Water treatment method with renewal of the adsorbent to a targeted intermediate age
A method for treating fluid, notably water, includes a renewal step in order to recover the adsorption capacities of an adsorbent bed, including the extraction of a sample of adsorbent from the adsorbent bed, the determination of a target mean age of the extracted adsorbent sample, in particular by the rejuvenation of at least one portion of the extracted adsorbent sample, at which target mean age the extracted adsorbent has a real abatement of pollutants corresponding to a previously set abatement objective, the rejuvenation of the adsorbent bed to the predetermined target mean age. The method makes it possible to improve the treatment of a fluid by adsorption, and notably to take into account the new contaminants. The disclosure also relates to a plant for treatment according to the proposed method.
1 . A method for treating fluid, the method comprising an adsorption step of adsorbing pollutants contained in the fluid by an adsorbent bed, and a renewal step to recover adsorption capacities of the adsorbent bed, the renewal step including:
extracting a sample of adsorbent from the adsorbent bed;
determining a target age of a rejuvenated adsorbent sample comprising at least a portion of the sample of adsorbent extracted from the adsorbent bed, at which target age the rejuvenated adsorbent sample achieves a real abatement of pollutants that meets a previously fixed abatement objective; and
rejuvenating the adsorbent bed to the determined target age,
wherein the rejuvenated adsorbent sample comprises a mixture of at least a portion of the sample of adsorbent and adsorbent of young age.
2 . The method according to claim 1 , wherein the renewal step is triggered periodically at a previously determined renewal frequency.
3 . The method according to claim 1 wherein the renewal step is triggered after a detection step of a quality defect in the fluid downstream of the adsorption step.
4 . The method according to claim 3 , wherein the detection step of a quality defect is performed when implementing the treatment of the fluid to be treated.
5 . The method according to claim 1 , wherein the extraction of the sample of adsorbent is carried out at a shutoff phase of the treatment of the fluid to be treated.
6 . The method according to claim 1 , wherein the extraction of the sample of adsorbent is carried out when implementing the treatment of the fluid to be treated, by sampling at one or more points of the adsorbent bed.
7 . The method according to claim 1 wherein, determining the target age of the rejuvenated adsorbent sample comprises measuring the real abatement of pollutants in a sample of fluid treated by the rejuvenated adsorbent sample.
8 . The method according to claim 7 wherein:
the rejuvenation of the adsorbent bed to the determined target age is obtained by partial replacement of adsorbent in the adsorbent bed with adsorbent of young age until the determined target age is obtained for the adsorbent bed.
9 . The method according to claim 8 , wherein determining the target age of the rejuvenated adsorbent sample comprises measuring a real abatement of pollutants in a number of sub-samples of rejuvenated adsorbent obtained by mixing portions of the sample of adsorbent with adsorbent of young age, in varying proportions, the sub-samples of rejuvenated adsorbent having a range of intermediate ages between an age of the sample of adsorbent and an age of the adsorbent of young age, and determining the target age based on the age of a sub-sample of the sub-samples of rejuvenated adsorbent having a real abatement of pollutants that meets the previously set abatement objective.
10 . The method according to claim 9 , wherein the number of sub-samples of rejuvenated adsorbent is 2 to 10.
11 . The method according to claim 8 , wherein measuring the real abatement of pollutants in the sub-samples of rejuvenated adsorbent is performed by Short Bed Adsorber measurements on beds of the sub-samples of rejuvenated adsorbent having volumes less than or equal to 100 mL.
12 . The method according to claim 1 , wherein the real abatement of pollutants is determined for a group of pollutants selected from the group formed by desethylhydroxyatrazine, metaldehyde, aminotriazole, metazachlorine, metazachlorine ESA, metalochlorine, metalochlorine ESA, desethylatrazine, chlortoluron, atrazine, terbuthylazine.
13 . The method according to claim 1 , wherein the previously fixed abatement objective is a minimum abatement value of the concentration of each pollutant in a group of pollutants.
14 . The method according to claim 1 , wherein the adsorbent bed comprises granular activated carbon and the adsorption step is performed by passing the fluid to be treated, in the form of an upflow through the adsorbent bed.
15 . An installation for treating a fluid, the installation comprising:
a reactor comprising an adsorbent bed configured to adsorb pollutants contained in the fluid to be treated and an orifice for withdrawal, at least partial, of spent adsorbent from the adsorbent bed;
a mixer configured to prepare rejuvenated adsorbent samples each comprising a mixture of spent adsorbent extracted from the adsorbent bed and adsorbent of young age; and
a measuring unit configured to measure a real abatement of pollutants by the rejuvenated adsorbent samples.
16 . The method according to claim 7 , wherein the sample of fluid is taken from the fluid downstream of the adsorption step and doped with pollutants prior passing the sample of fluid through the rejuvenated adsorbent sample to measure the real abatement of pollutants by the rejuvenated adsorbent sample.
17 . The installation for treating a fluid according to claim 15 , wherein the measuring unit is a Short Bed Adsorber measuring unit configured to measure the real abatement of pollutants by beds of the rejuvenated adsorbent samples each having a volume less than or equal to 100 mL.
18 . The method according to claim 8 , wherein the adsorbent bed has an age corresponding to a volume of fluid treated by the adsorbent in the adsorbent bed relative to a volume of the adsorbent bed.
19 . The method according to claim 18 , wherein the target age of the rejuvenated adsorbent sample indicates a volume fraction of the adsorbent in the adsorbent bed that must be replaced by adsorbent of young age for the adsorbent bed to meet the previously fixed abatement objective when implementing the method for treating fluid.
20 . The method according to claim 19 , wherein the previously fixed abatement objective requires a minimum percentage of each pollutant in a group of pollutants are retained by the adsorbent bed relative to an amount of each pollutant in the group of pollutants entering the adsorbent bed.