METHOD FOR TREATING AT LEAST ONE TOTAL COLLOIDAL ORGANIC CARBON

Abstract

A treatment method of at least one colloidal TOC present in wastewater, said at least one colloidal TOC being selected among starch, oil, and dye, comprising the steps of: (a) un-stabilizing the at least one colloid TOC by adding an alkaline source to the wastewater to raise the pH to 11 to 12.5; (b) precipitating the at least one colloid TOC by adding a polymer flocculant; and (c) separating the at least one precipitated colloid TOC into solid and liquid under conditions of pH 11 to 12.5 and discharging it out of the system.

Description

24 METHOD FOR TREATING AT LEAST ONE TOTAL COLLOIDAL ORGANIC CARBON Technical Area

[001] The present invention relates to a method for treating non-biodegradable TOC (Total Organic Carbon) sources, for example, in wastewater from paper manufacturing and in water reused in the process, more specifically, to the treatment technology for starch, oil and dye, which are the main substances responsible for colloidal TOCs, but which are not treated by the general coagulation and flocculation process during chemical treatment and have low biodegradability, therefore causing loads in the biological treatment process.The present invention aims to treat sources of non-biodegradable TOCs that accumulate without decomposition in continuous circulation within the system, although the treated water must be reused due to the nature of the paper manufacturing process. Therefore, the present invention relates to a technology that aims to reduce odor in the paper manufacturing process, reduce foam generation, and improve productivity by improving chemical efficiency during the process. Background of the technique.

[002] The conventional treatment method is generally a chemical treatment method, which consists of a process of adding inorganic coagulants such as alum, PAC (polyaluminum chloride), ferric chloride, and ferric sulfate to precipitate soluble COD sources through a coagulation reaction, flocculating by applying a polymer flocculant, and then separating into solid and liquid. Subsequently, it is common to apply various methods, such as aerobic and anaerobic treatment as a biological treatment method, and to apply activated carbon adsorption, Fenton oxidation, etc. as a third advanced treatment method. However, when applied in practice, there has been a problem with the efficiency of TOC treatment being very low. In particular, there are large Petition 870250080289, dated 08 / 09 / 2025, page 13 / 44 / 24 changes in the efficiency of the input contaminant load, such as changes in the rates of used paper and changes in process chemicals depending on the type of paper produced, and there is a large amount of polyvalent metal ions, which are sources of hardness, such as circulating process water, and under accumulation conditions, there is a disadvantage that causes a decrease in productivity and a decrease in the quality of the paper produced due to a decrease in reactivity with polymeric substances and other additives that are papermaking chemicals in the process.

[003] Furthermore, due to continuous circulation within the system, as starch among non-biodegradable TOC sources, such as starch in used paper and starch added to develop paper strength during the process, fails to deposit on the paper stock during the manufacturing process and is lost in the anaerobic decomposition of white water, they lower the pH of the white water in the process, allowing more of the hardness source to dissolve, and the production of organic acids due to decomposition causes bad odors and foam generation in the process, and creates a vicious cycle that lowers the pH of the process water. In addition, oil does not decompose and adheres to the paper, causing paper breakage, or reduces the efficiency of process chemicals and becomes a causative agent that reduces the activity of microorganisms during the biological treatment process, and dyes, etc. are also fixed along with the starch and stabilized in a colloidal state, causing problems.

[004] To solve these problems, several wastewater treatment technologies have been developed, but the reality is that there are limits to improvements due to the nature of wastewater from papermaking, which exhibits large changes in properties and actual conditions and changes in load, and in particular, the development of treatment technology for colloidal sources of TOC has not been achieved and, due to this, Petition 870250080289, dated 08 / 09 / 2025, page 14 / 44 / 24, presents problems such as causing a decrease in the efficiency of the process chemicals, as well as an unexplained decline in quality, paper breakage, and excessive foam formation in the process.

[005] The Japanese patent, JP 2017-001015, is a technology that removes non-biodegradable phenol-based pigments in drainage water to reduce chromaticity while simultaneously removing phenols and TOC components, but has limitations in selectivity for phenol-like substances and in reducing non-biodegradable TOCs.

[006] International Publication PCT / JP1997 / 001785 refers to a method for improving the dispersibility and stability of bacterial cellulose suspension as a simple and economical method of producing a cellulose concentrate with improved papermaking properties, dispersibility, suspension stability and viscosity, and to a method for improving the papermaking properties of bacterial cellulose, which consists of concentrating an aqueous suspension of bacterial cellulose that has been subjected to disintegration treatment and then dispersing it again in an aqueous liquid, and in a bacterial cellulose concentrate thereof, but uses bacteria to stabilize a cellulose suspension and is therefore a technology that solves the opposite problem to that of the present invention.

