to width in a rectangular classifier?

<p>At least 6 (A)</p> Signup and view all the answers

What is the condition for the overflow rate in a horizontal flow sedimentation tank?

<p>At least four times the settling velocity (D)</p> Signup and view all the answers

What can be used to check on turbulence and back-mixing in the settling zone?

<p>Reynolds and Froude numbers (A)</p> Signup and view all the answers

What is the condition for the horizontal velocity in a horizontal flow sedimentation tank?

<p>At most one-third of the scour velocity (C)</p> Signup and view all the answers

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Study Notes

Environmental Protection and Pollution Control

  • Environmental degradation is a complex issue that requires a multi-dimensional approach.
  • Environmental education can play a crucial role in negating the adverse impacts of pollution.

General Standards for Discharge of Environmental Pollutants

  • Part-A: Effluents
    • Suspended solids: maximum 100 mg/L (inland surface water), 600 mg/L (public sewers), 200 mg/L (land for irrigation)
    • Particle size: shall pass 850 micron IS Sieve

Minimal National Standards (MINAS) for Industries

  • CPCB lays down specific standards for effluents discharged from industries
  • Standards are based on techno-economic capability of the industry to take anti-pollution measures
  • MINAS cannot be relaxed, but State Pollution Control Boards can prescribe stricter standards if necessary

Primary Water Quality Criteria

  • CPCB has developed a concept of "designated best use" for water bodies
  • 5 designated best uses have been identified

Hindered Settling

  • Hindered settling velocity (uH) = us
  • Methods to calculate uH: Stoke's law region (very small particles), Newton's law region (large particles)

Ideal Sedimentation Basin

  • Assumptions: discrete particle settling, four zones in the basin (inlet, outlet, sludge, and settling), even distribution of flow and particles
  • Particles that enter the sludge zone are captured and remain in the sludge zone

Sedimentation Zones

  • Horizontal flow clarifier
  • Upflow clarifier
  • Settling in an upflow clarifier: particles having settling velocity ut ≥ vo will be completely removed

Scour Velocity

  • Maximum horizontal velocity through the tank that does not allow resuspension (scouring) of settled particles
  • Formula: VH = (8k ρp - ρf) gDp / (f ρf)

Design of a Municipal Wastewater Plant

  • Flow rate: 60000 m3/d
  • Target particle characteristics: DP = 200×10-6 m, k = 0.05, f = 0.025, ρP = 1.25×103 kg/m3
  • Design considerations: rectangular classifier, overflow rate, horizontal velocity, scour velocity, diffuser wall

Inlet Zone

  • Velocity must be reduced and flow spread evenly over the cross section of the settling tank
  • Diffuser wall is used to accomplish this
  • Port velocities: 0.20 to 0.30 m/s, hole diameter: 0.10 to 0.20 m, spacing: 0.25 to 0.60 m apart

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