<p>In ambition to produce more and better harvests, artificial fertilizers are used to produce a better growth of crops in the agriculture landscape. This contributes to leakage of nutrients. Our forests also exhibit a leakage of nutrients. Air pollution contributes to more nutrients. High precipitation with high water flows as a consequence seems currently to occur more frequently in the county of Halland. The high precipitation could be a consequence of climate changes. Increased precipitation increases the flow of nutrients into watercourses and causes eutrophication problems. For the best possible nutrient uptake, wetlands should be designed after local circumstances. One way is to construct production wetlands where biomass in form of plants is harvested to remove nutrients. In order to get the best possible decrease of eutrophication, production wetlands should be constructed on a large scale. Often flooded areas are suited for constructing new production wetlands. The production wetland could be planted with common reed (Phragmites australis) which grows fast and creates a large biomass and therefore a high nutrient uptake. In order to take in water and emptying a production wetland before harvesting, it should also be constructed with controllable in - and outflow of water. Harvesting is a sensitive aspect and the production wetland should be constructed so harvesting with agricultural machines is possible to reduce the costs. The harvested biomass should be used in biogas production. The material that remains after digestion in the biogas plant can be used as fertilizer on agricultural land to replace artificial fertilizers. This contributes to more ecological agriculture where artificial fertilizers are forbidden. From an environmental point of view, this process is clearly the best way where nutrients can be re-circulated.</p>

In ambition to produce more and better harvests, artificial fertilizers are used to produce a better growth of crops in the agriculture landscape. This contributes to leakage of nutrients. Our forests also exhibit a leakage of nutrients. Air pollution contributes to more nutrients. High precipitation with high water flows as a consequence seems currently to occur more frequently in the county of Halland. The high precipitation could be a consequence of climate changes. Increased precipitation increases the flow of nutrients into watercourses and causes eutrophication problems. For the best possible nutrient uptake, wetlands should be designed after local circumstances. One way is to construct production wetlands where biomass in form of plants is harvested to remove nutrients. In order to get the best possible decrease of eutrophication, production wetlands should be constructed on a large scale. Often flooded areas are suited for constructing new production wetlands. The production wetland could be planted with common reed (Phragmites australis) which grows fast and creates a large biomass and therefore a high nutrient uptake. In order to take in water and emptying a production wetland before harvesting, it should also be constructed with controllable in - and outflow of water. Harvesting is a sensitive aspect and the production wetland should be constructed so harvesting with agricultural machines is possible to reduce the costs. The harvested biomass should be used in biogas production. The material that remains after digestion in the biogas plant can be used as fertilizer on agricultural land to replace artificial fertilizers. This contributes to more ecological agriculture where artificial fertilizers are forbidden. From an environmental point of view, this process is clearly the best way where nutrients can be re-circulated.

Denna litteraturstudie syftade till att identifiera olika design- och skötselkriterier för anlagda våtmarker vars huvudsyfte är att producera biomassa till biogastillverkning. Syftet var även att utveckla en planeringsmodell för att säkra att alla aspekter som är viktiga beaktas i processen. Dessa aspekter inkluderar placering, utformning, val av växtlighet, reglering av vattennivåer och utformning av våtmarkens skörde- och skötselregim. Rapporten behandlar också kriterier för att sådana våtmarker även ska kunna leverera ekosystemtjänster, såsom kväve- och fosforavskiljning, biologisk mångfald och fiske. Resultatet visar att det går att kombinera en del av dessa med skörd med hjälp av mindre förändringar i designen. Studien visar även på motstående intressen som kan förekomma mellan olika sekundärintressen och produktionen, alltså hur vissa ändringar inte är förenliga med produktionssyftet. Rapporten tar upp kriterier för att gynna utvalda helofyter och hydrofyter som kan vara lämpliga som produktionsväxter. Avslutningsvis appliceras planeringsmodellen som stöd vid planering av en våtmark på en testgård i östra Östergötland, för att visa hur en planeringsprocess kan se ut. / The aim of this literature review was to identify design criteria for the construction of wetlands whose primary purpose is to produce plant biomass for biogas production. The study deals with aspects that are important for decisions regarding location, design, choice of vegetation as well as the design of the wetlands harvesting and maintenance regime. A conclusion is that other ecosystem services such as nutrient retention and biodiversity can be combined with plant production, by considering alternative pathways during the planning process. The report presents a schematic planning model that will guide the reader through the steps that the planning process involves. The report discusses selected helophytes and hydrophytes that may be suitable production plants. The study also shows conflicting interests which may exist between different interests and secondary production, i.e. how certain changes are not compatible with optimal biomass production. A result of the study is a conceptual planning model that can be used as a decision support tool in the planning process. The model is applied on a test farm in eastern Östergötland to show how a planning process should look like according to the planning model.