[007] Japanese patent 2012-143739 A refers to an effective treatment device and treatment method for water treated with low COD concentration, low TOC concentration and low dye concentration, which is a technology for the biological treatment carrier and filtration method that uses a granular material made of pumice stone as a biological support, a granular material made of diatomaceous earth as a biological support and a non-woven fabric as a filter medium, but has the problem of being limited to biodegradable TOCs.

[008] Korean patent KR 10-1998-0085025 refers to a Petition 870250080289, dated 09 / 08 / 2025, p.15 / 44 / 24 A method for treating paper manufacturing wastewater by irradiating paper manufacturing wastewater with electron beams and adding a flocculant to remove various harmful organic substances from the wastewater. This method decomposes or converts harmful substances in paper manufacturing wastewater by blowing a bubbling gas into the wastewater and irradiating it with electron beams generated by an electron beam accelerator. This technology can remove harmful substances from paper manufacturing wastewater more efficiently compared to conventional methods, but the decomposition characteristics caused by electron beam irradiation have limitations in treating large quantities of paper manufacturing wastewater and require additional treatment of the decomposition products. Description Technical problem

[009] Thus, as a result of the research and efforts to solve the above problems, the inventor of the present invention seeks to provide a treatment method for the removal of non-biodegradable colloidal TOC sources in the paper manufacturing process and in wastewater. Technical Solution

[0010] According to the first aspect of the present description, the present description provides a method for treating at least one colloidal TOC present in wastewater, especially originating from a paper manufacturing process or the food industry, said colloidal TOCs being selected from starch (also called colloidal starch), oil and dye, and the method comprises the steps of destabilizing at least one colloidal TOC present in wastewater by adding an alkaline source to the wastewater to raise the pH to 11 to 12.5; precipitating Petition 870250080289, dated 09 / 08 / 2025, p. 16 / 44 / 24 or at least one colloidal TOC by adding a polymer flocculant; and separate the at least one colloidal TOC precipitate into solid and liquid under pH conditions of 11 to 12.5 and discharge it out of the system.

[0011] According to the second aspect of the present description, the present description provides a method for treating at least one colloidal TOC present in wastewater, especially originating from a paper manufacturing process or the food industry, said colloidal TOCs being selected from starch (also called colloidal starch), oil and dye, and the method comprises the steps of removing suspended solids (SS) by applying a polymeric flocculant to the wastewater, or removing suspended solids (SS) and some dissolved organic substances by applying an inorganic coagulant and a polymeric flocculant to the wastewater; destabilizing the at least one colloidal TOC present in the wastewater by adding an alkaline source to the wastewater to increase the pH to 11 to 12.5; precipitating the at least one colloidal TOC by adding a polymeric flocculant;Separate at least one colloidal TOC precipitate into solid and liquid under pH conditions of 11 to 12.5 and discharge it out of the system.

[0012] Advantageously, the inorganic coagulant is alum, PAC (polyaluminum chloride).

[0013] In one specific embodiment, the wastewater originates from a recycled paper manufacturing process.

[0014] In one specific form, TOCs are a mixture of starch and oil. Advantageous effects

[0015] According to the present invention, the present invention can treat stabilized and non-biodegradable colloidal TOC sources that accumulate without decomposition in continuous in situ circulation in the paper manufacturing process or in the food industry, which requires reuse of Petition 870250080289, dated 08 / 09 / 2025, page 17 / 44 / 24 treated water due to its nature and, through this, can reduce odor, reduce foam generation and improve chemical efficiency during the process. Description of the Drawings

[0016] Figure 1 is a graph of the reaction with colloidal sources of TOC according to the amount of alkaline chemicals input.

[0017] Figure 2 is a photograph showing the colloidal state when treated with alkaline chemicals, treated with amphoteric polymer flocculant, and neutralized with acid.

[0018] Figure 3 is a photograph showing the state of change in turbidity due to alkaline treatment.

[0019] Figure 4 is a graph of changes in pH and turbidity according to alkaline treatment.

[0020] Figure 5 is a photograph showing the state of change in turbidity due to alkaline treatment.

[0021] Figure 6 is a graph of changes in pH and turbidity according to alkaline treatment. Best Way

[0022] The terminology used herein is intended to refer only to specific examples and is not intended to limit the invention. As used herein, singular forms include plural forms unless the sentences clearly indicate otherwise. As used in the specification, the meaning of comprising specifies specific features, areas, whole numbers, steps, operations, elements and / or components, and does not exclude the presence or addition of other features, areas, whole numbers, steps, operations, elements and / or components.

[0023] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as those generally understood by those skilled in the art in the field. Petition 870250080289, dated 08 / 09 / 2025, page 18 / 44 / 24 technical to which the present invention relates. Terms defined in commonly used dictionaries are interpreted as having meanings consistent with the related technical literature and the content currently described, and should not be interpreted in an idealized or overly formal sense unless otherwise defined.

[0024] Examples of the present invention will be described in detail below so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in many different ways and is not limited to the examples described herein.

