University of Twente Student Theses
Improving the Purifying Effect of the Kristalbad
Bralts, T.R. (2022) Improving the Purifying Effect of the Kristalbad.
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| Abstract: | Nitrogen emissions have become a pressing issue in the last twenty years. The Kaderrichtlijn Water (KRW) is a piece of European legislation which all member states must abide by. Waterschap Vechtstromen maintains a water harmonica called the Kristalbad which is constructed in part to purify water. The performance of the Kristalbad is lower than expected however and the effluent of the Kristalbad does not achieve the goals set for several parameters, among which total nitrogen is the most pressing issue. The target value of total nitrogen in the Elsbeek, of which the Kristalbad is part, is 2.2 mg/l. The effluent of the Kristalbad currently contains 5.2 mg/l total nitrogen on average. This research investigates how the purifying effect of the Kristalbad can be improved. This is done by conducting a model study, studying literature and gathering experiences from other water harmonicas. From the model, it can be concluded a total nitrogen reduction of 43% is possible, as opposed to 6% for the current situation in the model. This is done by making sure a mix of emergent macrophytes and submerged macrophytes live in the Kristalbad. The macrophytes should be present in the six basins in the last two columns of the Kristalbad. They should be sufficiently dense and cover the entire basins. From literature, it can be concluded the water level is currently too high in the Kristalbad. The water level needs to be sufficiently low to allow the emergent macrophytes to live and spread. An Expert from Waterschap the Dommel further advises to intervene in time when floating algae spread in the summer. This should be removed ones a basin is around 50 percent covered with floating algae. In addition, the expert from Waterschap de Dommel stresses the importance of well-structured management of a water harmonica. Assigning final responsibility to one person or department will make sure issues are handled properly, everyone knows who to approach with regards to issues with the Kristalbad and experience gained in the management of the Kristalbad stays with the person or department who is responsible. From this research several recommendations are made. First, it is recommended to plant extra submerged and emergent macrophytes under favourable conditions. This should be done in the spring with a sufficiently low water level. Research needs to be done on what intervention could best lower the water level in an effective and cost-efficient way. Second, the water quality should be monitored better. The most effective way of improving the performance of the Kristalbad is by getting insight in the current performance. It is recommended to measure the water quality of the inflow and outflow and in each basin of the Kristalbad. This makes it possible to compare the performance of each basin and each street, making it possible to find differences and improve the purifying performance of the Kristalbad according to these findings. It can also detect any drop in performance of a basin or street, making it possible to intervene in time. It also enables experiments to be conducted. An experiment could be set up in one street, while the two other streets function as control. Third, the advice by the expert from Waterschap de Dommel to restructure the management of the Kristalbad differently is recommended. The advice to intervene timely to remove floating algae is also recommended. Lastly, the wastewater treatment plant and the Kristalbad should work together to improve water quality. Goals should be set for both systems to get the optimal performance of the two systems combined. Especially the Kristalbad currently has no clear goals in terms of water quality parameters. These goals should be set. Setting these goals will make it easier to design and maintain the Kristalbad as there are benchmarks which should be reached. These goals make it clear what to work towards and makes it clear to the management what interventions can help achieve this goal. |
| Item Type: | Essay (Bachelor) |
| Faculty: | ET: Engineering Technology |
| Programme: | Civil Engineering BSc (56952) |
| Link to this item: | https://purl.utwente.nl/essays/93569 |
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