Method for treating wastewater containing multiple metal ions and organic compounds and wastewater treatment system performing the same

Abstract

The present invention relates to a wastewater treatment method and system capable of effectively removing multiple metal ions and organic compounds from wastewater containing multiple metal ions such as Co, Cu, Ni, Sr, and Cs, as well as non-biodegradable and biodegradable organic compounds, contained in radioactive wastewater, industrial wastewater, medical wastewater, etc.

Description

Technology Field

[0001] The present invention relates to a wastewater treatment method and system capable of effectively removing multiple metal ions and organic compounds from wastewater containing multiple metal ions such as Co, Cu, Ni, Sr, and Cs, as well as non-biodegradable and biodegradable organic compounds, contained in radioactive wastewater, industrial wastewater, medical wastewater, etc. Background Technology

[0003] Currently, wastewater generated at general industrial sites, including specific industries such as nuclear power plants and hospitals, contains a mixture of various organic compounds and metal ions, such as heavy metals, that are toxic to the human body.

[0004] In particular, at nuclear-related facilities such as nuclear power plants, the use of organic decontamination agents for chemical decontamination results in the presence of environmentally toxic organic acids, such as oxalic acid, and various other chemicals in the wastewater.

[0005] Oxalic acid, primarily used as a decontamination agent, exists in wastewater bound to metal ions and is a difficult-to-decompose organic compound; as such, research to effectively remove it is continuously ongoing.

[0006] Currently, commonly used wastewater treatment technology involves the oxidation and decomposition of organic matter using ultraviolet rays and hydrogen peroxide. However, this method has the disadvantage that it requires a large number of UV devices to use high-energy ultraviolet rays, and also requires a large amount of oxidizing agent.

[0007] In addition, treating 95% of difficult-to-decompose organic compounds such as oxalic acid in decontamination wastewater requires more than 5 hours, so there is a need for high-efficiency treatment technology that can be done in a short time.

[0008] In addition, existing wastewater treatment methods generate a large amount of wastewater sludge, and the treatment of the generated wastewater sludge is also causing other environmental problems. Prior art literature

[0010] Korean Registered Patent Publication No. 10-0659482 (Publication Date Dec. 19, 2006) Korean Registered Patent Publication No. 10-2073018 (Publication Date Feb. 4, 2020) The problem to be solved

[0011] The present invention aims to provide a wastewater treatment method and system capable of efficiently precipitating and removing in a single reaction tank (treatment tank) while reducing the amount of precipitated sludge generated and ensuring the stability of the generated sludge in a basic environment, by selectively removing sparingly soluble organic compounds in wastewater containing multiple metal ions and organic compounds by inducing a stable precipitation reaction without an extreme pH environment and sequentially removing harmful metal ions. means of solving the problem

[0013] The method for treating wastewater containing multiple metal ions and organic compounds according to the present invention for solving the above problem comprises a process including: a first step of precipitating a non-degradable organic compound from wastewater containing multiple metal ions and organic compounds; and a second step of precipitating multiple metal ions from the wastewater that has undergone the first step.

[0014] As a preferred embodiment of the present invention, the multiple metal ions are a 4th-period metal ion, a 5th-period metal ion, a 6th-period metal ion, and Ra 2+ Includes one or more types selected from among.

[0015] As a preferred embodiment of the present invention, the 4th period metal ion is Cu 2+ , Ni 2+ , Co 2+ and Zn 2+ It includes one or more selected from among, and the 5th period metal ion is Sr 2+ , Cd 2+ and Ag + It includes one or more selected from among, and the 6th period metal ion is Cs + , Ba 2+ , Hg 2+ and Pb 2+It may include one or more types selected from among.

[0016] As a preferred embodiment of the present invention, the non-degradable organic compound comprises one or more selected from oxalic acid, maleic acid, tartaric acid, malic acid, succinic acid, phthalic acid, and salts thereof.

[0017] As a preferred embodiment of the present invention, the organic compound of step 1 may further include one or more selected from biodegradable organic compounds and surfactants.

[0018] As a preferred embodiment of the present invention, the wastewater of the first step may have a pH of 1 to 5.

[0019] As a preferred embodiment of the present invention, the precipitation reaction of the first step and the precipitation reaction of the second step are performed under a pH of 7.5 to 9.5.

[0020] As a preferred embodiment of the present invention, in the first step, after adding a Ca precursor, the pH is adjusted to 7.5 to 9.5 to Ca 2+ It can be performed by precipitating the reaction product that was reacted with it.

[0021] As a preferred embodiment of the present invention, the Ca precursor may include one or more selected from CaCl2, Ca(NO3)2, Ca(CH3COO)2, CaSO4, CaCO3, CaO, and Ca(OH)2.

[0022] As a preferred embodiment of the present invention, the second step can be performed by adding K4Fe(CN)6 to the wastewater from the first step and reacting it with multiple metal ions to precipitate the reaction product.

[0023] As a preferred embodiment of the present invention, the second step comprises, wherein the multiple metal ions in the wastewater of the first step, together with the 4th period metal ions, 5th period metal ions, 6th period metal ions, and Ra 2+In cases where it contains one or more metal ions selected from among, a sulfate containing one or more selected from Na2SO4, K2SO4, and (NH4)2SO4 is added to and reacted with the wastewater from which Step 1 has been performed to produce 5th period metal ions, 6th period metal ions, and Ra 2+ Step 2-1 for precipitating reaction products; Step 2-2 for adding and reacting K4Fe(CN)6 to the wastewater from Step 2-1 to precipitate 4th period metal ion reaction products; and FeX3 (where X is Cl) to the wastewater from Step 2-2. - , F - or OH - A process including 2-3 steps of adding an iron salt represented by ) to form and precipitate iron ferrocyanide crystals may also be performed.

[0024] As a preferred embodiment of the present invention, the wastewater of the first stage comprises multiple metal ions together with 4th-period metal ions, 5th-period metal ions, 6th-period metal ions, and Ra 2+ In the case where one or more metal ions selected from among are included, a pretreatment process may be performed to precipitate the reaction products of period 5 metal ions and period 6 metal ions by adding and reacting a sulfate containing one or more selected from Na2SO4, K2SO4, and (NH4)2SO4 to the wastewater before performing step 1, and if the pretreatment process is performed, the step 2-1 process may be omitted.

[0025] As a preferred embodiment of the present invention, the first and second steps can be performed as a batch process in a single reactor.

[0026] As a preferred embodiment of the present invention, a third step may be further performed, in which, after removing the precipitate from the wastewater that has undergone the second step, a process for removing residual organic compounds from the wastewater from which the precipitate has been removed is performed, or a process for removing residual organic compounds from the supernatant is performed after separating the supernatant excluding the precipitate from the wastewater that has undergone the second step.