[0025] Normally, the process described in this specification refers to the treatment of wastewater from the paper manufacturing process, but it can be extended to other fields, such as the treatment of wastewater from the food industry.

[0026] In the present invention, the chemical treatment prior to the TOC removal process refers to a suspended solids (SS) removal process by applying a polymeric flocculant alone to the raw wastewater in the water collection tank, or a colloidal TOC removal process after the removal of suspended solids (SS) and some dissolved organic substances by applying an inorganic coagulant and a polymeric flocculant in parallel.

[0027] The biological treatment process is a process that decomposes and removes biodegradable TOC sources, which are organic substances, during the metabolic process of microorganisms. In general, several methods, such as the activated sludge process, A2O, and SBR, have been developed, but in the case of wastewater containing colloidal TOCs, it is common for the efficiency of biological treatment to decrease during the biological treatment process because the degradation of colloidal TOC sources is preferred over the degradation process by microorganisms of soluble TOC sources, or interfering forms and colloidal TOC sources are decomposed. Petition 870250080289, dated 08 / 09 / 2025, page 19 / 44 / 24 and become sources of dissolved TOC or exist as sources of low molecular weight colloidal TOC. For example, in the case of starch, due to its high molecular weight, its molecular weight decreases when decomposed by microorganisms, but it continues to exist as a source of TOC, and in the case of oil, it binds to the surface of microorganisms and becomes a causative agent that interferes with the transfer of material and the metabolism of microorganisms, and in the case of dye, it binds to starch and becomes a source of colloidal TOC that inhibits both starch and oil due to its hydrophobic nature. Therefore, the present invention is a technology for maximizing the efficiency of treating TOC sources by eliminating colloidal TOC sources and improving the reduction in efficiency caused by colloidal TOC sources during the biological treatment process, which is a pre-treatment process prior to biological treatment.

[0028] In the present invention, biological treatment refers to methods such as activated sludge process, A2O and SBR.

[0029] The papermaking process using ordinary white water has a pH of 6.0 to 7.2, and raw wastewater has a similar pH level. In the case of general wastewater treatment and in-process neutralization, there is an alkali treatment method for simple pH adjustment to bring the pH into the neutral range, or in some cases, a salinization treatment method that utilizes the characteristic that the solubility of metals decreases under alkaline conditions. However, when performing alkaline treatment for organic substances, it is not treated at pH 8 or higher, and the general treatment method is to adjust the pH back to neutral for chemical treatment after the process.

[0030] In other words, the objective of the above method is to precipitate the metal ions contained in the water by temporarily adjusting the pH to such a condition that the metal ions become suspended in the water, and then a polymeric coagulant is added to form a precipitate. This Petition 870250080289, dated 08 / 09 / 2025, page 20 / 44 / 24, describes a process used to treat wastewater, for example, from an electroplating plant, wastewater from flue gas desulfurization, wastewater from a power plant, and wastewater from a waste incinerator (see JP2019111513A). Such a process is also described in KR101955048, which refers to a method for treating wastewater using colored filters and mixing copper corrosion wastewater and aluminum corrosion wastewater.

[0031] In contrast, the purpose of the invention process is not to precipitate an inorganic metal by reversible pH change, but to pretreat colloidal TOCs such as starch, which acts as a dry strength agent in recycled paper, colloidal starch, which is a decomposition product thereof, and lubricants discharged from machinery during the process. Thus, the present invention does not directly remove TOC, but pretreats these colloidal starches and oils that exist as interfering substances in the overall wastewater treatment process, which is the TOC removal process.

[0032] According to the present invention, the treatment efficiency of non-biodegradable TOCs, turbidity removal efficiency, and pH characteristics according to neutralization can be evaluated to assess applicability in unit processes such as the paper production process, raw wastewater flowing to the wastewater treatment plant, primary chemically treated water, and secondary biologically treated water. Unlike adjusting the pH of the paper manufacturing process to 6.0 ~ 7.2 using white water, the present invention is distinguished by the simultaneous flocculation of unstabilized colloidal starch, dye deposited on the colloidal starch, oil solidified by the saponification reaction, and a source of hardness with reduced solubility, by removing suspended solids (SS) from the incoming raw wastewater, and then by adding alkaline chemicals to increase the pH to 11 or Petition 870250080289, dated 08 / 09 / 2025, page 21 / 44 / 24 further to destabilize colloidal TOC sources and flocculation by applying an amphoteric polymer flocculant in a highly alkaline state without pH neutralization.

[0033] According to an essential feature of the invention process, alkaline conditions are maintained until the treated water is discharged. If the pH is neutralized in the meantime, the colloidal components will be re-stabilized.

[0034] The reaction mechanism of colloidal TOC sources with the alkalinity source in the present invention is divided into a section where the pH increases in proportion to the amount of alkaline chemicals input when alkaline chemicals are added below C in Figure 1, a section of colloidal destabilization of the colloidal TOC sources and alkaline chemicals, where the alkaline chemicals are consumed with almost no increase in pH, even if the amount of alkaline chemicals input is continuously increased, as in the section of amount of alkaline chemicals input from C to D, and a section where the pH rises proportionally again when alkaline chemicals are added, as in the amount of input above D.

