• Yasir Talib Hameed Environmental Engineering Department, College of Engineering, Mustansiriyah University, Baghdad, Iraq
  • Narmeen Abdalwahhab Abdalqadir Environmental Engineering Department, College of Engineering, Mustansiriyah University, Baghdad, Iraq
  • Hala Husham Nussrat Environmental Engineering Department, College of Engineering, Mustansiriyah University, Baghdad, Iraq
  • Khaled muftah Shahot Department of Civil Engineering, Faculty of Engineering, Almergib University, Khoms-Libya.




constructed wetlands, nitrification, ammonia, total nitrogen


Constructed wetlands attracted the attention of researchers as a sustainable, economic, and efficient wastewater treatment technique. Many papers showed the efficient performance of constructed wetlands to treat municipal, industrial, livestock, petroleum, and other types of wastewater, effectively removing organic matters, phosphate, nitrogen, and contaminants of emerging concern such as pharmaceuticals and antibiotics. There have been numerous reviews in the literature that studied nitrogen removal in constructed wetlands from different perspectives. However, the majority are concerned about the conventional nitrification process. It is worth mentioning that some biological nitrogen pathways other than the conventional nitrification process were implemented in constructed wetlands efficiently such as partial nitrification and denitrification, simultaneous nitrification and denitrification, anaerobic ammonium oxidation, and completely autotrophic nitrogen removal over nitrite which have been reviewed in this study. The outcomes of this study showed that anaerobic ammonium oxidation is the most common pathway applied in constructed wetlands. Moreover, this review showed that the efficient performance of these novel pathways is constrained by the difficulty of controlling the operating parameters such as dissolved oxygen, temperature, and pH.


Wu, H., et al. (2015). A review on the sustainability of constructed wetlands for wastewater treatment: design and operation. Bioresource technology, 175: p. 594-601.

Zhang, D.Q., et al. (2014). Application of constructed wetlands for wastewater treatment in developing countries–a review of recent developments (2000–2013). Journal of environmental management. 141: p. 116-131.

Liu, R., et al. (2015). A review of incorporation of constructed wetland with other treatment processes. Chemical Engineering Journal. 279: p. 220-230.

Langan, C., et al. (2018). Tropical wetland ecosystem service assessments in East Africa; A review of approaches and challenges. Environmental Modelling & Software. 102: p. 260-273.

Xu, X., et al.(2020). Wetland ecosystem services research: A critical review. Global Ecology and Conservation. 22: p. e01027.

Mekonnen, A., S. (2015). Leta, and K.N. Njau, Wastewater treatment performance efficiency of constructed wetlands in African countries: a review. Water Science and Technology. 71(1): p. 1-8.

Ingrao, C., S. (2020). Failla, and C. Arcidiacono, A comprehensive review of environmental and operational issues of constructed wetland systems. Current Opinion in Environmental Science & Health. 13: p. 35-45.

Sehar, S. and H. Nasser (2019). Wastewater treatment of food industries through constructed wetland: a review. International Journal of Environmental Science and Technology. 16(10): p. 6453-6472.

Li, Y., et al. (2014). A review on removing pharmaceutical contaminants from wastewater by constructed wetlands: design, performance and mechanism. Science of the Total Environment. 468: p. 908-932.

Liang, Y., et al. (2017). Constructed wetlands for saline wastewater treatment: A review. Ecological Engineering. 98: p. 275-285.

Wu, S., et al. (2013). Sulphur transformations in constructed wetlands for wastewater treatment: a review. Ecological engineering. 52: p. 278-289.

Khan, N.A., et al. (2020). Horizontal sub surface flow Constructed Wetlands coupled with tubesettler for hospital wastewater treatment. Journal of environmental management. 267: p. 110627.

Wang, M., et al. (2018). Application of constructed wetlands for treating agricultural runoff and agro-industrial wastewater: a review. Hydrobiologia. 805(1): p. 1-31.

Jain, M., et al. (2020). A review on treatment of petroleum refinery and petrochemical plant wastewater: a special emphasis on constructed wetlands. Journal of Environmental Management. 272: p. 111057.

