Not all individual houses, restaurants, small businesses and companies can be connected to the public sewer network and use its wastewater treatment systems. Either for cost reasons or because it is not technically feasible.

Small wastewater treatment plants are built at this point to ensure reliable wastewater treatment. For this purpose, the required domestic sewage treatment plant is newly constructed or existing pits are upgraded to the latest sewage treatment technology.

The small wastewater treatment plant involves sophisticated wastewater technology that takes place in several stages. During biological wastewater treatment, the wastewater is cleaned by naturally occurring bacteria, just like in rivers. The biomass is collected in the secondary clarifier so that the settled sludge is then transported back to the primary clarifier of the wastewater treatment plant. This allows the treated wastewater to flow away on the surface or be pumped out.