[0035] The pH adjustment in the present invention is a treatment method for destabilizing colloidal TOCs that are stabilized and dispersed in water by adding alkaline chemicals at pH 11 or higher, depending on the TOC sources present in the raw wastewater, to precipitate colloidal and dissolved TOCs, and perform flocculation treatment under highly alkaline conditions without neutralization. To prevent the removal of colloidal TOCs from becoming impossible due to the property that unstabilized colloidal TOC sources are re-stabilized when adjusted to pH 7-8 by neutralization again as in C of Figure 2, the pH range at the time of precipitation should be adjusted to 8 or higher, or Petition 870250080289, dated 08 / 09 / 2025, page 22 / 44 / 24 preferably from 10.5 to 12.5. As the precipitation conditions of colloidal and dissolved TOCs are different, a treatment method according to their properties is an important technology.

[0036] Meanwhile, in the case where there are no colloidal sources of TOC, if the alkaline chemicals are increased, the pH continues to rise; however, in the case where there are colloidal sources of TOC, if the alkaline chemicals are increased, when the pH is above a certain pH, as in sections C to D of Figure 1, the main mechanism is to precipitate the colloidal sources of TOC while the increase in pH is no longer large, or the pH is reduced or does not change, and in sections C to D, the alkaline chemicals are consumed due to continuous reactions and therefore a reaction may occur that further reduces the pH.

[0037] This mechanism for removing colloidal TOC exhibits two main turbidity change characteristics. In the first change characteristic, the turbidity starts with high turbidity, as in A of Figure 1, and then there is no change in turbidity, and then the turbidity decreases rapidly. In the second change characteristic, the turbidity shows a change in the form of a continuous increase from low turbidity, as in B, and then a rapid decrease again. This is classified into form A, where there appears to be no change in turbidity when there is a substance causing high turbidity in the wastewater, but as the colloidal TOC sources are precipitated and precipitated, the turbidity decreases rapidly, and in form B, where only the colloidal TOC sources exist without a turbidity source, and then as the TOC sources are precipitated at the time of alkaline treatment, the turbidity increases rapidly, and when at pH levels above that, as precipitation occurs, the turbidity decreases.

[0038] When testing wastewater from which the SS present in raw wastewater from paper manufacturing has been removed, Figures 3 and 4 show that the initial turbidity is low, but continues to increase during the Petition 870250080289, dated 08 / 09 / 2025, page 23 / 44 / 24 alkaline treatment and then rapidly decreases when a certain amount of alkali is added, and Figures 5 and 6 show that the turbidity was initially high, but it changes and then rapidly decreases to the same level when a certain amount of alkali is added. All this is caused by the induction of turbidity by precipitated colloids according to the reaction between the alkaline chemicals and the colloidal TOCs, and when the pH is above a certain level, the unstabilized colloids are precipitated, resulting in a sharp decrease in turbidity.

[0039] The reaction by the colloidal TOC removal technology of the present invention is a reversible reaction. Consequently, when the pH is adjusted again with acid, it is re-stabilized and thus the precipitate disappears to form stabilized colloids. Therefore, for the present invention to be effective, the impact of its circulation can only be eliminated by discharging the colloidal TOC sources out of the system by means of solid-liquid separation, applying sedimentation and pressure flotation and treating them separately, after flocculation by a polymer flocculant under pH 11 or higher conditions. The polymeric flocculant applied here is a general chemical treatment in which only anionic polymeric flocculants with a negative charge (-) maintain their charge under alkaline conditions with a pH of 11 or higher.However, in the present invention, since the unstabilized colloidal TOCs are a complex composition or a single composition of starch, oil and dye, and the dissolved TOCs are also partially removed, anionic and cationic flocculants can be applied and, more preferably, it is more efficient to apply an amphoteric polymer flocculant that has (-) and (+) between the polymer flocculants.

[0040] Precipitation is possible even without the application of a flocculant under alkaline conditions of pH 11 or higher, but to increase the efficiency of solid-liquid separation and reduce processing time and plant capacity, it is efficient to apply a polymeric flocculant. It can Petition 870250080289, dated 08 / 09 / 2025, page 24 / 44 / 24 There may be differences in efficiency depending on the type and amount of charge of the polymeric flocculant, but this is not limited to the type. Preferably, an amphoteric polymer flocculant with 30 to 50 mol% cationic content and 20 mol% or less anionic content can be used for sediments from colloidal TOC sources with a complex composition.

