Method for large-scale preparation of Magnetic Activated Carbons (MAC)

Abstract

The present invention relates to large-scale preparation method of Magnetic Activated Carbon (MAC) suiting the process of micropollutants (1) removal from a liquid by● Pyrolyzing biomass at 100 to 1000°C, under reduced oxygen, to obtain charcoal comprising a residual volatile content of 4-16wt% and an ash content below 3wt%,● Pulverizing the charcoal and mixing with iron oxide or iron salt,● Mixing a binder and optionally extrusion aids to the mixture at elevated temperature, followed by kneading and homogenizing,● Extruding the mixture in pelletized form with diameters of 0.1 to 15mm, by using a hydraulic press and / or a screw extruder in various sequences or by using only a hydraulic press or only a screw extruder twice where the pressure is equal or different in each repetition.● Curing and subsequently activating the pellets at 700 to 900°C under reduced oxygen pressure with water as activation agent.

Description

The present invention relates to a method for large-scale preparation of Magnetic Activated Carbon (MAC), suitable for use in a process for removing micropollutants (1) from a liquid stream and use of the MAC.BackgroundActivated carbon with magnetic properties has the advantage of being easily separable from a system using magnetic forces. The idea to precipitate or crystallize a magnetic component into the porous network of an already activated carbon is straightforward and has been successfully applied. Incorporating iron components together with a precursor during the synthesis is the preferable procedure to obtain a functional and magnetic activated carbon. However, such incorporation reduces the surface area and pore volume of the activated carbon, and the magnetic component is only loosely integrated and may leach.Hydrothermal carbonization can provide an effective process for introducing nanosized iron components into carbonized material. Hydrothermally carbonized (HTC) biomass is a stable organic material with many prospective applications. Its associated carbonization process has high carbon efficiency, it is exothermic, and it has minor associated release of greenhouse gases. Baccile et al. determined the molecular nature of HTC glucose by carbonizing glucose that was enriched in 13C and studied the product with multidimensional solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.9 From such data they concluded that HTC biomass was on an average consisting of a heavily cross-linked polymer with mainly furanic moieties. Recently they showed that when nitrogen was present in the organic raw material, it was included in the cross-linked HTC biomass.10Activation of regular biomass into activated carbon can be performed physically or chemically. Physical activation is typically performed by treating various carbonaceous matter with air, carbon dioxide or steam at high temperature. Chemical activation is performed at elevated temperatures with addition of compounds such as KOH, ZnCI and H3PO4. Sevilla et al. chemically activated HTC biomass produced from eucalyptus sawdust with KOH at a temperature of 800ºC.12 Liu et al. activated HTC biomass prepared from pinewood sawdust and rice husk with carbon dioxide and reached specific surface areas of 569 m2 / g·13Waste biomasses often have environmental problems. Composting of horse manure releases climate gases and does not fully destroy pharmaceutical residues and pathogens that may leach into the environment. Grass cuttings releases both nitrous oxide and methane to the atmosphere, which both are greenhouse gases. Coconut shells and fruit pits have insignificant commercial values.US 7429330 and US 7879136 disclose a process for preparing magnetic activated carbon by adding solid-based iron oxide to a coal / pitch mixture, and compacting it before carbonization, followed by activation into activated carbon according to existing activation processes.US20100155335 discloses a process for preparing magnetic activated carbon by mixing already activated carbon with an iron solution, which has an 2 or 3 form, and followed by increasing the pH to let iron oxide precipitated in the pores of activated carbon.US20040147397 discloses a process, whereby magnetic activated carbons are prepared in a traditional two step method of carbonization and activation. Soluble iron is introduced into the carbon prior to carbonization by soaking the carbon precursors into a solution of the magnetic material precursor.US 8097185 discloses a process for preparing magnetic activated carbon, whereby a carbon precursor of soft wood is soaked in a solution of a ferric salt, dried, pyrolyzed and activated.WO2014027953A1 (Niklas Hedin, Malte LILLIESTRÅLE, Hao WENMING, Eva BJÖRKMAN) discloses an invention relating to a process for preparing magnetic activated carbons comprising the steps of a) treating an aqueous solution comprising a biomass hydrothermally at autogenic pressure at a temperature 180 and 250 °C, under acidic conditions in the presence of iron ions, to obtain a precursor product, b) activating the precursor product obtained in step a) by mixing an activating