A method for remediating wastewater containing heavy metals and / or metalloids

Abstract

The present application relates to a method for repairing wastewater containing heavy metals and / or metalloids, and belongs to the field of polluted wastewater treatment technology. The method for repairing wastewater containing heavy metals and / or metalloids of the present application includes the following steps: adding ferrous salt solution to wastewater containing heavy metals and / or metalloids, adjusting pH value to 3 6, obtaining mixed wastewater, the final concentration of ferrous ions in the mixed wastewater is 1.5 1.9 mmol / L; Algae-bacteria symbiont is inoculated into mixed wastewater, left to stand to heavy metals and / or metalloids adsorption precipitation in wastewater, filtered, and the water body after repair is obtained. The present application obtains algae-bacteria symbiont with aquatic organism crust as provenance enrichment, is mixed with ferrous salt and applied to heavy metal and / or metalloid wastewater, can make the heavy metal and metalloid in wastewater form precipitation, has the effect of synchronously repairing wastewater.

Description

Technical Field

[0001] The present application relates to the technical field of contaminated wastewater treatment, and in particular to a method for repairing wastewater containing heavy metals and / or metalloids. Background Art

[0002] Acid mine drainage (AMD) generated during mining or ore accumulation has a low pH and high concentrations of sulfate and heavy (metal) metals, which is a very serious environmental problem facing the global mining industry. Common AMD remediation methods include neutralization, adsorption and microbial methods. Among them, the neutralization method mainly uses alkaline neutralizers for remediation, the adsorption method mainly uses porous adsorption materials for remediation, and the microbial method mainly uses iron-oxidizing bacteria or sulfate-reducing bacteria for remediation. However, when using a single method for remediation, there are often disadvantages such as high cost, weak targeting or slow effect. More importantly, heavy metals and metalloids represented by Cd and As have different environmental behaviors, making it difficult to implement synergistic remediation. Therefore, it is worthwhile to explore an economical and effective simultaneous remediation model for heavy metals and / or metalloids. Summary of the Invention

[0003] The purpose of this application is to overcome the shortcomings of the existing technology and provide a method for simultaneously repairing heavy metal and metalloid polluted wastewater.

[0004] To achieve the above objectives, the technical solutions adopted in this application are:

[0005] The present application provides a method for remediating wastewater containing heavy metals and / or metalloids, comprising the following steps:

[0006] (1) adding a ferrous salt solution to wastewater containing heavy metals and / or metalloids, adjusting the pH value to 3-6, and obtaining mixed wastewater, wherein the concentration of ferrous ions in the mixed wastewater is 1.5-1.9 mmol / L;

[0007] (2) adding the algae-bacteria symbiont to the mixed wastewater, allowing it to stand until the heavy metals and / or metalloids in the wastewater are adsorbed and precipitated, and filtering to obtain the repaired water body;

[0008] The algae-bacteria symbiont mainly includes microalgae and bacteria, wherein the microalgae are mainly mixed microalgae of Chlorella sp. and Chlorococcum sp.; and the bacteria mainly belong to the phyla Bacteroidota, Gemmatimonadota, Acidobacteriota and Proteobacteria.

[0009] The present application applies the algae-bacteria symbiont to heavy metal and / or metalloid wastewater with a final ferrous ion concentration of 1.5-1.9mmol / L, which can cause the heavy metals and metalloids in the wastewater to form precipitation, thereby achieving the effect of synchronously repairing the wastewater. When the ferrous ion concentration is greater than 1.9mmol / L, a large amount of ferrous ions enter the microalgae to form hydroxyl radicals, which destroy the biomolecules such as the DNA and cell membrane of the microalgae and even cause the death of the microalgae. In addition, ferrous ions can be oxidized to form trivalent iron ions. When too much trivalent iron ions combine with the biogenic element P, the microalgae are deficient in nutrients. When the ferrous ion concentration is less than 1.5mmol / L, the iron oxide content in the wastewater decreases, thereby reducing the fixation efficiency of the metalloids, thereby causing the repair effect of the wastewater to decrease.

