Method for removing dissolved organic matter from liquid using ultrafine particle adsorbent and reagent for carrying out said method

Abstract

Method for removing dissolved organic matter from liquid using ultrafine particle adsorbent and reagent for carrying out said method The present invention relates to a method for removing dissolved organic matter from a liquid using an ultrafine particle adsorbent, and also to reagents for carrying out the method. In order to achieve an improved method for removing (dissolved) organic matter in liquids using ultrafine particle adsorbents, the present invention provides a method according to the preamble, comprising the following method steps: - Measuring the concentration of dissolved organic matter in the liquid adding submicron pulverized activated carbon to the liquid to be treated in response to the measured organic matter concentration; and Mixing the powdered activated carbon with the liquid to be treated maintaining the mixture for a residence time sufficient for the powdered activated carbon to adsorb dissolved organic matter in the liquid; and removing the powdered activated carbon from the liquid by filtration.

Description

[Technical field]

[0001] The present invention relates to a method for removing dissolved organic matter from a liquid using an ultrafine particle adsorbent in a liquid flow system in which the liquid flows from a liquid inlet to a liquid outlet, and also to reagents for carrying out the method. [Background technology]

[0002] From the prior art, ultrafine particle adsorbents such as superfine powdered activated carbon (sPAC) for adsorption 50 It is known to use a sieve with a diameter of 1 to 5 μm to remove dissolved organic matter such as dissolved organic carbon (DOC), trace substances or microcontaminants (e.g., pharmaceuticals, industrial and household chemicals) from liquids.

[0003] Patent Document 1 discloses a method for removing impurities from water, particularly groundwater and drinking water, which method comprises: adding submicron pulverized activated carbon (sPAC) to the inflow of water to be treated; mixing the sPAC with the water to be treated; introducing the mixture of sPAC and water into an adsorption reactor for treatment; maintaining the mixture in an adsorption reactor for a residence time sufficient for the sPAC to adsorb impurities in the water; transporting the mixture from the adsorption reactor using a recycle pump to a high-rate ceramic membrane filter unit operating in cross-flow filtration, where the treated water is discharged as permeate and the sPAC is returned to the adsorption reactor as retentate.

[0004] Patent Document 2 discloses a method for pretreating organically polluted wastewater, which includes the steps of introducing wastewater into a reactor, adding an adsorbent, and separating thin sludge, and provides a method for pretreating organically polluted wastewater that can rapidly and effectively pretreat medium to large amounts of industrial wastewater, thereby allowing the pretreated water to be directly supplied to a bioreactor or a further pretreatment step.

[0005] Patent Document 3 describes a water treatment method in which powdered activated carbon is added.

[0006] Patent Document 4 describes a method for treating wastewater containing dioxins by adding activated carbon.

[0007] Patent Document 5 describes a water quality monitoring system that can control the chlorine concentration.

[0008] US Pat. No. 5,399,633 describes an activated carbon slurry process.

[0009] Non-Patent Document 1 describes a feasibility study on the separation of ultrafine activated carbon using fabric filters. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. 2020 / 180513A1 [Patent Document 2] European Patent Publication No. 1146016A1 [Patent Document 3] JP 2019-162583 A [Patent Document 4] JP 2002-153866 A [Patent Document 5] JP 2004-351326 A [Patent Document 6] U.S. Patent Publication No. 2019 / 0381478A1 [Non-patent literature]

[0011] [Non-Patent Document 1] “Abscheidung ultrafeiner Pulveraktivkohle mittels Tuchfiltration” [Separation of ultra-fine powdered activated carbon by means of cloth filtration], Philipp Hodel, HSR Hochschule fur Technik Rapperswil, Bachelorarbeiten 2017, page 34 Summary of the Invention [Problem to be solved by the invention]

[0012] It is an object of the present invention to provide a method for removing (dissolved) organics in liquid flow systems using ultrafine particle sorbents. [Means for solving the problem]

[0013] The object of the invention is achieved by a method according to a preamble, comprising the following method steps:

