JP2005262174A - Method for decontaminating contaminated bottom sediment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for decontaminating bottom sediment contaminated with a chlorinated organic compound by a simple means. <P>SOLUTION: This method for decontaminating the contaminated bottom sediment comprises: a dredging step to dredge the bottom sediment contaminated with the chlorinated organic compound; an adding/mixing step to add a microbe having the ability to decompose the chlorinated organic compound to the dredged bottom sediment and mix them; a packing step to pack the obtained mixture in an air-permeable and water-permeable bag; and a settling step to settle the mixture-packed bag. The contaminated bottom sediment is dredged by a high-concentration dredger 10, which is then sent to a pneumatic conveyance ship 20 where the microbe and, if necessary, bio-organic matter, or the like, are further added to the sent bottom sediment. When the pneumatic conveyance is completed, the bottom sediment is mixed sufficiently homogeneously with the added microbe, or the like, so that the chlorinated organic compound in the microbe-added bottom sediment can easily be decontaminated efficiently. When the transfer is completed, the microbe-added bottom sediment discharged to a sludge storage pit 30 is pumped up by a pump 40 and press-injected/packed in the bag. The bottom sediment 50 packed in the bag is dehydrated, volume-reduced, settled and stored. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a contaminated sediment purification method, and more particularly to a contaminated sediment purification method for purifying a sediment contaminated with an organic chlorine compound such as dioxins by the action of microorganisms.

  Concerning sediment dredging, dredging with grab dredging device, bucket dredging device or high-concentration dredging device, and transferring the sediment to the mud pit by pump or pneumatic feeding device, and water permeability with pump A method of press-fitting into a large sandbag, dehydrating and reducing the volume, and storing is proposed (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 02-157099

  The bottom sediment packaged by the method as described in Patent Document 1 may be stored on land or returned to the dredging point or the seabed in the vicinity thereof as sand cover. The sandbag is made of special fibers, and even if the sediment contains contaminants such as organochlorine compounds, the pollutant does not exude from the sandbag. Therefore, the diffusion of contaminants can be prevented unless the sandbag is damaged. However, since the pollutant remains in the sandbag as it is, if the sandbag breaks, the contaminated sediment may leak out and the contamination may spread, which is fundamentally purifying the bottom sediment. Absent.

  Although it is theoretically possible to treat dredged contaminated sediment by chemical methods and remove organochlorine compounds, large-scale treatment equipment is required to treat all of the contaminated sediment generated in large quantities. In reality, it is difficult because of the great labor and cost.

  Therefore, an object of the present invention is to provide a method for purifying sediment contaminated with an organic chlorine compound by a simple means.

  In order to solve the above-mentioned problem, the first aspect of the present invention is a dredging process for dripping sediment contaminated with organochlorine compounds, and a microorganism having an ability to decompose organochlorine compounds is added to the drowned sediment and mixed. Contamination bottom characterized by including an addition mixing step, a bagging step of filling the obtained mixture into a bag having air permeability and water permeability, and a stationary step of standing the bag after filling It is a quality purification method.

  In this first aspect, microorganisms capable of decomposing organochlorine compounds are added to the dredged sediment, mixed, and allowed to stand to allow the microorganisms to act on the organochlorine compounds in the packed sediment. It becomes possible to disassemble. By using microorganisms, it is possible to purify the contaminated sediment by leaving it alone without requiring any special equipment, so that it is highly economical and there is no concern about the diffusion of organochlorine compounds.

  According to a second aspect of the present invention, in the first aspect, the addition and mixing step is performed by adding the microorganisms to the bottom and then transferring the bottom by a pneumatic feeding method. Is the method.

In this 2nd aspect, an addition mixing process can be implemented efficiently by utilizing a pneumatic feeding method.
That is, in the pneumatic feeding, in addition to the advantage that the dredged sediment can be conveyed quickly, the microorganisms added during the feeding are sufficiently mixed with the bottom sediment by the kneading action peculiar to the pneumatic feeding. There is no need.

  According to a third aspect of the present invention, in the first or second aspect, there is provided a method for purifying contaminated sediment, comprising a wastewater treatment step of treating the wastewater oozed from the bag in the stationary step. .

