CN101597181A - A method of using ammonium sulfate mixture to activate heavy metals in domestic waste composting - Google Patents

Abstract

The invention discloses a method for activating heavy metals in domestic garbage composting by using ammonium sulfate mixed solution. The method is to compost domestic garbage polluted by heavy metals, sieve and sort, and then mix it with different ammonium sulfate mixed solutions in 1:10-15 parts by weight. Separately leaching 2-3; then collecting the compost rinsing solution separately, filtering and digesting, measuring the content changes of heavy metals Cd, Cr, Cu, Ni, Pb, Zn in the solution, and realizing the activation effect of heavy metals in domestic waste composting . The present invention considers the joint effect between ammonium sulfate and EDTA or organic acid, and analyzes the activation effect of six heavy metal elements with higher content in domestic compost, and applies ammonium sulfate mixture to domestic waste compost to induce plant chelation Provide preliminary technical links in the restoration, and make technical support preparations for further application in the restoration of heavy metals in induced turf plants.

Description

A method of using ammonium sulfate mixture to activate heavy metals in domestic waste composting

technical field

The invention belongs to the technical field of environmental protection, and relates to a treatment and restoration method for composting urban domestic garbage. More specifically, it is a method for activating heavy metals in domestic garbage composting by using ammonium sulfate mixed solution.

Background technique

The process of collecting municipal solid waste into piles, storing it in heat preservation, fermenting, and using the biochemical action of microorganisms under artificial control conditions to degrade the organic matter in the waste into stable humus-like soil substances is called waste composting. This treatment process decomposes the perishable organic matter in the garbage and transforms it into an organic fertilizer rich in organic matter and nutrients such as nitrogen, phosphorus, and potassium, so that the garbage can realize a virtuous cycle from nature and back to nature, which is an economical and effective treatment and consumption An important way of urban waste. As far as the specific situation of domestic waste is concerned, the content of perishable organic matter in domestic waste is relatively high, and composting technology can achieve better treatment effects. Composting domestic waste can not only solve the problem of urban waste, but also achieve the purpose of recycling, which has certain economic and social benefits. At present, all countries in the world regard the "harmless, The "three modernizations" policy of "reduction and recycling" is the principle of comprehensively solving urban waste. From this development trend, the use of composting to deal with urban waste is in line with this direction and is regarded as a way to deal with urban domestic waste. path worthy of attention.

Because waste compost also contains heavy metals, pathogenic bacteria and other substances, people worry that it will cause poor quality of agricultural products, pollute the environment, and endanger health if it is directly used in agriculture, which seriously affects its agricultural prospects. For example, the content of vitamin C in Chinese cabbage decreased after continuous use of compost, and the greater the amount of compost used, the greater the decrease. The crude fiber content of Chinese cabbage decreased significantly compared with the control. Heavy metal pollution in garbage composting is the most serious negative effect. How to reduce the toxic effect of heavy metals in composting, improve and improve composting technology and quality has become a hot issue in garbage composting research in recent years.

Low molecular weight organic acids are a kind of functional organic matter ubiquitous in soil, mainly derived from organic matter decomposition, plant root secretion, microbial secretion and metabolism, and play an important role in the rhizosphere soil environment. Moreover, low-molecular-weight organic acids are natural chelating agents. Studies have shown that organic acids can release solid heavy metals from the soil through complexation, enhance the activity of heavy metals to enhance plant absorption and accumulation, thereby improving plant restoration efficiency and shortening the restoration cycle. At the same time, there are also research reports that organic acids can coordinate with heavy metals to form stable complexes, transform ionic metals into low-toxic or non-toxic chelated forms, and participate in the absorption, transportation, and accumulation of heavy metal elements. , so as to promote the super accumulation of heavy metals in plants, reduce the toxic effect of excessive metals on plants, and achieve the purpose of detoxifying heavy metals in plants. At present, many scholars have studied the effects of organic acids on the form, adsorption and desorption of cadmium in soil and the effect of organic acids on the growth and development of plants under cadmium stress. Some studies have also proved that organic acids can promote the release of cadmium in soil and promote The absorption of plants is to form a "cadmium-low molecular organic acid" complex. Therefore, the interaction between organic acids and metal ions in the soil-plant system is very important for the dissolution and migration of insoluble heavy metals. The research results also pointed out that the formation of metal chelates between organic acids and cadmium not only increases the mobility of cadmium in plants, but also It can also reduce the toxicity of cadmium in the environment to plants.