[0014] This method is measuring the concentration of dissolved organic matter at the liquid inlet and at the liquid outlet; Depending on the concentration of organic matter measured Particle diameter d 50 is 0.1-5 μm and is stored and added in the form of a suspension. adding an ultrafine particle adsorbent to the liquid to be treated and mixing said ultrafine particle adsorbent with the liquid to be treated; The mixture is subjected to a step of adsorbing dissolved organic matter in the liquid by the ultrafine particle adsorbent. 1 to 10 minutes holding for a residence time; The ultrafine particle adsorbent filter cloth filtration , preferably pile filtration or spatial filtration process and removing the liquid by

[0015] The present invention shows that it is useful to always add a sufficient amount of ultrafine particle adsorbent, while adjusting the amount of ultrafine particle adsorbent to the amount of dissolved organic matter contained in the liquid so as not to add too much.

[0016] Due to the short reaction time between the ultrafine sorbent and the dissolved organic matter resulting in a concentration difference between the inlet and the outlet, the addition of ultrafine sorbent is adjusted / controlled in real time to accommodate the concentration or removal at the liquid outlet, and this concentration difference is recorded by an online measurement. Conveniently, the concentration of the dissolved organic matter is measured (either as an individual substance or by a sum parameter) and the addition of ultrafine sorbent is adjusted or controlled based on this measurement.

[0017] Preferred, but not exclusive, fields of application of the method according to the invention are groundwater decontamination, urban and industrial wastewater treatment and water treatment, in particular wastewater filtration after chemical and biological treatment, which is the fourth treatment stage of wastewater treatment plants. Filtration in the context of the present invention is understood to mean all methods of surface and spatial filtration, in particular fabric filtration, in particular pile filtration.

[0018] The filter cloth filtration process, in particular the pile filtration process, proves to be particularly effective and economical in the context of the present invention. Depending on the particle size of the ultrafine particle adsorbent used, a corresponding fine mesh filter cloth can be used.

[0019] In the case of high loadings and / or to improve the separation of the ultrafine adsorbent by the filter cloth, multi-stage filtration, in particular two-stage filtration, can be used in the process, and filter cloths of different finenesses can also be used in the multi-stage filtration.

[0020] The liquid fed into the filtration system flows through the filter fabric, where organic matter and other solids are retained. This retention increases the resistance of the filter fabric, so that accumulated and embedded solids must be removed. Cleaning is performed by level control, time control or manually by suctioning the filter fabric, without interrupting the filtration during removal of the filter fabric. As mentioned above, the rinse water / process water generated here is preferably at least partially returned to the process or returned to an upstream process step.

[0021] The rinse water can also be treated / utilized separately.

[0022] The method according to the invention is suitable for liquid flow systems, where the liquid flows from the liquid inlet to the liquid outlet. It is reasonable to measure the concentration of dissolved organic matter at both the liquid inlet and the liquid outlet. Determined empirical values ​​for the concentration of dissolved organic matter at the liquid inlet and the liquid outlet, as well as the amount of ultrafine sorbent added in each case, are used to ensure that the appropriate amount of ultrafine sorbent is added in each case, so that a self-learning or self-regulating system can be created. The amount of ultrafine sorbent used is controlled and / or adjusted depending on the dissolved organic matter remaining in the liquid outlet, or the ratio of "dissolved organic matter at the liquid outlet" to "dissolved organic matter at the liquid outlet". For example, a UV-vis probe or a TOC / DOC analyzer is used for the online measurement of the concentration of dissolved organic matter. Due to the small particle size of the ultrafine sorbent, organic matter can be removed in a very short reaction time. Based on the concentration difference between the liquid inlet and the liquid outlet recorded by the online measurement, the addition of ultrafine sorbent is adjusted / controlled in real time, adapting to the concentration at the liquid outlet or the effective removal. This ensures that ultrafine particle adsorbents are always added as needed to ensure the removal of dissolved organic matter.

