Gracias Experimental Set ups

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There are several critical design decisions that must be made as we develop a design proposal for this plant. These design choices include:

• width and number of the sedimentation tanks
  • depth of the sedimentation tank is related to the width
  • maximum length of the sedimentation tanks is determined by the flow capacity of the two triangular manifold in the base of the sedimentation tank. In order to calculate this length we need to know the maximum velocity that we can use in the manifold without breaking up too many flocs. According to Water Treatment Plant Design (4th edition) page 16.3 the maximum velocity to avoid breaking up flocs is 15 cm/s. That sets the maximum length of a 1.08 m wide tank to ?? and the maximum length of a 2.16 m wide tank to ???.
• width of the flocculation tank - the flocculator for 3000 L/min must be at least 2 m deep and 1 m wide. It can, of course, be deeper, or wider, but it must be at least that large to get a G value of 10/s If the goal were to get to 5/s then it would need to be at least 2.4 m deep and 1.2 m wide. These calculations are based on the assumption that the flocculator dimensions were h=2b=2w.
• location of the inlet tank (on top of the floc tank or elsewhere)
• use of an elevated platform or backfill to create walkways
• depth of the channels with adequate carrying capacity but with a system for shutting off flow to individual sedimentation tanks.