Wastewater treatment with activated pre-clarifier and planted soil filters

With a series of buffer tank, activated pre-clarifier (SBR) and planted soil filters, it is possible to get a stable degradation and good effluent values in the case of unsteady inflow and changing concentrations. In the process presented here the activated pre-clarifier is working as a denitrification tank and the soil filter as a nitrification reactor. An automatic control manages the storm-water runoff, the water-recirculation returns the nitrate and provides a minimal feed. Experiences with this plant from 1999 to 2005 are given in this paper, research has been done in the project “Planted soil filters as a Biotechnological Process”, founded by the German Federal Environment Foundation (DBU). A full scale pilot plant was built to treat wastewater from composting sides, with a 42 m³ SBR and a bed area of 2 × 550 m² of the planted soil filters. Now, after six years of operation, the results are still satisfactory. Besides this pilot plant, landfill leakage and municipal wastewater have been treated in a technical scale plant with the same process in an 80 L SBR and 0.75 m² vertical flow soil filter with good results.