[0010] Both Chlorella and Chlorella vulgaris are autotrophic organisms, a type of microalgae. They possess multiple intracellular and extracellular detoxification mechanisms to cope with heavy metal and / or metalloid stress. They can survive and photosynthesize in the extreme environments of heavy metal and / or metalloid wastewater, increasing the pH value of the water and achieving acidic wastewater remediation. In addition, microalgae can form a mutually beneficial symbiosis with bacteria such as Bacteroidetes, Gemmatimonadetes, Acidobacteria, and Proteobacteria in wastewater environments, regulating the relative abundance of different bacterial communities in the wastewater and enriching iron-oxidizing bacteria, bacteria with sulfate-reducing ability, and other bacteria that are beneficial to the precipitation of heavy metals and metalloids, further improving the efficiency of wastewater remediation.

[0011] The microalgae contained in the algae-fungus symbiont of the present application can reproduce rapidly in an environment with a pH of 3-6, and increase the pH value of the wastewater through photosynthesis, promote ferrous ions to form iron oxides, and combine with metalloids to form metalloid precipitates. At the same time, it can also promote the hydrolysis and precipitation of heavy metals, thereby achieving the effect of synchronously repairing the wastewater.

[0012] As a preferred embodiment of the method described in the present application, the abundance of Bacteroidetes in the bacteria accounts for 25-75% of the bacteria, the abundance of Gemmatimonadetes in the bacteria accounts for 0.05-38% of the bacteria; the abundance of Acidobacteria in the bacteria accounts for 4-25% of the bacteria, and the abundance of Proteobacteria in the bacteria accounts for 10-80% of the bacteria. According to 16s rRNA gene amplicon sequencing and bioinformatics analysis, it was found that the algae-bacteria symbiont of the present application can regulate the structure of the bacterial community in wastewater, increase the abundance of Bacteroidetes, Gemmatimonadetes and Proteobacteria, and decrease the abundance of Acidobacteria, thereby changing the bacterial community structure of the wastewater and increasing the abundance of bacterial communities that are beneficial to the repair of wastewater, thereby improving the wastewater repair effect of the algae-bacteria symbiont.

[0013] As a preferred embodiment of the method described in the present application, in step (1), the ferrous ion concentration in the mixed wastewater is 1.6-1.8 mmol / L. Within the preferred ratio range, the present application can further improve the removal rate of heavy metals and metalloids in wastewater.

[0014] As a preferred embodiment of the method described in the present application, in step (1), the ferrous ion concentration in the mixed wastewater is 1.786 mmol / L. Under the preferred ratio, the present application can significantly improve the removal rate of heavy metals and metalloids in wastewater, up to 97%.

[0015] As a preferred embodiment of the method described in this application, the concentration of microalgae in the algae-bacteria symbiosis is (5-10)×10 6 cell / mL, and the concentration of bacteria in the algae-bacteria symbiosis is (0.5-6)×10 9 CFU / mL. During the experiment, the applicant found that the concentration of microalgae and bacteria in the algae-bacteria symbiosis was closely related to its restoration effect. When the microalgae concentration was lower than 5×10 6 cell / mL, bacterial concentration is less than 0.5×10 9 CFU / mL, the content of microalgae and bacteria in the algae-bacteria symbiont is low. When inoculated into wastewater, the high content of heavy metals and metalloids in the wastewater will limit the growth of microalgae, resulting in a decrease in the removal rate of heavy metals and metalloids in the wastewater. When the concentration of microalgae is higher than 10×10 6 cell / mL, bacterial concentration higher than 6×10 9 CFU / mL, the growth of microalgae is restricted, which reduces the removal rate of heavy metals and metalloids, and does not meet the purpose of wastewater remediation.

[0016] As a preferred embodiment of the method described in this application, in step (2), the volume ratio of the algae-bacteria symbiont to the mixed wastewater is algae-bacteria symbiont: mixed wastewater = 1:200-220. Through multiple experiments, the present application found that when the algae-bacteria symbiont is mixed with mixed wastewater at a volume ratio of 1:200-220, the algae-bacteria symbiont can stably remove heavy metals and metalloids from the wastewater.

[0017] As a preferred embodiment of the method described in the present application, in step (2), the reaction is carried out at 20-25°C, 14 hours of light per day, and a light intensity of 1000 lux; the reaction is allowed to stand for 30-90 days.