Saeed, T., et al. (2018). Industrial wastewater treatment in constructed wetlands packed with construction materials and agricultural by-products. Journal of Cleaner Production. 189: p. 442-453.

Liu, X., et al. (2019). A review on removing antibiotics and antibiotic resistance genes from wastewater by constructed wetlands: performance and microbial response. Environmental Pollution. 254: p. 112996.

Gagnon, V., et al. (2010). Treatment of hydroponics wastewater using constructed wetlands in winter conditions. Water, Air, & Soil Pollution. 212(1): p. 483-490.

Hussein, A. and M. Scholz. (2017). Dye wastewater treatment by vertical-flow constructed wetlands. Ecological Engineering. 101: p. 28-38.

Herouvim, E., et al. (2011). Treatment of olive mill wastewater in pilot-scale vertical flow constructed wetlands. Ecological engineering. 37(6): p. 931-939.

Sultana, M.-Y., et al. (2015). Constructed wetlands in the treatment of agro-industrial wastewater: A review. Hemijska industrija. 69(2): p. 127-142.

Foladori, P., J. Ruaben, and A.R. (2013). Ortigara, Recirculation or artificial aeration in vertical flow constructed wetlands: a comparative study for treating high load wastewater. Bioresource technology. 149: p. 398-405.

Wang, Z., et al. (2013). Screening of phosphate-removing substrates for use in constructed wetlands treating swine wastewater. Ecological Engineering. 54: p. 57-65.

Carvalho, P.N., et al. (2013). Potential of constructed wetlands microcosms for the removal of veterinary pharmaceuticals from livestock wastewater. Bioresource technology. 134: p. 412-416.

Saeed, T. and G. Sun. (2013). A lab-scale study of constructed wetlands with sugarcane bagasse and sand media for the treatment of textile wastewater. Bioresource technology. 128: p. 438-447.

Qasaimeh, A., H. AlSharie, and T. Masoud. (2015). A review on constructed wetlands components and heavy metal removal from wastewater. Journal of Environmental Protection. 6(07): p. 710.

Maine, M.A., et al. (2019). Hybrid constructed wetlands for the treatment of wastewater from a fertilizer manufacturing plant: Microcosms and field scale experiments. Science of the Total Environment. 650: p. 297-302.

Vymazal, J. and L. Kröpfelová.(2009). Removal of nitrogen in constructed wetlands with horizontal sub-sureface flow: a review. Wetlands. 29(4): p. 1114-1124.

Lee, C.g., T.D. Fletcher, and G. Sun. (2009). Nitrogen removal in constructed wetland systems. Engineering in life sciences. 9(1): p. 11-22.

Zhuang, L.-L., et al. (2019). The configuration, purification effect and mechanism of intensified constructed wetland for wastewater treatment from the aspect of nitrogen removal: A review. Bioresource Technology. 293: p. 122086.

Saeed, T. and G. Sun. (2012). A review on nitrogen and organics removal mechanisms in subsurface flow constructed wetlands: dependency on environmental parameters, operating conditions and supporting media. Journal of environmental management. 112: p. 429-448.

Vymazal, J. (2013). The use of hybrid constructed wetlands for wastewater treatment with special attention to nitrogen removal: a review of a recent development. Water research. 47(14): p. 4795-4811.

Wu, S., et al. (2014). Development of constructed wetlands in performance intensifications for wastewater treatment: a nitrogen and organic matter targeted review. Water research. 57: p. 40-55.

Hang, Q., et al. (2016). Application of plant carbon source for denitrification by constructed wetland and bioreactor: review of recent development. Environmental Science and Pollution Research. 23(9): p. 8260-8274.

Ilyas, H. and I. Masih. (2017). The performance of the intensified constructed wetlands for organic matter and nitrogen removal: A review. Journal of environmental management. 198: p. 372-383.

Tang, S., et al. (2020). Microbial coupling mechanisms of nitrogen removal in constructed wetlands: a review. Bioresource Technology. 314: p. 123759.