Kramer et al. (1996) found that the organic acids that chelate heavy metals in the rhizosphere mainly include citric acid, malic acid and oxalic acid. Citric acid can reduce the adsorption of lead and cadmium in the soil, that is, activate the lead and cadmium elements in the soil; at the same time, some studies have proved that small molecule organic acids in the rhizosphere environment can chelate or coordinate with heavy metals to affect the soil. The existing forms of heavy metals can improve the solubility of heavy metals, increase the ability of metal migration, and then achieve the effect of activation, and different types of organic acids have different effects on heavy metals in soil. Lawn plants combined with organic acids have also been reported in chelation-induced phytoremediation. The results show that the presence of low-molecular-weight organic acids significantly reduces the adsorption of cadmium on soil, and oxalic acid and citric acid and their respective organic acid salts Iron in brown soil has activation effect, and the iron released from dark brown soil after activation increases with the increase of low molecular organic acid/salt concentration, and the activation effect of citric acid is greater than that of oxalic acid, which may be due to the effect of citric acid on iron The chelating ability is stronger than oxalic acid and citric acid have larger dissociation constants. It can be seen from this that it is feasible to use organic acids to remediate heavy metals in soil, but there is no literature report on the method of using ammonium sulfate to prepare a mixed solution to activate heavy metals in domestic waste composting.

Contents of the invention

The purpose of the present invention is to activate the heavy metals in the domestic waste compost by adding ammonium sulfate, EDTA and three kinds of organic acids. After leaching or organic acid activation treatment, the heavy metal elements in the polluted domestic waste compost will be exposed or Increase the content of soluble heavy metals in the domestic waste composting solution, and then collect the domestic waste composting solution to process or improve the absorption of heavy metals by plants to achieve the purpose of phytoremediation, thereby reducing the pollution of domestic waste composting. The activation test of heavy metals in the compost, while considering whether there is an effect between ammonium sulfate and EDTA or organic acids, the activation effect on the six heavy metal elements (Cr, Zn, Cu, Cd, Ni, Pb) with high content in compost The analysis was carried out in order to provide preliminary research for the application of the ammonium sulfate mixture in the chelation-induced phytoremediation of domestic waste composting, and to prepare for the further application of the ammonium sulfate mixture in the study of the induction of heavy metal remediation characteristics of lawn plants. In order to achieve the above object, the present invention provides the following technical solutions:

A mixed solution of ammonium sulfate, characterized in that said mixed solution of ammonium sulfate is: ammonium sulfate and EDTA or ammonium sulfate and organic acid or ammonium sulfate and EDTA and organic; wherein:

(1) Ammonium sulfate: EDTA is 1g/L (NH ₄ ) ₂ SO ₄ : 50-100mmol/LEDT;

(2) Ammonium sulfate: organic acid 1g/L (NH ₄ ) ₂ SO ₄ : 50-100mmol/LEDTA;

(3) Ammonium sulfate: EDTA: organic acid: 1 g/L (NH ₄ ) ₂ SO ₄ : 50-100 mmol/LEDT: 50-100 mmol/L organic acid.

Ammonium sulfate mixed solution of the present invention, organic acid wherein is malic acid, citric acid or oxalic acid.

Ammonium sulfate mixed solution of the present invention, wherein ammonium sulfate: the weight volume ratio of EDTA is: 1: 0.01-0.03; Ammonium sulfate: the weight volume ratio of organic acid is 1: 0.01-0.03; Ammonium sulfate: EDTA: organic acid The weight to volume ratio is 1:0.01-0.03:1-3.