agent at elevated temperatures between 550 and 850 °C, for a period up to 9h. The invention also relates to magnetic activated carbon prepared according to said process and use of the carbon for separation and storage of gases and purification of liquids. Further, the invention relates to a method for separation of particles from a liquid and / or a gas, and method for regenerating magnetic activated carbon by heating using an oscillating electromagnetic field.There is still a need for a more efficient and cost-effective method for the preparation of active carbons. There is also a need for improved magnetic activated carbon products. The methods for preparing magnetic activated carbon that exist today are not adapted for large scale production. The existing methods are expensive and time consuming.SummaryIt is the aim of the present disclosure to provide a method for large-scale preparation of Magnetic Activated Carbon (MAC), suitable for use in a process for removing micropollutants from a liquid stream.This aim is achieved by a method as defined in claim 1.The disclosure provides a method for removing micropollutants from a liquid stream. The method comprises or consists of the steps of1) pyrolysis of biomass selected from the group comprising or consisting of wood, coconut shell, nutshell, fruit pit, manure, coffee grinds and agricultural waste, at a temperature of 100 to 1000°C, under reduced oxygen content, to obtain charcoal comprising a residual volatile matter content of 4-16 wt%, and comprising an ash content of less than 3 wt%, wherein weight percentages are percentages of the total weight of pyrolyzed biomass,2) pulverizing the obtained charcoal from step 1) and mixing with an iron oxide or iron salt in a proportion of 0.5 to 5 g iron per cm3 of charcoal,3) mixing the obtained mixture from step 2) with a binder and optionally other extrusion aids, at elevated temperature of 50 to 500°C, followed by kneading and homogenizing,4) extruding the mixture obtained in step 3) at a pressure of 7 to 35 MPa in pelletized form having a diameter of 0.1 to 15 mm, bya) first using a hydraulic press apparatus, and secondly using a screw extruder, orb) first using a screw extruder and secondly using a hydraulic press apparatus, orc) solely using a hydraulic press apparatus for at least 2 repetitions of extrusion, wherein the pressure applied is equal or different in each repetition, ord) solely using a screw extruder, for at least 2 repetitions of extrusion, wherein the pressure applied is equal or different in each repetition,5) curing the obtained pellets from step 4),6) activating the pellets at a temperature of 700 to 900°C under reduced oxygen pressure with the addition an activation agent.In some aspects, the activation agent is water.An advantage of the method of the invention is the provision of MAC at a large scale in an economically efficient manner. The iron becomes sintered into the carbonaceous skeleton of the activated carbon, preventing its ready elution from the surface by water or acids. This formation of nano-dispersed iron particles, induces a uniform magnetic characteristic throughout every particle of activated carbon, allowing attraction to permanent, temporary or electromagnets.In some aspects, the temperature in step 1) is 400 to 800°C or 400 to 600°C.In some aspects, the charcoal comprises a residual volatile matter content of 4 to 10 wt%, or 4 to 8 wt%. An advantage of the method of the invention is relatively low residual volatile matter.In some aspects, curing step 5) is performed in air, in two steps, first for at least 72 hours at room temperature and subsequently for at least 12 hours at a temperature of 250 to 600°C. One advantage of this aspect is the low energy consumption needed to perform this step hence allowing for large scale preparation.In some aspects, the binder in step 3) is selected from the group comprising or consisting of coal tar, molasses, whey and starch. Binders are substances that are added to biomass products during the production of pellets. The primary utility of binders is to provide cohesion as well as stability to pellets produced from biomass. They further ensure that the pellets preserve their shape in addition to their integrity throughout the production process and the transport stages. The use of a binder increases manufacturing efficiency and enhanced pellet quality. A binder also contributes to the fluidity of a mixture allowing for efficient subsequent extrusion. (Llamas-Unzueta et al. Journal of Environmental Chemical Engineering, Volume 10, Issue 3, June 2022). The use of binders such as whey can help in the production of pellets with good attrition resistance (ability to resist the impact of frictional forces generated in a milieu where hydrodynamic agitation exists). Furthermore, the binders mentioned can be obtained at low cost which is important in large preparation methods.The described method allows for large scale preparation as it uses biomass selected from a group comprising or consisting of wood, coconut shell, nutshell, fruit pit, manure, coffee grinds and agricultural waste. Importantly, those mentioned biomasses