[0027] As a preferred embodiment of the present invention, the second step may be performed with or without removing the precipitate generated and settled in the first step.

[0029] In addition, the present invention aims to provide a wastewater treatment system that performs the wastewater treatment method described above.

[0031] The expressions 4th period, 5th period, and 6th period of the terms 4th period metal ion, 5th period metal ion, and 6th period metal ion used in the present invention refer to the 4th period element, 5th period element, or 6th period element of the periodic table. Effects of the invention

[0033] The wastewater treatment method of the present invention can effectively remove sparingly soluble organic compounds by inducing a stable precipitation reaction without an extreme pH environment, and enables stable post-treatment by immobilizing metal ions in the wastewater within the lattice of iron ferrocyanide crystals. Furthermore, since the amount of reagent used is small, the amount of sludge generated during the treatment process is smaller than that of conventional wastewater treatment processes, thereby minimizing environmental problems caused by secondary waste. Brief explanation of the drawing

[0035] Figures 1A to 1C are graphs showing the TOC removal rate, Cu removal rate, and Ni removal rate measurements according to pH of the simulated waste liquid in Example 1. Figures 2A and 2B are graphs showing the TOC removal rate and metal ion removal rate measurements according to the concentration of K4Fe(CN)6 in the simulated waste liquid in Example 2. Figures 3A and 3B are graphs showing the TOC removal rate and metal ion removal rate at different concentrations of K4Fe(CN)6 in the simulated waste liquid in Example 3. Figure 4 is a graph showing the TOC and metal ion removal rates for simulated wastewater containing non-degradable organic compounds and biodegradable organic compounds (surfactants) and simulated wastewater containing only biodegradable organic compounds, as performed in Example 5. Figures 5 and 6 are graphs showing the TOC removal rate and metal ion removal rate measured at each reaction step in Example 6. Figures 7 and 8 are graphs showing the TOC removal rate and metal ion removal rate according to the presence or absence of precipitates when treating recalcitrant organic compounds and metal ions using Ca(OH)2 and / or Mg(OH)2 in the simulated wastewater treated in Example 7. Figure 9 is an XRD measurement graph for the final sludge performed in Example 7. Figures 10A and 10B are graphs measuring the TOC removal rate and metal ion removal rate according to the amount of Ca(OH)2 added to the simulated waste liquid in Example 8. Figures 11A and 11B are graphs of the TOC removal rate and metal ion removal rate measurements performed in Example 9. Figures 12A and 12B are graphs of the TOC removal rate and metal ion removal rate measured in Example 10. Specific details for implementing the invention

[0036] The expressions "4th period, 5th period, 6th period" in the terms 4th period metal ion, 5th period metal ion, and 6th period metal ion used in the present invention refer to a 4th period element, a 5th period element, or a 6th period element of the periodic table.

[0037] The present invention will be described in more detail below.

[0038] The wastewater treatment method of the present invention performs a process comprising: a first step of precipitating a non-degradable organic compound from the wastewater; and a second step of precipitating multiple metal ions from the wastewater that has undergone the first step; wherein the first step and the second step may be performed separately in different reactors (treatment tanks), and preferably, they may be performed as a batch process in the same reactor (treatment tank).

[0039] In addition, a third step process may be further performed to remove biodegradable organic compounds from wastewater from which non-degradable organic compounds and multiple metal ions have been removed by performing the second step.

[0040] The wastewater in step 1 may be wastewater generated from nuclear power plants, hospitals, research institutes, factories, etc., and may contain various multiple metal ions and sparingly soluble organic compounds.

[0041] The above multiple metal ions are 4th period metal ions, 5th period metal ions, 6th period metal ions, and Ra 2+ It may include one or more types selected from among.

[0042] The above 4th period metal ion is Cu 2+ , Ni 2+ , Co 2+ and Zn 2+ It may include one or more types selected from among.

[0043] The above 5th period metal ion is Sr 2+ , Cd 2+ and Ag + It may include one or more types selected from among.

[0044] The above 6th period metal ion is Cs + , Ba 2+ , Hg 2+ and Pb 2+ It may include one or more types selected from among.

[0045] In addition, the above-mentioned non-degradable organic compound may include one or more selected from oxalic acid, maleic acid, tartaric acid, malic acid, succinic acid, phthalic acid, and salts thereof.

[0046] In addition, the organic compounds in the wastewater may further include biodegradable organic compounds.

[0047] The wastewater of the above-mentioned first step may have a pH of 1 to 5, and if the wastewater is decontamination wastewater from a nuclear power plant, the pH may be 3 or lower.

[0048] As a preferred embodiment of the present invention, the precipitation reaction of the first step and the precipitation reaction of the second step are performed at a pH of 7.5 to 9.5, preferably at a pH of 7.8 to 9.0, and more preferably at a pH of 7.8 to 8.8. At this time, if performed at a pH below 7.5, there may be a problem with reduced metal ion removal efficiency, and if performed at a pH above 9.5, there may be a problem with reduced flame-retardant organic compound removal efficiency, so it is advantageous to perform the first and second steps within the above pH range.

[0049] In the wastewater treatment method of the present invention, the first step involves adding a Ca precursor and then adjusting the pH to 7.5 to 9.5, preferably 7.8 to 9.0, and more preferably 7.8 to 8.8 to treat recalcitrant organic compounds with Ca 2+ It can be performed by precipitating the reaction product that was reacted with it.

[0050] The Ca precursor of step 1 may include one or more selected from CaCl2, Ca(NO3)2, Ca(CH3COO)2, CaSO4, CaCO3, CaO, and Ca(OH)2, and preferably may include one or more selected from CaCl2 and Ca(OH)2.

[0051] In addition, the above pH can be adjusted using an aqueous solution of a base containing one or more selected from NaOH, KOH, NH4OH, Mg(OH)2 and Ca(OH)2.

[0052] As a preferred example of step 1, 1.8 to 2.5 moles of Ca precursor are added for every 1 mole of non-biodegradable organic compound in wastewater, preferably 2.0 to 2.2 moles.

[0053] For a specific example, in the case where 100 ml of wastewater contains 0.02 M of recalcitrant organic compounds, 0.05 to 0.15 M CaCl2 is added in a volume ratio (v / v) of 0.027 to 0.800, preferably 0.030 to 0.600, and more preferably 0.035 to 0.500. After adding NaOH to adjust the pH, the sparingly soluble organic compounds (e.g., HC2O4) dissolved in the wastewater are... - , C2O4 2- etc.) Ca 2+ The reaction product (CaC2O4, Ca(HC2O4)2) generated by the reaction with precipitates.