[0018] During the experiment, the applicant found that the algae-bacteria symbiosis was carried out at 20-25°C, 14h / day of light, and 1000lux of light intensity, which was conducive to the photosynthesis of microalgae in the algae-bacteria symbiosis, and that different standing times had significant differences in the remediation effect of wastewater. In the dynamic process of observing the algae-bacteria symbiosis to repair wastewater, when the standing time reached 30 days, the concentration of metalloids dropped significantly to close to 0, and the concentration of heavy metals also dropped significantly; when the standing time reached 70 days, the concentration of metalloids continued to drop, and the concentration of heavy metals dropped to half of the initial concentration; when the standing time reached 90 days, the concentration of heavy metals tended to 0, while the concentration of metalloids showed an upward trend. This is because after the metalloids are adsorbed and precipitated by the algae-bacteria symbiosis, the vitality of some algae-bacteria symbionts will decrease after a period of cultivation, which will release metalloids.

[0019] As a preferred embodiment of the method described in the present application, in step (2), the algae-bacterial symbiont is enriched in BG-11 culture medium using aquatic biocrust as the seed source; the enrichment conditions are 14 hours / day of illumination, a light intensity of 1000 lux, a temperature of 20-25°C, and a time of 2-4 days. The present application uses aquatic biocrust as the seed source to enrich an algae-bacterial symbiont in BG-11 culture medium in which microalgae and microorganisms coexist. The microalgae can recruit different types of microorganisms to form a mutually beneficial symbiosis with them according to different environments, allowing the microalgae to grow rapidly under metal stress environments.

[0020] In a preferred embodiment of the method described herein, the aquatic biocrust is derived from mine wastewater. Mine wastewater contains significant amounts of heavy metals and metalloids. The aquatic biocrust collected under this environmental stress exhibits a degree of stress resistance, making it particularly suitable for remediation of heavy metal and / or metalloid wastewater.

[0021] As a preferred embodiment of the method described in the present application, the ferrous salt solution is one of ferrous sulfate solution, ferrous chloride solution, and ferrous carbonate solution; the heavy metal is one or more of cadmium, chromium, cobalt, lead, zinc, tin, and mercury; and the metalloid is one or more of arsenic, antimony, tellurium, and boron.

[0022] As a preferred embodiment of the method described in this application, the ferrous salt solution is a ferrous sulfate solution. During the experiment, the applicant found that adding ferrous sulfate solution as the ferrous salt solution to the algae-bacteria symbiosis can provide a substrate for sulfate-reducing bacteria, further improving the effect of wastewater remediation.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The present application obtains algae-bacteria symbionts by enriching aquatic biological crusts, and inoculates the algae-bacteria symbionts into heavy metal and metalloid wastewater containing ferrous salt solution. The heavy metals and metalloids in the wastewater can be precipitated by standing, which has the effect of simultaneously repairing heavy metal and metalloid wastewater.

[0025] (2) This application enriches algae-bacteria symbionts to simultaneously repair heavy metal and metalloid wastewater. With the assistance of coexisting microorganisms, microalgae resist metal stress and grow rapidly. On the one hand, microalgae can increase the pH of the water body through photosynthesis, promote the oxidation of divalent iron to form iron oxides and fix metalloids, and can also achieve heavy metal hydrolysis and precipitation by increasing the pH. On the other hand, microalgae specifically recruit functional microorganisms related to metal fixation to further improve the effect of wastewater remediation, such as recruiting iron-oxidizing bacteria to form biogenic iron oxides with stronger ability to fix metalloid As, or recruiting sulfate-reducing bacteria to form cadmium sulfide precipitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The dynamic changes of pH, Fe, As, Cd and P in the mixed wastewater treated by Example 1, Comparative Examples 1 to 3 and the blank control are shown;

[0027] Figure 2 This is a scanning electron microscope image of the precipitate in the mixed wastewater treated by Example 1, Comparative Examples 2-3, and a blank control;

[0028] Figure 3 is the sedimentation ratio of As / Fe in the mixed wastewater treated by Example 1, Comparative Examples 2-3 and the blank control;

[0029] Figure 4 This is the element distribution diagram of the mixed wastewater treated in Example 1;

[0030] Figure 5 The results are as follows: the changes in the microbial community structure of the mixed wastewater treated by Example 1, Comparative Example 1 and the blank control group. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose, technical solutions and advantages of this application, this application will be further described below in conjunction with specific embodiments.

