Mixing System for the Clarifier

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At one of the drinking water treatment plants, we have 4 longitudinal gravity soil clarifiers with a trapezoidal cross-section with a base width of 18 m and a water mirror of 30 m. The length is 750 m. The depth of the basins varies between 2.5 and 4 m, depending on the degree of clogging. The water passes from one clarifier to the other.

The dosage of the coagulant is done in several points without mixing, only at one decanter with driving water under pressure (at decanter number 1).

Does anyone know if there are mixing systems for this type of clarifier?

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5 Answers

  1. To have good sedimentation in clarifier you need to use coagulants and flocculant aid. It is recommended to first insert rapid mixing unit with coagulant dosing and after it a flocculation chambers where the formed flocs will grow in size.

    For more details on design parameters  kindly contact me through direct message

     

    2 Comments

    2. Thank you all for your answer.I want to say that I have over 20 years of experience in water treatment

      In this case we are talking about clarifiers  with ​a trapezoidal ​cross-section ​with a base ​width of 18 m ​and a water ​mirror of 30 m,the length is ​750 m and  no reaction chamber.

      The sludge that gathers is cleaned annually with the dear river.It is difficult to place ordinary mixers because it  lifting deposits from the bottom of clarifiers.  We do not need a flocculant because decanting is done gravitationally over the length of decanters (1.5 kilometers) and water quality is very good.

      What we want is to optimize the amount of coagulant and so we need a solution to better mix the coagulant with water.

      1 Comment reply

      1. For coagulation you could also use hydraulic jump instead of rapid mixers.  The coagulant optimisation is possible but some parameters are needed like water flow and its fluctuation, turbidity and suspended solids, pH etc...

        You could contact me for more details  

  2. U can provide a flash mixer st the inlet or if u use aeration or an aerator where there is turbulence, before the water flows into the clarifier u can dose the coagulant at that point. Mixing is very important 

  3. If there is a inlet pump, you could add reagent into its intake and the pump will mix it.

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  4. The mixing of the coagulant is more than important. You need to go this far if soon as possible and there are several approaches that I have used to make sure that the interaction for coagulation is at optimum.  There are way too many approaches to even begin to write it down in this very short blog box.  If you are truly in the need,  and would like my assistance, please do not hesitate to contact me.  Just giving back, as so many have for me in the past..  My mobile number is 239-989-3581.  Best of luck and happy Thanksgiving – Sran.

  5. its essential that the coagulants are well mixed into the flow and ideally it needs a turbulent zone to ensure effective mixing. Could a flash mixer be installed at the inlet to the first clarifier to ensure this occurs quickly. 

    1 Comment

    1. I agree with David's comments an inline static mixer should be install to solve your problem where the coagulant are well mix before flow slows down to allow for sludge blanket to form