[0041] The types of alkaline chemicals are not limited to these types, and sodium hydroxide, calcium hydroxide, sodium aluminate, sodium bicarbonate, ammonium hydroxide, and ammonia can be used. This is possible with an alkaline treatment method that increases the pH by adding the alkalinity source in the gaseous state. Preferably, in order to suppress the increase in conductivity while decreasing the hardness caused by calcium (Ca) in the process, the application of calcium hydroxide is more preferable. In some cases, it is possible to apply both simple alkaline chemicals and mixed alkaline chemicals, such as the application of a mixture of sodium alginate and sodium hydroxide.

[0042] The amount of alkaline chemicals to be added varies depending on the content of the colloidal TOC sources to be treated and the properties of the process water and wastewater to be treated. However, it is most efficient to adjust the pH to 10.5 or higher. Because colloidal TOC sources become unstable above pH 8 and cause turbidity, the amount of added is not specified. However, based on examples, it is preferably used in the range of 0.05 to 0.3% by weight based on sodium hydroxide. If the amount used is less than 0.05% by weight, there will be no improvement effect because the removal efficiency of the colloidal TOC sources is low. If the amount used exceeds 0.3% by weight, unnecessary amounts will be added, making it less economical.

[0043] As an application method, a method is possible in which a portion of the white water flow within the papermaking process is collected, treated with colloidal TOCs, and then introduced back into the process. Petition 870250080289, dated 08 / 09 / 2025, page 25 / 44 / 24 and is carried out in the form of processing colloidal TOCs as pre- or post-treatment at each stage of the water collection tank, the first, second and third treatment in the wastewater treatment process, or a method is possible in which part of the wastewater treatment process is collected and then used to treat the colloidal TOCs and mixed with reused water for reuse in the process, and so on.Ideally, this is the most efficient method for optimizing the efficiency of biological treatment, removing suspended solids (SS) by applying a polymeric flocculant to the raw wastewater in the collection tank, or removing suspended solids (SS) and some dissolved organic substances by applying an inorganic coagulant and polymeric flocculant and then passing through the colloidal TOC removal process (chemical treatment before the TOC removal process) and subsequently returning to the collection tank (first chemical treatment), or mixing the first chemical treatment with the biological treatment process, thus reducing the processing load of colloidal TOCs during the biological treatment process.The method of applying only polymeric flocculant to raw wastewater is a method to reduce the unnecessary consumption of alkaline chemicals during alkaline treatment due to a neutralization reaction with the components of suspended solids (SS) and to increase the efficiency of the reaction with colloidal TOC sources and, depending on the process, can be applied without removing suspended solids (SS) from the raw wastewater in the water collection tank.

[0044] By applying this colloidal TOC removal technology, it is also possible to treat the entire amount of wastewater generated and white water circulating in the process. However, preferably, if the amount treated is greater than the amount accumulated in the system, the system can be continuously stabilized. In real-world application, it was Petition 870250080289, dated 08 / 09 / 2025, page 26 / 44 / 24 confirms that it is possible to stabilize the entire process within a given period of time by treating only 5 to 20% of the amount of wastewater generated, but there is no limitation on the application capacity.

[0045] In the present invention, the type of wastewater is also not limited, and both wastewater containing starch and process water can be used.

[0046] Thus, to avoid the problem of continuous circulation destabilizing non-biodegradable TOC colloidal sources, causing them to precipitate and stabilize again when the pH is reduced, in conventional TOC treatment technology that uses alkaline chemicals in the treatment of wastewater and production process water containing starch, oil, and dyes as colloidal sources of TOC, the present invention is a technology that can improve the accumulation of TOC through circulation by reusing it, and the accumulation of organic acids, the reduction of pH, and the interference in the mechanism of action of process chemicals through acid fermentation after decomposition, by applying solid-liquid separation under an alkaline condition and thus removing the colloidal sources of TOC, which are interfering substances in the physical, chemical, and biological treatment process, and therefore,The present invention can be applied in various industrial fields where TOCs are high or treatment efficiency is reduced by colloidal TOCs. Example

[0047] TOCs after first treatment and turbidity after first treatment refer to the concentration and turbidity of TOCs after treatment according to Comparative Examples or Examples, respectively.

[0048] TOCs and turbidity after the second treatment refer to the concentration and turbidity of TOCs after application of the Examples and Comparative Examples during the first treatment and after passing through Petition 870250080289, dated 08 / 09 / 2025, page 27 / 44 / 24 biological treatment.

[0049] In all examples, the wastewater originates from corrugated cardboard.

