In Sweden we nowadays have rules that determine how our individual sewage must be dimensioned considering out coming emissions. Nearly half of the 700 000 existing properties using individual sewage have a system that isn’t approved. In Sweden the individual sewage systems releases as much phosphorus as the communal wastewater treatment plants according to Havs- och vattenmyndigheten (Marine and Water Authority).
The communal authority in Sweden has been entrusted to carry out extended control of the private sewage system in effort to inform the problems with what the insufficient of wastewater treatment entails and in pursuit of "sustainable development". In guidance for decisions about what applies to the individual property, the communal authority in Sweden has applied the manual by Naturvårdsverkets allmänna råd (NFS 2006:7) (Environmental Protection Agency's guidelines)
The purpose of this report is to study various methods of purification of individual sewer systems. A comparison between a couple of different techniques in chemical and biological treatment is going to be studied. The issue we will addressed in this report are following: Which of biological- or chemical technology water purification is from a sustainability perspective, the best solution when replacing or renovation is taken place of an individual sewer systems;
- Which solution is most optimal where the normal level of protection required?
- Which solution is most optimal where the high level of protection required?
This study has several methods and instrument used to achieve the high reliability of the collected data. Literature studies, surveys, interviews, correspondences and analysis of these are instruments that largely have been used in the implementation. The compilation of the results from the surveys is presented in a pie chart.
In normal protection level, we believe that the infiltration is the most optimal solution.
At the high level, we believe that the vertical flow constructed wetland in combination with a pond is the most optimal solution.