AbstractThere is currently a lack of understanding of the design principles and performance monitoring relating to the use of Integrated Constructed Wetlands (ICW) for the treatment of domestic wastewater. This lack of understanding is limiting their development for domestic wastewater treatment in Northern Ireland. The aim of this thesis is to improve the understanding of ICW performance for the treatment of domestic wastewater in Northern Ireland. This thesis achieves the following 6 objectives:
1. Critically review existing knowledge on constructed wetlands, and specifically the use of Integrated Constructed Wetlands for the treatment of domestic wastewater.
2. Determine key variables for assessing Integrated Constructed Wetland performance.
3. Review the design, construction and operation of a full-scale Integrated Constructed Wetland located at Stoneyford to assess its ability to treat domestic wastewater.
4. Design, build and monitor a small-scale research facility at Stoneyford.
5. Offer advice to a revised guidance document for future Integrated Constructed Wetland provision for the treatment of domestic wastewater in Northern Ireland.
6. Investigate the use of drones as a method of monitoring plant performance and identify links to wastewater treatment performance.
This thesis considers the early life performance of Stoneyford Integrated Constructed Wetland in treating domestic wastewater in Northern Ireland. It details issues regarding the design, construction, operation and maintenance of Stoneyford ICW as a full-scale pilot system commissioned by Northern Ireland Water (NIW). This thesis uses water quality, weather and vegetation performance data from the Stoneyford ICW as a full-scale pilot scheme. Water quality and flow data from a small-scale test rig helps further knowledge and understanding of design principals and wastewater treatment performance monitoring. Weekly samples were taken manually from each of the 5 ICW ponds and 8 beds of the test rig to monitor water quality over a 19-month period. Results found water quality to improve as it flowed through the 5 ponds of the ICW system. On average, water quality data showed a 13 reduction of 97% BOD, 86% suspended solids, 90% ammonia and 81.5% COD over the 19- month period. Change in water depth, particularly for pond 1 had a significant detrimental impact on plant growth as illustrated by drone footage taken over a 7-month period. Seasonal differences were found during this period as the ICW and its plant life eco-system is becoming established. Analysis of the test rig water quality found a shallower depth of 50mm with a larger surface area of 40m2/pe was more effective in the treatment of domestic wastewater, although the differences were marginal at a small scale. The benefit of using a drone was apparent as it was able to highlight issues relating to plant growth not evident from walking around the ponds. New methods of monitoring plant growth were developed using 2D and 3D image analysis techniques. This allowed for a better understanding of plant performance over time in terms of volume, density and species differentiation. Stoneyford is the first full-scale ICW for the treatment of domestic wastewater in Northern Ireland. This research concludes that an ICW is a viable alternative to traditional wastewater treatment works in treating domestic sewage in Northern Ireland.
|Date of Award||Mar 2018|
|Sponsors||Department of Employment and Learning & Northern Ireland Water|
|Supervisor||Alan Strong (Supervisor), Rodney Mc Dermott (Supervisor) & David Woodward (Supervisor)|