Institutional Repository
Technical University of Crete
Technical University of Crete
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| URI: | http://purl.tuc.gr/dl/dias/2154FE55-D851-4C4C-A00E-EE9D95872D0E | ||
| Year | 2025 | ||
| Type of Item | Diploma Work | ||
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| Bibliographic Citation | Eleni Dardamani, "Study of pilot sludge treatment wetlands with different substrate under different sludge loading rates", Diploma Work, School of Chemical and Environmental Engineering, Technical University of Crete, Chania, Greece, 2025 https://doi.org/10.26233/heallink.tuc.103871 | ||
| Appears in Collections |
This thesis presents the construction and comparative evaluation of four pilot-scale Sludge Dewatering Constructed Wetlands (SDCWs) using different substrate materials and operated under varying sludge loading rates. The experiment was conducted outdoors at the Chania Wastewater Treatment Plant (WWTP). All units (P60, P80, PES60, and PES80) were filled with river gravel of varying grain sizes, planted with Phragmites australis, and constructed with dimensions of 100 cm × 120 cm × 100 cm (L×W×H). The PES60 and PES80 units included an additional sand layer and were inoculated with Eisenia fetida earthworms. Units P60 and PES60 operated under a sludge loading rate (SLR) of 60 kgTS/year, while P80 and PES80 operated at 80 kgTS/year.The units were fed with sludge from the secondary effluent of the Chania WWTP, according to a controlled loading rate and frequency, as defined in the experimental protocol. The study lasted eight months and involved weekly sampling and analysis of the influent sludge, residual sludge, and leachate. Analyses included parameters such as BOD₅, COD, NO₃⁻-N, NH₄⁺-N, PO₄³⁻-P, total phosphorus (TP), electrical conductivity (EC), and pH. In the dewatered residual sludge, total solids (TS), volatile solids (VS), sludge layer thickness, and concentrations of metals and metalloids were also measured.The results showed sludge volume reduction rates of 96.4%, 92.7%, 92.5%, and 89.7% for P60, P80, PES60, and PES80 respectively. TS content reached 48.8%, 22.6%, 55.0%, and 46.3% respectively. VS values indicated limited organic matter degradation. Nitrogen and phosphorus compound concentrations varied, with PES units showing improved removal performance. Metal concentrations in all units remained within permissible limits for agricultural use. Overall, units PES60 and P60 demonstrated the best performance in terms of volume reduction and solids content. Additionally, the use of earthworms and sandy substrate in PES units enhanced sludge stabilization and improved nitrogen and phosphorus removal, confirming that appropriate substrate selection and bioaugmentation are key factors for optimal SDCW performance.
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