These provide a very crude method of treating sewage for possessions which aren’t connected to mains drainage. Many septic tank systems throughout the world are not kept and so do not work properly and pollution control laws exist to attempt to limit the amount of ecological and health risks they cause. These laws are becoming tighter, and minimal criteria have been put in place for replacement or new septic systems. Oftentimes you’ll have to put in a sewage treatment plant program instead. Consistently get the sewage system assessed by a waste water system expert before buying a property in order to stop a pollution issue.
There are various types of septic tank systems. They consist of an underground Septic Tank Sales in diverse shapes and dimensions, which then connects to a secondary land treatment system, normally a land drainage system in the kind of a soakaway or drainfield, or a mound soakaway.
How a Septic Tank functions
Raw sewage and waste water from baths, kitchens, etc. discharges into the tank, where the solids are separated from the liquid waste. Fats and oils float to the peak of the tank and form a crust layer. Faeces and food scraps sink to the bottom of the tank and form a sludge layer. Anerobic germs which are natural colonisers in the tank”digest” this sludge by up to 70%.
The filthy septic water flows out of the tank into a soakaway or drainfield. Baffles or’T’ pipes in the tank hold back the floating crust and stop it from going into the outlet of the tank. In order that the sludge and crust layers don’t become overly deep, septic tanks should be emptied annually. This also prevents a greater and higher concentration of suspended solids washing into the soakaway. Solids can obstruct the air spaces in the soil drainage system, developing a drainage problem along with the septic tank effluent will not be able to soak off or be treated by the natural soil bacteria.
Variations in Septic Tank systems
Conventional septic tanks comprise of two rectangular chambers: the primary one being 2/3 of the entire and the second 1/3, usually constructed in concrete or brick. Strict design rules are in place and septic tanks have to be made in accordance with BS 6297 1983. The inlet pipe into the first room ends in a’T’ pipe which travels down the least 450mm (18″) below top water level (TWL), and the chamber must be a minimum of 1500mm (5′-0″) deep from TWL. The pipe from the first chamber into the second chamber consists of an ‘H’ pipe and the bottom of the pipe is a min. Of 300mm (12″) under TWL from the first chamber and 450mm (18″) below top water level (TWL) when it enters the second chamber.This second stage chamber is usually square.
Vent pipes needs to be installed in the first and second chambers for venting the gases, mainly methane and hydrogen sulphide, that are produced by the sludge. Strong covers must always be put entirely over a septic tank to prevent children / animals falling into the tank. There are many instances of thcovers collapsing and many people have been killed as a result.
These days, septic tanks are made in GRP and polyethylene which are spherical in shape with a narrow shaft at the top into a manhole ground level. These do not produce exactly the same caliber of effluent as two chamber tanks and can’t be placed in front of many conversion components.
Care needs to be taken to ensure that problems won’t occur due to the tank climbing out of the floor, when it is emptied in large water table websites. It’s always advisable to put in the tank using a concrete surround.