Patent FR-2793484-A1 (FR)
Title: Elimination of metal elements present in ionized state in water comprises oxidation of water by aeration, and passing through biofilter comprising bed of filter material supporting bacteria
Inventor: MOUCHET PIERRE
IPC: C02F3/00
Filed: 1999-05-12
Abstract: Ionized metals present in water are removed by oxidizing the water and passing through a bacteria-containing biofilter. The air flow is determined depending upon the redox potential of the aerated water before it passes through the biofilter. The patent refers to process of biological elimination of metal elements present in ionized state in water with low content of dissolved oxygen, comprising partial oxidation of water by specific aeration, followed by percolation through biofilter reactor comprising bed of bacteria-supporting filter material. The process comprises: (a) measuring at least one parameter related to redox potential (Eh) of aerated water before its passage through biofilter; (b) transmission of measured signal(s) to calculator and comparing the signal to at least one lower limit of this parameter determined as a function of a measure effected during the second stage of measuring a second parameter representing pH; and (c) optional correction of air flow according to the command of the organ of its regulation according to the signal determined by the calculator on basis of results of two previous stages.  The process preferably also comprises a stage of measuring a second parameter related to pH of aerated water before its passage through the biofilter and the stage of comparing with lower and upper limit of the first parameter. where the lower and upper limits are determined as a function of measure of the second parameter. The process preferably also comprises the stage of compensation of default of regulation of air flow by the first parameter by means of complementary regulation system utilizing at least one signal supplied by measuring residual content of oxygen dissolved in treated water, and optionally a second signal supplied by measuring pH of treated water simultaneously to measuring of dissolved oxygen. The process may also comprise the stage of regulation of pH of filtered water by injection of alkaline solution, in case when the measured signal is lower than that of required lower level; and a stage of measuring the efficacy of treatment by continuous measuring of content of residual dissolved iron and redox potential of filtered water, and launching alarm in case of detected anomaly.  Independent claims are also included for: (1) the use of process as claimed, with biofilter in form of bed of filtering material supporting the ferro-, manganese- or autotrophic bacteria, or using two consecutive biofilters, first with the bed of filtering material supporting ferro-bacteria, and the second with the bed supporting manganese-bacteria; and (2) the device for treatment of oxygen-poor water, comprising aeration chamber, with aeration conducted under pressure and with exit connected to biofilter reactor, first means of measuring pH and second means of measuring of redox potential of treated water, disposed within aeration chamber and the filter, calculating devices and means delivering command signal to the means of regulation of air flow, regulating valve, optional means of pH regulation, optional second aeration chamber, second biofilter reactor, and respective measuring means.