Wastewater Treatment Process: The Primary Stage

Amanda Jones July 31 , 2019


Wastewater treatment is no joke. It's a complex process that involves specific steps that businesses need to follow. In return, however, it is well worth the end result where these companies are able to have clean, reusable water. Sounds like a solid deal to us!

Having a better concept of each of the steps is necessary to understanding the process of wastewater treatment as a whole. That's why we decided to create a four-part blog series describing each step and how these steps are completed.  Although it is not the only way to go through the process of cleaning wastewater, it is the most-used and most popular way to go about it.

If you need a quick refresher on what the wastewater treatment process exactly is, take a quick peek at the first blog post of the series - Got Dirty Water? Learn to Clean it up with the 3 Main Treatment Stages for Wastewater.


Figure 1: Dissolved Air Flotation (DAF) Unit Helps to Remove Suspended Matter, FOG, TSS, and Insoluble BOD from Wastewater Streams.

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The Primary Stage:

The primary - or pre-treatment - stage begins with an initial screening process to remove large particulates, which can contribute to the strength of the wastewater, as well as large foreign bodies (leaves/branches, plastic bags and other general refuse, etc.) that can cause damage to treatment equipment or blockages in pipes.

After the screening is completed, the wastewater is then typically directed to an equalization tank, where the pH and nutrient concentrations are adjusted to support the growth of microorganisms. An important aspect of the equalization tank is that the contents are adequately mixed to ensure that the secondary treatment stage is fed a steady stream of wastewater with a relatively constant organic load.

Depending on the characteristics of the wastewater, additional removal of suspended solids and Fat, Oil, and Grease (FOG) may be required. This is typically  accomplished through the use of either a clarifier, a large tank with little agitation that allows solids to settle to the floor and FOG to float to the surface for removal, or a Dissolved Air Flotation (DAF) unit, which uses tiny air bubbles to carry solids and FOG to the surface to be removed.

The clean water, or effluent, is then allowed to continue through to the secondary stage of the wastewater treatment process.


Figure 2: Media Carriers

Food & Beverage Industry Case Study:

The Guggisberg Cheese facility in Ohio is a great case study of ours to refer back to for some insight on wastewater treatment. The facility needed to install a wastewater treatment system in order to reduce the BOD, TSS, and Nitrogen from a commingled process water stream that was generated during the cheese and dairy production.

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Click the photo below to read more about how the bioprocessH2O team and the bioPULSE™ Airlift Membrane Bioreactor (MBR) System were able to reduce more than 90% of the BOD at the Guggisberg Cheese facility, as well as help remove issues with any Cheese & Dairy Production.

Guggisberg Cheese - Ohio Case Study

Figure 3: The bioPULSE™ Airlift Membrane Bioreactor (MBR) System Reduced BOD More Than 90% for Permit Compliance

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