Removal of nitrogen and phosphorus from wastewater using layered filter media

Abstract

After biological wastewater treatment, ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), and phosphate phosphorus (PO4-P) remain in the effluent, which is discharged into natural water bodies. For further removal of these wastewater compounds, three selected materials were used as filter media: quartz sand used in drinking water treatment plants, Purolite A502PS resin, and natural zeolite. After placing all selected materials in the first filtration column (height of each layer-30 cm), the concentration of NH4-N in the wastewater was reduced by 5 times (from 8.22 to 1.5 mg/L), the concentration of NO3-N by 6 times (from 2.46 to 0.44 mg/L), and the concentration of PO4-P by 3 times (from 1.56 to 0.45 mg/L). The second column was without a Purolite A502PS layer, so the concentration of NO3-N in the filtrate from the second column was not reduced. The filtration columns were operated for about 2 months, and the filtration was stopped due to clogging with suspended solids (TSS) with an average concentration of 53.2 mg/L. The preliminary removal of TSS from wastewater before filtration through sorbents is recommended. The tested materials effectively treat wastewater of nitrogen (average efficiency 80–83%) or phosphorus (average efficiency 65–67%) and do not pollute the wastewater with environmentally hazardous substances, so they can be used in the development of tertiary wastewater treatment filters.