The ultimate goal of the present study is to design and investigate the bio-geo-filters for nitrate removal from the runoffs. This research uses alternate layers of non-woven geotextile and granular soil to reduce and remove pollution. These layers are of paramount importance in permeability and adsorption capability. Some points have been considered for selecting the materials, including the material capability for pollution removal, their accessibility, and maximal cost-effectiveness. After conducting the permeability tests, the weight mixing ratio of the materials used in permeable reactive barriers (PRB) was considered to be 25% sand, 20% zeolite, 20% iron filings, and 10% poplar wood sawdust. For pH 7, zeolite's maximal nitrate adsorption efficiency is about 69%, sawdust 29%, and iron filings 12%. The investigation of nitrate adsorption through the final prepared PRB for different nitrate concentrations under the optimal pH conditions showed maximal adsorption of about 83% for a nitrate concentration of 150 mg/L. The more the initial nitrate concentration, the more the absorption amount. Moreover, nitrate was removed with equal amounts of absorbent at optimal pH at different times to determine the equilibrium time. The maximal removal of 100% was obtained at an equilibrium time of 96 hours. In the pollution removal test with biomass grown in the filter environment, the filter decreased the nitrate content up to 99% after nine days, i.e., the final nitrate content was reduced from 100 to 1 mg/L.

This study uses alternate layers of non-woven geotextile and granular soil to remove soluble nitrate. The mixing weight ratios of PRB materials are 25% sand, 25% anthracite, 20% zeolite, 20% iron filings, and 10% poplar sawdust. Synthetic wastewater with an initial nitrate concentration of 100 mg/l is introduced to the filter over 25 minutes of the filter breakthrough curve (BTC). The BTC from the column test is assumed as a normal curve and the obtained longitudinal dispersion coefficient is equal to 1×10− 7m2/s. The filter reduces the amount of nitrate by 99% within nine days. CTRAN/W software properly estimates the contaminant transport in the filter. However, the BTC obtained by the software cannot estimate the total time for a complete breakthrough under laboratory conditions. At the same time, it can determine the nitrate breakthrough time close to the experimental model.