Septic Tanks

SEPTIC TANKS

WHY DO WE NEED A SEPTIC TANK?

Septic Systems are underground wastewater treatment structures, commonly used in rural areas without centralized sewer system. We need these tanks to manage the daily waste that produced from our house. They use a combination of nature and proven technology to treat wastewater from household produced by bathrooms, kitchen drains and laundry etc. 

SO WHAT WILL BE THE DEFINITION OF SUCH TANK?

A septic tank is an underground chamber made of concrete, fiberglass, or plastic through which domestic wastewater flows for basic treatment. Settling and *anaerobic processes reduce solids and organics, but the treatment efficiency is only moderate. Septic tank systems are a type of simple onsite sewage facility.

(* There are septic tanks which works on aerobic process)

Basically its job is to differentiate the solid organic matter and the other floatable matter and liquid. Also it holds the waste water long enough to allow the above segregation take place properly. 

 INLET :  This part of tank is from where all the waste will enter into the septic tank. Here it considered as a part because there are some materials which should not enter in the septic tank for its proper functioning. 

Do not put cigarette butts, paper towels, sanitary tampons, condoms, disposable diapers, anything plastic or similar non-biodegradables into a septic tank system. Avoid washing food scraps, coffee grinds, and other food items down the drain.

So, we should have a proper inlet keeping in mind all the above items.

Terms Used

 EFFLUENT : The watery waste collected in the tank. Basically we can say it a liquid waste having black water as well as grey water but not the solid waste.

SLUDGE :  The solid waste collected at the bottom of the tank is called sludge. It is basically toilet waste.

SCUM: It is the floating waste collected in the tank. It is composed of oil, grease, fats etc.

DRAINFIELD :  Also called leach fields or leach drains, are subsurface wastewater disposal facilities used to remove contaminants and impurities from the liquid that emerges after anaerobic digestion in a septic tank. Organic materials in the liquid are catabolized by a microbial ecosystem. Simply a bed or a surface where infiltration of water takes place after leaving a septic tank.

ANAEROBIC : Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen. 

AEROBIC : Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the presence of oxygen. 

BLACK WATER : Blackwater in a sanitation context denotes wastewater from toilets, which likely contains pathogens. Blackwater can contain feces, urine, water and toilet paper from flush toilets.

GREY WATER : Greywater is gently used water from your bathroom sinks, showers, tubs, and washing machines. It is not water that has come into contact with feces, either from the toilet or from washing diapers. Greywater may contain traces of dirt, food, grease, hair, and certain household cleaning products.

TYPES OF SEPTIC TANK

Septic Tanks can be divided in two types depending upon the process takes place in the chamber. These tanks are:  

• ANAEROBIC SEPTIC TANK (simply know as Septic Tank) 
• AEROBIC SEPTIC TANK (also known as Aerobic Treatment System)

Septic tanks can also be divided by number of chamber a tank have.

• SINGLE  CHAMBER 
• DOUBLE CHAMBER
• TRIPLE CHAMBER

It can be said that more the chambers a septic tank have better will be the working. Single chamber tanks are about to vanish these days. Three chambers will work best but two chambers are enough for a household use. All these tanks have same basic concept and work on the above mentioned processes.

ANAEROBIC SEPTIC TANK

Simply known as Septic Tank uses anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the presence of oxygen. 

Wastewater enters the first chamber of the tank, allowing solids to settle and scum to float. The settled solids are anaerobically digested, reducing the volume of solids. The liquid component flows through the dividing wall into the second chamber, where further settlement takes place. The excess liquid, now in a relatively clear condition, then drains from the outlet into the septic drain field, also referred to as a leach field, drain field or seepage field, depending upon locality. A percolation test is required prior to installation to ensure the porosity of the soil is adequate to serve as a drain field.

Link for detailed aerobic tank : https://en.wikipedia.org/wiki/Septic_tank

AEROBIC SEPTIC TANK

Also known as Aerobic Treatment System uses aerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the presence of oxygen.

The ATS process generally consists of the following phases:

Pre-treatment stage to remove large solids and other undesirable substances.

Aeration stage, where aerobic bacteria digest biological wastes.

Settling stage allows undigested solids to settle. This forms a sludge that must be periodically removed from the system.

Disinfecting stage, where chlorine or similar disinfectant is mixed with the water, to produce an antiseptic output. Another option is UV disinfection, where the water is exposed to UV light inside of a UV disinfection unit.

Link for detailed aerobic tank : https://en.wikipedia.org/wiki/Aerobic_treatment_system

There are different types of drain fields. These are basically the water treatment systems after water comes out from a septic tank. Some of them are listed below:

Conventional System

Chamber System

Drip Distribution System

Mound Systems

Recirculating Sand Filter System

Evapotranspiration System

Constructed Wetland System

Cluster / Community System

 

It is found that people prefer sewerage system over septic tank system, it is so because sewer system don't need maintenance, it is done by the local authority while in septic tank system it is the duty of the house owner to maintain the tank.

A septic tank generally don't need any cleaning for about four to five years but it also depends on the size and the waste produced on daily basis. On the other hand, toilet pits are also a kind of septic tank just not having the drain field generally.

In India, before 2014 or the Swachh Bharat Abhiyaan most of the toilet pits or septic tanks are single chambered, but during the Abhiyaan two chambered toilet pits or septic tanks are promoted.

Here we can find that one can use any type of septic tank or we say a toilet pit according to their need. If you are a farmer then two pit system will be beneficial for you as you can use the waste as manure in fields. It will have least bad effect on nature. Otherwise you may also use the other septic systems also.

*If you have any Query, please comment it down.