[0023] It should be noted that, advantageously, when the dissolved organic matter at the liquid outlet exceeds a set value, liquid is returned from the liquid outlet to the liquid inlet.

[0024] This prevents liquid with a dissolved organic matter content exceeding the target value from leaking from the liquid outlet.

[0025] It is within the scope of the present invention for the ultrafine particle adsorbent to be added in an amount of 0.1 to 1000 mg / l, preferably 1 to 100 mg / l, and particularly preferably 2 to 20 mg / l.

[0026] The amount used will vary depending on the dissolved organic matter and the ultrafine particle adsorbent used, or their interactions.

[0027] Ultrafine particle adsorbent 、0 Particle size d of 0.5 to 5 μm, particularly preferably 0.8 to 3 μm 50It is advantageous to have

[0028] When the specific surface area of ​​the ultrafine particle adsorbent is large, the dissolved organic matter has a large particle diameter (d 50 >5-10 μm adsorbents, the removal is much faster, taking only a few minutes (≦1-10 min). Furthermore, less adsorbent is required while maintaining the same removal of dissolved organic matter.

[0029] When activated carbon is used as the adsorbent, the ultrafine particle adsorbent is advantageously added in the form of a suspension, preferably at a concentration of 5 to less than 30% by weight, preferably 8 to 25% by weight, particularly preferably 10 to 15% by weight.

[0030] When ultrafine particle adsorbents such as activated carbon are added to a suspension, there is no risk of explosion. When granular activated carbon is used as a raw material for manufacturing ultrafine particle adsorbents, there is no risk of explosion in the process from storage of the raw material to use of the suspension (there is no explosion-proof area).

[0031] The suspension is produced either in batches or continuously, directly on-site or off-site. For this purpose, the adsorbent is ground, for example in a ball mill. In the single-stage grinding process and the use of activated carbon as the adsorbent, granular (≦500 μm) or powdered activated carbon (≦500 μm) is used as the starting material, and the grinding time is set to 100 s to reach the target particle size d 50 The grinding time is less than 5-60 minutes to produce ultrafine activated carbon with a particle size of ≦1-5 μm. The grinding is carried out in a single-stage process with activated carbon (≦500 μm) as the adsorbent. According to DIN EN 12915-1:2009-07, granular activated carbon is a granular product, according to which at least 90% of the mass fraction is retained on a test sieve of 180 μm. According to DIN EN 12903:2009-07, powdered activated carbon has a particle size of less than 150 μm and a mass fraction of 95%.

[0032] According to the present invention, the ultrafine particle adsorbent may contain activated carbon and / or bentonite and / or zeolite and / or polymeric adsorbent and / or silica gel, and mixtures thereof.

[0033] In principle, any adsorbent capable of adsorbing dissolved organic matter is suitable. These may be, for example, artificial organic trace substances (active pharmaceutical ingredients, X-ray contrast agents, substances from personal care and cleaning products, pesticides, flame retardants, perfluorinated chemicals, etc.) and / or organic carbon compounds. The raw materials of ultrafine particle adsorbents are usually powdery and / or granular and consist of substances that are compatible with the dissolved organic matter or water matrix. Furthermore, the adsorbents may contain suitable additives such as metal salts (e.g. divalent or trivalent iron salts and / or aluminum salts) and / or (cationic, anionic and / or nonionic) polymers to improve properties such as the outlet quality for separation by filter cloth. Such additives are added both before and after the preparation of the suspension.

[0034] A further development of the invention consists of ultrafine particle adsorbents which contain additives, in particular metal salts and / or polymers.

[0035] The suspension containing the ultrafine adsorbent may already contain additives such as metal salts and / or polymers, which are added together in the present process. The additives may be added directly during or after the production of the suspension. Alternatively, the additives may be added to the liquid separately from the ultrafine adsorbent. To better separate the ultrafine adsorbent during filtration, metal salts and / or polymers are optionally added, for example to the filtration liquid inlet and / or to the upstream catalytic reactor. The additives may be added simultaneously with the ultrafine adsorbent or immediately after the ultrafine adsorbent is added. The amount of additive used must be adjusted according to the process and is usually proportional to the amount of ultrafine adsorbent. The solids concentration in the liquid is used as an adjustment or control variable for the amount of additive.