can be obtained at low cost and have reserves which are abundantly available, rendering them perfect for large-scale preparation methods.In some aspects, the other extrusion aids in step 3) are selected from the group comprising or consisting of lignocellulose, lignin and syrups.The use of extrusion aids improves the processability and quality of the thermoplastic polymer during the extrusion process. They also reduce friction between the melt and the metal parts of the extruder, allowing a smooth flow of the melt. This is especially important for large-scale production of MAC.In some aspects, the pellets have a diameter of 0.5 to 10 mm.The pellets have a high mechanical strength which in turn means that they can be transported more efficiently.In some aspects, in step 4c) or 4d) the pressure applied is higher in the first extrusion and lower in the second extrusion or lower in the first extrusion and higher in the second extrusion.An extrusion step allows for a high production volume at a low cost. Furthermore, extrusion on biomass can produce a reduction of the particle size distribution, an increase of the specific surface area (SSA) along with changes in crystallinity. (Duque et al. Renewable Energy, Volume 114, Part B, December 2017, Pages 1427-1441).In some aspects, the obtained pellets are subsequently crushed and sieved to obtain particles having a diameter between 0.045 to 6 mm.In some aspects, at least 90% of the particles have a diameter between 0.2 mm and 6 mm. In some aspects at least 95% of the particles have a diameter between 0.045 mm and 0.2 mm. In some aspects at least 90% of the particles have a diameter of less than 0.1 mm.In some aspects, the obtained crushed and sieved particles have a minimum magnetism of 1 emu / g. In some aspects, the magnetism is in the range of 1 to 50, or 10 to 25, or about 15 emu / g.ln some aspects the particles have a surface are of 400 to 2000 m2 / g, and a total pore volume of 0.050 and 2.0 cm3 / g, or 0.250 and 1.5 cm3 / g, or 0.50 and 1.5 cm3 / g as measured by nitrogen adsorption isotherm and calculated using BET (Brunauer-Emmett-Teller) model to calculate the pore volume and pore size. The microporous fraction may be 20 to 60, or 30 to 50% of the overall pore volume as measured using BET.The invention also relates to a use of the Magnetic Activated Carbon (MAC) prepared by the method defined anywhere herein, in a continuously process for removing micropollutants from a suspended liquid stream comprising or consisting of:a) providing a continuous flowing suspended liquid to a first container adapted to hold the suspended liquid, wherein the suspended liquid comprises micropollutants to be removed and at least 25 wt% of suspended solids, wherein weight percentages are percentages of the total weight of the suspended liquid,b) providing magnetic activated carbon (MAC) to the first container via a recirculation arrangement comprising a second container adapted to receive new MAC (and used MAC from a magnetic separator and configured to mix 1 to 50 wt% or 15 to 25 wt% new MAC and 50 to 99 wt% or 75 to 85wt% used MAC, prior to adding the 100 wt% MAC to the first container, wherein weight percentages are percentages of the total weight of MAC,c) adding the MAC (4) from the second container to the flowing suspended liquid in the first container,d) transferring the liquid mixed with the MAC to the magnetic separator,e) separating 50 to 99 wt% or 75 to 99wt% of the MAC from the suspended liquid using a magnetic separator,f) removing 50 to 99 wt% or 75 to 99wt% of the separated used MAC from the magnetic separator and transporting this MAC either to the second container for reuse or a recovery container for recovery of the adsorbed micropollutant,g) removing the suspended liquid from the magnetic separator, andh) repeating step a) to g) at least one time.An advantage of the MAC produced by the method as defined anywhere herein is that it can be used in suspended liquids. The iron will not leach from the carbon in the MAC particles, even when it is treated roughly in a suspended liquid.Brief description of the drawingsThe invention will now be explained more closely by the description of different embodiments of the invention and with reference to the appended figures.Fig. 1 shows a schematic overview of the method of claim 1.Fig. 2 shows different aspects of extrusion step 4).Fig. 3 shows a simplified cleaning process of the invention for cleaning a liquid.Aspects of the present disclosure will be described more fully hereinafter with reference to the accompanying drawing. The process disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout.The terminology used herein is for the purpose of describing aspects of the disclosure only and is not intended to limit the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.The term "liquid" includes the term wastewater and other liquids that are not water from which micropollutants need to be removed.The term "suspended liquid" used herein means a liquid comprising at least 25 wt% of suspended solids, wherein weight percentages are percentages of the total weight of the suspended liquidThe term "micropollutant" used herein means one or more organic or inorganic pollutant or contamination in a liquid or gas at a molecular level. The term micropollutant includes mineral micropollutants, such as metals and heavy metals, and radioactive isotopes of any micropollutant.The term "weight percentage" or" wt%" are weight percentage of the total weight of the ingredients, such as charcoal or MAC, unless stated otherwise.The term "unused magnetic activated carbon" may include regenerated and / or re-activated and / upgraded magnetic activated carbon.The term "PFAS" includes fluorinated carbon compounds, which may be poly- and perfluoronated compounds, such as for example compounds selected from the group comprising or consisting of PFBS, PFHxS, PFOS, 6:2 FTSA, PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, and PFDA, or any mixtures thereof.The terms "compound", "substances" and "molecule" have the same meaning unless expressly stated otherwise.Definition of "Residual volatile matter content" is the mass that can be removed from the resulting charcoal by heating in a controlled atmosphere to 950°C in a test similar to that provided in ASTM D5832 (2021).ASTM D5832 (2021) Volatile matter, when determined as herein described, may be used as a relative measure of the extent of carbonization in an activated carbon and the extent of loading of volatile material on an activated carbon that has been used in an adsorption application.Combined with other information, the volatile matter of an activated carbon may be useful in evaluating its performance in an adsorption application.Other automated methods for the determination of the volatile content of solids, such as using a thermogravimetric analyzer (TGA), can be used in place of this test method with equally reliable results.A method is disclosed for a large-scale preparation of Magnetic Activated Carbon (MAC) which is suitable for use in a process for removing micropollutants from a liquid stream. The method is achieved by the pyrolysis of biomass in step 1). The biomass may be selected from the group comprising or consisting of wood, coconut shell, nutshell, fruit pit, manure, coffee grinds and agricultural waste. The biomass may be selected from the group comprising or consisting of wood, coconut shell, nutshell and fruit pit. The biomass may be coconut shell.The pyrolysis is performed at a temperature of 100 to 1000°C, or 300 to 9000°C, or 500 to 800°C under reduced oxygen content, to obtain charcoal.The charcoal may comprise a residual volatile matter content of 4 to 16 wt%, or 4 to 12, or 4 to 10, or 4 to 8 wt%.The charcoal may comprise an ash content of less than 3 wt%, or 2 wt%, wherein weight percentages are percentages of the total weight of pyrolyzed biomass.Subsequently, in step 2) the obtained charcoal is pulverized and mixed with an iron oxide or iron salt in a proportion of 0.1 to 10 g, or 0.5 to 5 g, or 1 to 4.5 g iron per cm3 of charcoal. Examples of iron salts may be FeS04.In step 3) the mixture obtained from step 2) is further mixed with a binder and optionally other extrusion aids, at elevated temperature of 25 to 650°C, or 50 to 500°C, or 100 to 400°C followed by kneading and homogenizing.The binder used in step 3) may be selected from the group comprising or consisting of coal tar, molasses, whey and starch, or any mixture thereof. The binder used in step 3) may be coal tar, molasses and / or starch. The binder used in step 3) may be starch.Extrusion aids are materials used to improve the processability and quality of the thermoplastic polymer during the extrusion process. They are used to reduce friction between the melt and the metal parts of the extruder, allowing a smooth flow of the melt. The other extrusion aids used in step 3) may be selected from the group comprising or consisting of lignocellulose, lignin and syrups. The other extrusion aids used in step 3) may be lignocellulose.In step 4) this mixture is then extruded at high pressure of 5 to 40 or 7 to 35 MPa in pelletized form having a diameter or length of 0.1 to 15 mm. This can be achieved in different manners. In one method this is achieved by first using a hydraulic press apparatus, and secondly using a screw extruder. In another method, this is achieved by first using a screw extruder and secondly using a hydraulic press apparatus. In yet another method, this step 4) can also solely use a hydraulic press apparatus for at least 2 repetitions of extrusion, whereby the pressure applied is equal or different in each repetition. In yet a further method, this step 4) can solely use a screw extruder, for at least 2 repetitions of extrusion, wherein the pressure applied is equal or different in each repetition. The pressure applied in step 4 may be higher in the first extrusion and lower in the second extrusion. The pressure applied in step 4 may be lower in the first extrusion and higher in the second extrusion.Subsequently in step 5), the obtained pellets are cured. Pellets may be cured by different methods. In one curing method, the pellets are exposed to ambient air by creating thin layers (<300 mm) in a covered but open area for a period of not less than 72 