Ecological village Lahstedt
The EXPO-Reed Belt Sewage farm Gadenstedt, community Lahstedt, country of Peine (Lower, Saxony, Germany), a new and an excellent bird habitat inmidst wheat-sugar beet fields of the loess zone Hildesheim-Peine.
Between 1998, the start, and 2006 the 1,6 ha EXPO-reed belt sewage farm (presented 2000 as a prototype for less expensive organic sewage cleaning) on former monotone agricultural area (wheat-sugar beet) bordering the river Fuhse valley has developed a spectacular breeding bird population and bird species diversity (32 breeding species, 49 – 88 breeding pairs). Reed Warbler, Reed Bunting, Mallard, Greylag Goose and Tufted Duck dominate the high bird density (338 – 488 BP/10 ha). In more than 330 nist netting hours (net length 100 – 120 m) more than 70 species and more than 1380 individuals have been caught and ringed.
Some oft them are rather rare and red list species. Some remarkable recoveries of long distant migrants have been already achieved from up to Ibiza, Southern Spain and France. The basis for the rich bird fauna is laid by high organic productivity, especially the rich invertebrate fauna oft the farm. There is no hunting but consequent bird protection. Wing length and weights of some species are presented. Hitherto more than 579 birds have been recaptured.
The council of the municipality of Lahstedt has decided to renovate its remaining three conventional sewage treatment plants with sustainable and ecologically sound methods in order to limit the consumption of natural resources.
Artificial wetlands for waste water treatment, which have low operational costs, are established in various forms as a pilot project in the village of Gadenstedt (2.600 P.E.). The project is divided into three parts: polishing biotope (reed bed treatment system); combined waste water biotope (cascade of ponds and reed beds); reed planted dry beds for sewage sludge.
The processed sewage effluent from the existing trickling filter undergoes polishing treatment. The total area required is 1,1 ha. of which 7.300 m2 is covered by reeds (Phragmites) in four vertically percolated soil filters. These filters are sealed with a lining. When the existing trickling filter treatment plant becames dilapidated in years to come, the reed beds should function as the main biological purification step. This application will be piloted during the course of the project.
The purification performance of the existing sewage treatment plant is improved by advanced nitrification, phosphate elimination and reduction of pathogens, easily fulfilling the existing authority limits.
Combined waste water biotope
The impact on the receiving river from combined water discharge is reduced (in terms of pollutant load per hectare of paved area) far below the legal requirements. This will be achieved through an innovative cascade of unaerated ponds (8.820 m2 net )and a final soil filter planted with reeds (1.330 m2 net).
The construction and operational costs are below those of concrete storm water tanks with overflow.
A secondary wetland complex with valuable biotope functions has been created.
Sewage sludge dewatering and mineralization in reed beds
The scarcely known method of dewatering and stabilising sewage sludge in dry beds planted with reeds has been in practice in Lahstedt for nine years at two other treatment plants. Dry matter content of over 50 % is currently achieved. In the future, all of the sewage sludge deriving from the four treatment plants in the villages of Lahstedt will be dewatered and stabilised with the same energy- saving method.
A build-up of surplus sludge which cannot be put to agricultural use in the winter months is avoided. Transport costs are lowered by volume reduction and new options for utilisation and recycling of this valuable nutrient source in landscaping, horticulture and recultivation can be explored.
The total project „Ecotechnological treatment of waste water and sewage sludge in Lahstedt“ will be presented as a registered and officially sponsored project at the world exhibition EXPO 2000 in Hanover.
* constructed wetlands for waste water treatment
* vertical subsurface flow reed bed treatment system
* advanced treatment of domestic waste water
* Phragmites australis
* open lagoons and planted soil filter basins for detention and treatment
of combined sewer owerflows
* sewage sludge dewatering and mineralization in reed beds
Operation & Maintenance
Download 1: Constructed wetlands for treatment of municipal wastewater and sewage sludge using reed and pond biotopes in Lahstedt- Gadenstedt, Germany
Download 2: The EXPO 2000 - Constructed wetland in Lahstedt - Gadenstedt, an excellent bird habitat between sugar beet and wheat fields by Hans Oelke et al. (2006)
Download 3: Constructed wetlands at Lahstedt - Gadenstedt, Germany
Download 4: Planted sludge dewatering reed beds at wastewater treatment plant Groß Lafferde, Germany
Download 5:Stormwater treatment wetlands at Muenstedt, Germany
Download 6: Stormwater treatment wetlands at Oberg, Germany