[0054] As another desirable example of step 1, when using Ca(OH)2 as a Ca precursor, using Mg(OH)2 as a pH adjuster is advantageous for the reaction, and after adding 0.01 to 0.12 M Ca(OH)2 to the wastewater in a volume ratio (v / v) of 0.20 to 1.0, 0.05 to 0.15 M Mg(OH)2 is added to adjust the pH and perform the precipitation reaction.

[0055] In addition, it is advantageous in terms of metal ion removal efficiency to perform the reaction and precipitation in step 1 at 20°C to 30°C for 1 to 4 minutes, preferably at 24°C to 26°C for 1 to 2 minutes.

[0056] If the wastewater of the first stage contains multiple metal ions, including one or more metal ions selected from the 5th and 6th period metal ions along with the 4th period metal ions, a pretreatment process may be performed to precipitate the reaction products of the 5th and 6th period metal ions by adding and reacting a sulfate containing one or more selected from Na2SO4, K2SO4, and (NH4)2SO4 to the wastewater before the first stage is performed, and if the above pretreatment process is performed, the 2-1 stage process described below may be omitted.

[0058] In the wastewater treatment method of the present invention, the second step is a process of removing multiple metal ions from wastewater by introducing K4Fe(CN)6 into the wastewater that has undergone the first step and reacting it with multiple metal ions to precipitate the reaction product.

[0059] In addition, the second step may be performed with or without removing the precipitate generated and settled in the first step, and preferably, it may be performed without removing the precipitate generated and settled in the first step.

[0060] The above Step 2 comprises, in the case of the multiple metal ions in the wastewater of Step 1 together with 4th period metal ions, 5th period metal ions, 6th period metal ions, and Ra 2+ Step 2-1, in which, if containing one or more metal ions selected from among, a sulfate is added and reacted to precipitate the reaction products of 5th-period metal ions and 6th-period metal ions; Step 2-2, in which K4Fe(CN)6 is added and reacted to the wastewater from Step 2-1 to precipitate the reaction products of 4th-period metal ions; and FeX3 (where X is Cl) to the wastewater from Step 2-2. - , F - or OH - A process including 2-3 steps of adding an iron salt represented by ) to form and precipitate iron ferrocyanide crystals may also be performed.

[0061] The sulfate in step 2-1 may include one or more selected from Na2SO4, K2SO4, and (NH4)2SO4, and an example of the step 2-1 reaction is Sr 2+ ga SO4 2- Reacting with, SrSO4 2 The reaction products of will form and precipitate.

[0062] The main metal ions reacting with sulfates in step 2-1 are period 5 and 6 metal ions, Ra 2+ Also, some of the 4th period metal ions may react with sulfates to contain 4th period metal ion reaction products.

[0063] In addition, the concentration and amount of sulfate used in step 2-1 can be adjusted according to the period 5 and / or period 6 metal ion content in the wastewater, and as a preferred example, it is appropriate to use 0.2 to 1.0 M sulfate, preferably 0.3 to 0.7 M sulfate.

[0064] In addition, in step 2-1, performing the reaction and precipitation at 21℃ to 30℃ for 1 to 2 minutes, preferably at 24℃ to 26℃ for 1 to 2 minutes, is advantageous in terms of metal ion removal efficiency.

[0065] Step 2-2 performs Step 2-1 to obtain Period 5 and Period 6 metal ions and / or Ra 2+ This is a process of removing period 4 metal ion reaction products by adding and reacting K4Fe(CN)6 to the removed wastewater to form and precipitate them. At this time, using K4Fe(CN)6 with a concentration of 0.05 to 0.20 M, preferably using K4Fe(CN)6 with a concentration of 0.05 to 0.15 M, and more preferably using K4Fe(CN)6 with a concentration of 0.05 to 0.12 M is advantageous in terms of generating less sludge and metal ion removal efficiency.

[0066] And, in step 2-2, in addition to period 4 metal ions, residual period 5 and 6 metal ions, Ra, which were not removed after reacting with sulfates and precipitating in step 2-1, are removed. 2+ It may also be removed by reacting with K4Fe(CN)6.

[0067] In addition, in step 2-2, it is advantageous in terms of metal ion removal efficiency to perform the reaction and precipitation at 21℃ to 30℃ for 1 to 5 minutes, preferably at 24℃ to 26℃ for 4 to 5 minutes.

[0069] In addition, Step 2-3 is a process for removing metal ions and / or cationic elements remaining in the wastewater that were not reacted to precipitate in Step 2-1 and / or Step 2-2, wherein FeX3 (where X is Cl) - , F - or OH - This is a process of removing residual metal ions and / or cations by adding an iron salt represented by ) to adsorb residual metal ions and form iron ferrocyanide crystals immobilized within the lattice, and then precipitating them.

[0070] At this time, the above-mentioned cation element refers to a cation element generated from a reagent used in wastewater treatment or a cation metal ion excluding metal ions removed in steps 2-1 and 2-2 within the wastewater.

[0071] And, each of the processes in steps 2-2 to 2-3 may be performed independently with or without removing the precipitate generated and settled in step 2-1 and / or step 2-2, and preferably without removing the precipitate generated and settled in step 2-1 and / or step 2-2.

[0072] The wastewater treatment method of the present invention may further perform a third step of removing the precipitate from the wastewater from which the second step was performed, and then performing a process to remove residual organic compounds from the wastewater from which the precipitate has been removed, or separating the supernatant excluding the precipitate from the wastewater from which the second step was performed, and then performing a process to remove residual organic compounds from the supernatant.

[0073] Step 3 is a process for removing residual organic compounds, such as biodegradable organic compounds and / or surfactants, from the wastewater after performing Step 2, and can be carried out using general methods used in the industry, for example, by performing a post-treatment process through microbial treatment.

[0074] In addition, the present invention aims to provide a wastewater treatment system that performs the wastewater treatment method described above.

[0076] The wastewater treatment method of the present invention described above can satisfy a TOC removal rate of 90.0% or higher, preferably 95.0% or higher. In this case, the TOC removal rate refers to the removal rate of non-biodegradable organic compounds in the wastewater.

[0077] In addition, the wastewater treatment method of the present invention can satisfy a Cu ion removal rate of 90.0% or more, preferably 95.0% or more, and more preferably 98.0% or more.

[0078] In addition, the wastewater treatment method of the present invention can satisfy a Ni ion removal rate of 90.0% or more, preferably 92.0% or more, and more preferably 95.0% or more.

[0080] The present invention will be explained in more detail below through examples, but the following examples are not intended to limit the scope of the invention and should be interpreted as being for the purpose of aiding understanding of the invention.

