The depletion of underground water resources and increase in population growth, has forced societies toward the application of non-conventional water resources. The use of municipal wastewater not only provides water necessary for landscape and athletic fields turf irrigation and industrial complexes water needs, it also prevents numerous environmental problems caused by the sewage systems in metropolitans and their suburban areas. Biological wastewater treatment system is recognized as an effective method of reducing nitrate, salts and mineral soluble materials in wastewater. In this method, the process of denitrification takes place in biofilters containing absorbent material. Absorbent material selected in this study consisted of sand, wood chips, sugarcane tops and leaves, wheat straw, and zeolite each separately in 4 biofilter cylinders and also in sequential arrangements of top–down layers in another four cylinders and lastly a complete mixture of the four material in one cylinder. Sand filters were used to absorb suspended material in the wastewater before entering the biofilters. The aim of this study was to evaluate the effect of different organic and inorganic adsorbents singularly and in combination with each other on reducing and eliminating pollutants. The study of the trend in changes in nitrate concentrations over a time period of 8 weeks revealed significant differences between the type of filters and experiments’ steps (p 0.05). The maximum nitrate removal rate during the period of testing of filters was for zeolite with 45.51 % at a pH level of 7.26; the lowest absorption rate was observed for the sand filter with 8.85% at a pH level of 7.84. Wood chips, sugarcane tops and leaves and wheat straw showed a reduction in nitrate with 41.16, 43.04 and 43.04 % at pH levels of 7.60, 6.83 and 6.77, respectively. The rate of nitrate absorption for sequential layers of wheat straw-wood chips-sugarcane–zeolite, wood chips-sugarcane-zeolite-wheat straw, sugarcane-zeolite-wheat straw-wood chips and zeolite-wheat straw-wood chips-sugarcane were 42.80, 44.33, 40.29, 43.44 percent which indicate higher absorption compared to some of the main treatments in this study. Maximum electrical conductivity and total dissolved solids were observed for the first week after the operation of the biofiltration system was initialized. Percentage changes in electrical conductivity and total dissolved solids content increased from the third week of the experiments, meaning that over the time the amount of salt and water solubles further decrease. Highest reduction in salinity and total dissolved solids was observed in the sand filter. Considering changes in temperature and retention time in each filter, maximum absorption rate was achieved in zeolite filter with an optimum retention time of 1.32 hours at 12 °C.