Influence of the vertical filter media on phosporus removal from the domestic wastewater

Modelling of the domestic wastewater treatment and removal of the P total in the vertical filters with the sand, dolomite powder and dolomite chippings each separately used as a filter media was performed. Six filter models taking 0.2 m2 each were installed. The length he of the filtration path was equal to 0.8 m in three of these models and 0.4 m in the other three models. The hydraulic load on the filters was equal to 0.03 m3 m~2 d"1 in 2008, and it was equal to 0.06 m3 m"2 d"1 in 2009. The domestic wastewater which had undergone the pre-cleaning in the septic systems was poured into the models. Their average pollution with the Ptotal reached 14.6 mg L ;in the first year and 9.2 mg L"1 in the second year. When the filtration path was equal to 0.8 m and the hydraulic load was equal to 0.03 m3 m~2 d"1, the P was removec : wastewater with the efficiency of 99.9% in the dolomite powder filter. In the filter models with the sand and dolomite chippings, the P total was removed with the same efficiency of 87.7%. When the hydraulic load doubled, the efficiency of P removal decreased to 59,8% in the sand filter and down to 45.7% in the dolomite chippings filter. When the hydraulic load reached 0.06 m3 m~2 d"1, only the . powder filter could ensure the adequate cleaning of the domestic wastewater up to the allowable normsVytauto Didžiojo universitetasŽemės ūkio akademij