Alabdula’aly A.I. (1997): Nitrate concentrations in Riyadh, Saudi Arabia drinking water supplies. Environmental Monitoring and Assessment, 47: 315–324. https://doi.org/10.1023/A:1005756904710 Alabdula’aly A.I., Al-Rehaili A.M., Al-Zarah A.I., Khan M.A. (2010): Assessment of nitrate concentration in groundwater in Saudi Arabia. Environmental Monitoring and Assessment, 161: 1–9. https://doi.org/10.1007/s10661-008-0722-7 Al-Khanbashi A., Al-Kaabi K., Hammami A. (2005): Date palm fibres as polymeric matrix reinforcement: fibre characterization. Polymer Composites, 26: 486–497. https://doi.org/10.1002/pc.20118 Al-Omran A.M., Mousa M.A., AlHarbi M.M., Nadeem M.E.A. (2018): Hydrogeochemical characterization and groundwater quality assessment in Al-Hasa, Saudi Arabia. Arabian Journal of Geosciences, 11: 79. https://doi.org/10.1007/s12517-018-3420-y Bashir M.T., Azni S.A., Harun R. (2018): A sustainable approach of nitrate adsorption from water using palm oil agricultural waste. Asian Journal of Microbiology, Biotechnology and Environmental Sciences, 20: 451–457. Behrouz M., Seyed M.A., Leila M. (2019): Enhanced adsorption of nitrate from water by modified wheat straw: equilibrium, kinetic and thermodynamic studies. Water Science and Technology, 79: 302–313. https://doi.org/10.2166/wst.2019.047 Carter M.C., Kilduff J.E., Weber W.J. (1995): Site energy distribution analysis of preloaded adsorbents. Environmental Science and Technology, 29: 1773–1780. https://doi.org/10.1021/es00007a013 Cheng H.M., Zhu Q., Xing Z.P. (2019): Adsorption of ammonia nitrogen in low temperature domestic wastewater by modification bentonite. Journal of Cleaner Production, 233: 720–730. https://doi.org/10.1016/j.jclepro.2019.06.079 Dabbagh A.E., Abderrahman W.A. (1997): Management of groundwater resources under various irrigation water use scenarios in Saudi Arabia. Arabian Journal for Science and Engineering, 22: 47–64. Derylo-Marczewska A., Blachnio M., Marczewski A.W., Seczkowska M., Tarasiuk B. (2019): Phenoxyacid pesticide adsorption on activated carbon – equilibrium and kinetics. Chemosphere, 214: 349–360. https://doi.org/10.1016/j.chemosphere.2018.09.088 Derylo-Marczewska A., Jaroniec M., Gelbin D., Seidel A. (1984): Heterogeneity effects in single-solute adsorption from dilute solutions on solids. Chemica Scripta, 24: 239–246. Freundlich H., Heller W. (1939): The adsorption of cis- and trans-azobenzene. Journal of the American Chemical Society, 61: 2228–2230. https://doi.org/10.1021/ja01877a071 Hafshejani L.D., Hooshmanda A., Naseri A.A., Mohammadi A.S., Abbasi F., Bhatnagar A. (2016): Removal of nitrate from aqueous solution by modified sugarcane bagasse biochar. Ecological Engineering, 95: 101–111. https://doi.org/10.1016/j.ecoleng.2016.06.035 Hajhamad L., Almasri M.N. (2009): Assessment of nitrate contamination of groundwater using lumped-parameter models. Environmental Modelling and Software, 24: 1073–1087.  https://doi.org/10.1016/j.envsoft.2009.02.014 Haycarb (2019): Activated carbon basics. Available at: https://www.haycarb.com/activated-carbon Hegazi H.A. (2013): Removal of heavy metals from wastewater using agricultural and industrial wastes as adsorbents. HBRC Journal, 9: 276–282. https://doi.org/10.1016/j.hbrcj.2013.08.004 Hu Q.L., Chen N., Feng C.P., Hu W.W., Liu H.Y. (2016): Kinetic and isotherm studies of nitrate adsorption on granular Fe-Zr-chitosan complex and electrochemical reduction of nitrate from the spent regenerant solution. RSC Advances, 6: 61944–61954. https://doi.org/10.1039/C6RA04556A Jin Z.F., Pan Z.Y., Jin M.T., Li F.L., Wan Y., Gu B. (2012): Determination of nitrate contamination sources using isotopic and chemical indicators in an agricultural region in China. Agriculture, Ecosystems and Environment, 155: 78–86. https://doi.org/10.1016/j.agee.2012.03.017 Kalaruban M., Loganathan P., Kandasamy J., Naidu R., Vigneswaran S. (2017): Enhanced removal of nitrate