[0032] Unless otherwise specified, other materials, reagents, etc. used in the Examples, Comparative Examples, and Experimental Examples can be obtained from commercial sources.

[0033] BG-11 culture medium formula: 1.5g / L NaNO3, 0.04g / L K2HPO4·3H2O, 0.075g / LMgSO4·7H2O, 0.036g / L CaCl2·2H2O, 0.006g / L citric acid, 0.006g / L ammonium ferric citrate, 0.001g / L EDTA, 0.02g / LNa2CO3, 2.86mg / L H3BO3, 1.81mg / L MnCl2·4H2O, 0.222mg / L ZnSO4·7H2O, 0.390mg / LNa2MoO4·2H2O, 0.079mg / L CuSO4·5H2O, 0.049mg / L Co(NO3)2·6H2O.

[0034] Prepare simulated heavy metal wastewater: prepare Na3AsO3 solution and CdCl2 solution, add them to BG-11 culture medium to make the initial concentration of As 10 mg / L and the initial concentration of Cd 4 mg / L, and adjust the pH to 6.0 with dilute hydrochloric acid.

[0035] Aquatic biocrusts were collected from the lead-zinc tailings pond wetland in Bingcun, Meizhou City, Guangdong Province.

[0036] Example 1

[0037] An embodiment of the method for remediating heavy metal and / or metalloid contaminated wastewater of the present application comprises the following steps:

[0038] (1) Aquatic biocrust was inoculated into BG-11 culture medium and cultured for 2-4 days under the conditions of 14 h / day light intensity of 1000 lux and temperature of 20-25°C to obtain algae-bacteria symbionts. The algae-bacteria symbionts were identified to contain microalgae and bacteria. The microalgae were a mixture of Chlorella vulgaris and Chlorella, and the bacteria included Bacteroidetes, Acidobacteria and Proteobacteria. The concentration of microalgae was (5-10)×10 6 cell / mL, the concentration of bacteria is (0.5-6)×10 9 CFU / mL;

[0039] (2) adding ferrous sulfate solution to simulated heavy metal wastewater and adjusting the pH to 6 to obtain mixed wastewater, wherein the concentration of ferrous ions in the mixed wastewater is 1.786 mmol / L;

[0040] (3) 1 mL of algae-bacteria symbiont was added to 200 mL of mixed wastewater, and the mixture was allowed to stand for 90 days under the conditions of 14 h / day of illumination, 1000 lux of light intensity, and 20-25°C of temperature. The mixture was then filtered to obtain the repaired water.

[0041] Comparative Example 1

[0042] A comparative example of the method for repairing heavy metal and / or metalloid contaminated wastewater of the present application is similar to Example 1, except that the FeSO4 solution in step (1) is replaced by BG-11 culture medium.

[0043] Comparative Example 2

[0044] A comparative example of the method for repairing heavy metal and / or metalloid contaminated wastewater of the present application is similar to Example 1, except that the algae-bacteria symbiont in step (3) is replaced by purified microalgae 1, and the remaining steps and parameter conditions remain unchanged.

[0045] The cultivation method of microalgae 1 is as follows: microalgae 1 is added to BG-11 culture medium, and cultured for 2 days under conditions of 14 hours / day of light intensity of 1000 lux and temperature of 20-25°C to obtain microalgae 1 in the logarithmic growth phase; microalgae 1 is isolated and purified from aquatic biological crust and identified as Chlorella sp. by phenotype and molecular identification.

[0046] Comparative Example 3

[0047] A comparative example of the method for remediating heavy metal and / or metalloid contaminated wastewater of the present application is similar to Comparative Example 2, except that microalgae 2 is used instead of microalgae 1. Microalgae 2 is isolated and purified from aquatic biocrusts and identified as Chlorococcum aquaticum Archibald 1979 through phenotypic and molecular identification.

