Understanding Integrated Removal of Heavy Metals, Organic Matter and Nitrogen in a Constructed Wetland System Receiving Simulated Landfill Leachate
This study investigated the integrated removal of heavy metals, organic matter and nitrogen from landfill leachate using a novel laboratory scale constructed wetland system. The main objectives of this study were: (i) to assess the overall effectiveness of the constructed wetland system for treating landfill leachate; (ii) to examine the interactions and impact of key leachate constituents (heavy metals, organic matter and nitrogen) on the overall removal dynamics and efficiency. The constructed wetland system consisted of four stages operated in tidal flow and anoxic conditions. Results obtained from 215 days of operation have demonstrated extraordinary heavy metals removal up to 100%. Analysis of the physico- chemical data reveal that the controlling factors for metals removal were the anoxic condition and the use of the novel media (dewatered ferric sludge which is a by-product of drinking water treatment process) as the main substrate in the constructed wetland system. Results show that the use of the ferric sludge enhanced heavy metals removal and brought more flexibility to simultaneous nitrification and denitrification which occurs within the microbial flocs. Furthermore, COD and NH4-N were effectively removed in the system and this coincided with enhanced aeration in the 2nd and 3rd stages of the constructed wetland system. Overall, the results demonstrated that the ferric dewatered sludge constructed wetland system would be an effective solution for integrated removal of pollutants from landfill leachates.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1129870Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 520
 R. Connolly, Y. Zhao, G. Sun, S. Allen, Removal of ammoniacal-nitrogen from an artificial landfill leachate in downflow reed beds, Process Biochem. 39 (2004) 1971–1976. doi:10.1016/j.procbio.2003.09.020.
 S. Lavrova, B. Koumanova, Influence of recirculation in a lab-scale vertical flow constructed wetland on the treatment efficiency of landfill leachate, Bioresour. Technol. 101 (2010) 1756–1761. doi:10.1016/j.biortech.2009.10.028.
 A.K. Yadav, N. Kumar, T.R. Sreekrishnan, S. Satya, N.R. Bishnoi, Removal of chromium and nickel from aqueous solution in constructed wetland: Mass balance, adsorption-desorption and FTIR study, Chem. Eng. J. 160 (2010) 122–128. doi:10.1016/j.cej.2010.03.019.
 A. Mohammed, T. Al-Tahmazi, A.O. Babatunde, Attenuation of metal contamination in landfill leachate by dewatered waterworks sludges, Ecol. Eng. 94 (2016) 656–667. doi:10.1016/j.ecoleng.2016.06.123.
 G. Sun, Y. Zhao, S. Allen, Enhanced removal of organic matter and ammoniacal-nitrogen in a column experiment of tidal flow constructed wetland system, J. Biotechnol. 115 (2005) 189–197. doi:10.1016/j.jbiotec.2004.08.009.
 J. Fan, W. Wang, B. Zhang, Y. Guo, H.H. Ngo, W. Guo, J. Zhang, H. Wu, Nitrogen removal in intermittently aerated vertical flow constructed wetlands: Impact of influent COD/N ratios, Bioresour. Technol. 143 (2013) 461–466. doi:10.1016/j.biortech.2013.06.038.
 R.H. Kadlec, S.D. Wallace, Treatment Wetlands, Second edi, New York, 2008.
 Y. Chang, S. Wu, T. Zhang, R. Mazur, C. Pang, R. Dong, Dynamics of nitrogen transformation depending on different operational strategies in laboratory-scale tidal flow constructed wetlands, Sci. Total Environ. 487 (2014) 49–56. doi:10.1016/j.scitotenv.2014.03.114.
 P. Castaldi, M. Silvetti, G. Garau, D. Demurtas, S. Deiana, Copper(II) and lead(II) removal from aqueous solution by water treatment residues, J. Hazard. Mater. 283 (2015) 140–147. doi:10.1016/j.jhazmat.2014.09.019.
 D.B. Kosolapov, P. Kuschk, M.B. Vainshtein, A. V. Vatsourina, A. Wießner, M. Kästner, R.A. Müller, Microbial processes of heavy metal removal from carbon-deficient effluents in constructed wetlands, Eng. Life Sci. 4 (2004) 403–411. doi:10.1002/elsc.200420048.
 L. Marchand, M. Mench, D.L. Jacob, M.L. Otte, Metal and metalloid removal in constructed wetlands, with emphasis on the importance of plants and standardized measurements: A review, Environ. Pollut. 158 (2010) 3447–3461. doi:10.1016/j.envpol.2010.08.018.
 W. Zhi, L. Yuan, G. Ji, C. He, Enhanced long-term nitrogen removal and its quantitative molecular mechanism in tidal flow constructed wetlands, Env. Sci Technol. 49 (2015) 4575–4583. doi:10.1021/acs.est.5b00017.
 J. Fan, B. Zhang, J. Zhang, H.H. Ngo, W. Guo, F. Liu, Y. Guo, H. Wu, Intermittent aeration strategy to enhance organics and nitrogen removal in subsurface flow constructed wetlands, Bioresour. Technol. 141 (2013) 117–122. doi:10.1016/j.biortech.2013.03.077.
 W. Zhi, G. Ji, Quantitative response relationships between nitrogen transformation rates and nitrogen functional genes in a tidal flow constructed wetland under C/N ratio constraints, Water Res. 64 (2014) 32–41. doi:10.1016/j.watres.2014.06.035.
 Y. Hu, Y. Zhao, A. Rymszewicz, Robust biological nitrogen removal by creating multiple tides in a single bed tidal flow constructed wetland, Sci. Total Environ. 470–471 (2014) 1197–1204. doi:10.1016/j.scitotenv.2013.10.100.
 F.A. Koch, Controlling Factors for Simultaneous Nitrification and Denitrification in a Two- Stage Intermittent Aeration Process Treating, 33 (1999).
 J. Zhang, P. Wu, B. Hao, Z. Yu, Heterotrophic nitrification and aerobic denitrification by the bacterium Pseudomonas stutzeri YZN-001, Bioresour. Technol. 102 (2011) 9866–9869. doi:10.1016/j.biortech.2011.07.118.
 Gao, F. Schreiber, G. Collins, M.M. Jensen, J.E. Kostka, G. Lavik, D. de Beer, H. Zhou, M.M. Kuypers, Aerobic denitrification in permeable Wadden Sea sediments, ISME J. 4 (2009) 417–426. doi:10.1038/ismej.2009.127.