4 Basic Functions Of A Septic Tank

What is the function of a septic tank? Here are four reasons to have one installed in your home.

The importance of a septic system is never in doubt due to the crucial role it plays in waste treatment. One major component of this system is the septic tank.

As the name suggests, septic waste gets into the tank through a major pipe.

Once such waste finds its way into the tank, it is held for further treatment until it’s ready for the next stage. Our discussion here will be focused on the functions of septic tanks.

As you read on, you’ll be amazed at the critical waste treatment functions your septic tank performs.

Septic Tank Functions

The functions of a septic tank border around its uses or how it works. These tanks are quite large and play a crucial role in the treatment of waste. Quite a lot goes on in the septic tank.

These actions include the storage of solids, decomposition or breakdown of waste, and the separation of waste. Other functions include the passing out of partially clarified water or effluent out of the tank to the drain field.

All of these functions are a combination of both physical and biological processes. Without these, it would be impossible to treat waste.

Simple as they may seem, these functions are key to the treatment of waste being held in a septic tank.

To better understand what goes on with each of these actions or functions, it’s necessary to discuss the above points individually.

Let’s begin as follows;

  • Storage of Wastewater

Whenever you install a septic tank, its first function is to receive wastewater coming in from drain pipes. These include fecal matter from toilets among other things. Such wastes need to be held or stored for treatment.

This is where your septic tank comes in handy.

Note that we’re only specifying the most immediate function performed by a septic tank. As you’ll soon find out, a lot of other functions or processes play out within your tank.

As wastewater continues to empty into the tank, the treatment process commences immediately.

This takes us to the next point;

  • Separation Of Waste

When wastewater comes into the septic tank through the drainage pipes it will need to be retained long enough for phase separation to occur.

What’s this about? It’s simply a process where wastewater gets separated into its constituent parts. That is the separation of solids through settling and floatation.

This is known as the primary treatment of wastewater. Without this happening, other processes or functions won’t be able to unfold. Phase separation of wastewater results in the formation of three distinct layers.

These include the scum layer, the effluent, and sludge layers.

  • Scum Layer

The scum layer is the lightest of all three layers. This is why it comes first and is the layer you see when the tank is opened. The scum layer consists of soap scum, oil, fat, paper products, and hair.

Paper products float temporarily before they sink to the bottom of the tank.

To better understand how this works; consider the scum layer as an internal lid that helps to keep air out. This is especially true for anaerobic systems where digestive bacteria thrive in the absence of oxygen.

In other words, the scum layer enhances the breakdown of bacteria.

However important the scum layer is, it becomes a problem when it’s left to become too thick. The continued accumulation of scum results in issues such as the formation of clogs in your filter.

Apart from that, some of it might end up finding its way to the drain field.

Apart from having your septic tank pumped on schedule, there are other ways to regulate scum buildup. What you pour down your drains determines its volume.

Consider limiting the number of fatty foods emptied into your drain. Also, never pour cooking oils down your drain. You can also use septic-safe tissue papers.

  • Effluent Layer

The effluent layer is found immediately after the scum layer.

This phase consists of clarified wastewater. The effluent layer forms the bulk of your septic tank contents. It is this layer that flows out to the drain field for further treatment or filtration.

Before effluent leaves the tank to the drain field, it needs to pass through a filter. This filter keeps out any floating solids from getting to the drain field.

The ideal retention time for effluent is 24 hours. This allows sufficient time for phase separation.

  • Sludge Layer

The sludge layer is heavier than the other two, hence its position at the bottom of the septic tank.

As the name suggests, it is composed of solids that settle below. These consist of food particles, bones, and other non-liquid materials including solid fecal matter.

As digestive bacteria act or feed on the solids, gases, and water are released as by-products. When these bacteria die off, they too become part of the sludge layer.

  • Breakdown Of Waste

A septic tank will always receive a fresh supply of wastewater every day.

Such wastewater will have to be treated. Treatment follows the steps outlined above. In other words, wastewater gets separated into its constituent parts.

Waste decomposition happens most in the sludge layer. Here, bacteria act on freshly accumulated solids.

As older sludge layers compact, fresh layers are further reduced by digestive action. Gases and water are by-products of decomposition.

The gases generated are channeled out through vents designed for this purpose. Such vents are usually located around rooftops to ensure they’re safely channeled away.

  • Exit Of Semi-Clarified Water (Effluent) To The Drain Field

As the contents of a septic tank accumulate, the tank will need to dispel excess effluent.

This semi-clarified water leaves the tank through the exit pipe to a drain field. Before it does, it must pass through a septic filter to keep out any solids from finding their way out to the leach field.

Only effluent or clarified water gets to leave the septic tank to the drain field. The other two layers consisting of the scum and sludge, including some effluent gets removed via pumping.

These are all important septic tank functions that happen continuously. A lot of people are oblivious to this fact.

With the knowledge provided here, you’re able to better appreciate the processes that take place within your septic tank.

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