Master’s dissertation submitted in partial fulfilment of the requirements for the joint degree of International Master of Science in Environmental Technology and Engineering an Erasmus+: Erasmus Mundus Master Course jointly organized by Ghent University, Belgium University of Chemistry and Technology, Prague, Czech Republic UNESCO-IHE Institute for Water Education, Delft, the Netherlands Academic year 2014-2015 Impact of aeration on the performance of wastewater treatment wetlands – a pilot scale study Ghent University, Belgium Iva Havran Promotor: Prof. dr. ir. Gijs Du Laing Co-promotor: Prof. dr. ir. Diederik Rousseau This thesis was elaborated at Ghent University, Belgium and defended at Ghent University, Belgium within the framework of the European Erasmus Mundus Programme “Erasmus Mundus International Master of Science in Environmental Technology and Engineering " (Course N° 2011-0172) © [2015] [Ghent], [Iva Havran], Ghent University, all rights reserved. Deze pagina is niet beschikbaar omdat ze persoonsgegevens bevat. Universiteitsbibliotheek Gent, 2021. This page is not available because it contains personal information. Ghent University, Library, 2021. Abstract In this study, a horizontal subsurface flow constructed wetland (HSSF CW) was used to examine the effects of artificial aeration and hydraulic retention time on the removal of traditional contaminants and pharmaceutical compounds from domestic wastewater. The HSSF CW was placed at an Aquafin wastewater treatment plant and it had a surface area of 1.09 . The HSSF CW was installed at the site in March 2015 and monitored weekly for 8 weeks before the sampling campaign started. Within the campaign, the following three treatment designs were applied: continuous aeration at HRT=1d (AER- HRT1), continuous aeration at HRT=0.5d (AER-HRT0.5) and no aeration at HRT=1d (N-AER). Generally, the experiment showed that removal rates were always higher for the aerated treatment designs when compared to non-aerated phase of the study. The statistically significant differences concerning aeration were found for all targeted pollutants, except for several recalcitrant pharmaceutical compounds (carbamazepine, diclofenac, sotalol and tramadol). HRT influence seemed to be negligible since statistical analysis of data did not show any positive correlation between effluents in regard to HRT. Enhanced oxygen transfer rate within the wetland and internal mixing of the influent promoted aerobic processes which proportionally increased removal efficiency of conventional quality parameters such as COD, TSS, -N, -P. However, high dissolved oxygen (DO) rates suppressed anaerobic mechanisms which halted the removal of -N by means of denitrification. N-AER had lower treatment efficiency than commonly reported for HSSF CWs. This is probably due to the fact that HRT of 1 day was too short for the anaerobic removal pathways to be completely carried out or that anaerobic microbial community did not have time to fully develop during the N-AER treatment phase ( 3 weeks). Targeted pharmaceutical compounds could be divided into two groups according to the results: readily degradable compounds (valsartan and metformin) that were almost fully eliminated during the applied aeration and recalcitrant compounds that were not significantly affected. First group was presumably removed by biodegradation under aerobic conditions prevailing in the pilot during aeration, while the other group was either affected by several removal mechanisms (diclofenac and solatol) or mainly removed by sorption (carbamazepine and tramadol). Findings of this study suggest that artificially aerated HSSF CW for treating domestic wastewater is able to provide not only better effluent quality when compared to conventional HSSF CW but also to save operational and building costs due to higher treatment efficiency. iii Acknowledgements First of all, I would like to sincerely thank my Promotor Professor Gijs Du Laing for giving me the opportunity to work on this thesis topic and whose guidance helped me in writing of this thesis. Furthermore, I would like to express my gratitude to my Co-promotor Professor Diederik Rousseau for hosting me in his lab and whose guidance led me through the thesis research and writing of this document. Moreover, my special thanks goes to Hannele Auvinen for going above and beyond her call of duty as being my tutor during this study and for all the help I received from her from the beginning of the research until the final revision of this thesis. I would also like to thank Ghent University for providing me with the equipment for the part of analytical analyses during my thesis work and Joachim Neri who helped me with this process. Moreover, I would express my appreciation to the Aquafin Company for their cooperation and for providing us with the possibility for conducting our research at their site. Furthermore, I would express my gratitude to the Institut für Siedlungswasserwirtschaft in Aachen, Germany for facilitating the analysis of pharmaceutical compounds and in that manner helped me to complete my research results. In addition, I would like to thank Dion Van Oirschot for his help with the design of the pilot wetland and for sharing his expert opinion. The last, but not the least I would like to acknowledge my family and my best friend for all their love, patience and support they unselfishly shared with me not only while writing this thesis but throughout my life. Special words I would dedicate to my boyfriend Dušan who loved me and supported me during these 2 years of long-distance relationship and whose love, trust and care helped me to endure through all the difficult times. iv List of Tables Table 2.1 Treatment efficiency of HSSF CWs for removal of organics , total suspended solids (TSS), total nitrogen (TN) and total phosphorus (TP) based on the annual average values ....................... 