[0050] In all examples except examples 15 and 17, the TOCs are a mixture of starch and oil. Comparative Example 1

[0051] As a chemical treatment at the rear of the water collection tank, 500 mg / l of PAC and NaOH were added to adjust the pH to 7, and then an anionic polymer flocculant was added to prepare a first treated water. After that, biological treatment was carried out on the first treated water, and then the treated water was reused in the process. Comparative examples 2 to 4

[0052] The same method as in Comparative Example 1 was performed, except that in Comparative Example 1, the PAC is increased to 1,000, 1,500 and 2,000 mg / l as the first treatment, and the amount of NaOH and flocculating agent input is adjusted proportionally. Examples 1 to 3

[0053] The pH was adjusted to 11.4 by adding 0.15 wt% NaOH to 10% of the flow rate in the raw wastewater, and EM533 (70 / 30 AM / AA.Na) as an anionic polymer flocculant, C-540CT (50 / 50 AM / ADAME.Quat) as a cationic polymer flocculant, and F-540HIB (40 / 50 / 10 AM / ADAME.Quat / AA.Na) as an amphoteric polymer flocculant were applied respectively, and after flocculation, the colloidal TOCs were collected as foam, dehydrated, and removed to produce a first treated water. After biological treatment was applied to the first treated water, the treated water was reused in the process. Examples 4 to 6

[0054] As a chemical treatment at the rear of the collection tank Petition 870250080289, dated 08 / 09 / 2025, page 28 / 44 / 24 of water, 500 mg / l of PAC were added and thus coagulation was carried out by chemical treatment and, after removal of suspended matter by application of a polymeric flocculant, the pH was adjusted to 11.4 by adding 0.15% by weight of NaOH to 10% of the flow rate. EM533 as an anionic polymer flocculant, C-540CT as a cationic polymer flocculant and F-540HIB as an amphoteric polymer flocculant were applied respectively, and thus flocculation was carried out and then by means of pressure flotation, the colloidal TOCs were collected as foam and removed by dewatering to prepare primary treated water. After the biological treatment was applied to the first treated water, the treated water was reused in the process. Examples 7 to 11

[0055] As a chemical treatment at the rear of the water collection tank, 500 mg / l of PAC was added, thus coagulation was carried out by chemical treatment and, after removal of suspended matter by application of a polymeric flocculant, alkaline treatment was carried out by adding 0.05, 0.1, 0.2, 0.25 and 0.3 wt% NaOH to 10% of the flow rate. F-540HIB was applied as an amphoteric polymer flocculant, and thus flocculation was carried out, and then, by means of pressure flotation, the colloidal TOCs were collected as foam and removed by dewatering to prepare the first treated water. After biological treatment was applied to the first treated water, the treated water was reused in the process. Table 1

[0056] Evaluation of the efficiency of biological treatment according to the removal of colloidal sources of TOC by alkaline treatment. Item Content of the change condition TOC after the first treatment (mg / l) Turbidity after the first treatment TOC after the second treatment (mg / l) Turbidity after the second treatment TOC removal efficiency Example Comparative 1 500 mg / l of PAC 1560 298 847 121 45.7% Petition 870250080289, dated 08 / 09 / 2025, page 29 / 44 / 24 Comparative Example 2: Increase in quantity for PAC 1,000 mg / l: 1540, 283, 831, 109, 46.0%. Comparative Example 3: Increase in quantity for PAC 1,500 mg / l: 1531, 308, 834, 112, 45.5%. Comparative Example 4: Increase in quantity for PAC 2.000mg / l 1533 321 829 108 45.9% Example 1 Anionic polymer flocculation treatment after colloidal treatment of raw water 1502 94 512 43 65.9% Example 2 Cationic polymer flocculation treatment after colloidal treatment of raw water 1498 83 488 22 67.4% Example 3 Amphoteric polymer flocculation treatment after colloidal treatment of raw water 1478 64 465 14 68.5% Example 4 Anionic polymer treatment after PAC treatment and colloid treatment 1452 25 412 24 71.6% Example 5 Cationic polymer treatment after PAC treatment and colloid treatment 1433 21 398 10.3 72.2% Example 6 Treatment with Amphoteric polymer after treatment with PAC and treatment with colloid 1398 13 392 8.2 72.0% Example 7 In Example 4, colloidal treatment with 0.05% NaOH 1528 199 634 83 58.5%. Petition 870250080289, dated 08 / 09 / 2025, page 30 / 44 / 24 Example 8 In Example 4, colloidal treatment with 0.1% NaOH 1514 132 576 62 62.0% Example 9 In Example 4, colloidal treatment with 0.2% NaOH 1411 10 145 9.4 89.7% Example 10 In Example 4, colloidal treatment with 0.25% NaOH 1342 8.3 118 5.4 91.2% Example 11 In Example 4, colloidal treatment with 0.3% NaOH 1313 6.5 96 2.1 92.7% Comparative Example 1

[0057] When treating wastewater containing colloidal TOC sources according to Example 1, the TOC removal rate and turbidity removal rate were measured at 45.7% and 59.4% after the second treatment. Comparative examples 2 to 4

[0058] As in Comparative Examples 2 to 4, even if the amount of PAC input as an inorganic coagulant applied to the chemical treatment is continuously increased from 500 mg / l to 2,000 mg / l, the treatment efficiency is not significantly improved, with the TOC removal rate remaining at the 46% level. Therefore, it has been confirmed that there is a limit to improving efficiency even if biological treatment is carried out after overall chemical treatment. Examples 1 to 3