[0081] [Example]

[0082] Example 1: pH and CaCl 2 Measurement of Wastewater Treatment Efficiency According to Solution Concentration and Input Amount 1

[0083] After preparing 100 ml of simulated waste liquid (organic compound: oxalic acid 20 mM solution alone, metal ions: Cu and Ni 2 mM each), it was introduced into a reactor to prepare 9 simulated waste liquids.

[0084] 0.1M or 0.2M CaCl2 solution was added to each reactor containing 100 ml of the above-mentioned simulated waste liquid at volume ratios (v / v) of 0.2, 0.4, and 1.0, respectively, and an appropriate amount of 5 M NaOH was added to adjust the pH to 6, 7, 8, 9, and 12, respectively. Subsequently, the reaction was carried out at 25 ℃ for 1 minute to form a precipitate. The pH of 6 is shown in Table 1, pH of 7 in Table 2, pH of 8 in Table 3, pH of 9 in Table 4, and pH of 12 in Table 5.

[0085] Next, 0.1 M K4Fe(CN)6 was added to each reactor while maintaining the pH in each reactor, and the reaction was carried out at 25°C for 1 minute to form a metal precipitate.

[0086] Next, residual Fe(CN)6 by adding 0.1M FeCl3 while maintaining the pH in each reactor 4- The residual metal ions were reacted with the Prussian blue crystals to produce the residual metal ions, which were then immobilized in the lattice of the Prussian blue crystals and precipitated.

[0087] The entire reaction time was approximately 10 minutes, and the precipitated sludge was separated from the supernatant, dried at 60°C, and weighed. The supernatant was filtered to 0.45 µm and analyzed for TOC and ICP. The results are shown in Tables 1 to 5 below.

[0088] In addition, the theoretical amount of sludge (g) produced during a 500L reaction was calculated using Equation 1 below.

[0089] [Equation 1]

[0090] Theoretical amount of sludge generated (g) = (Measured amount of sludge (g) × 500L) / 0.1L

[0091] The measured amount of sludge in Equation 1 is the amount of sludge generated after treating 0.1L of wastewater.

[0092] In addition, the results of measuring the removal rates of TOC, Cu, and Ni separately at pH are shown in Figures A to C of Figure 1.

[0093] pH 6 after adding NaOH CaCl2 Concentration (M) Input amount (v / v) 0.1 0.4 TOC removal rate (%) 98.49 Cu removal rate (%) 82.64 Ni removal rate (%) 20.87 Amount of sludge (g) 0.33 Theoretical amount of sludge (g) generated per 500L reaction 1,650

[0094] pH 7 after adding NaOH CaCl2 Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) 0.1 0.4 0.2M 0.2 TOC removal rate (%) 99.45 98 Cu removal rate (%) 86.03 80.61 Ni removal rate (%) 49.74 40.17 Amount of sludge (g) 0.34 0.22 Theoretical amount of sludge (g) generated per 500L reaction 1,700 1,100

[0095] pH 8 after adding NaOH CaCl2 Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) 0.1 0.4 0.1 0.2 TOC removal rate (%) 99.99 or higher 78.02 Cu removal rate (%) 99.99 or higher 84.33 Ni removal rate (%) 99.91 67.38 Amount of sludge (g) 0.36 0.22 Theoretical amount of sludge (g) generated per 500L reaction 1,800 1,100

[0096] pH 9 after adding NaOH CaCl2 Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) 0.1 M 0.2 0.1 M 0.4 0.1 M 1.0 TOC removal rate (%) 74.01 94.76 >99.99 Cu removal rate (%) 98.85 99.97 99.91 Ni removal rate (%) 93.56 99.88 89.01 Amount of sludge (g) 0.24 0.34 0.54 Theoretical amount of sludge (g) generated per 500L reaction 1,200 1,700 2,700

[0097] pH 12 after adding NaOH CaCl2 Concentration (M) Input amount (v / v) 0.1 0.2 TOC removal rate (%) 99.99 or higher Cu removal rate (%) 99.99 or higher Ni removal rate (%) 99.99 or higher Amount of sludge (g) 0.35 Amount of sludge (g) per 500 L reaction 1,750

[0099] Looking at Tables 1 to 5 and Figure 1 above, it was confirmed that in order to remove 92% or more of 20 mM oxalic acid, 0.1 M CaCl2 with a volume ratio of 0.4 (v / v) or more relative to the simulated waste liquid must be added, and if a volume ratio of 0.2 (v / v) is used, the same TOC removal efficiency can be expected by using a high concentration of 0.2 M CaCl2.

[0100] After oxalate precipitation, it was confirmed that the metal ion removal rate decreased significantly when the pH of the solution was 7 or lower, and increased significantly to over 95% when the pH was 8 or higher.

[0101] In addition, the estimated amount of sludge that can be generated in a 500 L reaction is approximately 2,000 g or less, and increases to 2,700 g if 0.1 M CaCl2 is added excessively at a volume ratio of 1.0 (v / v). Considering the reduction of secondary waste and the economical use of reagents, it was determined that using 0.1 M CaCl2 at a volume ratio of 0.4 (v / v) is appropriate. It was confirmed that it is advantageous to adjust the pH to 8 or higher for the effective removal of metal ions, and preferably to perform the process at a pH of 8 or higher and below 9.

[0103] Example 2: Measurement of Sludge Generation According to Ferrocyanate Concentration

[0104] 0.1 M CaCl2 solution was added to 100 ml of simulated waste liquid (organic compound: oxalic acid 20 mM, metal ions: Cu, Ni, Co, Sr, Cs 1 mM each) at a volume ratio of 0.4 (v / v), and 5 M NaOH was added to adjust the pH to approximately 8.5. Then, the reaction was carried out at 25°C for 1 minute to generate and precipitate a precipitate.

[0105] Next, 0.5M Na2SO4 was added to remove Sr while maintaining pH, and the reaction and precipitation were carried out at 25℃ for 1 minute.

[0106] Next, K4Fe(CN)6 was added at 0.06M, 0.1M, and 0.2M while maintaining the pH, and the reaction was carried out at 25℃ for 1 minute to generate and precipitate metal precipitates.

[0107] Next, 0.1M FeCl3 is added while maintaining the pH and reacted at 25°C for 1 minute to remove residual Fe(CN)6 4- Unreacted Cs and residual metal ions were immobilized in the lattice by generating Prussian blue crystals.

[0108] The entire reaction time is about 10 minutes, and the precipitated sludge is separated from the supernatant, dried at 60°C, and then weighed.

[0109] The supernatant was filtered through a 0.45 μm filter and analyzed for TOC and ICP, and the results are shown in Table 6 and Figure 2 below.

