CN109970299B - Sequencing batch biological self-leaching process for removing heavy metals in bottom mud - Google Patents
Sequencing batch biological self-leaching process for removing heavy metals in bottom mud Download PDFInfo
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- CN109970299B CN109970299B CN201910245633.1A CN201910245633A CN109970299B CN 109970299 B CN109970299 B CN 109970299B CN 201910245633 A CN201910245633 A CN 201910245633A CN 109970299 B CN109970299 B CN 109970299B
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
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Abstract
The invention discloses a sequencing batch biological self-leaching process for removing heavy metals in bottom mud. Aiming at the sediment with specific properties, the indigenous bacteria in the sediment are activated by adding a sulfur matrix and changing conditions such as Eh, and the bioleaching process does not need to add leaching functional bacteria and can use various soil conditioners containing sulfur simple substances as the sulfur matrix. The invention effectively solves the problems of long microorganism inoculation and domestication time, serious substrate sludge nutrition loss and the like in the traditional method, simplifies the process steps, reduces the operation difficulty, improves the treatment capacity, saves the capital construction investment and further promotes the engineering application of the substrate sludge bioleaching technology.
Description
Technical Field
The invention belongs to the field of heavy metal pollution treatment, and particularly relates to a method for bioleaching heavy metals in bottom sludge.
Technical Field
The bioleaching technology is a technology for separating, leaching and removing insoluble heavy metals in a solid phase by using direct action of leaching functional bacteria or indirect action of metabolites of the leaching functional bacteria through ways of generating oxidation, reduction, complexation, adsorption or dissolution and the like. The technology originates from microbial hydrometallurgy, and then research and application of the technology are gradually expanded to the field of environmental pollution remediation and treatment, such as recycling of heavy metals in electronic wastes, removal of heavy metals in waste incineration fly ash, removal of heavy metals in overproof soil, sludge and bottom mud, and the like. In these applications, the technology has been developed. Among them, the bioleaching technology is considered to be one of the promising heavy metal contaminated sediment treatment technologies due to the urgent nature of large sediment dredging amount, high heavy metal content and urgent need for effective treatment in China and the limitation that detoxification and dehydration by the existing physical and chemical methods cannot be combined.
At present, most of research on the bioleaching process of the sediment is in a small test or a pilot test stage, and few reports of actual engineering are provided. At present, the existing leaching process mostly adopts a sludge reflux method or a multiple inoculation method for treatment, leaching functional bacteria such as thiobacillus thiooxidans and the like and corresponding growth substrates are added artificially, dehydration and drying are carried out after the leaching end point is reached for resource utilization of the next step, the sulfur substrate mainly adopted is sulfur simple substance or biological sulfur, and the process has the problems of long inoculation and acclimation time of the leaching functional bacteria, low treatment capacity, large occupied area of the treatment process and the like.
Disclosure of Invention
The invention aims to provide a sequencing batch biological self-leaching process for removing heavy metals in bottom mud, which can save the operation cost, the technical cost and the capital construction cost of the process and conveniently and quickly treat the bottom mud.
The applicant finds that the bottom sediment has leaching functional bacteria, and the high-throughput analysis result of microorganisms shows that the bottom sediment contains acid bacillus, thiobacillus halophila, sulfur monads, acinetobacter, pseudomonas and the like (figure 1), and the leaching mechanisms of the bacteria are different but have the leaching function. The research and development of the technology can improve the treatment efficiency of the bioleaching technology and promote the engineering application of the technology. Therefore, aiming at the bottom sludge with specific properties, the invention provides a sequencing batch biological self-leaching process for removing heavy metals in the bottom sludge.
The invention specifically adopts the technical scheme that:
a sequencing batch biological self-leaching process for removing heavy metals in bottom mud comprises the following steps:
1) adjusting the water content of the initial bottom mud polluted by the heavy metals to enable the bottom mud to become a mud-water mixture with the water content of 95% -98%;
2) adding 3-10g/L of sulfur matrix into the treated mud-water mixture of 1);
3) continuously oxygenating the mud-water mixture treated in the step 2), so as to change the bottom mud Eh to form an environmental condition favorable for leaching, and when the pH value is less than 3.0, determining that the leaching end point is reached;
4) and (3) standing the mud-water mixture after the leaching end point is reached, discharging supernatant after mud-water separation, and dehydrating the lower layer mud.