The ammonium sulfate mixed solution of the present invention prepares the method for activating domestic waste composting heavy metals, and it carries out according to the following steps:

(1) Compost the domestic waste containing heavy metal pollution, sieve and sort, air-dry naturally, grind, sieve, and set aside;

(2) leaching the standby domestic waste compost and different ammonium sulfate mixtures in 1:10-15 parts by weight for 2-3 hours;

(3) Then collect the compost rinsing solution separately, filter and carry out digestion treatment, and measure the content changes of heavy metals Cd, Cr, Cu, Ni, Pb and Zn in the solution.

Experimental result of the present invention shows: each treatment ammonium sulfate mixed solution all has activation effect to the content of heavy metal element in the compost, wherein the effect with EDTA is the best, reaches 66.5% to the activation percentage of Cd in the compost, and in each processing mainly is The changes of EDTA and organic acid concentrations had the main influence on the activation of heavy metal elements in compost. For example, ammonium sulfate and 100mmol/L malic acid treatment showed a promotion effect on the activation of Pb; after treating compost with ammonium sulfate, EDTA and organic acid, the activation effect of heavy metal elements was 100mmol/L EDTA has the best activation effect, and the activation effect on Pb is the strongest. It can activate and extract Pb that cannot be dissolved in the compost after digestion treatment, so the activation amount of Pb under this treatment is greater than that of the original compost.

Compared with the prior art, the method for utilizing ammonium sulfate to activate heavy metals in domestic waste composting disclosed by the present invention has the following positive effects:

The present invention aims at composting municipal solid wastes polluted by heavy metals, utilizes ammonium sulfate, EDTA and three kinds of organic acids (malic acid, citric acid, oxalic acid) to carry out activation test on heavy metals in compost, and considers ammonium sulfate and EDTA or organic acids simultaneously Whether there is an effect between them, the activation effect of six heavy metal elements (Cr, Zn, Cu, Cd, Ni, Pb) with high content in compost was analyzed, in order to provide a basis for the application of organic acids in domestic waste compost to induce phytoremediation. Provide preliminary research and prepare for the further application of organic acids in the research of inducing heavy metal repair properties of turf plants.

Detailed ways

For the purpose of simplicity and clarity, descriptions of known technologies are appropriately omitted below, so as not to affect the description of the technical solution with unnecessary details. Below in conjunction with example the present invention will be further described.

Example 1

(1) Compost the domestic waste containing heavy metal pollution, sieve and sort, air-dry naturally, grind, sieve, and set aside;

(2) Leach the spare domestic waste compost and different ammonium sulfate mixtures at a ratio of 1:10 by weight for 2 hours, wherein the ammonium sulfate is 1 g/L (NH ₄ ) ₂ SO ₄ :EDTA 50 mmol/LEDT.

(3) Then collect the compost rinsing solution separately, filter and carry out digestion treatment, and measure the content changes of heavy metals Cd, Cr, Cu, Ni, Pb and Zn in the solution. See embodiment 3 for details.

Example 2

(1) Compost the domestic waste containing heavy metal pollution, sieve and sort, air-dry naturally, grind, sieve, and set aside;

(2) Leach the spare domestic waste compost and different ammonium sulfate mixtures in 1:15 parts by weight for 3 hours; ammonium sulfate: EDTA: organic acid: 1g/L(NH ₄ ) ₂ SO ₄ : 100mmol/ LEDT: 50 mmol/L citric acid.

(3) Then collect the compost rinsing solution separately, filter and carry out digestion treatment, and measure the content changes of heavy metals Cd, Cr, Cu, Ni, Pb and Zn in the solution. See embodiment 3 for details.

Example 3

(1) Experimental materials

Reagents for testing

Disodium ethylenediaminetetraacetic acid (EDTA-Na ₂ for short), chemically pure, content not less than 99.0%; DL-malic acid (C ₄ H ₆ O ₅ ), analytically pure, content not less than 99.0%; citric acid (C ₆ H ₈ O ₇ ·H ₂ O), analytically pure, with a content of not less than 99.5%; oxalic acid (C ₂ H ₂ O ₄ ·2H ₂ O), analytically pure, with a content of not less than 99.5%; ammonium sulfate ( (NH ₄ ) ₂ SO ₄ ), chemically pure, with a content of not less than 99.0%.