[0036] Preferably, the ultrafine particle adsorbent is added to the liquid inlet.

[0037] The liquid inlet is defined here as the pre-filtration area where the liquid is treated. It may be, for example, the liquid inlet of a filtration system in a sewage treatment plant. By adding the ultrafine sorbent to the filtration liquid inlet, the reaction time for removing the organic matter corresponds to the hydraulic residence time of the method, which is 1-60 minutes or less at maximum filtration speed. Depending on the reaction behavior of the organic matter, a separate contact reactor for the action of the ultrafine sorbent before removing it from the liquid can therefore be omitted. To decouple the reaction time from the hydraulic residence time, the rinse / treatment liquid generated during filtration can be (partially) recirculated to the filtration liquid inlet or to a contact reactor upstream of the liquid inlet.

[0038] this method are used to treat liquids (municipal or industrial wastewater, drinking water, groundwater, lake, sea and river water, storm water, combined wastewater, road runoff, etc.) to remove dissolved organic matter such as dissolved organic carbon (DOC), trace substances or micropollutants (e.g. pharmaceuticals, industrial and household chemicals) and / or inorganic matter such as phosphates, ammonium compounds, metals, etc.

[0039] After preparation, the at least one adsorbent is mixed with at least one powdered or liquid flocculant before being added to the water treatment process, and the resulting agent containing the at least one adsorbent and the at least one flocculant is used to treat the liquid.

[0040] Preferably , suck Suspension of adhesives and flocculants With liquid The cumulative concentration of the adsorbent and flocculant in the suspension is 2 to 40% by weight, preferably 5 to 30% by weight, and particularly preferably 10 to 25% by weight.

[0041] Addition of a suspension of the adsorbent and flocculant ensures that the adsorbent and flocculant are added in the same location and at the same point in the process.

[0042] In this context, the pH value of the suspension is below 4 or above 10, preferably below 2.5 or preferably above 11.5. After addition of the agent according to the invention, the pH value of the liquid treated with the agent is preferably in the range of 5 to 10, preferably 6.5 to 8.5.

[0043] The at least one adsorbent is preferably selected from the group consisting of activated carbon, bentonite, zeolite, polymeric adsorbents, silica gel, iron oxide, iron hydroxide, and mixtures thereof.

[0044] In principle, any adsorbent capable of adsorbing dissolved substances, especially organic matter, is suitable. These may be, for example, artificial organic trace substances (active pharmaceutical ingredients, X-ray contrast agents, substances from personal care and cleaning products, pesticides, flame retardants, perfluorinated chemicals, etc.) and / or organic carbon compounds. The raw material of the adsorbent is usually in powder form (such as powdered activated carbon (PAC)) and / or superfine powdered activated carbon (sPAC) and consists of a material adapted to the dissolved organic matter or water matrix. Preferably, the raw material of the adsorbent consists of renewable or regenerative raw materials.

[0045] Adsorbent is in suspended form, so there is no explosion risk during the entire process from storage to use (no explosion-proof areas), even when using ultrafine particle adsorbents. The form of the agent also allows for simple and on-demand application in method steps, depending for example on the concentration and / or mass of organics to be removed or / and the amount of water to be treated. The agent allows for efficient and short application prior to the separation process. When using sPAC to remove >80% of organic trace substances, the required contact time is significantly shorter than 5 minutes.

[0046] In a preferred embodiment of the present invention, the at least two different adsorbents , includingThe first and second adsorbents preferably have different particle sizes. One adsorbent should usually be ultrafine and the other may be fine. For example, the reagent may contain a first adsorbent having a particle size in the range 0.1-10 μm, preferably 0.8-2 μm, and a further adsorbent having a particle size in the range 5-50 μm, preferably 5-15 μm.