Preferably, the initial sediment satisfies the following conditions:
1) the pH of the bottom mud is less than 7.5;
2) the heavy metal content in the bottom mud exceeds the screening value of the soil pollution risk;
3) acid Consumption Capacity (ACC) is less than 2 mol/kg.
In the invention, the pH of the sediment is determined by reference to the national standard HJ 962-2018, and the soil pollution risk screening value is determined by reference to the national standard GB 15618-2018.
Preferably, the sulfur-based substance can be various agricultural sulfur substrates containing sulfur in addition to industrial and commercial elemental sulfur powder.
Preferably, the agricultural sulfur matrix is soil conditioner bentonite sulfur and agricultural fertilizer coated urea sulfur, so that the agricultural sulfur matrix is non-toxic and harmless, and the subsequent resource utilization of the bottom mud can be widened.
Preferably, the oxygenation operation is aeration, shaking or stirring, and any operation capable of oxygenating the mud-water mixture can be used.
Preferably, steps 1) to 4) can be carried out in the same cell body.
Compared with the background art, the invention has the advantages and effects that:
first, the indigenous bacteria in the sediment with specific properties are utilized to activate the indigenous bacteria by adding sulfur matrix and changing external conditions such as oxygenation, so as to carry out bioleaching. The leaching function microbial inoculum is not required to be added, and the leaching function microbial inoculum is not required to be enriched, cultured and stored, so that the process steps are greatly simplified, the operation difficulty is reduced, the traditional process equipment such as a backflow pipeline, an adjusting tank, enrichment culture and reinforcement of microorganisms is saved, the required capital construction investment is less, the occupied area is small, and the bottom sludge can be conveniently and quickly treated.
And secondly, selecting bentonite sulfur or coated urea sulfur as a sulfur matrix for bioleaching according to actual operation and budget conditions. The bentonite sulfur is originally a soil conditioner, the coated urea sulfur is originally an agricultural fertilizer, and the two sulfur matrixes are non-toxic and harmless and can widen the subsequent resource utilization of the bottom mud.
Drawings
FIG. 1 microbial community structure distribution in sediment;
FIG. 2 is a flow chart of a sequencing batch biological self-leaching process for removing heavy metals from bottom mud;
FIG. 3 is a graph showing the pH variation of bioleaching sediment with sulfur powder as a growth substrate;
FIG. 4 shows the heavy metal removal rate of bioleaching of sediment using sulfur powder as a growth substrate;
FIG. 5 is a graph of the change in pH of bioleaching sediment using coated urea sulfur as the growth substrate;
FIG. 6 shows the heavy metal removal rate of bioleaching of sediment with coated urea-sulphur as the growth substrate.
Detailed Description
The invention will be further described with reference to the drawings and examples, but the scope of the invention is not limited thereto.
For the bottom sludge meeting specific conditions, heavy metal can be removed according to the sequencing batch biological self-leaching process. The bottom sludge that can be treated with the process of the invention needs to satisfy the following conditions:
1) it has a pH <7.5, determined according to the national standard (HJ 962-.
2) The heavy metal content of the sediment polluted by the heavy metal exceeds the screening value of the soil pollution risk by referring to the national standard (GB 15618-2018).
3) Acid Consumption Capacity (ACC) is less than 2 mol/kg.
The method mainly depends on indigenous leaching functional bacteria to produce acid after utilizing sulfur powder and then dissolve out heavy metal, so that the process can be influenced or even inhibited if the pH and the acid consumption are too high. In addition, the optimum survival condition of the bacteria is the condition of lower pH, so the pH of the initial bottom sediment also needs to be ensured not to be too high, otherwise, the content of indigenous leaching functional bacteria in the initial bottom sediment is lower, and the process of the invention can not be applied.
For the sediment satisfying these three conditions, as shown in fig. 2, the treatment is performed according to the following steps:
1) adjusting the water content: adjusting the water content of the initial bottom mud polluted by the heavy metals to enable the bottom mud to become a mud-water mixture with the water content of 95% -98%;
2) adding an energy source substrate: adding 3-10g/L of sulfur matrix into the treated mud-water mixture of 1);
3) oxygenation: continuously oxygenating the mud-water mixture treated in the step 2), so that the bottom mud Eh is changed to form an environmental condition favorable for leaching, and when the pH value is less than 2.5-3.0, the end point of leaching is considered to be reached;
4) separating mud from water: and (3) standing the mud-water mixture after the leaching end point is reached, discharging supernatant after mud-water separation, and dehydrating the lower layer mud.