Domestic waste composting for test

Domestic waste compost (hereinafter referred to as compost) came from Tianjin Xiaodian Compost Plant, and its basic physical and chemical properties are shown in Table 1. Stones, glass, plastic bags, plant residues, etc. were removed from the domestic waste compost for the test, air-dried naturally, ground and ground with a ball mill, then passed through an 80-mesh sieve, and stored for later use.

Table 1 The physical and chemical properties of domestic waste composting

Determination indicators Domestic waste composting pH 7.62 Saturated water content ml/g 0.76 Bulk density g/ml 0.85 Total Nitrogen % 5.18 Total potassium g/kg 50.83 Available phosphorus mg/kg 77.92 Organic matter% 12.12 Cu(μg/g) 238.73 Cd(μg/g) 1.97 Zn(μg/g) 496.38 Ni(μg/g) 33.42 Pb(μg/g) 172.11 Cr(μg/g) 67.00

(2) Test method

Accurately weigh 2.5g of ground compost and put it into a 100ml Erlenmeyer flask. The treatment of L(NH ₄ ) ₂ SO ₄ was used as a control, and each treatment was repeated three times.

Table 2 The scheme of adding liquid in different treatments of ammonium sulfate treatment garbage composting

deal with Add liquid deal with Add liquid 1 distilled water 10 100mmol/L malic acid+1g/L(NH ₄ ) ₂ SO ₄ 2 1g/L(NH ₄ ) ₂ SO ₄ 11 50mmol/L citric acid 3 50mmol/L EDTA 12 100mmol/L citric acid 4 100mmol/L EDTA 13 50mmol/L citric acid+1g/L(NH ₄ ) ₂ SO ₄ 5 50mmol/L EDTA+1g/L (NH ₄ ) ₂ SO ₄ 14 100mmol/L citric acid+1g/L(NH ₄ ) ₂ SO ₄ 6 100mmol/L EDTA+1g/L(NH ₄ ) ₂ SO ₄ 15 50mmol/L oxalic acid 7 50mmol/L malic acid 16 100mmol/L oxalic acid 8 100mmol/L malic acid 17 50mmol/L oxalic acid+1g/L(NH ₄ ) ₂ SO ₄ 9 50mmol/L malic acid+1g/L(NH ₄ ) ₂ SO ₄ 18 100mmol/L oxalic acid+1g/L(NH ₄ ) ₂ SO ₄

Put the Erlenmeyer flask filled with compost and different treatment solutions into a constant temperature shaker at 25°C for 2 hours, take out the Erlenmeyer flask and let it stand for 0.5 hours to balance, then filter the compost extract and dilute to volume with distilled water. 25ml volumetric flask. The specific digestion method of the extract is as follows: transfer the constant-volume compost extract into a 100ml beaker that has been acidified with nitric acid, add 10ml of nitric acid, heat it on an electric heating plate, and add 1ml when the liquid in the beaker is nearly evaporated to dryness. The _HClO continues to be heated on the electric heating plate to catch the acid, and finally the precipitate in the beaker is dissolved and transferred with 1% nitric acid, and the volume is fixed to a 25ml volumetric flask, and the heavy metal in the solution is measured with a TAS-990 atomic absorption spectrophotometer (Cd, Cr, Cu, Ni, Pb, Zn) content, data collection is carried out by AAWin2.1 software.

(3) Data processing: Excel 2003 software and SPSS 14.0 statistical analysis software were used for data analysis.