  According to this 3rd aspect, the spreading | diffusion of an organic chlorine compound can be prevented by collect | recovering and processing the waste_water | drain which exuded from the bag.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the contaminated sediment is characterized by including a sand-covering step of laying the bag on the bottom of the water following the stationary step. It is a purification method. Bags filled with sediment are highly environmentally compatible, so by laying on the bottom of the water, if the laying location is the same as the dredging location, the original environment can be restored, and the laying location is the dredging location. If it is different from the above, the bottom environment can be improved. In addition, since the organochlorine compound is decomposed by the action of microorganisms, even if the bag is damaged at the bottom of the water, recontamination due to diffusion of the organochlorine compound does not occur.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a biological organic material and / or a biodegradable plastic is added together with the microorganism. It is a quality purification method.

  According to the fifth aspect, by adding biological organic substances and / or biodegradable plastics, a carbon source necessary for the growth of microorganisms is ensured, and the proliferation of microorganisms and active metabolic activity are achieved. As a result, biological decomposition of the organochlorine compound proceeds rapidly.

  A sixth aspect of the present invention is the contamination according to any one of the first aspect to the fifth aspect, wherein the microorganism is a group of microorganisms containing an anaerobic microorganism and an aerobic microorganism. It is a method for purifying sediment. According to the sixth aspect, the treatment period can be shortened by using a group of microorganisms containing both anaerobic microorganisms and aerobic microorganisms having different roles for the decomposition of the organochlorine compound. .

  According to the present invention, it is possible to purify organochlorine compounds in the bottom sediment by simple means of bagging the bottom sediment and allowing it to stand and allowing microorganisms to act.

  The method of the present invention is carried out so as to include a drought step, an addition mixing step, a bagging step, and a stationary step.

<Purification target>
The object to be purified by the method of the present invention is contaminated sediment containing organochlorine compounds. Here, the sediment means substances such as gravel, sand, clay, sludge, etc. that constitute a sediment layer on the bottom of a river, lake, marine, or the like.

  Organochlorine compounds to be decomposed / removed are mainly dioxins such as polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF), including, for example, coplanar PCB (Co-PCB). Organic chlorinated solvents such as PCBs, tetrachlorethylene and trichlorethylene can also be targeted. Further, as organic chlorine-based pesticides, for example, DDT, DDE, DDD, BHC, aldrin, endrin, dieldrin, endosulfan, heptachlor, polyhaloalkyl agent, PCNB agent, DD agent, DCIP agent, chlorothalonil, dicohol, fusalide, tetradiphone, etc. It can also be applied to disassembly and removal.

<Coffee process>
The dredging process is a process of dredging sediment using a dredger or the like. The dredging method is not particularly limited, and dredging methods such as high-concentration dredging, grab dripping, and backhoe dredging can be employed.

<Adding and mixing step>
The adding and mixing step is a step of adding and mixing microorganisms or the like having an organochlorine compound resolution to the soot sediment. Here, since the dredged sediment is transferred to the land by a method such as pneumatic feeding or pumping, it is possible to add and mix microorganisms or the like in the transfer process. In particular, it is preferable to add microorganisms to the bottom, and then transfer by pneumatic transfer method, since transfer and mixing can be performed simultaneously. In the case of pumping, microorganisms or the like can be added before the pump is charged, and stirring can be performed, for example, with a stirrer. Uniform mixing creates a state where microorganisms are likely to come into contact with organochlorine compounds.

The microorganism used for purification is not particularly limited as long as it has a resolution for organochlorine compounds. The anaerobic microorganism or aerobic microorganism having a resolution of organochlorine compounds is not limited to a single species, and a group of microorganisms including a plurality of species and strains can also be used. Since these microorganisms can be collected by a known screening method from soil contaminated with organochlorine compounds, they can be cultured and used as seeds.

  In addition, since various microorganisms exist in the compost, compost having enhanced ability to decompose organochlorine compounds can be used in these composts. Needless to say, known microbial species, strains, fungal groups and the like that are known to have a degrading activity for dioxins and the like can be used within a range compatible with the method of the present invention.

Representative examples of anaerobic microorganisms with the ability of organochlorine compounds are anaerobic archaea such as the genus Methanobacterium, Methanosarcina, and Methanolobus, and Acetobacterium. Genus, Desulfobacterium genus, Desulfomonile genus, Dehalospirillum genus, Dehalobacter genus, Dehalobacterium genus, Dehalococcoides genus, Clostridium ) In addition to anaerobic bacteria such as genus, Citrobacter genus, Escherichia genus, Enterobacter genus, Serratia genus, Proteus genus, Shewanella genus, staphylo Coccus (Staphylococcus) genus Mention may be made of facultative anaerobic bacteria.

