The septic tank collects and holds wastewater from your toilets, washing machine, and garbage disposal. It allows solids to settle at the bottom forming sludge while liquid exits through the tank outlet into the buried drain field.
Knowing what can and cannot be flushed is important because certain items clog pipes or damage the microorganisms that break down waste. These include hygiene products, paint, grease and oil, cat litter or paper towels. Click https://www.septictankarmadale.com.au/ to learn more.
A septic tank acts as a filter to prevent solids from entering the drain field. Wastewater enters the tank through a main drainage pipe from your home. Inside the tank, bacteria break down biodegradable solids while heavier solids sink to form a sludge layer at the bottom of the tank. The liquid that remains is called effluent.
A baffle separates the inflow and outlet pipes of your septic tank. The inlet baffle helps keep the scum layer from clogging the inflow pipe, and the outlet baffle keeps sludge and non-biodegradable solids out of the septic tank and out of the drain field. Non-biodegradable solids include pet litter, kitty litter and other synthetic materials that don’t break down in water.
The septic tank’s inlet and outlet pipes are usually 4-inch-diameter Schedule 40 PVC, cast iron or acid-resistant fiberglass. The inlet and outlet pipes are covered with baffles or sanitary tees, and a 6-inch inspection pipe is located above the baffles for checking solids levels and clogs.
During the bacterial treatment process in the tank, the wastewater and sludge are separated into three layers: a sludge layer, a wastewater layer and a scum layer. The sludge layer is a dense, dark material that forms on the bottom of the tank, while the wastewater layer is clear and has little to no odor. The scum layer is lighter and thicker than the wastewater layer and contains toilet paper, human waste, and other organic materials that don’t decompose easily.
Once the bacterial treatment in the tank is complete, the liquid effluent leaves the septic tank through the outlet pipe. The septic tank is a sealed, water-tight container that must be designed by a Missouri registered professional engineer and constructed of concrete, fiberglass or metal. A septic system also includes a drain field and an absorption field in the yard where the sewage is absorbed into the soil.
To maintain a proper operating level, the septic tank should be pumped every three to five years by a licensed professional pumper. When you have the septic tank pumped, ask your pumper to inspect the condition of the baffles and tees. Don’t use chemical drain openers, septic tank additives or yeast to improve bacterial action in the tank, as these can harm soil and pollute groundwater.
Outlet Pipe
The septic tank is designed to retain wastewater at low velocity and under anaerobic conditions for at least 48 hours, which allows time for thorough bacterial digestion. Solids that cannot be digested float to the surface and form the scum layer or settle to the bottom of the tank as sludge. The sludge and scum are separated from the clear wastewater (effluent) by a series of baffle walls. Wastewater exits through the outlet pipe and flows into the absorption field.
Bacteria produce gases while breaking down the organic material in the septic tank. These gases, including hydrogen sulfide that smells like rotten eggs, must escape to prevent the buildup of pressure that could cause the system to clog or back up. The septic system has a vent that extends through the roof of the tank. The vent is often fitted with a charcoal filter to reduce odors.
A septic tank should have an inlet baffle and an outlet baffle. The inlet baffle forces the wastewater downward as it enters the septic tank, preventing solids from skimming across the surface of the tank and exiting untreated through the inlet pipe. The inlet baffle also helps prevent the scum layer from exiting directly into the outlet pipe, which can cause drainfield clogs and premature system failure.
When the liquid level in your septic tank is below the outlet line, it may indicate that you need to have the septic tank pumped out by a certified pumper. It is important to have your septic tank pumped regularly to keep the liquid level above the outlet line.
The septic tank must be large enough to allow for proper detention time and bacterial digestion. It is important to avoid dumping hazardous materials into the septic system, such as grease, chemical drain openers, solvents, paint, fuels and pesticides. These materials can contaminate groundwater or upset the bacterial process. Other items that should not be poured down the drains include coffee grounds, bones, cigarette butts, paper towels, facial tissues and diapers.
An aeration system in the septic tank adds oxygen to the wastewater to support the aerobic bacteria that digest suspended solids. The aeration system should be professionally installed and maintained.
Sludge Layer
A septic tank is a large, watertight concrete or fibreglass tank that is buried below ground. It’s designed to hold wastewater until solids settle and scum rises for removal. A septic tank is used in areas where it’s not feasible or practical to connect homes to municipal sewer systems. Wastewater from household plumbing drains into the septic tank where it’s held until solids separate and the liquid portion is discharged into a sewage system drain field for natural filtration in the soil.
In a well-designed septic tank, density differences automatically separate the sewage into three distinct layers. The top layer is scum, the middle bulk liquid, and the bottom sludge layer. Each of these sewage layers contains organic materials that are differently sized and decompose in their own way.
Substances that are lighter than water (oils, fats, soap byproducts, and cooking oils) float to the surface of the septic tank where they form the scum layer. Aerobic bacteria work in this scum layer to digest floating solids so they can fall back down into the liquid layer. Substances that are denser than water (fecal waste, grit, bones, and unconsumed food particles) sink to the bottom of the septic tank to form the sludge layer. Anaerobic bacteria work in the sludge layer to break down these heavy, insoluble substances to form a slurry that is less dense than water.
As the sludge layer grows, it becomes compressed and takes up more of the tank volume. When a septic tank’s sludge layer takes up more than 35% of its total volume, it is considered full and requires pumping.
If septic tanks are pumped too often, the solids in the sludge layer don’t have time to separate from the liquid part of the wastewater. This prevents the septic tank from having enough capacity to properly treat and dispose of the entire load of wastewater.
Excessive septic tank sludge also decreases the tank’s overall storage volume and increases its operational cost. This can lead to overflowing septic tanks, which create environmental hazards by contaminating groundwater and other water sources with pathogenic organisms.
Drain Field
As the liquid wastewater (effluent) exits the septic tank, it flows into the drain field. The absorption area, also known as a leach field, mound, seepage bed or cesspool is designed to naturallly purify the wastewater. It does this by allowing the soil to filter the wastewater and absorb it into groundwater, removing harmful pathogens along the way.
The drain field consists of a network of perforated pipes buried in the soil, with a layer of gravel between each pipe. The size of the drain field is determined by how many people are living in the home and how much wastewater they use on a daily basis. The piping network is typically made of PVC and has small holes that allow the wastewater to trickle out. The gravel layer helps distribute the wastewater evenly throughout the field, preventing large solids from entering the soil.
Once the wastewater is in the soil, it’s filtered by the bacteria and other microorganisms that live there. The process removes the pathogens and dissolved nutrients.
Since the septic system is so complex, it’s important to maintain proper septic tank maintenance in order to avoid costly repairs. This includes keeping the septic tank itself in good condition and avoiding flushing items that could disrupt the microbiological treatment process. Non-biodegradable toilet paper and other debris can clog the system, and it’s a good idea to only use biodegradable products in your home.
Other maintenance tips include avoiding driving or parking on the drain field, as this can crush or compact the soil, which can prevent it from absorbing the wastewater. It’s also a good idea to plant shallow-rooted grass or flowers around the septic drain field, as this will help minimize erosion and surface runoff. Lastly, don’t dig near or build structures over the septic tank or distribution box, as this can damage these crucial components.
A septic system can become overloaded when it receives more wastewater than it is designed to handle. This can cause foul odors and sewage backups in the home. You can help to reduce your septic system’s workload by using less water, using low-flush toilets and encouraging other members of the household to do the same.