Sewage
With the advent of regulations and penalties to deter water pollution, construction companies must endeavour to provide the best sewage solutions possible. Decisions have to be made as to whether it is advantageous to use a traditional septic tank or a sewage plant system.
Septic Tank
Consisting of two parts, the initial chamber is used as the storage section into which the effluent water flows via an inlet pipe, the solid matter settles to the bottom, and a natural scum forms on the top, the solid matter is held until it is collected, once a year. The lighter matter, is removed via an outlet pipe, and is filtered through yet further tanks, which ultimately lead to a soakaway system. The type of soakaway to be used will depend on the permeability of the soil (a Percolation Test will need to be carried out in accordance with British Standard) and the size of the construction the septic tank is expected to support.
Sewage Plant
Though they work along the similar principals to a septic tank, they are designed to be used where it is inappropriate to use a septic tank. They are designed to comply with Environment Agency requirements. They are a three stage effluence treatment system.
- Primary - the heavy solids sink to the bottom within this first chamber, and smaller particles of effluence are removed into the second chamber.
- Biological oxidation - this chamber provides a supply of oxygen to the effluent waste, naturally occurring organisms breakdown the matter and help to reduce its contents even further.
Final settlement - this is the final stage of treatment, the waste matter is left to dry and can be removed, though the contents can be reprocessed through the plant if it is deemed necessary.
Reed Beds
According to The Chartered Institution of Water and Environmental Management, "Reed bed technology is based upon the cleansing power of three main elements: soil dwelling microbes, the physical and chemical properties of the soil, sand or gravel, and finally the plants themselves."
Horizontal Reed Beds
These are designed to act as a final tertiary treatment of effluent from a sewage treatment plant. They are sometimes required as an additional treatment level to water already produced by a treatment plant, under Environmental legislation.
They work via a process of osmosis and photosynthesis, enabling oxygen to be released. Water passes around the roots system of the reeds and absorption combined with the micro-organisms that inhabit the water break down the effluence. These systems are very easy to install and they require very little maintenance.
Sodium Betonies Reed beds (vertical system)
These reed bed constitute a dust filtration system. The effluence water passes through the dust, turning it to sludge or paste. These systems are designed to produce virtually no odor, as they are full of air. An impermeable layer is required to prevent leakage. However, a pre-treatment or settlement tank system is necessary to filter out the solids, before the effluent flows into the Reed bed System.
Treatment and disposal of sewage where no foul sewer is available:PPG4 Tests must be carried out to ensure outflow meets with Environment Agency standards. There is further information at The Chartered Institution of Water and Environmental Management has a factsheet on their website at |