  Representative examples of aerobic microorganisms capable of decomposing organochlorine compounds include the genus Sphingomonas, Burkholderia, Ralstonia, Pseudomonas, and Nocardioides. (Nocardioides) genus, Rhodococcus genus, Terrabacter genus and the like.

  Among the above, anaerobic microorganisms capable of degrading dioxins and the like using hydrogen under anaerobic conditions include, for example, dehalococcides, dehalospirillum, dehalobacter, dehalobacteria, etc. Can be mentioned. Further, for example, Clostridium, Citrobacter, Enterobacter and the like are useful as anaerobic microorganisms that can decompose organic matter anaerobically to produce hydrogen. Hydrogen produced by these anaerobic microorganisms contributes to the dechlorination of organochlorine compounds.

  Also, in the stationary process described later, since the aerobic state is partially formed by the air that has entered from the bag surface, dioxins with low chlorine valence are decomposed by aerobic microorganisms, and the skeletal structure is decomposed. Is done. Examples of aerobic microorganisms involved in these include Sphingomonas, Pseudomonas, Nocardioides, Rhodococcus, and the like.

  As the microorganism, a mixture of the above-mentioned exemplified microorganism species can be used, and a complex microorganism agent produced by alternately repeating anaerobic conditions and aerobic conditions can be used. In particular, anaerobic microorganisms and aerobic microorganisms are included in complex microbial agents by culturing and growing together with organic matter and organochlorine compounds in a cycle that switches between anaerobic and aerobic conditions (anaerobic-aerobic cycle). Anaerobic microorganisms and aerobic microorganisms can be used in a fully acclimatized state.

Organochlorine compounds that can be added in the production of complex microbial agents can be the same as the organic chlorinated compounds that are subject to decomposition and removal in the purification stage, as well as polycyclic compounds that can substitute for chlorinated organic compounds. Aromatic compounds, polycyclic aromatic compounds containing heteroatoms, agricultural chemicals, and the like can be used. Pesticides are easily available, and can be advantageously used when the organic chlorinated compound as a pollutant cannot be specified. Pesticides that can be used for acclimatization include organochlorine pesticides such as DDT, DDE, DDD, BHC, aldrin, endrin, dieldrin, endosulfan, heptachlor, polyhaloalkyl agent, PCNB agent, DD agent, DCIP agent, chlorothalonil , Dicohol, fusalide, tetradiphone and the like, and organophosphorus pesticides can also be used. Examples thereof include EPN, methyl dimethone, methyl parathion, parathion and the like.

Moreover, when adding an organic chlorine type compound and acclimatizing in the manufacture process of a composite microbial agent, it is preferable to carry out in presence of a neutralizing agent. This is because by neutralizing the hydrogen chloride produced by dechlorination of the organic chlorine compound, the pH of the composite microbial agent can be prevented from being lowered, and the adverse effects of hydrogen chloride on microorganisms can be suppressed. As the neutralizing agent, an alkaline substance such as calcium carbonate may be used directly, but waste containing a large amount of calcium carbonate such as eggshell can be used. The use of waste as a neutralizing agent will also promote its effective use.

The preparation method of a composite microbial agent is illustrated below. A complex microbial agent is obtained by placing anaerobic microorganisms and aerobic microorganisms in a microaerobic condition in the presence of organic matter, or by acclimatizing alternating anaerobic and aerobic conditions. is there. Preparation of a complex microbial agent can be performed using a microbial agent production apparatus. The microbial agent production apparatus is composed of a single tank or a tank divided into a plurality of tanks, and continuously composts organic matter such as garbage and dock food that are periodically added and fed by a composting method. For the preparation of this complex microbial agent, soil contaminated with dioxins, bottom mud, compost, etc. or soil, bottom mud, compost etc. not contaminated with dioxins were collected and adapted to organic matter such as garbage Can be used as an inoculum.

During the composting process, the atmosphere in the microbial agent production apparatus is placed in slightly aerobic conditions, or alternately anaerobic and aerobic conditions, and both anaerobic microorganisms and aerobic microorganisms are proliferated. Make it.

