Abstract: The inflow control means comprise either a contact buffer or a buffer reservoir and pump means or both in combination with the inlet of a soil-based filter bed like a root space installation. The contact buffer is in direct flow communicating contact with an upper section of the filter bed on the infiltration side and dimensioned in adaptation to the throughput capacity of the soil-based filter bed such that variations in the waste water inflow are evened out. The same effect is achieved by the buffer reservoir and pump means wherein the pump delivers waste water from the buffer reservoir to the inlet and excess waste water is returned from the inlet to the buffer reservoir through a return line having a receiving end at a level which is preferably adjustable relative to the top surface of the filter bed.

Abstract: A plant containing filter bed contains a bottom gravel bed below a soil matrix. The bottom gravel bed extends along part of a length of the filter bed from an inlet and is hydraulically connected thereto. Preferably the bottom gravel bed extends at a downwardly directed inclination relative to a bottom of the filter bed at a downward inclination in the throughflow direction in the range of 1% to 5%. Due to the length of the bottom gravel bed, the hydraulic gradient and thereby the throughflow through the soil matrix is internally set, i.e. within the soil matrix in adaptation to an infiltration cross-sectional area.

Abstract: The filter bed containing aquatic plants planted therein is provided with a lengthwise and/or transverse drainage arrangement containing a predetermined number of drain pipes. Particularly during the growth phase of the aquatic plants, the drainage arrangement constitutes a by-pass flow path by-passing the aquatic plant-containing filter bed. The throughflow through such by-pass flow path is controlled as a function of the operating conditions using adjustable control devices. Furthermore and in order to also control the hydromorphous conditions of the aquatic plant-containing filter bed, outfeed level control devices are provided for controlling the hydraulic gradient along substantially the entire aquatic plant-containing filter bed as a function of its operating conditions. The throughflow through the aquatic plant-containing filter bed thus can be controlled for achieving optimum purification of the inflowing liquid under substantially all occurring operating conditions.

Abstract: The filter bed containing aquatic plants planted therein is provided with a lengthwise and/or transverse drainage arrangement containing a predetermined number of drain pipes. Particularly during the growth phase of the aquatic plants, the drainage arrangement constitutes a by-pass flow path by-passing the aquatic plant-containing filter bed. The throughflow through such by-pass flow path is controlled as a function of the operating conditions using adjustable control devices. Furthermore and in order to also control the hydromorphous conditions of the aquatic plant-containing filter bed, outfeed level control devices are provided for controlling the hydraulic gradient along substantially the entire aquatic plant-containing filter bed as a function of its operating conditions. The throughflow through the aquatic plant-containing filter bed thus can be controlled for achieving optimum purification of the inflowing liquid under substantially all occurring operating conditions.

Abstract: With the method for the purification of sewage waters, in a first purification stage favorable conditions (pH, suspended matter) for the growth of ubiquiteous nitric bacteria are adjusted, whereby the loads of ammonia are to the major extent converted to nitrate. In a subsequent second purification stage in the form of a fixed mineral bed planted with emersed helophytes, the nitrate is reduced to nitrogen, and phosphate, sulfur, heavy metals and refractory carbon compounds are eliminated.

Abstract: For simultaneous elimination and fixation of phosphates from phosphate burdened aqueous liquids like sewage water a deposit space is formed by a soil matrix containing iron and/or aluminum. The soil matrix is defined by layers of poor hydraulic conductivity along its sides and at the bottom thereof and Limnophytae species like Phragmites, Typha, Carex, Glyceria, Eleocharis, Juncus, Iris pseudacorus, Iris versicolor, Schoenoplectus, Phalaris, Arundo are planted in the soil matrix to form a reactive space penetrated by the root systems of said plants. The phosphate containing liquid is introduced along one side of the deposit space and leaves the same with a phosphate content in the 0.1 mg/l range at flow rates in the range of 10.sup.-3 to 10.sup.-2 m per sec. Valuable phosphate deposits useful as arable land not requiring any phosphate fertilizer or useful as recoverable phosphate are obtained in amounts depending on the capacity and time period of phosphate fixation.