6. Floc Tank Setup, Optimization and Operation

6. Floc Tank Setup, Optimization and Operation

FLOCCULATION TANK

The flocculation tank plays a crucial role in the treatment process by mixing the injected polymer with the manure before it flows over the Microscreen unit. To ensure effective floc formation while minimizing the use of chemicals, the tank is equipped with individual mixing chambers and a mixer assembly, which provide the necessary agitation.

The mixing chambers and mixer assemblies work in tandem to create turbulence and promote the thorough blending of the polymer with the manure. This agitation is essential for achieving optimal floc formation, where small particles clump together to form larger, more easily separated solids. The flocculation tank is designed to maximize the efficiency of the treatment process.


INITIAL FLOC TANK SET UP

During the initial setup of the flocculation tank, it is important to consider the proper placement of the tank to ensure that the flocculated liquids can effectively spill onto the screen.

To optimize the mixing process, a Variable Frequency Drive (VFD) is provided with the flocculation tank. The VFD enables operators to adjust the mixing speed, thereby achieving an optimal level of agitation. By controlling the mixing speed, the blending of the injected polymer with the manure can be fine-tuned, resulting in the formation of high-quality floc while minimizing chemistry consumption.

For the initial setup, it is recommended to set the VFD speed to 79 rpm (52Hz). This speed has been determined to deliver sufficient mixing force, ensuring thorough blending of the polymer within the flocculation tank. By achieving a well-mixed solution, the desired floc formation can be achieved, leading to improved performance of the system.

MIXING OPTIMIZATION

To optimize the mixing operation in the flocculation tank, adjustments to the mixing speed can be made while closely observing the flocculated material. It is recommended that any changes to the mixing speed are done in increments of 5 rpm (3Hz) to achieve the desired floc characteristics. The goal is to generate large flocs with clear liquid filling the spaces between them. Follow the steps below to optimize the mixing speed:

  1. Record the initial mixing speed, inlet flow rate, and screen flow rate for reference.
  2. On the MX-160 screen control panel, adjust the mixer Variable Frequency Drive (VFD) in 5 rpm (3Hz) increments.
  3. Observe the flocculated material at the spillway of the flocculation tank. It may take up to 90 seconds for any changes to become apparent.
  4. Record the updated mixing speed, inlet flow rate, and screen flow rate.
  5. If there is no noticeable change in the flocculated material or the screen flow rate compared to the inlet flow rate, make another adjustment to the mixer speed.
  6. Record the new mixing speed, inlet flow rate, and screen flow rate.
  7. If, after two speed adjustments, there is still no significant difference in the flocculated material or the screen flow rate, try reducing the mixing speed instead.
  8. Repeat steps 1-7 until the largest flocs are produced, and the maximum amount of screen filtrate is obtained.
  9. If at any point the flocculated material starts to break up or shear from excessive mixing, immediately reduce the mixing speed to prevent further disruption.

By systematically adjusting the mixing speed and monitoring the resulting floc characteristics and screen performance, operators can fine-tune the flocculation process to achieve optimal results. Regularly record the relevant parameters to track the progress of optimization and ensure the desired treatment outcomes are consistently attained.

MIXER BLADE DIRECTION

The Mixer blades should spin clockwise when looking down at them from above.

OPERATING THE FLOCCULATION TANK

The flocculation tank requires some adjustments to maximize the formation of large flocs. It is crucial to ensure the proper installation of the floc tank, specifically by maintaining the spillway in a level position. If the spillway is not level, uneven flows across the spillway can cause the flocculated material to accumulate and hinder the uniform distribution of liquids across the screen.

The floc tank is equipped with chemical injection ports that facilitates the even introduction of the grō17 polymer into the mixer blade assembly. This injection allows for effective mixing and flocculation. By following these operating instructions, the flocculation tank can achieve optimal floc formation, ensuring efficient performance and even distribution of liquids across the screen.

Here are some key points to consider when operating the flocculation tank:

1.     Once the flocculation tank is properly set up and operational, it requires minimal operator attention. The system is designed to function efficiently with little intervention.

2.     Minor adjustments to the mixer speed can be made to promote the formation of larger flocs. This adjustment allows for optimization of the mixing process.

3.     It is important to exercise caution when increasing the mixer speed during adjustments to prevent the shearing of the flocs by the mixer blades. Careful monitoring ensures that the flocs maintain their integrity throughout the process.


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