The microaerobic condition can be maintained by ventilating N ₂ gas, controlling the stirring frequency, or opening the sealed device periodically (for example, once a day). For example, the microaerobic condition can be realized by blowing N ₂ gas with moderate stirring and adjusting the oxygen concentration in the microbial agent production apparatus to 0.05 to 0.1 v / v%. Even at this concentration, an oxygen concentration sufficient for the metabolic activity of aerobic microorganisms can be supplied.

In order to make it an anaerobic condition, deaeration may be performed, but an anaerobic state can be usually created by standing for a certain period of time. On the other hand, aerobic conditions can be created by operations such as stirring and aeration. Therefore, a processing environment in which the anaerobic condition and the aerobic condition are alternately repeated can be created by intermittently performing the operation for creating the aerobic condition. More specifically, for example, an environment in which anaerobic conditions and aerobic conditions are alternately repeated can be created by stirring for about 5 minutes per hour and allowing the remaining 55 minutes to stand.

Moreover, it is preferable to set the timing of an anaerobic-aerobic cycle suitably according to the addition method of organic substance. Hereinafter, two methods of adding an organic substance (Method A) and a method of adding an organic substance every one week (Method B) will be described as an organic substance adding method. The former (Method A) is suitable for producing a large amount of complex microbial agent, and the latter (Method B) is suitable for producing a small amount of complex microbial agent.

Method A: (1) An organic substance of 0.3 to 1.0 kg (wet weight after draining) is charged once a day per 10 kg of contents of the microbial agent production apparatus. (2) Immediately after the addition of organic matter, perform mechanical stirring for 5 minutes and mix well with the contents. (3) Thereafter, batch operation is performed in an anaerobic-aerobic cycle. (4) In one cycle of anaerobic-aerobic, the ratio of anaerobic time / aerobic time is set to be between 12-60. That is, if the anaerobic time is 1 hour, the aerobic time is set between 1 and 5 minutes. (5) One cycle of anaerobic time is 1 to 6 hours.

Method B: (1) An organic substance of 1.0 kg (wet weight after draining) is charged per 10 kg of the contents of the microbial agent production apparatus every week. (2) Immediately after the addition of organic matter, perform mechanical stirring for 5 minutes and mix well with the contents. (3) Thereafter, batch operation is performed in an anaerobic-aerobic cycle. (4) In one cycle of anaerobic-aerobic, the ratio of anaerobic time / aerobic time is set to be between 12-60. That is, if the anaerobic time is 3 hours, the aerobic time is set between 3 and 15 minutes. (5) One cycle of anaerobic time is 3 to 12 hours.

In both cases A and B, the aerobic condition can be achieved by mechanical stirring. At this time, air can be blown simultaneously. Moreover, it is preferable to adjust so that a predetermined moisture content may be maintained by blowing in warm air as appropriate. The water content of the mixture to be treated in the microbial agent production apparatus is preferably set to be 30 to 60% by weight, and the optimum range is 35 to 45% by weight.

Moreover, it is preferable to make it the temperature in a microorganism agent manufacturing apparatus become 10-70 degreeC during a process, and the optimal range is 25-55 degreeC. Furthermore, it is preferable to adjust the pH of the mixture to be treated in the microbial agent production apparatus to be pH 6 to 9, and the optimum range is pH 7.5 to 8.5. In addition, while adding organic substance, pH fall (about pH 6) is seen at the initial stage, but it becomes stable between pH 7 and 9 as the number of days elapses. Therefore, although it is not necessary to adjust the pH in particular, if the pH changes beyond the range of pH 6-9, the pH can be appropriately adjusted with 6N-dilute sulfuric acid, 4N-caustic soda solution, or the like. Active growth and metabolic activity can be maintained by adjusting the water, temperature, and pH, which are basic conditions for microbial growth, to the above ranges.

The above operation has the effect of culturing and proliferating a large amount of anaerobic and aerobic microorganisms, which are inoculums, in complex microbial agents. Can be increased. In addition, since the inoculum uses a complex microbial system in nature or contaminated soil, it is not driven out by indigenous bacteria in the soil.

In addition, as described above, the preparation of the composite microbial agent can be performed by adding an organic chlorine compound such as dioxins, an agrochemical, an oil and fat, and / or a surfactant. By these additions, it is possible to obtain a complex microbial agent acclimatized with an organochlorine compound, pesticide or oil.

