Category Archives: PSD Method Development

Laser Diffraction PSD Method

This is one of the dominant techniques many industries use to measure particle size dissolution.


It involves the use of complex technology, standard and computerized data processing. Mie Theory of light scattering is always employed in Laser PSD method development to calculate the size of particles that are responsible for different light scattering patterns.

The operations of Laser Diffraction Technique

  1. The Presence of Laser Diode:  A laser diode is the device that produces a single but coherent beam of light.
  2. Light Detectors: they could be two or three. They help to collect the data of light intensity that scatter at different angles.
  3. Lenses: they are always in front of the particles. They focus the light rays that pass through the particles.

Using PSD method development, a laser beam of light will pass through the particles. All particles will scatter at different diffraction angles. Small particles scatter light at large angles and vice versa. Thus, the data of the particle size dissolution will be easy to calculate.Laser_diffraction_analysis_small_particle.


Benefits of Using Diffraction PSD Method.


As complex as PSD method development may look, it is very simple and fast to operate. It has an advantage over sieving technique because it can be used to measure liquids, sprays,powders and aerosols.

The use of special light detectors make it faster to collect the result or data of particles size distribution. Also, it produces high level of reproduction and precision. There is absence or lesser work hazard with its use. No industrial worker can intrude, interrupt nor disturb the process once it is  in progress.


Disadvantages of Diffraction PSD Measurement


The resolution of Laser PSD method development diffraction varies with the size or amount of the particle. If there are mistakes in the refractive indices, there will be errors in the results.

To cap it all, it does not allow the measurement of  two or more particles with different optic properties. This is due to the fact that the use of laser is monochromatic in nature. That is, it only produces a beam of light.


Influence of PSD method development on Sedimentation Process

Industries always consider particle size distribution in the treatment of water.

It helps in the PSD method development on sedimentation process of storm water treatment. This is done by the removal of heavy metals or solids and pollutants. The velocity or speed of the sediments are determined by the shape, size, density and texture of the particles.

Notions Guiding PSD in the Removal of Sediments

The first is the belief that the size of particles influences the settling speed or velocity of the particles. That is, the weight of the particles, which is based majorly on how big or small they are, determines how they settle. Also, it is of the notion that the coming together or concentration of metals depend solely on their sizes.


Instruments of PSD Sedimentation Process

Detention ponds

These are the common PSD method development on sedimentation methods industries use in water treatment and pollutants removal. The operations of the detention ponds depend on the size of the ponds, detention time and the conditions of mixing.

Detention time = pond volume ÷ inflow. Inflow is the highest flow rate of rain that falls on impermeable surface. To model the removal performance,  fully mixed condition must represent the minimum percent while the quiescent condition is the maximum percent.

Hydrodynamic Seperators

They are one of the PSD method development on sedimentation process’ devices industries use to treat stormwater. They calculate the percent removal as a function of settling velocity and flow. In its calculation, it takes in the consideration of some  variables, such as the diameter of separator, the depth of water, removal efficiency, and pecelet number.

Heavy Metals

Metals absorb with sediments. Small sediments attract more metals while particles of large sediments attract lesser metals. Large particles have large surface area per mass and large settling velocities. Thus, large particles retain more in the sedimentation process.


The PSD method development is an important feature that helps in the water treatment by the use of sedimentation  practice.