PROCESS AND INSTALLATION FOR LIQUID PURIFICATION EMPLOYING A CONTROLLED-FLOW FILTER BED CONTAINING PLANTS

摘要

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.