Organic matter such as kitchen garbage introduced into the microbial agent production apparatus is composted to become a composite microbial agent (including complex microorganisms composed of anaerobic bacteria, aerobic bacteria, etc. and organic matter). The remaining complex microbial agent can be effectively used as compost in fields such as agriculture and horticulture.

  In the addition and mixing step, for example, biological organic substances, biodegradable plastics and the like can be added in addition to microorganisms.

  In order to efficiently decompose dioxins, it is necessary to secure the amount of microorganisms involved in the decomposition. In addition, hydrogen necessary for dechlorination is generated by anaerobic decomposition of biological organic matter, and biological organic matter is also necessary for this purpose. Needless to say, when the sediment contains abundant biological organic matter, the contained biological organic matter can be used.

  The biological organic material is not particularly limited as long as it is a biodegradable biological organic material, but it is economical to use waste such as food waste, straw or waste vegetable oil. The amount of biological organic matter added is, for example, 0.01 to 0.5% by weight per day with respect to the mixture of pollutants and microorganisms. It can be added in advance when mixing pollutants and microorganisms.

  The present invention is a method of allowing a mixture of sediment and microorganisms to stand for a certain period of time and decomposing organochlorine compounds in the sediment, and when this standing period is long, normal biological organic matter In this case, decomposition by microorganisms may end during the treatment period after the start of standing, and it may be difficult to supply biological organic substances necessary for the growth / activity maintenance of microorganisms and hydrogen supply over the entire treatment period. In order to solve this problem, a biodegradable plastic can be added in the addition and mixing step, for example, when contaminated sediment and microorganisms are mixed. Biodegradable plastics have the property of being gradually degraded by microorganisms, and can supply a substrate necessary for the growth and activity maintenance of microorganisms involved in the degradation of organochlorine compounds over a long period of time. That is, since the biodegradable plastic is composed of an organic substance that becomes a carbon source of microorganisms, it functions as a continuous supply source of the carbon source.

  Biodegradable plastics are a source of carbon for microorganisms and other nutrients such as nitrogen and phosphorus are required for growth, but compost with enhanced ability to decompose organochlorine compounds and the above complex microbial agents are used. In that case, nutrient sources other than the carbon source are included in the compost and the complex microbial agent, and it is not particularly necessary to supply them. When these nutrient sources such as nitrogen and phosphorus are insufficient, these nutrient sources may be added separately when mixing the sediment and microorganisms.

  As the biodegradable plastic, for example, any of starch, polylactic acid, aliphatic polyester, polyprolactone, and the like can be used. Examples of the shape of the biodegradable plastic include a granular or powdered biodegradable plastic having an average particle diameter of 1 to 2 mm to 3 to 5 cm.

<Packing process>
In the purification method of the present invention, biological purification is performed by a bagging method using a bag having air permeability and water permeability. Purifying by this bagging method is a mixture in which air-permeable and water-permeable bags are added and mixed with bottom organic matter and microorganisms, as well as biological organic matter, biodegradable plastics, etc. as necessary (stirred in advance) Is done by filling.

The bagging step is a step of filling a bag having air permeability and water permeability with a mixture containing contaminated sediment, microorganisms, and other additives as required. The breathable and water-permeable bag is not particularly limited, and for example, a woven fabric made of polyester fiber can be suitably used.
<Standing process>
In the standing step, a bag filled with a mixture of sediment and microorganisms is left on land. The standing period may be a period in which biodegradation of the organochlorine compound is possible, and can be set as appropriate depending on the concentration of contaminants in the sediment, for example, from 3 months to 2 to 3 years. Here, the water content of the contents (the mixture) can be set to 30 to 60% by weight, preferably 35 to 45% by weight.
In this method, it is preferable to cover the bag with a breathable sheet in order to prevent moisture from being diffused from the mixture. In addition, by covering the packaged mixture with a non-permeable sheet and injecting high-humidity air between the bag and the sheet, the moisture in the mixture is prevented from being diffused, and the organic chlorine compound is decomposed. It is also possible to maintain a suitable moisture content for a long time. In the bagging state, a certain level of air permeability is maintained, and air that has entered from the bag surface enters the bag and partially forms an aerobic state. In this state, a microaerobic state is created inside the breathable container, and the decomposition of the organic chlorine compound proceeds by the action of the anaerobic microorganism and the aerobic microorganism.