(4) Results and analysis

Activation Effects of Ammonium Sulfate and EDTA Treatment on Compost Heavy Metals

The activation effects of ammonium sulfate and EDTA on heavy metals in compost are shown in Table 3. Ammonium sulfate and EDTA treatment can significantly increase the activation amount of heavy metals in compost compared with the control, and the activation ability is enhanced under the condition of high concentration EDTA treatment. Among the 6 heavy metal elements measured in the test, the activation amount of heavy metal elements under high concentration (100mmol/L) EDTA treatment conditions is extremely significant compared with the distilled water control and (NH ₄ ) ₂ SO ₄ control (p<0.01) difference. In the two different concentrations of EDTA treatment, whether there is (NH ₄ ) ₂ SO ₄ treatment or not, the contents of the six heavy metal elements measured showed extremely significant (p<0.01) differences between the different concentrations of EDTA treatment. The treatment of ammonium sulfate and 100mmol/L EDTA showed a negative effect on Zn activation, that is, the activation amount of Zn after ammonium sulfate and treatment was significantly (p<0.01) lower than that of 100mmol/L EDTA treatment.

Table 3 Ammonium sulfate and EDTA treatment on the activation of compost heavy metals

Note: EDTA-50 in the table means 50mmol/L EDTA, EDTA-(NH4)2SO4-50 means 1g/L (NH4)2SO4 and EDTA with a concentration of 50mmol/L, the same below. The data in the table are expressed as mean ± standard error (SE). Different lowercase letters in the same column indicate significant differences at the 0.05 level, and different uppercase letters indicate significant differences at the 0.01 level. The same below.

Activation effects of ammonium sulfate and malic acid treatment on heavy metals in compost

The activation effects of ammonium sulfate and malic acid treatment on compost heavy metals are shown in Table 3.4. After treatment with ammonium sulfate and malic acid, the activation ability of the six heavy metal elements determined in the test increased with the increase of the concentration of malic acid, and compared with the two groups of controls, the activation of the six heavy metal elements was extremely significant. (p<0.01) difference; the activation amount of heavy metal elements reached a very significant (p<0.01) difference between the two treatment concentrations of malic acid. Compared with the (NH ₄ ) ₂ SO ₄ control treatment, the activation amount of Cr reached a significant difference (p<0.05) level under the treatment of 50mmol/L malic acid, and the activation amounts of the other five elements were extremely significant in each treatment (p<0.01) difference. The treatment of ammonium sulfate and 100mmol/L malic acid showed a promotion effect on the activation of Pb, and the activation of Pb in this treatment was significantly (p<0.01) greater than that of 100mmol/L malic acid.

Table 4 Ammonium sulfate and malic acid treatment on the activation of compost heavy metals

Activation Effects of Ammonium Sulfate and Citric Acid Treatment on Compost Heavy Metals

The activation effects of ammonium sulfate and citric acid on compost heavy metals are shown in Table 5. Compared with the two groups of control treatments, the activation amounts of the six heavy metal elements measured in the test after being treated with ammonium nitrate and citric acid all showed extremely significant (p<0.01) differences. At the same time, the activation ability of heavy metal elements increases with the increase of the concentration of citric acid treatment. Except for Cd, which is only treated with citric acid, the other five elements, regardless of whether there is ammonium nitrate and treatment, are between two different citric acid treatment concentrations. All showed extremely significant differences (p<0.01). For Zn and Cu elements, compared with ammonium nitrate and the same concentration of citric acid in the treatment of citric acid as 50mmol/L, the activation amount of the two elements reached a very significant (p<0.01) difference, and it is in the process And the activation amount of elements after treatment is extremely significantly reduced, showing the negative effect of treatment.