[0110] division Amount of measured sludge (g) Theoretical sludge generation amount (g) based on 500 L 0.2 M K4Fe(CN)6 0.40 2,000 0.1 M K4Fe(CN)6 0.40 2,000 0.06 M K4Fe(CN)6 0.38 1,900

[0111] As shown in Table 6 and Figure 2, it was confirmed that the TOC removal rate was improved and metal ions were efficiently removed simultaneously through the control of the ferrocyanide concentration. A lower TOC removal rate was observed as the concentration of potassium ferrocyanide used increased, which is due to residual Fe(CN)6 rather than the organic carbon of oxalic acid. 4- It was confirmed that this can be compensated for by adjusting the appropriate concentration of ferrocyanide.

[0113] Example 3: Wastewater treatment efficiency according to ferrocyanide concentration

[0114] 0.1 M CaCl2 solution was added to 100 ml of simulated waste liquid (organic compound: oxalic acid 20 mM, metal ions: Cu, Ni, Co each 1 mM) at a volume ratio of 0.4 (v / v), and 5 M NaOH was added to adjust the pH to approximately 8.5. Then, the reaction was carried out at 25°C for 1 minute to generate and precipitate the precipitate.

[0115] Next, K4Fe(CN)6 was added at 0.05M, 0.06M, 0.07M, 0.1M, 0.25M, and 0.5M while maintaining the pH, and the reaction and metal precipitate were generated and precipitated for 1 minute at 25℃.

[0116] Next, 0.1M FeCl3 is added while maintaining the pH and reacted at 25°C for 1 minute to remove residual Fe(CN)6 4- The residual metal ions were reacted with Prussian blue to produce Prussian blue crystals, and the residual metal ions were immobilized in the lattice of the Prussian blue crystals to precipitate them. The entire reaction time was approximately 10 minutes, and the precipitated sludge was separated from the supernatant, dried at 60°C, and then weighed.

[0117] The supernatant was filtered through a 0.45 μm filter and analyzed for TOC and ICP, and the results are shown in Table 7 and Figures 3A and B below.

[0118] K4Fe(CN)6 concentration (M) TOC removal rate (%) Metal ion removal rate (%) Fe residual concentration (ppm) Theoretical sludge generation amount (g) based on 500 L Cu Ni Co 0.05 >99.99 >99.99 94.20 91.60 0 1,662 0.06 99.88 >99.99 96.36 95.12 0 1,800 0.07 99.66 >99.99 98.70 97.94 0 1,792 0.1 91.56 >99.99 >99.99 >99.99 27.9 1,847 0.25 81.75 >99.99 >99.99 >99.99 67.34 2,098 0.5 44.24 >99.99 >99.99 >99.99 207.55 2,239

[0119] As shown in Table 7 and Figure 2 above, it was confirmed that as the concentration of K4Fe(CN)6 increased, the removal rate of metal ions exceeded 99.99%, meaning they were all removed; however, residual Fe(CN)6 4- It can be seen that the TOC removal rate decreases significantly as the presence of [subject] increases. In addition, as the concentration of K4Fe(CN)6 increases, the amount of sludge generated also increases and the residual Fe concentration in the treated water rises above the regulated concentration, so it was confirmed that the appropriate concentration of K4Fe(CN)6 is 0.1M or less.

[0121] Example 4: pH and CaCl 2 Measurement of Wastewater Treatment Efficiency According to Input Amount 2

[0122] (1) Measurement of wastewater treatment efficiency by pH

[0123] To verify the change rate of TOC removal at different pH levels, the pH was measured and adjusted using a pH meter. 100 ml of simulated wastewater (organic compound: oxalic acid 20 mM solution alone, metal ions: Cu and Ni 2 mM each) was prepared and then introduced into a reactor to prepare six simulated wastewater solutions.

[0124] 0.1 M CaCl2 solution was added to each of the reactors containing 100 ml of the above-mentioned simulated waste liquid at a volume ratio (v / v) of 0.4, and an appropriate amount of 2.5 M NaOH was added to adjust the pH to 7.80–7.85, 8.00–8.05, 8.70–8.75, and 9.90–9.95, respectively, after which the reaction and precipitate were formed at 25°C for 1 minute.

[0125] Next, 0.06 M K4Fe(CN)6 was added to each reactor while maintaining the pH inside each reactor, and the reaction was carried out at 25°C for 1 minute to form a metal precipitate.

[0126] Next, residual Fe(CN)6 by adding 0.1M FeCl3 while maintaining the pH in each reactor 4- The residual metal ions were reacted with the Prussian blue crystals to produce the residual metal ions, which were then immobilized in the lattice of the Prussian blue crystals and precipitated.

[0127] The entire reaction time was approximately 10 minutes, and the precipitated sludge was separated from the supernatant, dried at 40°C, and weighed. The supernatant was filtered through a 0.45 μm filter and analyzed for TOC and ICP, and the results are shown in Table 8 below.

[0128] In addition, the theoretical amount of sludge (g) produced during a 500L reaction was calculated using Equation 1.

[0129] pH pH 7.80~7.85 pH 8.00~8.05 pH 8.70~8.75 pH 9.90~9.95 CaCl2 Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) 0.1 0.4 0.1 0.4 0.1 0.4 0.1 0.4 TOC removal rate (%) 99.59 99.99 or higher 99.27 96.12 Cu removal rate (%) 99.99 or higher 99.99 or higher 99.99 or higher 99.99 or higher Ni removal rate (%) 93.68 94.36 99.99 or higher 99.99 or higher Residual Fe concentration (ppm) 0 0 1.51 14.14 Amount of sludge (g) 0.387 0.3728 0.367 0.3645 Theoretical amount of sludge (g) generated per 500L reaction 1935 1864 1835 1822.5

[0130] As shown in Table 8, experiments were conducted by more precisely classifying the pH range of Example 1, and a TOC removal rate of over 99% was confirmed at pH 7.5 to less than pH 9.

[0131] Although it showed a TOC removal rate of over 95% even at pH 9 or higher, it was confirmed that there was a problem with the concentration of Fe ions, which are environmentally regulated metal ions in the treated water, rising to over 10 ppm.

[0133] (2) CaCl 2 Measurement of wastewater treatment efficiency according to additive amount

[0134] After preparing six simulated waste liquids with the same composition as (1) above, the TOC removal rate, Cu removal rate, Ni removal rate, Fe residue amount, and generated sludge amount were measured using the same method, and the results are shown in Table 9 below.

[0135] 0.1 M CaCl2 solution of simulated waste liquid was added at volume ratios (v / v) of 0.4, 0.6, and 0.8, and an appropriate amount of 2.5 M NaOH was added. After adjusting the pH to a range of 8.00 to 8.10, the reaction and precipitate formation were carried out at 25 ℃ for 1 minute.