15 Table 3.1 Operation of the pilot system and sampling strategy ................................................................. 26 Table 3.2 Monitored pharmaceutical compounds ...................................................................................... 30 Table 4.1 Physico-chemical characteristics (maximum, minimum and mean ± SD) of the samples gathered during the different phases of the experiment ........................................................................................... 32 Table 4.2 COD in influent and effluent samples from the sampling campaign .......................................... 34 Table 4.3 TSS in influent and effluent samples collected during the 3-phase sampling campaign ............ 36 Table 4.4 -N in influent and effluent samples collected during the 3-phase sampling campaign ...... 38 Table 4.5 -N in influent and effluent samples collected during the 3-phase sampling campaign ...... 40 Table 4.6 -P concentrations in influent and effluent samples collected during the 3-phase campaign ..................................................................................................................................................................... 42 Table 4.7 Pharmaceutical compounds found in treated municipal wastewater ........................................ 46 Table 4.8 Pharmaceutical compounds in influents and effluents collected during the 3-phase sampling campaign ..................................................................................................................................................... 46 Table 5.1 Influent and effluent concentrations (mean ± SD) and removal efficiency of Aquafin treatment system and pilot wetland ............................................................................................................................ 54 v List of Figures Figure 3.1: Picture of the pilot wetland under construction ....................................................................... 24 Figure 3.2 Schematic representation of the experimental setup ............................................................... 25 Figure 3.3 Picture of a fully operational pilot wetland installed in-situ ...................................................... 27 Figure 3.4 (a) Effluent and influent sample (aerated wetland); (b) Influent and effluent sample (non- aerated, wetland) ........................................................................................................................................ 31 Figure 4.1 Boxplot representing the distribution of COD in the samples of three phases of the campaign ..................................................................................................................................................................... 34 Figure 4.2 Boxplot representing the distribution of TSS in samples of all three phases of the sampling campaigns .................................................................................................................................................... 36 Figure 4.3 Boxplot representing the distribution of -N concentrations in the samples of 3-phase sampling campaign ...................................................................................................................................... 38 Figure 4.4 Boxplot representing the distribution of -N concentrations in the samples of 3-phase sampling campaign ...................................................................................................................................... 40 Figure 4.5 Boxplot representing the distribution of -P concentrations in the samples of 3-phase sampling campaign ...................................................................................................................................... 42 Figure 4.6 Boxplots representing the distribution of pharmaceutical concentrations in the samples of 3- phase sampling campaign. .......................................................................................................................... 47 vi List of Abbreviation Anammox Anaerobic Ammonium Oxidation APIs Active Pharmaceutical Ingredients BOD Biological Oxygen Demand Canon Completely autotrophic nitrogen removal over nitrite COD Chemical Oxygen Demand CWs Constructed Wetlands Deammox Denitrifying Ammonium Oxidation DO Dissolved Oxygen FWS CWs Free Water Surface Constructed Wetlands HC Hydraulic Conductivity HLR Hydraulic Loading Rate HRT Hydraulic Retention Time HSSF CWs Horizontal Subsurface Flow Constructed Wetlands LECA Light Expanded Clay Aggregate O&M Operation and Maintenance PhCs Pharmaceutical Compounds PVC Polyvinyl Chloride SS Suspended Solids SSFCWs Subsurface Flow Constructed Wetlands TN Total Nitrogen TP Total Phosphorus TSS Total Suspended Solids VF Vertical Flow WWTP Waste Water Treatment Plant vii
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