Based on this method, the technical effects of the present invention are shown below by examples.
Example 1
Heavy metal polluted bottom mud is collected in a river, and the heavy metal content is measured to be Cu 284.48mg/kg, Zn394.00mg/kg, the acid consumption is 1.28mol/kg, and the pH is 7.29. Adding bottom sludge and water with the total volume of 6L into a reactor to enable the water content of the bottom sludge and the water to be 97%, adding 18g of sulfur powder, aerating the sludge-water mixture at room temperature, wherein the aeration amount is 160L/h, and leaching reaction of heavy metals is realized in the aeration process.
Meanwhile, three single-factor control groups are provided for the present embodiment, wherein the first group of control groups is different from the present embodiment in that leaching functional bacteria are additionally added, the second group of control groups is different from the present embodiment in that no sulfur powder is added, and the third group of control groups is different from the present embodiment in that the initial bottom sludge is sterilized and no sulfur powder is added.
The results of the change of pH with time in the slurry-water mixture systems of this example and each control group are shown in FIG. 3, in which the initial pH of the slurry-water mixture in the process was 6.95, and the pH decreased to 2.5 within 8 days, while the pH trends of the other two control groups are much different from those of the present invention and the conventional process (i.e., the first control group). From the leaching amounts of Cu and Zn shown in FIG. 4, the leaching amounts of Cu and Zn in the process of the present invention are substantially the same as those in the conventional process. This indicates that indigenous leaching functional bacteria in the sediment can be activated to perform bioleaching under the conditions of changing Eh and adding sulfur matrix. The process has good effect of removing Cu and Zn, is comparable to the traditional process of adding a microbial inoculum, and shows that the sequencing batch biological self-leaching process has good effect of removing heavy metals. Meanwhile, the leaching time is calculated, so that the domestication and culture time of an additional microbial inoculum can be saved, and 22.5 percent of bottom mud can be processed in the same time compared with the traditional process with the reflux amount of 30 percent.
Example 2
The substrate sludge used in this example was reacted with the substrate sludge of example 1 in a 250ml glass Erlenmeyer flask containing 150ml of a mixture of sludge and water having a water content of 97% and 4.5g of coated urea-sulfur in a constant temperature shaking incubator at 28 ℃ and 180 rpm. The initial pH of the slurry mixture was 7.24.
Meanwhile, a single-factor comparison group is set for the embodiment, and the comparison method is different from the embodiment in that leaching functional bacteria are additionally added, and the other methods are the same.
The results of the change of pH with time in the slurry-water mixture systems of this example and the control group are shown in FIG. 5, which shows that the pH can be reduced to 3 or less at day 9, and whether the pH of the external bacteria agent is reduced substantially uniformly, indicating that the coated urea-sulfur can be used as a sulfur-based substance for biological self-leaching. The effect of removing heavy metals in the bottom sediment is shown in fig. 6, and similarly, the process has a good effect of removing Cu and Zn, wherein the leaching amount of Cu and Zn is comparable to that of the traditional process with an external microbial inoculum, which indicates that the sequencing batch biological self-leaching process has a good effect of removing heavy metals. In addition, the total nitrogen of the sediment subjected to biological self-leaching by adopting the coated urea sulfur and the sulfur powder is respectively 15.60mg/g and 3.27mg/kg, which shows that the problem of nutrient loss can be solved to a certain extent by adopting the coated urea sulfur as a sulfur matrix, and the resource utilization way of the sediment after leaching for agriculture is widened.
As can be seen from the two examples, the end point of leaching can be considered to be reached when the pH of the mud-water mixture during leaching is less than 3.0. In the practical application process, after the leaching end point is reached, the mud-water mixture is stood, after mud-water separation, the supernatant is discharged, and the lower layer mud is dewatered, so that the aim of removing heavy metals in the bottom mud can be fulfilled.