[0136] pH pH 8.00 ~ 8.10 pH 8.00 pH 8.09 pH 8.05 CaCl2 Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) Concentration (M) Input amount (v / v) 0.1 0.4 0.1 0.6 0.1 0.8 TOC removal rate (%) 100 99.58 99.54 Cu removal rate (%) 99.99 or higher 99.99 or higher 99.99 or higher Ni removal rate (%) 94.36 97.76 97.86 Residual Fe concentration 0 0 0 Amount of sludge (g) 0.3728 0.3874 0.3929 Theoretical amount of sludge (g) generated per 500L reaction 1864 1937 1964.5

[0137] Looking at the measurement results in Table 9 above, in the pH range of 8.00 to 8.10, even if the amount (volume ratio) of the CaCl2 solution added was increased from 0.4 to 0.8, there was no significant increase in the removal rate of TOC, Cu, Ni, etc., and rather, there was a tendency for only the amount of sludge to increase slightly. Through this, it was confirmed that in the pH range of 8.00 or higher to 9.00 or lower, it is advantageous to add and use the CaCl2 solution at a volume ratio of 0.8 or less, preferably 0.6 or less.

[0139] Example 5: Measurement of wastewater treatment efficiency according to the type of organic compound

[0140] To compare wastewater treatment efficiency according to the type of organic compound, a mixed solution (containing 20 mM oxalic acid, 0.1 wt% of ELLOTANT MILCOSIDE 100 (MC-100), a nonionic surfactant that is a biodegradable organic compound, and 2 mM each of Cu and Ni) and a single solution (containing 0.1 wt% of ELLOTANT MILCOSIDE 100, a nonionic surfactant, and 2 mM each of Cu and Ni) were prepared.

[0141] Next, 0.2 M CaCl2 solution at a volume ratio of 0.2 (v / v) was added to each 100 ml of simulated wastewater, and 5 M NaOH was added to adjust the pH to 8.5. Then, the reaction and precipitation were carried out at 25°C for 1 minute.

[0142] Next, 0.1 M K4Fe(CN)6 was added while maintaining the pH, and the reaction and metal precipitation were formed at 25°C for 1 minute.

[0143] Next, 0.1 M FeCl3 was added while maintaining the pH and reacted at 25°C for 1 minute, so that the residual Fe(CN)6 4- Unreacted metal ions are immobilized on the lattice by generating Prussian blue crystals. The supernatant is separated from the sludge and filtered through a 0.45 μm filter for TOC and ICP measurement analysis, and the results are shown in Figure 4.

[0144] As shown in Figure 4, it was confirmed that the removal rate of TOC and metal ions was improved in the mixed solution with oxalic acid compared to the single solution containing the surfactant.

[0146] Example 6: Measurement of wastewater treatment efficiency of a wastewater treatment step (process) according to the characteristics of pollutants in the wastewater

[0147] To check the change in TOC at each stage of wastewater treatment, 400 ml each of mock wastewater A (organic compound: mixed solution of oxalic acid 10 mM, citric acid 5 mM and surfactant; metal ions: Cu, Ni, Co, Sr 1 mM each) and mock wastewater B (organic compound: single solution of oxalic acid 20 mM; metal ions: Cu, Ni, Co, Sr 1 mM each) were prepared in a 1,000 ml reactor.

[0148] 0.1 M CaCl2 solution was added to each of the above-mentioned simulated waste liquids A and B, with a volume ratio (v / v) of 0.4, and an appropriate amount of NaOH was added to adjust the pH to 8.5. Then, the reaction and precipitate were formed at 25 ℃ for 1 minute.

[0149] Next, 0.5M Na2SO4 was added to remove Sr while maintaining pH, and the reaction and precipitation were carried out at 25℃ for 1 minute.

[0150] Next, 0.06 M K4Fe(CN)6 was added to each reactor while maintaining the pH inside each reactor, and the reaction was carried out at 25°C for 1 minute to form a metal precipitate.

[0151] Next, residual Fe(CN)6 by adding 0.1M FeCl3 while maintaining the pH in each reactor 4- The residual metal ions were reacted with the Prussian blue crystals to produce the residual metal ions, which were then immobilized in the lattice of the Prussian blue crystals and precipitated.

[0152] The entire reaction time was approximately 10 minutes, and the precipitated sludge was separated from the supernatant, dried at 40°C, and weighed. The supernatant for each reagent step was filtered through a 0.45 µm filter and analyzed for TOC and ICP. As a result, the TOC, Cu, and Ni removal rates measured at each step are shown in Table 10, Figure 5, and Figure 6 below.

[0153] In addition, the theoretical amount of sludge (g) produced during a 500L reaction was calculated using Equation 1.

[0154] In addition, the TOC removal rate of the mixed solution in Table 9 below was measured for both non-degradable organic matter and degradable organic matter.

[0155] Step-by-step hazardous substance removal rate (%) Mixed solution (oxalic acid 10 mM + citric acid 5 mM + surfactant 0.1 wt%) Single solution (20 mM oxalic acid) TOC With 2+ In 2+ Co 2+ Sr 2+ TOC With 2+ In 2+ Co 2+ Sr 2+ Precipitation reaction of recalcitrant organic matter 0.1 M CaCl2 48.50 17.3 28.9 28.2 30.7 91.46 32.8 36.5 33.9 42.7 NaOH (pH 8.5) 53.33 47.8 61.3 46.3 34.0 99.75 >99 >99 >99 46.7 Multimetal ion precipitation reaction 0.06M K4Fe(CN)6 53.10 60.0 83.9 66.7 36.4 97.00 >99 >99 >99 48.5 0.1M FeCl3 55.53 68.7 90.7 76.0 37.3 98.04 >99 >99 >99 49.0 Amount of sludge (g) 0.5847 1.1277 Theoretical amount of sludge (g) generated per 500L reaction 730.9 1,410

[0156] Referring to Table 10 and Figure 5, it was confirmed that for the oxalic acid single solution, over 90% of the oxalic acid was removed by precipitation during the CaCl2 addition step of precipitation stage 1, and over 99% was removed through pH adjustment in the NaOH step. Additionally, the TOC removal rate showed a tendency to decrease slightly with the addition of K4Fe(CN)6 and FeCl3 in metal precipitation stage 2, which is attributed to residual Fe(CN)6 4- It is unrelated to oxalic acid removal due to the influence of, and residual Fe(CN)6 resulting from the control of FeCl3 addition amount and K4Fe(CN)6 concentration 4- It was confirmed that removal of is possible.