[0059] It was confirmed that, as a result of adding 0.15% by weight of alkali to the same raw wastewater from Comparative Example 1 to destabilize the colloidal TOCs and thus achieve precipitation, and then adding anionic, cationic and amphoteric polymer flocculants, respectively, the reduction of TOCs during the first chemical treatment process is as low as 5% compared to Example 1. Petition 870250080289, dated 09 / 08 / 2025, p. 31 / 44 / 24 Comparative Example 1 (3.7%, 4.0%, and 5.2%, respectively), but after the second treatment, the TOC removal rate of the second treated water is 65.9~68.5%, which represents an improvement of more than 20% compared to Comparative Example 1. This means that, although the removal of dissolved TOCs is not significant through alkaline treatment, efficiency can be increased by reducing the load caused by colloidal contaminants during the biological treatment process by removing the sources of colloidal TOCs.Furthermore, it was confirmed that in the case of Example 3, where the amphoteric polymer flocculant is applied, since colloids can be destabilized and removed in the form of anionic or cationic properties, depending on the ionic species during alkaline treatment, the colloidal sources of TOC are destabilized from uncharged stabilized colloids and, at the same time, are flocculated and precipitated along with other ionic substances, thus showing greater efficiency in TOC removal. Examples 4 to 6

[0060] It was confirmed that the concentration of TOCs after the first treatment according to Example 4 was improved by 6.9% compared to Comparative Example 1, which was also improved by 3.2% compared to the concentration of TOCs after the first treatment according to Example 1. Furthermore, it was confirmed that the turbidity after the first treatment was improved by 91.6% compared to Comparative Example 1, and was also improved by 23.2% compared to the turbidity after the first treatment according to Example 1. Thus, Table 2 shows the comparison of Example 5 with Comparative Example 1 and Example 2, and the comparison of Example 6 with Comparative Example 1 and Example 3. Petition 870250080289, dated 08 / 09 / 2025, page 32 / 44 / 24 Table 2 TOC after the first treatment (mg / l) Turbidity after the first treatment Rate of improvement in TOC compared to Comparative Example 1 Difference in rate of improvement in TOC Rate of improvement in turbidity compared to Comparative Example 1 Difference in rate of improvement in turbidity Comparative Example 1 1560 298 Example 1 1502 94 3.7% 68.5% Example 2 1498 83 4.0% 72.1% Example 3 1478 64 5.3% 78.5% Example 4 1452 25 6.9% 3.2% 91.6% 23.2% Example 5 1433 21 8.1% 4.2% 93.0% 24.5% Example 6 1398 13 10.4% 5.1% 95.6% 17.1%

[0061] It was confirmed that the concentration of TOCs after the second treatment according to Example 4 is improved by 51.4% compared to Comparative Example 1, which is further improved by 11.8% compared to the concentration of TOCs after the second treatment according to Example 1. Furthermore, it was confirmed that the turbidity after the second processing was improved by 80.2% compared to Comparative Example 1, and was further improved by 15.7% compared to the turbidity after the first processing according to Example 1. Thus, Table 3 shows the comparison of Example 5 with Comparative Example 1 and Example 2, and the comparison of Example 6 with Comparative Example 1 and Example 3. Table 3 TOC after the second treatment (mg / l) Turbidity after the second treatment Rate of improvement in TOC compared to Comparative Example 1 Difference in rate of improvement in TOC Rate of improvement in turbidity compared to Comparative Example 1 Difference in rate of improvement in turbidity Comparative Example 1 847 121 Example 1 512 43 39.6% 64.5% Example 2 488 22 42.4% 81.8% Example 3 465 14 45.1% 88.4% Example 4 412 24 51.4% 11.8% 80.2% 15.7% Petition 870250080289, dated 08 / 09 / 2025, page 33 / 44 / 24 Example 5: 398, 10.3%, 53.0%, 10.6%, 91.5%, 9.7% Example 6: 392, 8.2%, 53.7%, 8.6%, 93.2%, 4.8% Examples 7 to 11

[0062] It was confirmed that, in the case of Examples 7 and 8, the alkaline chemicals were not added in an absolute quantity that could sufficiently destabilize the colloidal TOC source and, therefore, the TOC removal efficiency is low due to the influence of residual colloidal TOC sources (Removal efficiencies: 58.5% and 62.0%). It was confirmed that in the case of Example 9, by adding 0.2% by weight of the alkaline chemicals, the TOC removal rate of the second treated water is improved to 90% or more, up to 92.7%, and approximately 47% is removed compared to 45.7% in Comparative Example 1, and the removal efficiency is improved by more than two times.In Examples 10 and 11, the rate of increase in TOC removal efficiency was low compared to the effect of increasing the amount of alkaline chemicals input. Furthermore, mixing with existing first-treated water to increase the consumption of alkaline chemicals and introduce colloidal treated water into the downstream process, since the pH is increased, neutralization with an additional acidic material is necessary, which may be undesirable. Therefore, it was confirmed that the desirable amount of NaOH input is 0.1 to 0.2% compared to 10% of the raw wastewater flow rate. By reneutralizing the pH to neutral using acid again for downstream biological treatment, while maintaining TOC and turbidity removal efficiency, neutralization is possible by mixing with the first chemically treated water without the application of acidic material.