hours, where the product steeps and changes chemical characteristics (e.g. hardening) without changing morphological properties (e.g. shrinking). In another curing method, the raw pellets are transferred to a suitable vessel, where a forced draft of ambient air is provided for 12-18 hours during which time the chemical characteristics of the pellet develop (e.g. hardening) with a change in morphology (e.g. shrinking). The pellets may be cured in air, in two steps, first for at least 72 hours at room temperature and subsequently for at least 12 or 15 hours at a temperature of 250 to 600°C, or 300 to 500°C.In step 6), the cured product may be activated at a temperature of 600 to 1000°C, or 700 to 900°C, or 600 to 850°C under reduced oxygen pressure with the addition of an activation agent. The activation agent may be water. The activation agent may be carbon dioxide.The preparation method of the invention may be a continuous method.The obtained pellets may subsequently be crushed and sieved to obtain particles having a diameter of 0.01 to 10 mm, or 0.045 to 6 mm, or 0.05 to 5 mm.At least 90% of the particles may have a diameter between 0.2 mm and 6 mm. At least 95% of the particles have a diameter between 0.045 mm and 0.2 mm. At least 90% of the particles have a diameter of less than 0.1 mm.The crushed and sieved particles may have a minimum magnetism of 0.5 or 1 emu / g.The obtained crushed and sieved particles may have a surface are of 300 to 3000, or 400 to 2500, or 400 to 2000 m2 / g, and a total pore volume of 0.050 and 2.0 cm3 / g, or 0.250 and 1.5 cm3 / g, or 0.50 and 1.5 cm3 / g as measured by nitrogen adsorption isotherm and calculated using BET (Brunauer-Emmet-Teller) model to calculate the pore volume and pore size. The microporous fraction may be 20 to 60, or 30 to 50% of the overall pore volume as measured using (Brunauer-Emmett-Teller) model to calculate the pore volume and pore size.ExperimentalTwo activation trials were carried out, 70 and 74% CTC.The pellets are magnetic.The results obtained are shown in table 1.Table 1wherein CTC = carbon tetrachloride, MC =, VM = volatile matter, ASH = ash content, BPH =, AD =The particles as prepared by the method of the invention may be used for removal of micropollutants 1 from a liquid stream. The micropollutants may be organic, inorganic or mineral pollutant or contamination in a liquid. Examples of micropollutants may be metals and heavy metals, such as gold and radioactive isotopes of any micropollutant.The liquid stream may be a suspended liquid stream, such as a stream comprising or consisting of at least 25 wt% of suspended solids, wherein weight percentages are percentages of the total weight of the suspended liquid 2.The MAC particles prepared according to the method of the invention may be used in a continuous cleaning process for removing micropollutants 1 from a suspended liquid stream 2 comprising or consisting of:a) providing a continuous flowing suspended liquid 2 to a first container 3 adapted to hold the suspended liquid, wherein the suspended liquid 2 comprises micropollutants 1 to be removed and at least 25 wt% of suspended solids, wherein weight percentages are percentages of the total weight of the suspended liquid 2,b) providing magnetic activated carbon MAC 4 to the first container 3 via a recirculation arrangement 7 comprising a second container 6 adapted to receive new MAC 4a and used MAC 4b from a magnetic separator 5 and configured to mix 1 to 50 wt% or 15 to 25 wt% new MAC 4a and 50 to 99 wt% or 75 to 85wt% used MAC 4b , prior to adding the 100 wt% MAC 4 to the first container 3, wherein weight percentages are percentages of the total weight of MAC,c) adding the MAC from the second container 6 to the flowing suspended liquid 2 in the first container 3,d) transferring the liquid 2 mixed with the MAC 4 to the magnetic separator 5,e) separating 50 to 99 wt% or 75 to 99wt% of the MAC 4 from the suspended liquid 2 using a magnetic separator 5,f) removing 50 to 99 wt% or 75 to 99wt% of the separated used MAC 4 from the magnetic separator 5 and transporting this MAC either to the second container 6 for reuse or a recovery container 8 for recovery of the adsorbed micropollutant 1,g) removing the suspended liquid 2 from the magnetic separator 5, andh) repeating step a) to g) at least one time.The cleaning process can be used to remove short and / or long chain PFAS and for removal of metals such as gold, palladium or silver.In the process of the invention, no use of filters is used prior to the entering of the suspended liquid into the first container nor after removal of the suspended liquid from the magnetic separator and / or no settling time is used in the first container. In the process of the invention the use of filters is disclaimed. In the process of the invention the use of filters prior to the entering of the suspended liquid into the first container is disclaimed. In the process of the invention the use of filters after removal of the suspended liquid from the magnetic separator is disclaimed. In the process of the invention settling time of the liquid prior to or during cleaning of the liquid is disclaimed.