[0157] In the case of a mixed solution containing oxalic acid, citric acid, and a surfactant, a TOC removal rate of 48.5% was observed during the CaCl2 addition step of the first precipitation stage. Partial precipitation was induced through micelle formation with calcium ions by some citric acid and surfactants along with oxalic acid, and a TOC removal rate of 53% was confirmed through pH adjustment in the NaOH step. After the addition of K4Fe(CN)6 and FeCl3 in the second metal precipitation stage, a final TOC removal rate of 55.54% was confirmed. The contribution of oxalic acid to the initial TOC was estimated to be approximately 30%, and it was confirmed that about 20% of the finally removed TOC was attributed to the co-removal of citric acid and surfactants.

[0158] As shown in Figure 6, the metal removal rate in a single oxalic acid solution increases significantly starting from the pH adjustment step, which is due to the formation of metal hydroxides. It was confirmed that metal hydroxides have low stability with respect to pH, so they are converted and formed into metal-ferrocyanide precipitates through the subsequent addition of ferrocyanide, thereby maintaining a high metal removal rate.

[0159] In the mixed solution, the overall metal removal rate decreased compared to the single solution due to the suspension of metal chelates with citric acid and surfactants; however, a stepwise increase in the metal removal rate was confirmed through the formation of ferrocyanide precipitates and adsorption by the Prussian blue lattice.

[0160] However, when comparing the wastewater treatment efficiency for a single solution, it was confirmed that citric acid and surfactants were not effectively removed by the precipitation reaction of recalcitrant organic matter and the precipitation reaction of multiple metal ions using the CaCl2 solution of the present invention.

[0162] Example 7 : Experiment to confirm the tendency of calcium oxalate precipitation

[0163] (1) To check the tendency of calcium to precipitate oxalate, a low concentration of 0.02 M Ca(OH)2 solution was added to 100 ml of simulated wastewater (organic compound: oxalic acid 20 mM solution, metal ions: Cu and Ni 2 mM each) at a volume ratio of 0.27 (v / v), and the pH was adjusted to 5~6, pH 7, or pH 8~9 to remove residual oxalate precipitate and effectively remove metal ions by adding 0.1 M Mg(OH)2 solution.

[0164] In addition, to check the effect of the generated oxalate precipitate, the following metal precipitation step was performed by dividing the precipitate into a 0.45 μm filter before (BF) and after (AF) separation.

[0165] Next, 0.1M K4Fe(CN)6 was added while maintaining the pH, and the reaction was carried out at 25℃ for 1 minute to form a metal precipitate.

[0166] Next, 0.1M FeCl3 is added while maintaining the pH to Fe(CN)6 4- The residual metal ions were reacted with Prussian blue crystals to produce unreacted metal ions, which were then immobilized and precipitated in the lattice.

[0167] In addition, the entire reaction time was about 10 minutes, the precipitated sludge was separated, and the supernatant was filtered through a 0.45㎛ filter to measure and analyze TOC and ICP at each reagent addition step.

[0168] The same reaction was also carried out in the presence of only 0.1M Mg(OH)2 solution without 0.02M Ca(OH)2 solution to compare the results, and the results are shown in Figures 7 and 8.

[0169] As shown in Figures 7 and 8, it was confirmed that the TOC removal rate and metal ion removal rate increased when using a mixture of Ca(OH)2 and Mg(OH)2 compared to when using Mg(OH)2 alone, and the highest removal rate was observed at pH 8-9.

[0171] (2) In addition, the XRD measurement results for the final sludge are shown in Figure 9. Through XRD analysis, it was confirmed that after calcium oxalate precipitation, the oxalate was removed through a 0.45 μm filter and only ferrocyanide precipitate remained.

[0172] It was confirmed that during the precipitation reaction at each stage, whether the precipitate generated in the previous stage was removed or whether precipitate removal was not performed (i.e., whether filtering was performed) did not significantly affect the TOC removal rate and metal ion removal rate.

[0173] Through this, it was confirmed that it is advantageous to perform the wastewater treatment method according to the present invention in a batch manner.

[0176] Example 8: Measurement of the titration ratio of low-concentration calcium hydroxide

[0177] To find the optimal addition ratio of low-concentration calcium hydroxide, a low-concentration 0.02 M Ca(OH)2 solution was added to 100 ml of simulated waste liquid (organic compound: oxalic acid 20 mM single solution, metal ions: Cu and Ni 2 mM each) at volume ratios of 0.27, 0.36, 0.5, or 0.8 (v / v), respectively, to induce calcium oxalate precipitation, and then the pH was adjusted to approximately 8.5 by adding a 0.1 M Mg(OH)2 solution to perform the precipitation reaction.

[0178] Next, 0.1M K4Fe(CN)6 was added while maintaining the pH, and the reaction was carried out at 25℃ for 1 minute to form a metal precipitate.

[0179] Next, 0.1 M FeCl3 was added while maintaining the pH, and Fe(CN)6 was heated at 25°C for 1 minute. 4- The residual metal ions were reacted with Prussian blue crystals to produce unreacted metal ions, which were then immobilized and precipitated in the lattice.

[0180] The entire reaction time was approximately 10 minutes, the precipitated sludge was separated, and the supernatant was filtered through a 0.45 μm filter to measure and analyze the TOC removal rate and ICP. The results are shown in Figure 9.

[0181] As shown in Figure 10, it was confirmed that the TOC removal rate and radionuclide removal rate increased as the addition ratio of calcium hydroxide increased.

[0183] Example 9: Measurement of Calcium Hydroxide Titration Concentration

[0184] To find the optimal calcium hydroxide concentration, a low concentration 0.02 M Ca(OH)2 solution was added to 100 ml of simulated waste liquid (organic compound: oxalic acid 20 mM single solution, metal ions: Cu and Ni 2 mM each) at a volume ratio of 0.75 (v / v) to maintain the pH at approximately 2~3, and a high concentration 0.1 M Ca(OH)2 solution (0.1 M) was added at a volume ratio of 0.1 (v / v) to form a calcium oxalate precipitate and simultaneously adjust the pH to approximately 8.

[0185] Then, a low concentration 0.00015M Mg(OH)2 solution was added to maintain the pH at approximately 8.5, and a residual oxalate precipitation reaction was induced and precipitated.

[0186] Next, 0.1M K4Fe(CN)6 was added while maintaining the pH, and the reaction was carried out at 25℃ for 1 minute to form a metal precipitate.

[0187] Next, 0.1M FeCl3 was added while maintaining the pH, and Fe(CN)6 was heated at 25℃ for 1 minute. 4- The residual metal ions were reacted with Prussian blue crystals to produce unreacted metal ions, which were then immobilized and precipitated in the lattice.