[0063] It has been confirmed that, as a result of using treated water as process water in the paper production process, while colloidal TOCs are removed for 2 weeks using the method according to Example 9, mixed with the first chemically treated water or with the raw wastewater in the water collection tank and treated using the method of Petition 870250080289, dated 08 / 09 / 2025, page 34 / 44 / 24 existing processing, as the sources of colloidal TOC accumulated in the process water are removed, acid fermentation does not occur even in the paper production process under anaerobic conditions and therefore the pH of the white water in the process is maintained at 7 or higher. Furthermore, stable application was possible without the generation of odor or foam caused by organic acids generated by acid fermentation, and the colloidal treatment method of the present invention can be operated continuously, but when the accumulated colloidal TOC sources are small, it is treated for a certain period of time and, under low accumulation conditions, once the system is maintained in a stable state, intermittent application is considered possible. Examples 12 to 14

[0064] These examples show the impact of the treatment according to the invention (colloidal treatment) depending on the pretreatment that is carried out (polymeric flocculant or PAC) before said colloidal treatment. Table 4 Item Content of the change condition TOC before colloid treatment (mg / l) TOC after colloid treatment (mg / l) TOC removal efficiency Example 12 Original wastewater 587.8 409.0 30.4% Example 13 Wastewater after removal of suspended solids by application of a polymeric flocculant 587.8 390.4 33.6% Example 14 Wastewater after treatment with PAC (500 mg / l PAC) 481.9 320.4 33.5% Examples 15 to 17

[0065] These examples show the efficiency of the treatment, regardless of the nature of the wastewater. Petition 870250080289, dated 08 / 09 / 2025, page 35 / 44 / 24 Table 5 Item Wastewater Type TOC before any treatment (mg / l) TOC after treatment with PAC (500 mg / l PAC) TOC after treatment with PAC (500 mg / l PAC) + colloid treatment (mg / l) Example 15 Newspaper wastewater 347.9 304.6 272.8 Example 16 Corrugated cardboard wastewater 530.1 484.8 410.9 Example 17 High White paper wastewater 629.1 526.2 480.7 Petition 870250080289, dated 08 / 09 / 2025, pages 36 / 44

Claims

1 / 2 CLAIMS 1. A method for treating at least one colloidal Total Organic Carbon (TOC) present in wastewater, said at least one colloidal TOC being selected from starch, oil, and dye, characterized in that it comprises the steps of: (a) destabilizing the at least one colloidal TOC by adding an alkaline source to the wastewater to raise the pH to 11 to 12.5; (b) precipitating the at least one colloidal TOC by adding an amphoteric polymeric flocculant with 30 to 50 mol% cation content and 20 mol% or less anion content; and (c) separating the at least one precipitated colloidal TOC into solid and liquid under pH 11 to 12.5 conditions and discharging it out of the system.

2. A method for treating at least one colloidal Total Organic Carbon (TOC) present in wastewater according to claim 1, characterized in that the alkalinity source is at least one selected from sodium hydroxide, calcium hydroxide, sodium aluminate, sodium bicarbonate, ammonium hydroxide, and ammonia.

3. A method for treating at least one colloidal Total Organic Carbon (TOC) present in wastewater according to any of the preceding claims, characterized in that, prior to step (a), it comprises the steps of removing suspended solids (SS) by applying a polymeric flocculant to the wastewater, or removing suspended solids (SS) and some dissolved organic substances by applying an inorganic coagulant and a polymeric flocculant to the wastewater.

4. Method for treating at least one colloidal Total Organic Carbon (TOC) present in wastewater according to Petition 870250080289, dated 08 / 09 / 2025, page 43 / 44 2 / 2 claim 3, characterized in that the inorganic coagulant is alum or polyaluminum chloride.

5. A method for treating at least one colloidal Total Organic Carbon (TOC) present in wastewater according to any of the preceding claims, characterized in that the wastewater originates from a paper manufacturing process.

6. A method for treating at least one colloidal Total Organic Carbon (TOC) present in wastewater according to claim 5, characterized in that the wastewater originates from a recycled paper manufacturing process.

7. A method for treating at least one colloidal Total Organic Carbon (TOC) present in wastewater according to any one of claims 1 to 4, characterized in that the wastewater originates from the food industry.

8. A method for treating at least one colloidal Total Organic Carbon (TOC) present in wastewater according to any of the preceding claims, characterized in that the TOCs are a mixture of starch and oil. Petition 870250080289, dated 09 / 08 / 2025, p. 44 / 44

Images