Claims

1. A method for large-scale production of Magnetic Activated Carbon (MAC), suitable for use in a process for removing micropollutants (1) from a liquid stream, comprising the steps of1) pyrolysis of biomass selected from the group consisting of wood, coconut shells, nut shells, fruit kernels, manure, coffee grounds and agricultural waste, at a temperature of 100 to 1000 °C, under reduced oxygen, until charcoal is obtained comprising a residual volatile matter content of 4 to 16 wt. % measured according to test method ASTM D5832 (2021), and comprising an ash content of less than 3 wt. %, wherein the wt. % is a percentage of the total weight of pyrolysed biomass,characterized by2) pulverizing the charcoal obtained from step 1) and mixing with an iron oxide or an iron salt in a proportion of 0.5 to 5 g of iron per cm3 charcoal, 3) mixing the mixture obtained from step 2) with a binder and possibly other extrusion aids, at an elevated temperature of 50 to 500 °C, followed by kneading and homogenization,4) extruding the mixture obtained in step 3) at a pressure of 7 to 35 MPa into pelletized form with a diameter of 0.1 to 15 mm, bya) first using a hydraulic press, and then using a screw extruder, orb) first using a screw extruder and then using a hydraulic press, or(c) using only a hydraulic press for at least 2 repetitions of extrusion, the applied pressure being the same or different for each repetition, ord) using only a screw extruder, for at least 2 repetitions of extrusion, the applied pressure being the same or different for each repetition,5) hardening of the pellets obtained from step 4),6) activation of the pellets at a temperature of 700 to 900 °C under reduced oxygen pressure with the addition of an activating agent.