<Wastewater treatment process>
During the standing period, liquid components ooze out from the water-permeable bag. Since this exudate may contain an undecomposed organochlorine compound, a wastewater treatment step for performing wastewater treatment can be provided as necessary. The waste water treatment can be performed by a known method, for example, an activated carbon adsorption method or an accelerated oxidation method.

<Sand covering process>
In the method of the present invention, following the standing step, a sand covering step of laying the bag on the bottom of the water can be additionally performed. The sand-capping step is performed by laying the bottom of the bottom of the organic chlorine compound that has been biodegraded through the stationary step in a bagged state (returning the bottom). When the installation site is the same as the dredging site, the original environment can be restored, and when the installation site is different from the dredging site, the underwater environment can be improved. In addition, since the organochlorine compound is decomposed by the action of microorganisms, even if the bag is damaged at the bottom of the water, recontamination due to diffusion of the organochlorine compound does not occur.

Next, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a drawing for explaining an outline of a preferred embodiment of the bottom purification process of the present invention. In this bottom purification process, first, the contaminated bottom is dredged by the high concentration dredger 10. The dredged sediment is sent to the pneumatic ship 20, where microorganisms and biological organic substances are added to the sediment as required.
In the present embodiment, a pipe transfer method using a pneumatic feeder is adopted as a means for transferring the bottom sediment to which microorganisms or the like are added to the mud pit 30.
In this bottom sediment transfer, microorganisms for detoxifying contaminated sediment (organochlorine compounds) in the pneumatic feeder, near the root of the pipeline, or in the middle of the pipeline, and if necessary, activate the activity of the microorganism Biological organic materials, biodegradable plastics and the like are added. In the pipeline for pneumatically feeding the bottom sediment, a multiphase plug flow is generated by the bottom sediment to which air and microorganisms are added. This plug flow is a fluid state in which the liquid phase (bottom sediment to which microorganisms etc. are added) and the air phase flow alternately in the pipeline, and a strong vortex is generated in front of the liquid phase. . This vortex has an effect of stirring and mixing the microbially added bottom sediment that has settled and deposited at the bottom of the front tube of the liquid phase. This stirring and mixing is continued in the pumping section.

  At the end of pneumatic feeding, the sediment and microorganisms are mixed sufficiently evenly, and the organochlorine compound in the microorganism-added sediment is easily decomposed efficiently. After completion of the transfer, the microorganism-added bottom sediment discharged into the mud pit 30 is pumped up by the pump 40, press-filled into a bag to make a bottom 50, and then dehydrated, reduced in volume, and stored stationary. . Organochlorine compounds in the sediment in this state of standing in a bag are decomposed by the action of microorganisms.

  Depending on the dredging method, the bottom sediment immediately after bagging contains about 50 to 90% by weight of water. On the other hand, since the optimum moisture content in the stationary state is around 40% by weight, excess water is removed as an exudate. Since there is a possibility that the exudate contains an organic chlorine compound, for example, the waste water can be treated by a water treatment method such as an activated carbon adsorption method or an accelerated oxidation method.

FIG. 2 shows variations of the first half process (the dredging method, the dredging of the bottom sediment, and the bagging and filling) up to the standing step in the process of the present invention. As the dredging method, high-concentration dredging, grab dripping, backhoe dripping, etc. can be adopted. As a transfer method, pneumatic feeding, pump pumping, or the like can be used. The transferred mud may be stored in the onshore mud storage pit 30 or in the mud tank 31 on the carriage. Examples of these preferred combinations are as follows.
(1) After dredging with high-concentration dredger 10 and transported by pneumatic ship 20 and bagging in land storage mud pit 30; (2) After dredging with high-concentration dredger 10 and transported by pneumatic ship 20 (3) Method of bagging in a mud storage tank 31 on a trolley; (3) Method of bagging in a high-concentration dredger 10 and then transported by a pumping ship 21 and bagging in an onshore mud pit 30; (4) After dredging with high-concentration dredger 10, transfer by pumping ship 21 and bagging in mud tank 31 on the trolley; (5) After dredging with grab dredger 11, transfer by pneumatic ship 20, A method of bagging in the mud storage pit 30; (6) A method of transporting by the pneumatic ship 20 after dredging with the grab dredger 11; After dredging, it is transported by a pumping ship 21 and packed in a land storage mud pit 30. Method: (8) After dredging with grab dredger 11, transfer with pumping ship 21 and bagging with mud tank 31 on trolley; (9) After dredging with backhoe dredger 12, transfer with pneumatic ship 20 (10) A method of bagging in a mud storage pit 30 on land; (10) A method of carrying out bagging in a mud tank 31 on a trolley after being dredged by a backhoe dredger 12 and transferred by a pneumatic ship 20; After dredging at the backhoe dredger 12, it is transferred by the pump pressure ship 21 and packed in the mud pit 30 on land; (12) After dredging at the backhoe dredger 12, it is transferred by the pump pressure ship 21 and stored on the trolley. A method of bagging in the mud tank 31 is included.

