Meaning Of Words In The Wastewater Treatment Plant World

In the Wastewater Treatment Plant (WWTP) World, Words have Very Different Meanings!

Everyday words, ones that you and I use might use and not give a second thought, are found to have a very different meaning in the world of Wastewater Treatment!


To the general public, a slug is a familiar sight in yards and sometimes in the garden eating up all the lettuce. They are those tough-skinned, slow moving critters which secrete a film of mucus for protection. Not the most beloved of creatures but certainly common.

In Wastewater Treatment, the meaning is quite different. It is usually used in terms of a “slug discharge” into a municipal wastewater system.

A slug discharge is any discharge, including an accidental spill, which has a potential to cause interference or pass through of a publicly owned treatment works. A wastewater treatment operator would talk about how a “slug” caused an upset at their wastewater plant.


I bet you just thought about your little brother. Yes, as a kid, I’m sure he was an agitator. But that’s not exactly what we’re taking about when referring to an agitator in Wastewater treatment.

An agitator is a machine that mixes fluids. It is a critical component of the multi-step process of water and wastewater treatment. Different mixing solutions and agitators are configured specifically for each water or wastewater treatment application.


This one is easy right? Bugs are those pesky things that invade our homes and freak out the kids. Some of them bite and sting and some are harmless but in general, people cringe when they think of bugs.

In the wastewater treatment process, bugs are beneficial bacteria! They are actually quite useful so don’t cringe!

Treatment plant operators use the term bugs to describe the tiny microorganisms that consume organic matter and filter impurities from water. Our municipal wastewater treatment facilities make use of many different species of microorganisms to keep our water clean and safe. The “Bugs” function as decomposers and recyclers within the treatment system.


Do you need some clarification on this word? In everyday English clarification is the explanation of an obscure concept.

Now that we’ve clarified that, let’s look at the meaning of clarification as it refers to water and wastewater treatment.

Clarification is the process of separating solids out of a fluid. Clarification is highly effective at removing color, solids and colloidal material from water and wastewater when used together with chemical feed, sludge treatment and filtration of clarified elements. Clarification is the last step of a four-step treatment process.

Clarifiers consist of tanks or basins which hold water or wastewater for a period of time allowing suspended materials to settle to the bottom. The clarification process makes the water clear by removing all kinds of particles, sediments, oil, natural organic matter and color.

Mixed Liquor

Sure, I’ll have one! A rum and juice with an umbrella and a fruit skewer on top please! Sounds good right?

But in wastewater treatment, Mixed Liquor is not from a bar!

Mixed liquor is a mixture of raw or settled wastewater and activated sludge. It is contained in an aeration basin in the activated sludge process. Mixed liquor suspended solids is the concentration of suspended solids in mixed liquor. Not as appetizing as a rum drink but a very important step in the wastewater treatment process.


What are we celebrating? Cake is typically fluffy and sweet, and most times decorated with frosting! Butter cake, pound cake, sponge cake, chocolate cake, coffee cake, who cares, they are all delicious! The wastewater treatment cake is exactly the opposite of this!

In wastewater treatment, “cake” is basically dried sludge.

It is the sludge left after dewatering that is cake like, and compressed, sometimes also called sludge cake. You don’t want to eat this cake!

Cake is basically waste from sewer plants that has had all the water and fluid extracted from it. Because of its tendency to be hard and sticky, it’s difficult to remove and must be disposed of properly.


The everyday meaning and the wastewater treatment meaning for this word are actual quite similar. In the human body, digestion is the process of breaking down food by mechanical and enzymatic action into substances that can be used by the body.

In wastewater treatment, digestion is the breakdown of waste using biological processes in a treatment plant. This is what the previously mentioned “bugs” are busy doing.


Maybe your first thought when you saw the word Tank was an armored fighting vehicle designed for front-line combat. Or maybe you thought of the household applications for the word. Fish tank, toilet tank, gas tank.

If your first thought was the armored vehicle, you were pretty far off, but the household applications, receptacles or storage chambers for liquid, are a bit closer to the WWTP meaning.

The “tank” used in wastewater treatment refers to an elevated water tank or a wastewater treatment process tank. Other names include Sedimentation tank, settling tank or clarifier.

The tank is one component of a modern system of water supply or wastewater treatment. Suspended particles are able to settle out of water or wastewater as it flows slowly through the tank, which provides a degree of purification.

Many words in the English language have multiple meanings and those in Wastewater Treatment are no different. Just be careful if your ever offered and mixed liquor and some cake while visiting a treatment plant!

Meaning Of Words In The Wastewater Treatment Plant World – By DESCCOWATER

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