Table 5 Ammonium sulfate and citric acid treatment on the activation of compost heavy metals

Activation Effects of Ammonium Sulfate and Oxalic Acid Treatment on Compost Heavy Metals

The activation effects of ammonium sulfate and oxalic acid on compost heavy metals are shown in Table 6. The activation ability of heavy metal elements increased with the increase of oxalic acid concentration, except that the activation amount of Cd showed no difference with the increase of oxalic acid concentration, and all the other high-concentration oxalic acid treatments showed extremely significant (p< 0.01) difference. When the oxalic acid concentration is 50mmol/L, compared with the distilled water control, there is no significant difference in the activation ability of the elements. When the oxalic acid concentration is 100mmol/L, except for the ammonium sulfate and treatment of the two elements of Cd and Pb, the rest are the same as the control A very significant difference was reached (p<0.01). Compared with the (NH ₄ ) ₂ SO ₄ control, the activation amount of Cr showed a significant difference (p<0.01) when treated with two concentrations of oxalic acid; When the concentration is 50mmol/L, there is no significant difference, and when it is 100mmol/L, it shows a very significant difference (p＜0.01); the activation amount of Pb element is in the treatment that 100mmol/L oxalic acid does not add ammonium nitrate and the treatment, and the contrast shows a very significant difference. Significant difference (p<0.01), the activation amount of this element decreased during the treatment, which was at the same level as the control and low-concentration oxalic acid treatment, and also showed the negative effect of ammonium sulfate treatment. For the three heavy metal elements Zn, Cu, Ni, ammonium sulfate and 100mmol/L oxalic acid treatment significantly increased the activation of these three elements, showing the promotion effect of ammonium sulfate and treatment.

Table 6 Ammonium sulfate and oxalic acid treatment on the activation of compost heavy metals

Comparison of Activation of Heavy Metals in Compost by EDTA and Organic Acid Treatment at Optimum Activation Concentration

EDTA and three organic acids have the highest activation efficiency of heavy metals in compost at the concentration of 100mmol/L respectively. The activation results of heavy metals in compost are analyzed with 100mmol/L EDTA, malic acid, citric acid, and oxalic acid, as shown in Table 3.7 It can be seen that among the six heavy metal elements measured in the test, for the four elements Zn, Cd, Cu, and Pb, EDTA has the largest activation amount, and oxalic acid has the worst activation effect. The ratio difference is extremely significant (p<0.01); the activation effect of citric acid on Cr is better than that of EDTA, and its activation amount is significantly different from that of each treatment (p<0.01); the activation amount level of citric acid and EDTA on Ni Close to, all very significantly greater than malic acid and oxalic acid, and there is also a very significant (p<0.01) difference in the activation amount of Ni between malic acid and oxalic acid treatment.

Table 7 Comparison of 100mmol/L EDTA and organic acids on the activation of heavy metal elements in compost

Effects of Ammonium Sulfate, EDTA and Organic Acids on the Activation Percentage of Heavy Metals in Compost

Compared with the content of each heavy metal element in the original compost in Table 1, after treating the compost with ammonium sulfate, EDTA and organic acid, the influence on the percentage of activation effect of heavy metal elements is shown in Table 8. Among the six heavy metal elements measured in the test, except for Cr, for the other five elements, the activation effect of 100mmol/L EDTA is the best, and the activation effect for Pb is the strongest, which can be digested in compost The insoluble Pb was activated and extracted, so the activated amount of Pb under this treatment was greater than that of the original compost. At the same time, we have also seen that the activation treatment with organic acids has also achieved good results, and the treatment with ammonium sulfate and high-concentration organic acids and the use of high-concentration organic acids alone have the largest activation percentage.

Table 8 Comparison of ammonium sulfate, EDTA and organic acid treatment on the activation percentage of compost heavy metals