in an integrated electrochemical-adsorption system. Separation and Purification Technology, 189: 260–266. https://doi.org/10.1016/j.seppur.2017.08.010 Karthikeyan P., Banu H.A.T., Meenakshi S. (2019): Synthesis and characterization of metal loaded chitosan-alginate biopolymeric hybrid beads for the efficient removal of phosphate and nitrate ions from aqueous solution. International Journal of Biological Macromolecules, 130: 407–418. https://doi.org/10.1016/j.ijbiomac.2019.02.059 Katal R., Baei M.S., Rahmati H.T., Esfandia H. (2012): Kinetic, isotherm and thermodynamic study of nitrate adsorption from aqueous solution using modified rice husk. Journal of Industrial and Engineering Chemistry, 18: 295–302. https://doi.org/10.1016/j.jiec.2011.11.035 Keränen A., Leiviskä T., Hormi O., Tanskanen J. (2015): Removal of nitrate by modified pine sawdust: effects of temperature and co-existing anions. Journal of Environmental Management, 147: 46–54. https://doi.org/10.1016/j.jenvman.2014.09.006 Khan N.A., Ibrahim S., Subramaniam P. (2004): Elimination of heavy metals from wastewater using agricultural wastes as adsorbents. Malaysian Journal of Science, 23: 43–51. Langmuir I. (1918): The adsorption of gases on plane surfaces of glass, mica and platinum. Journal of the American Chemical Society, 40: 1361–1403. https://doi.org/10.1021/ja02242a004 Lim W.C., Srinivasakannan C., Balasubramanian N. (2010): Activation of palm shells by phosphoric acid impregnation for high yielding activated carbon. Journal of Analytical and Applied Pyrolysis, 88: 181−186. https://doi.org/10.1016/j.jaap.2010.04.004 Liu Y., Yan C.J., Zhao J.J., Zhang Z.H., Wang H.Q., Zhou S., Wu L.M. (2018): Synthesis of zeolite P1 from fly ash under solvent-free conditions for ammonium removal from water. Journal of Cleaner Production, 202: 11–22. https://doi.org/10.1016/j.jclepro.2018.08.128 Lv R.J., Wang Y., Yang X.X., Wen Y.P., Tan X.M., Zeng Y.J., Shang Q.Y. (2021): Adsorption and leaching characteristics of ammonium and nitrate from paddy soil as affected by biochar amendment. Plant, Soil and Environment, 67: 8–17. https://doi.org/10.17221/276/2020-PSE Mahmoud M.A., El-Halwany M.M. (2013): Kinetics and thermodynamics of date palm fibers (DPF) as agricultural waste materials. Journal of Chromatography and Separation Techniques, 4: 2157–7064. https://doi.org/10.4172/2157-7064.1000194 Manikam M.K., Halim A.A., Hanafiah M.M., Krishnamoorthy R.R. (2019): Removal of ammonia nitrogen, nitrate, phosphorus and COD from sewage wastewater using palm oil boiler ash composite adsorbent. Desalination and Water Treatment, 149: 23–30. https://doi.org/10.5004/dwt.2019.23842 Marshall W.E., Johns M.M. (1996): Agricultural by-products as metal adsorbents: sorption properties and resistance to mechanical abrasion. Journal of Chemical Technology and Biotechnology, 66: 192–198. https://doi.org/10.1002/(SICI)1097-4660(199606)66:2<192::AID-JCTB489>3.0.CO;2-C Mazarji M., Aminzadeh B., Baghdadi M., Bhatnagar A. (2017): Removal of nitrate from aqueous solution using modified granular activated carbon. Journal of Molecular Liquids, 233: 139–148. https://doi.org/10.1016/j.molliq.2017.03.004 Mehdinejadiani B., Amininasab S.M., Manhooei L. (2019): Enhanced adsorption of nitrate from water by modified wheat straw: equilibrium, kinetic and thermodynamic studies. Water Science and Technology, 79: 302–313. https://doi.org/10.2166/wst.2019.047 Milmile S.N., Pande J.V., Karmakar S., Bansiwal A., Chakrabarti T., Biniwale R.B. (2011): Equilibrium isotherm and kinetic modeling of the adsorption of nitrates by anion exchange Indion NSSR resin. Desalination, 276: 38–44. https://doi.org/10.1016/j.desal.2011.03.015 Nur T., Shim W.G., Loganathan P., Vigneswaran S., Kandasamy J. (2015): Nitrate removal using Purolite A520E ion exchange resin: batch and fixed-bed column adsorption modeling. International Journal of Environmental Science and Technology, 