[0048] Effect Example 1 Effect of different treatments on the remediation of mixed wastewater

[0049] During the treatment process, samples of the mixed wastewater of Example 1, Comparative Example 2, Comparative Example 3, and the blank control (no microorganisms added) were collected every 10 days. The water samples were filtered through a 0.45 μm filter membrane, and the pH value of the filtrate was measured. The filtrate was acidified to a pH < 1 with concentrated sulfuric acid to prevent further oxidation of ferrous ions and the formation of precipitation. K2HPO4 at a concentration of one-tenth of the culture medium was added to the mixed wastewater at each sampling. The contents of As, Cd, Fe, and P in the water samples were determined by ICP-OES. The results are shown in Table 1. Figure 1 .

[0050] like Figure 1As shown, when the standing time reaches 30 days, the As concentration of Example 1 drops significantly to near 0, and the Cd concentration also drops significantly; when the standing time reaches 70 days, the As concentration of Example 1 continues to drop, and the concentration of heavy metals drops to half of the initial concentration; after the repair time reaches 90 days, the As and Cd concentrations of Example 1 tend to 0, and the As and Cd removal rates reach 97%. When the repair time reaches 90 days, the As removal rate of Comparative Example 1 is much higher than that of other treatments. The As and Cd removal rates of Comparative Examples 2 and 3 are only 26%. The blank control group has only a slow As removal effect and has almost no effect on Cd. Compared with Comparative Example 1 without adding ferrous ions and Comparative Examples 2 and 3 with only microalgae, Example 1 with the addition of ferrous ions can help microalgae adapt to As and Cd stress faster, enable microalgae to grow rapidly, and increase the pH value of the water through photosynthesis.

[0051] The As and Cd contents in the mixed wastewater treated in Example 1 and Comparative Examples 1 to 3 were measured according to the above method, and the removal rates were calculated. The results are shown in Table 1.

[0052] Table 1 Removal rates of As and Cd in mixed wastewater after different treatments

[0053]

[0054] As shown in Table 1, the methods of Example 1 and Comparative Examples 1 to 3 can all effectively remove As and Cd from wastewater, among which Example 1 has the highest removal rate, indicating that the method of the present application can effectively and simultaneously remove heavy metals and metalloids from wastewater.

[0055] Effect Example 2 Characterization of the water composition after restoration

[0056] 1. After the algae-bacteria symbiont was added to the mixed wastewater, a precipitate was formed in the wastewater. The mixed wastewater of Example 1, Comparative Example 2, Comparative Example 3 and the blank control group after 90 days of cultivation was centrifuged, the precipitate was retained, washed, freeze-dried and characterized by SEM-EDX. The results are shown in FIG. Figure 2 .

[0057] like Figure 2 As shown, in Comparative Examples 2 and 3 in which only microalgae were added, granular iron oxides were generated, which had a structure similar to that of the blank control group; in Example 1 of the algae-bacteria symbiosis, rose-shaped iron oxides were generated, and the morphology was inconsistent with that of Comparative Examples 2, 3 and the blank control group.

[0058] 2. In order to better explain the relationship between the formation of different iron oxides and As fixation, the As / Fe sedimentation ratio of the mixed wastewater of Example 1, Comparative Example 2, Comparative Example 3 and the blank control group after 30 days of incubation was analyzed. The results are shown in Figure 3 .

[0059] like Figure 3 As shown in Figure 2, the As / Fe sedimentation ratio in the blank control group is below 0.2, which is lower than that in Example 1, Comparative Example 2, and Comparative Example 3 in which microalgae are added. This indicates that iron oxides doped with algae-derived organic matter can improve the As fixation effect. Figure 1 It can be seen that As had been basically completely settled by the 30th day, and the As / Fe settlement ratio was the largest at this time. This indicates that the iron oxides formed during the period of rapid As settlement from 20 to 30 days have a strong affinity for As. Microalgae may promote the growth of iron-oxidizing microorganisms by forming a specific algal environment, generating biogenic iron oxides with better As fixation effect, thereby facilitating the fixation of pollutants.

[0060] 3. In order to explore the fixation mechanism of As and Cd in this application, SEM-EDX was used to analyze the microscopic distribution of the main elements in the mixed wastewater after treatment in Example 1. The results are shown in Figure 4 .

