The most of the on site wastewater treatment systems in Poland discharges treated effluent to the soil. The goal of phosphorus (P) reduction from dispersed sources of pollution can be achieved by application of P reactive materials in the construction of wastewater infiltration systems.
Two P reactive materials were tested in this study: Polonite® in grains of 26 mm and lightweight aggregate Leca® in grains of 410 mm. Apparent P sorption capacity was assesed on 40.9 mg·g-1 (Polonite®) and 5.1 mg·g-1 (Leca®). Both materials sorbed P-PO4 very fast, after 15 min over 90% of P was removed from solution and wastwater. Wastewater used in this study came from the outlet from the septic tank of on site septic system. P-PO4 solution was prepared from KH2PO4 and the tap water. In the small column experiment, four collumns (2 filled with Polonite® and 2 filled with Leca®) were fed with wastewater and P-PO4 solution in hydraulic loadings of 3040 dm3·m-2·d-1. All the columns removed significant amounts of P from both solution and wastewater with the reduction between 28.3% and 72.5%. The mean P-PO4 effluent concentrations ranged from 1.21 mg·dm-3 to 7.12 mg·dm-3. The best overall performance was achieved by the Polonite® fed with solution. Both tested materials can support wastewater treatment in on site systems.