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Wastewater Treatment

Our wastewater treatment product range spans everything from cesspools to septic tanks to full sewage treatment plants.

Our services, as with all of our other systems also span everything from design through to installation, commissioning and maintenance/servicing. In order for us to propose the correct wastewater treatment system for your site, please send us as much information as you can about the use of the building, the number of people within the building, and consent to discharge documentation from the environment agency and any drainage layouts that you may have. We can then ensure that our proposal meets all relevant standards and planning criteria.

What is wastewater treatment?

The definition of sewage (wastewater) is grey water which is water used in private houses from toilets, dishwashers, sinks, baths and showers and black water which is any water from toilets. This foul water can be treated by using either biological matter to break down the waste or physical treatment using aeration to treat the water.

Wastewater treatment, also known as sewage treatment, is the process of removing contaminants and suspended solids from primarily household waste such as toilets, showers and sinks but also from commercial properties such as office spaces and factories and producing treated water to go back into a water course such as a stream or river. The treated water is not however clean enough to drink but is safe enough, so it will not harm the environment. If the water is not treated and discharged correctly this can cause pollution and diseases. In the past sanitary conditions were not very good at all which is why we now have regulations on how sewage should be dealt with.

If you are not connected to the main sewer network, then you will need to install some form of the sewage treatment system to process the wastewater into a form that can be safely drained into your local watercourse or can be discharged into a soakaway.

There are three levels of wastewater treatment; primary, secondary and tertiary. Primary treatment is when the waste water is temporarily held in the tank. The solids will settle at the bottom of the tank and the remaining water will discharge into a soakaway which is known as a septic tank. Secondary treatment is when the wastewater is treated using either oxygen or media which encourages the growth of bacteria to break down the solids. This is carried out in cycles. Tertiary treatment is used when additional treatment to the water is needed on top of the secondary treatment, for example, the Graf Klaro +P package will remove phosphate found in the water.

There are a few options for a wastewater treatment system.

Graf Septic Tank

Graf Advanced Sewage Treatment Plant

Graf Commercial Sewage Treatment Plant

1.Cesspool or Septic tank

A cesspool is a holding tank for waste water that does not have an outlet. No treatment is carried out and it will need emptying a minimum of every thirty days (monthly). If it needs emptying more regularly than this then it is the wrong size for the property. A larger tank volume is required for a cesspool compared to a treatment plant. A septic tank includes a baffle to keep the solids in the inlet side of the tank. This uses a natural bacterial breakdown to separate the sludge and liquid. The liquid then passes over the baffle and is discharged via the outlet to a soakaway where the liquid effluent is dispersed into the soil and the waste is broken down. A septic tank needs emptying approximately every six months.


Our one2clean system is a sewage treatment plant which will treat the water, so it is clean enough to be discharged into a water course. Whether the water can be used for irrigation depends on the local Water Authorities. The water discharged from the packaged treatment plant must meet the relevant British Standard which is BS EN 12566 for small sewage treatment plants and BS 6297:2007 for drainage fields. This does require a power source and will require emptying approximately every year. How often a system requires emptying depends on how frequently it is being used and the manufacturer’s guidelines. The sludge which builds up at the bottom of the tank must also be emptied in line with the manufacturer’s instructions. There are numerous Companies that can dispose of the waste and these must be registered waste carriers.

3. Advanced WWT system

Our advanced WWT systems work in a very similar way to our one2clean system, using SBR technology, however, they provide additional modules for further treatment of the water and much more.

4. Large Commercial Advanced WWT system

Our Large Advanced WWT systems are for more than 50 inhabitants and also use SBR technology. Click here for further information.