[0061] like Figure 4 As shown in the figure, Cd and S are clearly co-distributed, while the distribution of other elements in this area is not obvious. Therefore, it is believed that Cd exists mainly in the form of CdS. The microalgae of the present application can provide a carbon source and electron donor for sulfate-reducing bacteria, thereby promoting their growth. Therefore, the presence of sulfate reduction in the algae-bacteria symbiosis of the present application can further promote the fixation of heavy metals represented by Cd. As and Fe are clearly co-distributed, while the co-distribution of As and C is not obvious, indicating that the fixation of As in the present application is achieved by co-precipitation of As with iron oxides, rather than enrichment by microalgae.

[0062] Effect Example 3: Analysis of the microbial community structure of the restored water body

[0063] The mixed wastewater treated by Example 1, Comparative Example 1 and the blank control group was subjected to 16S rRNA gene amplicon sequencing and bioinformatics analysis. Figure 5 .

[0064] like Figure 5 As shown, the mixed wastewater treated in Example 1 is mainly enriched in Proteobacteria, followed by Bacteroidetes; the mixed wastewater treated in Comparative Example 1 is also mainly enriched in Proteobacteria, followed by Gemmatimonadota, and the abundance level of Bacteroidetes is significantly lower than that in Example 1; in the blank control group, Bacteroidetes has an absolute advantage, which shows that the present application achieves the effect of wastewater remediation by changing the microbial community structure of the mixed wastewater.

[0065] In summary, the method of the present application for remediating heavy metal and / or metalloid contaminated wastewater is to induce the oxidation of ferrous ions and promote the formation of iron minerals through microalgae to adsorb and fix heavy metals and metalloids. In addition, the microalgae can also specifically recruit microorganisms with the function of fixing heavy metals and metalloids, further improving the remediation effect and achieving simultaneous fixation of heavy metals and metalloids.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A method for remediating wastewater containing heavy metals and / or metalloids, characterized in that: The following steps are involved: (1) adding a ferrous salt solution to wastewater containing heavy metals and / or metalloids, adjusting the pH value to 3-6, and obtaining mixed wastewater, wherein the concentration of ferrous ions in the mixed wastewater is 1.5-1.9 mmol / L; (2) Adding the algae-bacteria symbiont to the mixed wastewater, allowing it to stand until the heavy metals and / or metalloids in the wastewater are adsorbed and precipitated, and filtering to obtain the repaired water body; The algae-bacteria symbiont mainly includes microalgae and bacteria, wherein the microalgae are mainly a mixed microalgae of Chlorella sp. and Chlorococcum sp.; the bacteria mainly belong to the phyla Bacteroidota, Gemmatimonadota, Acidobacteriota and Proteobacteria; The abundance of the Bacteroidetes phylum in the bacteria accounts for 25-75% of the bacteria, the abundance of the Gemmatimonadetes phylum in the bacteria accounts for 0.05-38% of the bacteria; the abundance of the Acidobacteria phylum in the bacteria accounts for 4-25% of the bacteria, and the abundance of the Proteobacteria phylum in the bacteria accounts for 10-80% of the bacteria; In step (2), the algae-bacteria symbiont is enriched in BG-11 culture medium using aquatic biological crust as a seed source; the enrichment conditions are 14 h / day of illumination, 1000 lux of illumination intensity, 20-25°C of temperature, and 2-4 days of time.

2. The method according to claim 1, wherein In step (1), the concentration of ferrous ions in the mixed wastewater is 1.6-1.8 mmol / L.

3. The method according to claim 2, wherein In step (1), the concentration of ferrous ions in the mixed wastewater is 1.786 mmol / L.

4. The method according to claim 1, wherein The concentration of microalgae in the algae-bacteria symbiosis is (5-10)×10 6 cell / mL, and the concentration of bacteria in the algae-bacteria symbiosis is (0.5-6)×10 9 CFU / mL.

5. The method according to claim 1, wherein In step (2), the standing is carried out at 20-25° C., 14 h / day of illumination, and a light intensity of 1000 lux; and the standing time is 30-90 days.

6. The method according to claim 1, wherein The aquatic biological crust is derived from mine wastewater.

7. The method according to claim 1, wherein The ferrous salt solution is one of ferrous sulfate solution, ferrous chloride solution, and ferrous carbonate solution; the heavy metal is at least one of cadmium, chromium, cobalt, lead, zinc, tin, and mercury; and the metalloid is at least one of arsenic, antimony, tellurium, and boron.

8. The method according to claim 7, wherein The ferrous salt solution is ferrous sulfate solution.

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