Up to now several new methods of wastewater treatment in rural districts have been
applied. The oldest and easiest type of wastewater treatment plants are sedimentation
and oxidation lagoons, also referred to as “oxidation ponds”, “anaerobic ponds” or
“naturally aerated ponds” respectively. However, to achieve satisfactory treatment
results oxidation lagoons require a large amount of land area. For example 10 – 15 m²
per population equivalent (p.e.) are needed in regions of temperate climate.
Particularly during the warm season anaerobic decomposition can generate odours.
Therefore wastewater lagoons without mechanical aeration should only be built as
temporary plants or in great distance from housing areas.
Small sewage treatment plants, which were frequently built in the past, often did not
achieve the requested results. They proved to be very maintenance-intensive and
susceptible to trouble.