2. The method according to claim 1, wherein curing step 5) is carried out in air, in two stages, first for at least 72 hours at room temperature and then for at least 12 hours at a temperature of 250 to 600 °C.

3. The method according to claim 1 or 2, wherein the activating agent in step 6) is water.

4. The method according to any one of claims 1 to 3, wherein the binder in step 3) is selected from the group comprising coal tar, molasses, whey and starch.

5. The method according to any one of claims 1 to 4, wherein the other extrusion aids in step 3) are selected from the group comprising lignocellulose, lignin and syrups.

6. The method according to any one of claims 1 to 5, wherein in step 4c) or 4d) the applied pressure is higher in the first extrusion and lower in the second extrusion or lower in the first extrusion and higher in the second extrusion.

7. The method according to any one of claims 1 to 6, wherein the pellets obtained are subsequently crushed and sieved to obtain particles with a diameter between 0.045 and 6 mm.

8. The method according to claim 7, wherein at least 90% of the particles have a diameter between 0.2 mm and 6 mm, orat least 95% of the particles have a diameter between 0.045 mm and 0.2 mm, orwherein at least 90% of the particles have a diameter of less than 0.1 mm.

9. The method according to claim 7 or 8, wherein the resulting crushed and screened particles have a minimum magnetism of 1 emu / g.

10. Use of Magnetic Activated Carbon (MAC) prepared by the method according to any one of claims 6 to 9, in a continuous process for removing micropollutants (1) from a stream of liquid suspension (2) comprising at least 25% by weight of suspended solids comprising:a) providing a continuously flowing liquid suspension (2) to a first container (3) adapted to hold the liquid suspension, the liquid suspension (2) comprising micro-contaminants (1) to be removed and comprising at least 25% by weight of suspended solids, the weight percentages being percentages of the total weight of the liquid suspension (2),b) providing Magnetic Activated Carbon (MAC) (4) to the first container (3) via a recirculation device (7) comprising a second container (6) adapted to receive new MAC (4a) and used MAC (4b) from a magnetic separator (5) and configured to mix 1 to 50 wt% or 15 to 25 wt% new MAC (4a) and 50 to 99 wt% or 75 to 85 wt% used MAC (4b), before adding the 100 wt% MAC (4a, 4b) to the first container (3), wherein the wt% are percentages of the total weight of MAC (4),c) adding MAC (4a, 4b) from the second container (6) to the liquid suspension (2) in the first container (3),d) transferring the liquid (2) mixed with MAC (4) to the magnetic separator (5), e) separating 50 to 99% by weight or 75 to 99% by weight of the used MAC (4b) from the liquid suspension (2) using a magnetic separator (5),f) removing 50 to 99% by weight or 75 to 99% by weight of the separated used MAC (4b) from the magnetic separator (5) and transporting this used MAC (4b) either to the second container (6) for reuse or a recovery container (8) for recovery of the adsorbed micropollutant (1),g) removing the liquid suspension (2) from the magnetic separator (5), and h) repeating steps a) to g) at least once,wherein no use of filters is employed before introducing the suspended liquid into the first container or after removing the suspended liquid from the magnetic separator, and a settling time for the liquid before or during cleaning of the liquid is excluded.