In most of the industrialized countries, wastewater is collected in large sewer systems and treated in centralized wastewater treatment plants. This system is beneficial for many reasons: infectious diseases spreading through deficient sanitary conditions have been eradicated, the wastewater is treated at one place under controlled conditions, the principle „out of sight, out of mind“ is very comfortable for the users.
But there are also some disadvantages:
- Groundwater is contaminated because of leaking pipes
- A high water consumption is required in order to ensure good flushing of the sewers
- The wastewater is diluted with uncontaminated water (rainwater, infiltrating groundwater)
- The nutrient cycle is not closed (sewage sludge has to be burned in Switzerland)
It’s called into question, whether there are good alternatives to this conventional system, without changing the habits of the users nor confining the existing comfort.
The requirements of an alternative system are the following:
- little water consumption or water recycling
- low costs (construction, maintenance)
- no concessions regarding the effluent quality
- the same comfort for the users
Based on these considerations, the canton Solothurn and Eawag initiated the „Aquamin“ project. Within this project, a small-scale wastewater treatment plant was installed in a one-family building in Zuchwil, SO, which is monitored by Eawag. The main goals of the project include the safe operation, effluent quality, water recycling and energy consumption. The project should be finished by the end of 2007.