[0047] The at least one flocculant is selected from the group consisting of divalent or trivalent metal salts, in particular iron(III) chloride, iron(III) chloride sulfate, iron(III) aluminum chloride, iron(III) aluminum sulfate, iron(III) aluminum chloride sulfate, iron(III) aluminum chloride hydroxide, sodium aluminate, and polyaluminum chloride. , suspension The adsorbent contains 1 to 2000 mg, preferably 10 to 500 mg, and particularly preferably 50 to 200 mg of the flocculant per 1 g of the adsorbent, in terms of dry mass.

[0048] According to the invention, the agent may also contain additional additives.

[0049] The additive may be in powder or liquid form.

[0050] Powdered and liquid additives may also be mixed into the reagent.

[0051] Preferably, the additive is selected from the group consisting of hydrochloric acid, caustic soda and dispersants.

[0052] These additives are used as stabilizers or dispersants for the product ingredients to improve separation in the liquid preparation process.

[0053] In the following, various embodiments of the agent according to the invention are presented in the form of batches, with an example using ultrafine activated carbon (sPACd50=1 μm, 10%) as adsorbent and iron(III) chloride as flocculating agent.

[0054] Each batch has a different ratio of adsorbent to flocculant.

[0055] The table below shows six batches containing different concentrations of sPAC in suspensions with different iron contents and the pH values ​​obtained in each case.

[0056] [Table 1]

[0057] The corresponding amount of coagulant (Fe 3+ Addition of 10 mg sPAC / l (containing 10 mg sPAC / l sPAC) reduces not only the phosphorus concentration but also the spectral absorption coefficients (SAC, which measures organic matter at 254 nm and true color at 436 nm, 525 nm, and 620 nm) at wavelengths of 254, 436, 525, and 625 nm.

[0058] The decrease in the spectral absorption coefficient at 254 nm serves as a proxy parameter for organic matter such as DOC and trace substances. In addition to removing phosphates, iron(III) chloride is also useful as a flocculant for ultrafine activated carbon.

[0059] The lower the turbidity of the suspension, the greater the flocculation efficiency of the ultrafine particle adsorbent and the greater the removal in the subsequent separation process.

[0060] [Table 2]

[0061] The removal of phosphates is not hindered by the adsorbent-flocculant mixture.

[0062] The table below shows that the corresponding phosphates are removed and the decrease in the spectral absorption coefficient is negligible.

[0063] [Table 3]

[0064] The reduction in the spectral absorption coefficient at wavelengths 254 nm, 436 nm, 525 nm and 625 nm is not prevented by the adsorbent-coagulant mixture. The adsorption mechanism is not affected by the combination of ultrafine particle adsorbent with ferric chloride. Phosphate is not removed and the adsorbable phosphorus fraction is removed by the use of the adsorbent.

[0065] [Table 4] TB: Turbidity LF: Conductivity NTU=Nephelometric Turbidity Units

[0066] When comparing the combined use of an adsorbent and a flocculant with the separate use of an adsorbent and a flocculant, there is no difference in the reduction in phosphate and the decrease in the spectral absorption coefficient at wavelengths of 254 nm, 436 nm, 525 nm, and 625 nm.

[0067] [Table 5]

[0068] Exemplary embodiments of the invention will now be described in more detail with reference to the drawings. [Brief description of the drawings]

[0069] [Figure 1] FIG. 1 shows a schematic diagram of the method according to the present invention when used in a distribution system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0070] The suspension is composed of a master adsorbent containing ground activated carbon, in this embodiment in the form of granular or powdered activated carbon, and a master suspension which in this embodiment contains water, the ground activated carbon being present in the suspension in a concentration of 5 to less than 30% by weight, preferably 8 to 25% by weight, particularly preferably 10 to 15% by weight.