The invention effectively solves the problems of long microorganism inoculation and domestication time, serious substrate sludge nutrition loss and the like in the traditional method, simplifies the process steps, reduces the operation difficulty, improves the treatment capacity, saves the capital construction investment and further promotes the engineering application of the substrate sludge bioleaching technology.
The above-described embodiments are merely preferred embodiments of the present invention, which should not be construed as limiting the invention. Various changes and modifications may be made by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present invention. Therefore, the technical scheme obtained by adopting the mode of equivalent replacement or equivalent transformation is within the protection scope of the invention.
Claims (4)
1. A sequencing batch biological self-leaching process for removing heavy metals in bottom mud is characterized by comprising the following steps:
1) adjusting the water content of the initial bottom mud polluted by the heavy metals to enable the bottom mud to become a mud-water mixture with the water content of 95% -98%;
2) adding 3-10g/L of sulfur matrix into the treated mud-water mixture of 1);
3) continuously oxygenating the mud-water mixture treated in the step 2), so as to change the bottom mud Eh to form an environmental condition favorable for leaching, and when the pH value is less than 3.0, determining that the leaching end point is reached;
4) standing the mud-water mixture after the leaching end point is reached, discharging supernatant after mud-water separation, and dehydrating the lower layer mud;
the initial bottom mud meets the following conditions:
1) the pH of the bottom mud is less than 7.5;
2) the heavy metal content in the bottom mud exceeds the screening value of the soil pollution risk;
3) the acid consumption is less than 2mol/kg, and the acid consumption refers to acid consumption capacity, which is abbreviated as ACC.
2. The sequencing batch biological self-leaching process for removing heavy metals from bottom sludge according to claim 1, wherein the sulfur matrix is elemental sulfur powder or agricultural sulfur matrix.
3. The sequencing batch biological self-leaching process for removing heavy metals from bottom mud according to claim 2, wherein the agricultural sulfur matrix is soil conditioner bentonite sulfur or agricultural fertilizer coated urea sulfur.
4. The sequencing batch bioleaching process for removing heavy metals from substrate sludge as claimed in claim 1, wherein the oxygenation operation is aeration, shaking or stirring.
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| CN113292214A (en) * | 2021-05-27 | 2021-08-24 | 浙江大学 | Heavy metal removal bioleaching process for carrying out classification treatment based on bottom mud properties |
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| JPH05227979A (en) * | 1992-02-14 | 1993-09-07 | Israel Electric Corp Ltd:The | Method for extraction of living organism |
| CN101475259A (en) * | 2008-10-31 | 2009-07-08 | 南开大学 | Method for removing heavy metal in excess activated sludge |
| CN105731750A (en) * | 2016-03-16 | 2016-07-06 | 福州大学 | Method for removing heavy metal in sludge by means of bioleaching by aid of mixed substrates |
| CN107352767A (en) * | 2017-06-22 | 2017-11-17 | 广东省生态环境技术研究所 | A kind of bioleaching hardening agent and the method for removing sludge heavy-metal |
| CN108486097A (en) * | 2018-05-17 | 2018-09-04 | 浙江大学 | The dual immobilization biological matter charcoal particle of sulphur-bacterium and preparation and bioleaching method |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05227979A (en) * | 1992-02-14 | 1993-09-07 | Israel Electric Corp Ltd:The | Method for extraction of living organism |
| CN101475259A (en) * | 2008-10-31 | 2009-07-08 | 南开大学 | Method for removing heavy metal in excess activated sludge |
| CN105731750A (en) * | 2016-03-16 | 2016-07-06 | 福州大学 | Method for removing heavy metal in sludge by means of bioleaching by aid of mixed substrates |
| CN107352767A (en) * | 2017-06-22 | 2017-11-17 | 广东省生态环境技术研究所 | A kind of bioleaching hardening agent and the method for removing sludge heavy-metal |
| CN108486097A (en) * | 2018-05-17 | 2018-09-04 | 浙江大学 | The dual immobilization biological matter charcoal particle of sulphur-bacterium and preparation and bioleaching method |
Non-Patent Citations (1)
| Title |
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| Bioleaching of Heavy Metal Polluted Sediment :Influence of Sediment Properties (Part 2);C. Löser et al.;《Engineering in Life Sciences》;20060906;第6卷(第4期);第364页左栏倒数第1段至右栏末尾 * |
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