Martínez-Espinosa, C., et al. (2021). Denitrification in wetlands: A review towards a quantification at global scale. Science of the total environment. 754: p. 142398.

Rampuria, A., et al. (2021). Novel microbial nitrogen transformation processes in constructed wetlands treating municipal sewage: a mini-review. World Journal of Microbiology and Biotechnology. 37(3): p. 1-11.

Pavlineri, N., N.T. Skoulikidis, and V.A. Tsihrintzis. (2017). Constructed floating wetlands: a review of research, design, operation and management aspects, and data meta-analysis. Chemical Engineering Journal. 308: p. 1120-1132.

Colares, G.S., et al. (2020). Floating treatment wetlands: A review and bibliometric analysis. Science of the Total Environment. 714: p. 136776.

Bi, R., et al. (2019) Giving waterbodies the treatment they need: a critical review of the application of constructed floating wetlands. Journal of Environmental Management. 238: p. 484-498.

Ilyas, H. and I. Masih. (2017). Intensification of constructed wetlands for land area reduction: a review. Environmental Science and Pollution Research. 24(13): p. 12081-12091.

Almuktar, S.A., S.N. Abed, and M. Scholz. (2018). Wetlands for wastewater treatment and subsequent recycling of treated effluent: a review. Environmental Science and Pollution Research. 25(24): p. 23595-23623.

Valipour, A. and Y.-H. Ahn. (2017). A review and perspective of constructed wetlands as a green technology in decentralization practices. Green Technologies and Environmental Sustainability. p. 1-43.

Gorgoglione, A. and V. Torretta. (2018). Sustainable management and successful application of constructed wetlands: a critical review. Sustainability. 10(11): p. 3910.

Parde, D., et al. (2021). A review of constructed wetland on type, treatment and technology of wastewater. Environmental Technology & Innovation. 21: p. 101261.

Kataki, S., et al. (2021). Constructed wetland, an eco-technology for wastewater treatment: A review on types of wastewater treated and components of the technology (macrophyte, biolfilm and substrate). Journal of Environmental Management. 283: p. 111986.

Wang, H., J. Xu, and L. Sheng. (2020).Purification mechanism of sewage from constructed wetlands with zeolite substrates: a review. Journal of Cleaner Production. 258: p. 120760.

Deng, S., J. Chen, and J. Chang. (2021). Application of biochar as an innovative substrate in constructed wetlands/biofilters for wastewater treatment: Performance and ecological benefits. Journal of Cleaner Production. 293: p. 126156.

Blanco, I., et al. (2016). Basic oxygen furnace steel slag aggregates for phosphorus treatment. Evaluation of its potential use as a substrate in constructed wetlands. Water Research. 89: p. 355-365.

Yin, H., X. Yan, and X. Gu. (2017). Evaluation of thermally-modified calcium-rich attapulgite as a low-cost substrate for rapid phosphorus removal in constructed wetlands. Water Research. 115: p. 329-338.

Wang, R., et al. (2022). Can we use mine waste as substrate in constructed wetlands to intensify nutrient removal? A critical assessment of key removal mechanisms and long-term environmental risks. Water research. 210: p. 118009.

Babatunde, A.O., J.L. Kumar, and Y. Zhao. (2011). Constructed wetlands using aluminium-based drinking water treatment sludge as P-removing substrate: should aluminium release be a concern? Journal of Environmental Monitoring. 13(6): p. 1775-1783.

Wang, Z., et al., (2013), Study of oyster shell as a potential substrate for constructed wetlands. Water science and technology. 67(10): p. 2265-2272.

Cheng, S., et al. (2021). Comprehensive evaluation of manganese oxides and iron oxides as metal substrate materials for constructed wetlands from the perspective of water quality and greenhouse effect. Ecotoxicology and Environmental Safety. 221: p. 112451.

Marcelino, G.R., et al. (2020). Construction waste as substrate in vertical subsuperficial constructed wetlands treating organic matter, ibuprofenhene, acetaminophen and ethinylestradiol from low-strength synthetic wastewater. Science of the Total Environment. 728: p. 138771.

Li, H., et al. (2017). Nitrogen removal in wood chip combined substrate baffled subsurface-flow constructed wetlands: impact of matrix arrangement and intermittent aeration. Environmental Science and Pollution Research. 24(5): p. 5032-5038.

Zhang, H., et al. (2021). A review on China's constructed wetlands in recent three decades: Application and practice. journal of environmental sciences. 104: p. 53-68.

Yan, Y. and J. Xu. (2014). Improving winter performance of constructed wetlands for wastewater treatment in northern China: a review. Wetlands. 34(2): p. 243-253.

Varma, M., et al. (2021). A review on performance of constructed wetlands in tropical and cold climate: Insights of mechanism, role of influencing factors, and system modification in low temperature. Science of the Total Environment. 755: p. 142540.

Wang, M., et al. (2017). Constructed wetlands for wastewater treatment in cold climate—A review. Journal of Environmental Sciences. 57: p. 293-311.

Garcia, J., et al. (2010). Contaminant removal processes in subsurface-flow constructed wetlands: a review. Critical Reviews in Environmental Science and Technology. 40(7): p. 561-661.

Golden, H.E. et al. (2019). Non-floodplain wetlands affect watershed nutrient dynamics: A critical review. Environmental Science & Technology. 53(13): p. 7203-7214.

Ji, B., et al. (2020). Can subsurface flow constructed wetlands be applied in cold climate regions? A review of the current knowledge. Ecological Engineering. 157: p. 105992.

Zhu, G., et al. (2008). Biological removal of nitrogen from wastewater. Reviews of environmental contamination and toxicology: p. 159-195.

Saeed, T. and G. Sun. (2017). A comprehensive review on nutrients and organics removal from different wastewaters employing subsurface flow constructed wetlands. Critical Reviews in Environmental Science and Technology. 47(4): p. 203-288.

Li, H., Z. Chi, and B. Yan. (2019). Successful start-up of the anammox process in constructed wetland microcosms: influence of the electron acceptors on performance, microbial community, and functional genes. Environmental Science and Pollution Research. 26(5): p. 5202-5209.

Rampuria, A., A.B. Gupta, and U. Brighu, (2020). Nitrogen transformation processes and mass balance in deep constructed wetlands treating sewage, exploring the anammox contribution. Bioresource Technology. 314: p. 123737.

Wang, Y.-F., et al. (2019). Interactions and responses of n-damo archaea, n-damo bacteria and anammox bacteria to various electron acceptors in natural and constructed wetland sediments. International Biodeterioration & Biodegradation. 144: p. 104749.

Shuai, W. and P.R. (2019). Jaffé, Anaerobic ammonium oxidation coupled to iron reduction in constructed wetland mesocosms. Science of the total environment. 648: p. 984-992.

Chen, L., et al. (2017). Anaerobic ammonium oxidation in sediments of surface flow constructed wetlands treating swine wastewater. Applied microbiology and biotechnology. 101(3): p. 1301-1311.

Chen, D., et al. (2019). Denitrification-and anammox-dominant simultaneous nitrification, anammox and denitrification (SNAD) process in subsurface flow constructed wetlands. Bioresource technology. 271: p. 298-305.

Dong, Z. and T. Sun. (2007). A potential new process for improving nitrogen removal in constructed wetlands—promoting coexistence of partial-nitrification and ANAMMOX. Ecological engineering. 31(2): p. 69-78.

Wang, L. and T. Li. (2015). Effects of seasonal temperature variation on nitrification, anammox process, and bacteria involved in a pilot-scale constructed wetland. Environmental Science and Pollution Research. 22(5): p. 3774-3783.

Erler, D.V., B.D. Eyre, and L. Davison. (2008). The contribution of anammox and denitrification to sediment N2 production in a surface flow constructed wetland. Environmental Science & Technology. 42(24): p. 9144-9150.

Fu, G., et al. (2016). Effects of nitrogen removal microbes and partial nitrification-denitrification in the integrated vertical-flow constructed wetland. Ecological Engineering. 95: p. 83-89.

Hu, Y., X. Zhao, and Y. Zhao. (2014). Achieving high-rate autotrophic nitrogen removal via Canon process in a modified single bed tidal flow constructed wetland. Chemical Engineering Journal. 237: p. 329-335.

Huang, M., Z. Wang, and R. Qi. (2017). Enhancement of the complete autotrophic nitrogen removal over nitrite process in a modified single-stage subsurface vertical flow constructed wetland: Effect of saturated zone depth. Bioresource technology. 233: p. 191-199.

Huang, T., et al. (2020). A stable simultaneous anammox, denitrifying anaerobic methane oxidation and denitrification process in integrated vertical constructed wetlands for slightly polluted wastewater. Environmental Pollution. 262: p. 114363.

Kraiem, K., et al. (2019). Comparative study on pilots between ANAMMOX favored conditions in a partially saturated vertical flow constructed wetland and a hybrid system for rural wastewater treatment. Science of the total environment. 670: p. 644-653.

Li, H. and W. Tao, (2017).Efficient ammonia removal in recirculating vertical flow constructed wetlands: complementary roles of anammox and denitrification in simultaneous nitritation, anammox and denitrification process. Chemical Engineering Journal. 317: p. 972-979.

Li, H., Z. Chi, and B. Yan. (2018). Insight into the impact of Fe 3 O 4 nanoparticles on anammox process of subsurface-flow constructed wetlands under long-term exposure. Environmental Science and Pollution Research. 25(29): p. 29584-29592.

Lin, Z., et al. (2020). Autotrophic nitrogen removal by partial nitrification-anammox process in two-stage sequencing batch constructed wetlands for low-strength ammonium wastewater. Journal of Water Process Engineering. 38: p. 101625.

Tao, W., et al. (2012). Nitrogen removal in constructed wetlands using nitritation/anammox and nitrification /denitrification: effects of influent nitrogen concentration. Water environment research. 84(12): p. 2099-2105.

Khajah, M. and A. Babatunde. (2016). Investigation of Nitrogen Removal via CANON Process in a Single Stage Constructed Wetland System. Journal of Water Sustainability. 6(2): p. 43.

Waki, M., et al. (2015). Distribution of anammox bacteria in a free-water-surface constructed wetland with wild rice (Zizania latifolia). Ecological Engineering. 81: p. 165-172.

Wang, L. and T. Li. (2011). Anaerobic ammonium oxidation in constructed wetlands with bio-contact oxidation as pretreatment. Ecological Engineering. 37(8): p. 1225-1230.

Wang, Z., et al. (2017). Enhancing nitrogen removal via the complete autotrophic nitrogen removal over nitrite process in a modified single-stage tidal flow constructed wetland. Ecological Engineering. 103: p. 170-179.

Xu, D., et al. (2017). Bacterial community and nitrate removal by simultaneous heterotrophic and autotrophic denitrification in a bioelectrochemically-assisted constructed wetland. Bioresource technology. 245: p. 993-999.

Zhan, X., et al. (2020). Treatment of secondary effluent by a novel tidal-integrated vertical flow constructed wetland using raw sewage as a carbon source: Contribution of partial denitrification-anammox. Chemical Engineering Journal. 395: p. 125165.

Zhu, G., et al. (2011). Anammox bacterial abundance, biodiversity and activity in a constructed wetland. Environmental science & technology. 45(23): p. 9951-9958.




Submission Dates

Received 19/05/2022 

Accepted 25/08/2022 

Published 01/09/2022 

How to Cite

Hameed, Y. T. ., Abdalqadir, N. A. ., Nussrat, H. H. ., & Shahot, K. muftah. (2022). EVALUATION OF NITRIFICATION PROCESS IN CONSTRUCTED WETLANDS: A REVIEW ON NOVEL BIOLOGICAL NITROGEN REMOVAL PROCESSES . Journal of Engineering and Sustainable Development, 26(5), 35–52. https://doi.org/10.31272/jeasd.26.5.4