[0071] This suspension is fed to a ball mill. After a grinding time of 5 to 60 minutes, the suspension is milled to produce a particle size d of 0.1 to 10 μm, preferably 0.5 to 5 μm, and particularly preferably 0.8 to 3 μm. 50 A suspension containing a fine particle adsorbent (preferably powdered activated carbon or the like) having the formula: is obtained. The grinding is preferably carried out in a single-stage process. The resulting product is stored in a master fine particle adsorbent.

[0072] In the method for removing dissolved organic matter from a liquid using the ultrafine particle adsorbent according to the present invention, the concentration of the dissolved organic matter in the liquid is measured, the ultrafine particle adsorbent is added to the liquid to be treated according to the measured concentration of the organic matter, and the ultrafine particle adsorbent and the liquid to be treated are mixed. When activated carbon is used as the adsorbent, powdered activated carbon in the form of a suspension is added from the master ultrafine particle adsorbent to the liquid inlet in an amount of activated carbon of 1 to 1000 mg / l, preferably 1 to 100 mg / l, particularly preferably 2 to 20 mg / l.

[0073] The mixture is then held for a reaction time sufficient for the ultrafine adsorbent to adsorb the dissolved organic matter in the liquid. At the end of the residence time, the ultrafine adsorbent is removed from the liquid. After the intended reaction time, the ultrafine adsorbent is preferably removed from the liquid by cloth filtration, particularly preferably polymer filtration, although multi-stage filtration, particularly two-stage filtration, is also possible.

[0074] Preferably, the concentration of dissolved organics is measured at both the liquid inlet and the liquid outlet, and when the dissolved organics at the liquid outlet exceed a target value, liquid is returned from the liquid outlet to the liquid inlet.

Claims

1. 1. A method for removing dissolved organic matter from a liquid using an ultrafine particle adsorbent in a liquid distribution system, wherein the liquid flows from a liquid inlet to a liquid outlet, comprising: preparing a suspension of ultrafine particle adsorbent having a particle size d50 of 0.1 to 5 μm and at least one powder or liquid flocculant, the suspension having a cumulative concentration of adsorbent and flocculant of 2 to 40 wt. %; measuring the concentration of dissolved organic matter at the liquid inlet and the liquid outlet; adding the suspension of ultrafine particle adsorbent and flocculant to the liquid to be treated in response to the measured concentration of the dissolved organic matter in the liquid to be treated and mixing the suspension with the liquid to be treated to form a mixture; allowing the mixture to stand for 1 to 10 minutes to allow the ultrafine particle adsorbent to adsorb the dissolved organic matter in the liquid; removing said ultrafine particle adsorbent from said liquid by a filter cloth filtration process.

2. 10. The method of claim 1, wherein when the dissolved organic matter at the liquid outlet exceeds a set value, the liquid is returned from the liquid outlet to the liquid inlet.

3. 2. The method of claim 1, wherein the ultrafine particle adsorbent is added in an amount of 0.1 to 1000 mg / l.

4. The ultrafine particle adsorbent has a particle diameter d of 0.5 to 5 μm. ５０ 2. The method of claim 1, comprising:

5. 2. The method of claim 1, wherein the ultrafine particle adsorbent is added in the form of a suspension at a concentration of 5 to less than 30% by weight.

6. 2. The method of claim 1, wherein the ultrafine particle adsorbent comprises activated carbon and / or bentonite and / or zeolite and / or polymeric adsorbent and / or silica gel and / or iron oxide and / or iron hydroxide or mixtures thereof.

7. 10. The method of claim 1, wherein the ultrafine particle adsorbent contains an additive.

8. 10. The method of claim 1, wherein the ultrafine particle adsorbent is added to the liquid inlet.

9. 10. The method of claim 1, wherein a multi-stage filtration is provided.

10. 2. The method of claim 1, wherein the suspension contains at least one flocculant selected from the group consisting of divalent or trivalent metal salts, and the suspension contains 1 to 2000 mg of the flocculant per 1 g of the ultrafine particle adsorbent on a dry weight basis.

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