Sewage treatment is basically to do with the disposal of human waste.  However, the nature of the waste we all produce so effortlessly requires very careful disposal in order to avoid polluting our environment and to ensure the maximum recycling of our precious water resources.  If untreated sewage is discharged into a watercourse it will remove oxygen, kill plants and can create a nuisance and cause a risk to health.  It will adversely affect the water supply, including its subsequent use in crop irrigation, fisheries and for recreational purposes.  Therefore, sewage treatment is more precisely to do with the separation from our waste of non-toxic liquid effluent and its safe dispersal, together with the regular removal of the remaining solids or 'sludge'.

The most effective off-mains sewage treatment usually involves systems based on septic tanks or modern package sewage treatment plants.  Both types of system are designed to separate the sewage into solids and liquid and to purify the liquid effluent so that it can be safely dispersed back into the environment.

The Environment Agency sets standards for the quality of effluent discharged from any septic tank or modern sewage treatment plant.  In almost all cases, it will be necessary to obtain Local Authority and Environment Agency consents before discharging effluent into drain systems or water courses.

Septic Tanks 

In a septic tank system the sewage is settled and partially digested by means of a simple biological process.  However the separated liquid effluent still contains about 70% of the original polluting matter.  This pollution is further reduced by discharging the liquid effluent into a soakaway system, usually of land drains, which allows the ground to treat the sewage pollutants.

In locations where the combination of a septic tank and land drainage system is unable to treat the sewage to the required standards then a package treatment plant is likely to be the preferred alternative.

Package Sewage Treatment Plants

A modern package sewage treatment plant utilises a more extensive biological process than occurs in a septic tank, to purify sewage to a greater degree. 

The sewage is first settled to remove most of the solids and then biologically treated in a filter bed, or by using rotating discs or air injection, before the final settlement stage removes the finer solids.  The resulting effluent can be discharged, about 95% clean, to a land drainage system and often directly to an open water course.

Maintenance of both types of system

In both types of sewage treatment system the settled solid matter, or 'sludge', requires emptying on a regular basis; usually at least once a year.

In addition, package sewage treatment plants will require regular maintenance to ensure that they are working at maximum efficiency. It may be convenient and cost-effective to choose a service agent who can combine the servicing visit with emptying the system.

Which system is most appropriate for your needs? How much will it cost?

We will advise you!  Call us to discuss your plans and requirements.