12: 1311–1320. https://doi.org/10.1007/s13762-014-0510-6 Öztürk N., Bekta T.E. (2004): Nitrate removal from aqueous solution by adsorption onto various materials. Journal of Hazardous Materials, 112: 155–162. https://doi.org/10.1016/j.jhazmat.2004.05.001 Öztürk N., Bektaş T.E. (2004): Nitrate removal from aqueous solution by adsorption onto various materials. Journal of Hazardous Materials, 112: 155–162. https://doi.org/10.1016/j.jhazmat.2004.05.001 Pollard S.J.T., Fowler G.D., Sollars C.J., Perry R. (1992): Low-cost adsorbents for waste and wastewater treatment: a review. Science of The Total Environment, 116: 31–52. https://doi.org/10.1016/0048-9697(92)90363-W Riahi K., Thayer B.B., Mammou A.B., Ammar A.B., Jaafoura M.H. (2009): Biosorption characteristics of phosphates from aqueous solution onto Phoenix dactylifera L. date palm fibers. Journal of Hazardous Materials, 170: 511–519. https://doi.org/10.1016/j.jhazmat.2009.05.004 Samatya S., Kabay N., Yüksel Ü., Arda M., Yüksel M. (2006): Removal of nitrate from aqueous solution by nitrate selective ion exchange resins. Reactive and Functional Polymers, 66: 1206–1214.  https://doi.org/10.1016/j.reactfunctpolym.2006.03.009 Sanati A.M., Bahramifar N., Mehraban Z., Younesi H. (2013): Lead removal from aqueous solution using date-palm leaf ash in batch system. Journal of Water and Waste Water, 4: 51–58. Sandor J., Kiss I., Farkas O., Ember I. (2001): Association between gastric cancer mortality and nitrate content of drinking water: ecological study on small area inequalities. European Journal of Epidemiology, 17: 443–447. https://doi.org/10.1023/A:1013765016742 Srivastava A., Singh P.K. (2017): Adsorption of nitrate from groundwater using Indian bentonite: fixed bed column study. International Journal of Engineering Research and Technology, 6: 390–394. Suryadi I., Dong S.T., Felycia E.S., Aning A., Wei H.Y., Chun H.Z. (2016): Bentonite hydrochar composite for removal of ammonium from Koi fish tank. Applied Clay Science, 119: 146–154. https://doi.org/10.1016/j.clay.2015.08.022 Tejada-Tovar C., Villabona-Ortíz Á., Gonzalez-Delgado Á.D. (2021): Removal of nitrate ions using thermally and chemically modified bioadsorbents. Applied Science, 11: 8455–8471. https://doi.org/10.3390/app11188455 Uzma N. (2013): Bioremediation of cadmium (II) from aqueous solution using agricultural waste: Zea maize leaves. European Chemical Bulletin, 2: 993–998. Wang T.T., Zhang D., Fang K.K., Zhu W., Peng Q., Xie Z.G. (2021): Enhanced nitrate removal by physical activation and Mg/Al layered double hydroxide modified biochar derived from wood waste: adsorption characteristics and mechanisms. Journal of Environmental Chemical Engineering, 9: 105184. https://doi.org/10.1016/j.jece.2021.105184 Weber W.J. (1974): Adsorption processes. Pure and Applied Chemistry, 37: 375–392. https://doi.org/10.1351/pac197437030375 Xu X., Gao B.Y., Yue Q.N., Li Q., Wang Y. (2013): Nitrate adsorption by multiple biomaterial based resins: application of pilot-scale and lab-scale products. Chemical Engineering Journal, 234: 397–405. https://doi.org/10.1016/j.cej.2013.08.117 Yang L.Y., Xu P., Yang M.M., Bai H. (2017): The characteristics of steel slag and the effect of its application as a soil additive on the removal of nitrate from aqueous solution. Environmental Science and Pollution Research, 24: 4882–4893. https://doi.org/10.1007/s11356-016-8171-2 Zare L., Ghasemii R. (2017): Influence of pyrolysis temperature and sodium bicarbonate on the efficiency of palm leaf residues on zinc and cadmium removal from aqueous solution. Journal of Natural Environment (Iranian Journal of Natural Resource), 70: 87–98. Zhang Y., Song X.L., Huang S.T., Geng B.Y., Chang C.H., Sung I.Y. (2014): Adsorption of nitrate ions onto activated carbon prepared from rice husk by NaOH activation. Desalination and Water Treatment, 52: 4935–4941. https://doi.org/10.1080/19443994.2013.809984