Technical application conclusion

In the study of using ammonium sulfate, EDTA and organic acid to activate the compost of domestic waste, the results show that: each treatment has an activation effect on the content of heavy metal elements in the compost, among which EDTA has the best effect, and the activation percentage of Cd in the compost It reached 66.5%, and in each treatment, the change of EDTA and organic acid concentration had the main effect on the activation of heavy metal elements in compost. The activation effect of heavy metal elements in compost increases with the increase of EDTA and organic acid concentration, and whether there is ammonium sulfate treatment or not, there is a significant difference in the activation amount of heavy metal elements between two different EDTA treatment concentrations (p< 0.05) and extremely significant (p<0.01) differences. Among the six heavy metal elements measured in the test, the treatment with ammonium sulfate alone has no significant activation effect on it, and the effect of ammonium sulfate and EDTA is not obvious, and even shows a negative effect of treatment on the activation of Zn; Simultaneously in Cu, Zn two kinds of elements under the citric acid treatment and Cd and Pb two kinds of elements under the oxalic acid treatment, the activation amount of the above-mentioned elements in the treatment is lower than when the organic acid is used alone. At the same level, it showed the negative effect of ammonium sulfate treatment, but in the treatment of ammonium sulfate and 100mmol/L malic acid and oxalic acid, the activation effects of Pb, Zn, Cu, Ni and other elements in compost showed the promotion of ammonium sulfate. effect. Therefore, in the activation treatment of domestic waste composting by EDTA and organic acids, the type and concentration of chelating agents used and whether ammonium sulfate should be added for co-treatment should be fully considered.

From the percentage of heavy metal activation after EDTA and organic acid treatment of compost, it can be seen that the concentration of the experimental design can significantly increase the activation of heavy metal elements. In terms of the overall activation effect, the activation effect of EDTA and the three organic acids is strong or weak The order is EDTA>citric acid>malic acid>oxalic acid. Citric acid is the acid with the strongest chelating ability among small molecular organic acids, but the test results show that the chelating ability of organic acids and the activation amount of heavy metal elements are smaller than EDTA, and in the leaching of Pb and Cd, each is lower than EDTA. The order of molecular organic acid capacity was citric acid > tartaric acid > oxalic acid, the desorption order of Cu was citric acid > oxalic acid > tartaric acid, and the desorption order of Zn was tartaric acid > citric acid > oxalic acid. It can also be seen from the results of the activation percentage that Cu and Zn elements in compost are more active and easier to be activated, which suggests that we should consider the dissolution and transfer of these two elements when performing activation and leaching treatment of waste compost question. Since the activation effect of heavy metal elements in the treatment with chelating agent EDTA or organic acid is obvious, we must consider the recovery and reprocessing of the leaching solution after the activation treatment, so as to effectively prevent secondary pollution while repairing domestic waste composting. The occurrence of secondary pollution, to avoid pollution of groundwater and subsoil.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to within the scope of the technical solutions of the present invention.

Claims (4)

1. A mixed solution of ammonium sulfate, characterized in that said mixed solution of ammonium sulfate is: ammonium sulfate and EDTA or ammonium sulfate and organic acid or ammonium sulfate and EDTA and organic; wherein: (1) Ammonium sulfate: EDTA is 1g/L (NH ₄ ) ₂ SO ₄ : 50-100mmol/LEDT; (2) Ammonium sulfate: organic acid 1g/L (NH ₄ ) ₂ SO ₄ : 50-100mmol/LEDTA; (3) Ammonium sulfate: EDTA: organic acid: 1 g/L (NH ₄ ) ₂ SO ₄ : 50-100 mmol/LEDT: 50-100 mmol/L organic acid. 2. The ammonium sulfate mixed solution as claimed in claim 1, wherein the organic acid is malic acid, citric acid or oxalic acid. 3. The ammonium sulfate mixed solution as claimed in claim 1, wherein the weight-volume ratio of ammonium sulfate: EDTA is 1: 0.01-0.03; the weight-volume ratio of ammonium sulfate: organic acid is 1: 0.01-0.03; ammonium sulfate: EDTA : The weight-to-volume ratio of the organic acid is 1:0.01-0.03:1-3. 4, a kind of method that adopts the described ammonium sulfate mixed solution of claim 1 to prepare activated domestic waste composting heavy metal, it carries out according to the following steps: (1) Compost the domestic waste containing heavy metal pollution, sieve and sort, air-dry naturally, grind, sieve, and set aside; (2) leaching the standby domestic waste compost and different ammonium sulfate mixtures in 1:10-15 parts by weight for 2-3 hours; (3) Then collect the compost rinsing solution separately, filter and carry out digestion treatment, and measure the content changes of heavy metals Cd, Cr, Cu, Ni, Pb and Zn in the solution.