[0188] The entire reaction process takes about 10 minutes, the precipitated sludge is separated, and the supernatant is filtered through a 0.45㎛ filter for TOC and ICP measurement analysis.

[0189] In addition, a very small amount of high-concentration 0.1M Ca(OH)2 solution was added to maintain the pH at 2~3, and a high-concentration 0.1M Mg(OH)2 solution was added to adjust the pH to 8. The same reaction was carried out and the results were compared, and the results are shown in Figure 11.

[0190] As shown in Figure 11, it was confirmed that calcium hydroxide alone tends to have a high TOC removal rate, and that with the addition of high concentrations of calcium hydroxide and magnesium hydroxide, a high metal ion removal efficiency of over 98% is observed in the presence of sufficient hydroxyl groups.

[0192] Example 10

[0193] According to Korean published patent 10-2013-0031018, to determine whether a pH adjustment step is necessary for an effective precipitation reaction of calcium oxalate, the total amount of 0.1 M Ca(OH)2 solution added to 100 ml of simulated wastewater (organic compound: oxalic acid 20 mM single solution, metal ions: Cu and Ni 2 mM each) was fixed at a volume ratio of 0.22 (v / v), and the final pH was adjusted to 8 by dividing the conditions into direct (amount added immediately) and step-by-step (amount added in part to achieve a pH of 2~3, and then the remainder added).

[0194] Next, 0.1M FeCl3 was added while maintaining the pH, and Fe(CN)6 was heated at 25℃ for 1 minute. 4- The residual metal ions were reacted with Prussian blue crystals to produce unreacted metal ions, which were then immobilized and precipitated in the lattice.

[0195] The entire reaction time was approximately 10 minutes, the precipitated sludge was separated, and the supernatant was filtered through a 0.45㎛ filter for TOC and ICP measurement and analysis, and the results are shown in Figure 12.

[0196] In addition, the results were compared by conducting conditions in which a low concentration 0.02M Ca(OH)2 solution (35% Ca(OH)2) was added at a volume ratio of 0.3 (v / v) to maintain a pH of 2 to 3, and a high concentration 0.1M Ca(OH)2 solution was added at a volume ratio of 0.1 (v / v) to adjust the pH to 8.

[0197] As shown in Figure 12, it was confirmed that the TOC removal rate and the removal rate of metal ions were maintained at a high level even when the pH was adjusted to 8 by adding calcium hydroxide all at once without adding it in separate concentration and pH steps.

Claims

Claim 1 4th period metal ions, 5th period metal ions, 6th period metal ions and Ra 2+ A process comprising: a first step of precipitating a recalcitrant organic compound from wastewater containing multiple metal ions and organic compounds including one or more selected from among; and a second step of precipitating multiple metal ions from the wastewater obtained by performing the first step; wherein the recalcitrant organic compound includes one or more selected from oxalic acid, maleic acid, tartaric acid, malic acid, succinic acid, phthalic acid, and salts thereof; wherein the precipitation reaction of the first step and the precipitation reaction of the second step are performed under a pH of 7.5 to 9.5; and wherein the multiple metal ions include 4th period metal ions, 5th period metal ions, 6th period metal ions, and Ra 2+ A method for treating wastewater containing multiple metal ions and organic compounds, characterized by performing a process comprising: Step 2-1, in which, when containing one or more metal ions selected from Na2SO4, K2SO4, and (NH4)2SO4, a sulfate containing one or more selected from Na2SO4, K2SO4, and (NH4)2SO4 is added and reacted to precipitate reaction products of 5th and 6th period metal ions; Step 2-2, in which K4Fe(CN)6 is added and reacted to the wastewater from which Step 2-1 was performed to precipitate reaction products of 4th period metal ions; and Step 2-3, in which an iron salt represented by FeX3 (where X is -Cl, -F, or -OH) is added to the wastewater from which Step 2-2 was performed to form and precipitate iron ferrocyanide crystals. Claim 2 A method for treating wastewater containing multiple metal ions and organic compounds according to claim 1, wherein the organic compound of the first step further comprises a biodegradable organic compound. Claim 3 In claim 1, the above step 1 is such that the wastewater has a pH of 1 to 5, and the above step 1 is such that after adding a Ca precursor, the pH is adjusted to 7.5 to 9.5 to Ca recalcitrant organic compounds 2+ A method for treating wastewater containing multiple metal ions and organic compounds, characterized by precipitating the reaction product reacted with the substance. Claim 4 A method for treating wastewater containing multiple metal ions and organic compounds according to claim 3, characterized in that the Ca precursor comprises one or more selected from CaCl2, Ca(NO3)2, Ca(CH3COO)2, CaSO4, CaCO3, CaO, and Ca(OH)2. Claim 5 delete Claim 6 delete Claim 7 In claim 1, the 4th period metal ion is Cu 2+ , Ni 2+ , Co 2+ and Zn 2+ It includes one or more selected from among, and the 5th period metal ion is Sr 2+ , Cd 2+ and Ag + It includes one or more selected from among, and the 6th period metal ion is Cs + , Ba 2+ , Hg 2+ and Pb 2+ A method for treating wastewater containing multiple metal ions and organic compounds, characterized by including one or more selected from among. Claim 8 delete Claim 9 In paragraph 1, the multiple metal ions together with the 4th period metal ions, the 5th period metal ions, the 6th period metal ions, and Ra 2+ A method for treating wastewater containing multiple metal ions and organic compounds, characterized by performing a pretreatment process in which, when one or more metal ions selected from among are included, a sulfate containing one or more selected from Na2SO4, K2SO4, and (NH4)2SO4 is introduced and reacted with the wastewater prior to the first step to precipitate reaction products of period 5 metal ions and period 6 metal ions, and not performing the 2-1 step process when performing the pretreatment process. Claim 10 A method for treating wastewater containing multiple metal ions and organic compounds according to claim 1, characterized in that the first and second steps are performed as a batch process in a single reactor. Claim 11 A method for treating wastewater containing multiple metal ions and organic compounds according to claim 1, further comprising: a third step of removing the precipitate from the wastewater from which the precipitate has been removed, and then performing a process to remove residual organic compounds from the wastewater from which the precipitate has been removed, or separating the supernatant excluding the precipitate from the wastewater from which the precipitate has been removed, and then performing a process to remove residual organic compounds from the supernatant. Claim 12 A wastewater treatment system for treating wastewater containing multiple metal ions and organic compounds, comprising: a treatment tank for precipitating recalcitrant organic compounds from wastewater containing multiple metal ions and organic compounds, wherein the treatment tank for precipitating recalcitrant organic compounds and the treatment tank for precipitating multiple metal ions from wastewater from which recalcitrant organic compounds have been removed are the same treatment tank or different treatment tanks.

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