The septic tank system is believed to have originated in the country of France.
John Mouras is credited for inventing the septic tank system on or around the year 1860.
Mouras designed a septic tank and built a prototype fabricated from concrete and also fabricated piping constructed of clay leading from his home to the septic tank located in his yard.
Approximately 10 years later John Mouras dismantled the unit and to the astonishment of his fellow townsmen found that the tank was virtually empty of any solid organic waist and only contained a liquid effluent scum layer.
Eventually Mouras approached a scientist of the era and Mr. Mouras submitted a patent application and was granted a paten in the year 1881.
The septic tank made its way to the United States of America in 1883 and some time after to Africa, believed by the British Navy.
A simple standard septic tank is typically 1000 to 2000 gallons.
The tank will have typically two inspection openings one inlet opening coming from the house and one outlet opening going the distribution box.
The distribution box is the junction between the septic system and the drain field which distributes the digested effluent material to the drain field.
There are three layers of waste in the septic system.
The top layer typically floats and is considered the scum layer until to digest and falls to the bottom.
The bottom layer is called the sludge layer.（底层称为“污泥层”。）
There is the liquid layer that lies in between the scum and the sludge layers.
This is also referred to as the effluent layer.（这也称为“流出层”。）
If not properly maintained, this is also the layer that is most likely to give you the sewer smell or seep through the top of the leach field if the field is clogged and not functioning properly.
You may introduce a bacteria enzyme treatment into the system to ensure a sufficient bacteria count and to ensure the digestation process.
Breaking down the solids through this process is essential to maintaining a safe and healthy system.
The volume of wastewater flow is determined by the type and frequency of common household activities.
Good water usage practices in the home will limit the flow into the system limiting the overall strain on the system.
Private Onsite Wastewater Treatment Systems (POWTS), more commonly referred to as septic systems, are used primarily in rural areas of the country where waste water treatment is not available.
Septic tanks are self-contained wastewater disposal systems.
Nearly 25 percent of United States households use a septic system as the means of water and sewage disposal.
Septic tank systems are something we don’t like to think about and, usually, don’t until there is a problem.
A septic tank handles all of the wastewater from homes that are not connected to a public sewer system.
This means that your septic system is not connected to the city water supply and that you are responsible for keeping your system operational.
When a septic tank is neglected, it can clog with sludge and scum that cannot be broken down by bacteria, leading to a costly systemic collapse.
For this reason, you need to keep your tank clean, inspected, and pumped regularly.
Using excessive amounts of soap or detergent can cause problems with the septic system.
Most private septic systems are made up of two parts: the holding and digesting tanks, and the dispersal field.
As the first holding tank fills up, the liquid waste will transfer to the second tank.
Once the second tank fills with liquid, it will disperse into the soil below it.
The basic idea of flush toilets combined with a septic tank hooked up to a drain field is to provide a small system with primary sewage treatment.
Sludge settles to the bottom of the septic tank, is partially reduced by anaerobic digestion, and fluid is dispersed in the leach field.
The leach field is usually under a yard growing grass.（通常院子中渗滤场地排水区域种着草。）
However, septic tank effluent has a very high Biological Oxygen Demand (BOD) which is harmful to soil fauna, as high BOD liquids strip oxygen out of the soil.
Failure to pump a septic tank can cause a high level of solids in the overflow liquid that damages the leach field, and contaminates ground water.
Septic tanks may also require some lifestyle changes, such as not using garbage disposals, minimizing fluids flushed into the tank, and minimizing nondigestible solids flushed into the tank.
For example, septic safe toilet paper is recommended.
Care must be taken as to the products that are allowed to enter the drains.
All septic tanks rely on a colony of anerobic bacteria to reduce the volume of organic matter in the sewage.
Any product that is anti-bacterial should not enter the tank.
These products include anti-bacterial cleaning products, bleach, toilet blocks, disinfectants, etc.
If you really want to you can dump some special ‘septic tank bacteria’ in it once in a while, or have it pumped out once a year.
Some would like to make use of the methane generated, or the heat, or the composted solids.
Many septic tanks are now manufactured with GRP(Glass Reinforced Plastic).
This technology is generally used where sewers have not been connected, as sewers are more reliable and can present less public health problems.
In many developed counties, Decentralization of sewage treatment plants (DEWATS) is being adopted for new ‘ECO’ towns to combat this problem.
In the developed world, this technology used to be used in remote areas; in poorer communities in the developing world, some form of septic tank may be the standard, even in high density settlements and increasingly, where DEWATS is adopted.
In the UK, septic tank installations are prohibited in many areas now, under the Environment Agency’s ‘General Binding Rules’ January 15th, 2015.
The outlet should be considered a source of contamination, even though it should be less dangerous and unpleasant than raw sewage.
Thus the tank and its discharge should be kept a safe distance from any water source.
10 m is generally considered adequate (Environment Agency Guidelines).
The tank should also be above the groundwater level. （化粪池也应高于地下水位。）
Antiseptics must NEVER be used in any toilet or drain leading to the septic tank, as they will kill the anaerobic bacteria, preventing decomposition, and leading to very unpleasant smells and an unsafe discharge.
Do not allow the sediment to build up too much, as this will greatly reduce efficiency, increasing the odor, and the level of contamination in the outlet.
UK Building Regulations Section H2 recommend an annual emptying interval.
Do not use any strong drain cleaners, caustic soda or similar products to clean the drains.
These will kill the beneficial anerobic bacteria in the septic tank.
How Your Septic System Works（化粪池系统如何工作）
Septic systems are underground wastewater treatment structures, commonly used in rural areas without centralized sewer systems.
They use a combination of nature and proven technology to treat wastewater from household plumbing produced by bathrooms, kitchen drains, and laundry.
A typical septic system consists of a septic tank and a drainfield, or soil absorption field.
The septic tank digests organic matter and separates floatable matter (e.g., oils and grease) and solids from the wastewater.
Soil-based systems discharge the liquid (known as effluent) from the septic tank into a series of perforated pipes buried in a leach field, chambers, or other special units designed to slowly release the effluent into the soil.
Alternative systems use pumps or gravity to help septic tank effluent trickle through sand, organic matter (e.g., peat and sawdust), constructed wetlands, or other media to remove or neutralize pollutants like disease-causing pathogens, nitrogen, phosphorus, and other contaminants.
Some alternative systems are designed to evaporate wastewater or disinfect it before it is discharged to the soil.
Specifically, this is how a typical conventional septic system works:
All water runs out of your house from one main drainage pipe into a septic tank.
The septic tank is a buried, water-tight container usually made of concrete, fiberglass, or polyethylene.
Its job is to hold the wastewater long enough to allow solids to settle down to the bottom forming sludge, while the oil and grease floats to the top as scum.
Compartments and a T-shaped outlet prevent the sludge and scum from leaving the tank and traveling into the drainfield area.
The liquid wastewater (effluent) then exits the tank into the drainfield.
The drainfield is a shallow, covered, excavation made in unsaturated soil.
Pretreated wastewater is discharged through piping onto porous surfaces that allow wastewater to filter though the soil.
The soil accepts, treats, and disperses wastewater as it percolates through the soil, ultimately discharging to groundwater.
If the drainfield is overloaded with too much liquid, it can flood, causing sewage to flow to the ground surface or create backups in toilets and sinks.
Finally, the wastewater percolates into the soil, naturally removing harmful coliform bacteria, viruses and nutrients.
Coliform bacteria is a group of bacteria predominantly inhabiting the intestines of humans or other warm-blooded animals.
It is an indicator of human fecal contamination.（它是人类粪便污染的指标。）