treatment plant FAQs

Sewage treatment plants are rapidly replacing septic tanks for both new and replacement sewage management systems. They provide an environmentally responsible, long-term solution to sewage treatment. That’s because sewage treatment plants use natural processes, such as aerobic bacterial digestion, to help break down and neutralise sewage waste.

Sewage treatment plants use physical, chemical, and biological processes to remove physical, chemical and biological contaminants. The purpose is to produce environmentally-safe fluid effluent and solid waste (sludge) suitable for disposal or reuse, sometimes as farm fertiliser.

Sewage treatment plants are now produced by a large number of different manufacturers. All of the systems are based on producing a final effluent that is significantly cleaner than that produced from a septic tank. Bates Environmental can advise on the sewage treatment plant that is most suited to your needs.

A modern sewage treatment plant is compact and extremely efficient. Sizes are available to suit anything from large commercial premises to a single household. This square sewage treatment plant would be installed under the ground at a shallow level, or above ground, to deal with the effluent from a house where up to six people live. This would serve the purpose of an ordinary treatment plant where one could not be fitted due to running silt in the land on the required site. The wider and longer shape gives the same surface area as the more usual treatment plants, so that the waste breakdown is equally effective. Conforms to standard BS EN 12566-3.

An alternative style sewage treatment plant with an integrated compressor to be installed under the ground to deal with the effluent from a house where up to six people live. This unit can also be installed with a pumped outlet for areas where natural fall is not available. The invert can be varied and risers of up to 1.2m extra can be fitted. Conforms to standard BS EN 12566-3.

A large sewage treatment plant can be installed to service buildings where there are 12 or more people using the facilities. This model has a compressor integrated into the internal structure. This unit can also be installed with a pumped outlet for areas where natural fall is not available. Conforms to standard BS EN 12566-3.

The compact, below-ground sewage treatment plant shown in this cutaway illustration is a watertight enclosure designed to allow solids in the sewage to settle and decompose via an aerobic (oxygen-assisted) biological action.

Coarse solids are screened out and retained for gradual breakdown.

The screened fluid is continuously distributed over plastic media by an airlift pump operated by an electric blower, which is sited a short distance away. This maximises the natural aerobic process.

Subject to relevant official consents, the resulting effluent can be dispersed into a watercourse or suitable ground soakaway.

Sewage treatment plants are typically of GRP (glass-reinforced plastic) construction.

The illustration to the left shows a typical sewage treatment plant installation. Key elements:

1. Wastewater and sewage from the property is fed through to the treatment plant.
2. The treatment plant allows the solids to settle out and actively treats the sewage via an aerobic (oxygen-dependent) process, breaking it down.
3. The resulting effluent, which is typically 95% clean, can be discharged into a nearby ditch, stream, river, lake or land drain system, subject to appropriate permissions and approvals.

Like a septic tank, a sludge of settled-out solids will accumulate inside. The sewage treatment plant will then need emptying, which Bates Environmental can arrange for you. The size of the sewage treatment plants needs to be matched to suit the level of usage it will encounter, which depends on the number of occupants in the property and levels of use.

Do Septic Tanks or Sewage TreaTment Plants Smell?

A well maintained septic tank or sewage treatment plant should not be giving off any unpleasant odours, despite that fact that it is a receptacle for human waste! Septic tanks and treatment plants are designed to contain the naturally occurring odours that will arise as part of the treatment process. If there is an unpleasant smell it could be due to a number of reasons and it is important to investigate the cause .....

Is the tank full and in need of emptying?

This is easily checked and resolved by having it desludged / pumped out.

Is there a clogged vent or is the vent missing altogether?

A vent allows the gases from the sewage to escape and prevent a buildup of toxic and flammable methane gases. Sometimes the vent can become clogged by an overfull tank, a wasp or bird's nest, snow or ice. Check the vent to ensure that the gases are able to escape.It may even be that the tank was poorly installed in the first place and the vent omitted, in which case the gasses (and smells!) will very likely come up through the drains and will make their presence felt (smelt?) in the bathroom, toilet or kitchen.

Has the system been contaminated?

Putting certain things down the toilet or sink, such as very harsh chemicals, grease or fat will interfere with the natural enzymes that work to break down the sewage. When the finely tuned 'eco-system' is disturbed by these contaminants, it loses its ability to work efficiently and smell is a likely result.

Bates Environmental can make a full assessment of your site. We will advise whether a septic tank or a sewage treatment plant would be more suitable. There are many factors to consider and our wealth of experience is at your disposal to ensure that you make a considered investment that complies with all relevant regulations.

British Water have produced a Guide to the Installation of Sewage Treatment Systems , which you can download in PDF format. Bates Environmental comply fully with the Code of Practice as recommended by British Water.

We can supply and install a range of sewage treatment plants manufactured by Marsh Industries.

Most of the major manufacturers, including Marsh Industries now produce treatment systems to meet the new European Standard EN12566-3.

A sewage treatment plant is a modern version of a septic tank, required by building regulations when new properties have been constructed. The primary tank has a compressor pump to continuously aerate the sewage and provide full treatment to crude sewage in normal domestic installations. Some units have the ability to pump the treated water to approved disposal points when natural inverts are not available. Sewage treatment plants must still be emptied of solid waste at least once a year or as per manufacturer's guidelines.

Order your domestic sewage treatment plant emptying online

Order your commercial sewage treatment plant emptying online

Bates Environmental Ltd recommends that your treatment plant also be serviced on a yearly basis, since if you do encounter a problem with the electrics, for example, it is likely to cause other more expensive knock-on effects, such as the pump burning out. If a sewage treatment plant is serviced every year, the parts can be checked, replaced if worn, and oiled or greased so that the optimum working state is maintained. This is also part of the Environment Agency Guidelines.

Bates Environmental Ltd offer a range of maintenance plans. To enquire, get in touch today.

By the 1st January, 2012, ALL discharges from septic tanks and sewage treatment plants will have to be registered with the Environment Agency. This applies to both new and existing systems, no matter how old they are.

Until recently, anyone who had a sewage treatment plant or septic tank that discharged either to the ground or a watercourse, needed to have a Consent to Discharge from the Environment Agency.

These rules changed on the 6th April 2010. The Consent to Discharge has been replaced by a Permit to Discharge under the Environmental Permitting Programme Second Phase.

However, as all sewage treatment plants now for sale must have been tested and hold the EN 12566-03 Certificate, an Exemption scheme has been introduced, as these plants should not pose a pollution problem if properly used and maintained. You can now register for an exemption online or via a form from a Permit to Discharge for:

1. Sewage Treatment Plants discharging up to 5m3 per day or less into surface water (27 population equivalent)
2. Septic Tanks / Sewage Treatment Plants discharging up to 2m3 per day or less into groundwater (11 population equivalent)

Please note that for approved treatment plants, such as those we recommend from Marsh Industries, there is no fee for the registration of an exemption.

Further information on how to register your septic tank or treatment plant is available on the Environment Agency Website.