  In the above, the combination has been described with three methods of high-concentration dredging, grab dredging, and backhoe dredging as the dredging method, but the combination is not limited to this, and for example, combination with pump dredging is also possible is there.

  In FIG. 2, each process is performed on a separate trolley (or onshore), but dredging and pumping may be performed on the same trolley. Further, dredging, pumping, and bagging may all be performed on the same trolley, or dredging and pumping, or pumping and bagging may be performed on the same trolley.

  In addition, in the case of pneumatic feeding, the addition position of microorganisms or the like may be performed at any position on the transport pipeline before, at the same time as or after loading the sediment into the pneumatic feeding device. In the case of the pumping system, microorganisms or the like can be added to the stirring and mixing tank 22 before the pump is charged.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not restrict | limited at all by this.
Example 1
Dioxin-contaminated sediments grabbed from the bottom of the water were used as test samples, and the water content was adjusted to 70%. The test sample and compost and wood chips with enhanced dioxin decomposition function were mixed at a weight ratio of 6: 2: 1, and 4.5% by weight of dog food was added to the mixture as an organic substance. A bag made of polyester fiber woven fabric was filled and allowed to stand.

  In mixing the test sample, the compost, and the wood chip, a small pneumatic feeder was used, and the mixture was stirred and mixed using the stirring effect of the plug flow in the pressure feed pipe. The mixture discharged from the terminal end of the pressure feed line was received in a container, and the mixture was further sucked from the container with a pump, and was press-fitted and filled into a woven bag made of polyester fiber.

In addition, the compost which improved the decomposition | disassembly function of dioxins was adjusted with the following method.
In other words, compost prepared by the garbage disposal method, wood chips as the base material, and incinerated ash containing dioxin are charged in equal amounts into a garbage disposal machine, mixed, and firewood is added every day for 3 months. did. At this time, the water content was adjusted to 40% by weight.

  The dioxin-contaminated sediment mixture filled in the bag was allowed to stand for 3 months. During this time, the water content decreased from 60% to 35%.

  As a result of analyzing the dioxin concentration contained in the mixture during the treatment period based on “Soil Survey and Measurement Manual for Dioxins” (Environment Agency, Water Quality Conservation Bureau, Soil Agricultural Chemicals Division; issued in January 2000), Table 1 It was as shown in. After 3 months, 33.6% of the initial value of dioxins was decomposed.

Example 2
Dioxin-contaminated sediments grabbed from the bottom of the water were used as test samples, and the water content was adjusted to 74%. The test sample, compost (the same as in Example 1) with enhanced decomposition function of dioxins and wood chips are mixed at a weight ratio of 6: 2: 2, and the dog food is mixed with the previous period as an organic substance. On the other hand, 1% by weight and 4% by weight of polycaprolactone powder, which is a kind of biodegradable plastic, were added, filled in a bag made of polyester fiber woven fabric, and allowed to stand.

  In mixing the test sample, the compost, and the wood chip, a small pneumatic feeder was used, and the mixture was stirred and mixed using the stirring effect of the plug flow in the pressure feed pipe. The mixture discharged from the end portion of the pressure feed line was received in a container, and the mixture was further sucked from the container with a pump, and was press-fitted and filled into a polyester fiber woven bag.

  The dioxin-contaminated sediment mixture filled in the bag was allowed to stand for 3 months. During this time, the water content decreased from 60% to 39%.

  As a result of analyzing the dioxin concentration contained in the mixture during the treatment period based on the “Soil Survey and Measurement Manual for Dioxins” (Environment Agency, Water Quality Conservation Bureau, Soil Agricultural Chemicals Division; issued in January 2000), Table 2 It was as shown in. