Experimental Study of Biological Nitrate Removal Performance in Semi-Arid Regions: Effects of Woodchips and Hydraulic Retention Times

IJEP 42(10): 1234-1240 : Vol. 42 Issue. 10 (October 2022)

Amirhossein Haddadi, Kamran Zeinalzadeh* and Sina Besharat

Urmia University, Department of Water Engineering, Faculty of Agriculture, Iran


Increasing fertilizer application to compensate for nutrient deficiency and ensure food security has caused leaching of more nitrate through sub-surface drainage and the spread of eutrophication in aquatic ecosystems. Woodchip bioreactors are a well-known method for removing nitrate from agricultural effluents. However, there is not enough knowledge about the performance of native woodchips in semi-arid ecosystems. 9 treatments, including 3 woodchips and 3 hydraulic retention times (HRTs) of 5, 12 and 24 hr were studied in 3 repetitions. Studied woodchips, walnut, beech and poplar were chosen from native trees of Urmia lake basin, known as a semi-arid region. The results disclosed that the HRT and woodchip significantly affected the nitrate removal rate (P<0.05). Walnut and beech woodchips had the highest and lowest nitrate reduction capability, respectively. The study showed an increase of about 16% in the nitrate removal efficiency in all woodchips due to an increase in the HRT from 5 to 12 hr. There were no significant differences between the HRTs of 12 and 24 hr (P>0.05). The results of this study confirm the desirable performance of walnut woodchip and 12 hr HRT in nitrate removal under semi-arid conditions.


Agricultural wastewater, biological process, nitrate reduction, Urmia lake basin


  1. FAO annual report. 2017. The future of food and agriculture- Trends and challenges. Food and Agriculture Organization.
  2. Balogh, J.M. and A. Jamber. 2020. The environmental impacts of agricultural trade : A systematic literature review. Sustain., 12 (3):1152.
  3. Ma, C., et al. 2021. Efficacy of heated tourmaline in reducing biomass clogging within woodchip bioreactors. Sci. Total Env., 755 (Part 1):142401.
  4. Martin, E.A., et al. 2019. Impact of hydraulic residence time on nitrate removal in pilot-scale wood-chip bioreaction. J. Env. Manage., 237(9): 424-432.
  5. Cui, G., et al. 2022. Varying water column stability controls the denitrification process in a subtropical reservoir, Southwest China. J. Env. Sci., 11(1):208-219.
  6. ULRP. 2018. Urma lake : Lessons and challenges. Urma lake restoration programme.
  7. Khazaei, B., et al. 2019. Climate or regionally induced by humans tracing hydro-climatic and landuse, changes to better understand the lake Urmia tragedy. J. Hydrol., 569(2):203-217.
  8. Ramsar Convention. 1975. Ramsar convention on wetlands of international importance especially as water fowl habitat.
  9. Ugboh, O. and J.U. Ulebor. 2011. Application of integrated soil fertility approach in the improvement of soil fertility in semiarid ecology. J. Agric. Social Res., 11(2):81-86.
  10. Chalibal, M.B. and Z. Moussavi. 2014. Development and environment in Urmia lake of Iran. European J. Sustain. Develop., 3(3):219-226.
  11. Barhagh, S.E., et al. 2021. System dynamics to assess the effectiveness of restoration scenarios for the Urima lake : A prey-predator approach for the human-environment uncertain interactions. J. Hydrol., 593 (2):125891.
  12. Sobti, R.C. and S.K. Sharma. 2011. Microbial denitrification of groundwater : Carbon batch study. Asian J. Water Env. Poll., 8(3):89-94.
  13. Zhang, W., et al. 2021. Efficient nitrate removal by Pseudomonas mendocina GL 6 immobilized on biochar. Bioresour. Tech., 320 (Part A):124324.
  14. Law, J.Y., et al. 2018. Exploring multiple operating scenarios to identify low-cost, high nitrate removal strategies for electrically stimulated woodchip bioreactors. Ecol. Eng., 120(11):146-153.
  15. Moorman, T.B., et al. 2015. Evaluating the potential role of denitrifying bioreactors in reducing watershed-scale nitrate loads : A case study comparing three mid western (USA) watershed. Ecol. Eng., 75(2):441-448.
  16. Robertson, W.D. and L.C. Merkley. 2009. In-stream bioreactor for agricultural nitrate treatment. J. Env. Qual., 38(1):230-237.
  17. Rivas, A., et al. 2020. Nitrate removal and secondary effects of a woodship bioreactor for the treatment of subsurface drainage with dynamic flows under pastoral agriculture. Ecol. Eng., 148(7):105786.
  18. Hassanpour, B., et al. 2019. Application of denitrifying bioreactors for the removal of atrazine in agricultural drainage water. J. Env. Manage., 239(11):48-56.
  19. Hassanpour, B., et al. 2020. Biochar acting as an electron acceptor reduce nitrate removal in woodchip denitrifying bioreactors. Ecol. Eng., 149(8):105724.
  20. Ghane, E., N.R. Fausey and L.C. Brown. 2014. Non-darcy flow of water through woodchip media. J. Hydrol., 519 (Part D):3400-3409.
  21. Woli, K.P., et al. 2010. Nitrogen balance in and export from agricultural fields associated with controlled drainage systems and denitrifying bioreactors. Ecol. Eng., 36(11):1558-1566.
  22. Bacalan, F., et al. 2020. Identification and antimicrobial susceptibility testing of anaerobic bacteria isolated from clinical samples. J. Bacterial Mycol., 8(1):29-32.
  23. Damaraju, S., et al. 2015. Denitrification in biofilm configured horizontal flow woodchip bioreactor : Effect of hydraulic retention time and biomass growth. Ecohydrol. Hydrobiol., 515(1):39-48.
  24. Li, S., et al. 2018. Evaluation of flyash pellets for phosphorus removal in a laboratory scale denitrifying bioreactor. J. Env. Manage., 207(3):269-275.
  25. Moorman, T.B., et al. 2010. Denitrification activity, wood loss and N2O emissions over 9 years from a woodchip bioreactor. Ecol. Eng., 36(11):1567-1574.
  26. Schipper, L.A., et al. 2010. Review : Denitrifying bioreactor-An approach for reducing nitrate loads to receiving waters. Ecol. Eng., 36(11):1532-1543.
  27. Povilaitis, A. and J. Matikiene. 2020. Nitrate removal from the drainage water : The performance of denitrifying woodchip bio-reactors amended with activated carbon and flaxseed cake. Agric. Water Manage., 229(3):105937.
  28. Hua, G., et al. 2016. Nitrate and phosphate removal from agricultural subsurface drainage using laboratory woodchip bioreactors and recycled steel by product filters. Water Res., 102 (15):180-189.
  29. Hoover, N.L., et al. 2016. Woodchip denitrification bioreactors : Impact of temperature and hydraulic retention time on nitrate removal. J. Env. Qual., 45(3):803-812.
  30. Meidute, S., F. Demoling and E. Baath. 2008. Antagonistic and synergistic effects of fungal and bacterial growth in soil after adding different carbon and nitrogen sources. Soil. Biol. Biochem., 40(9):2334-2343.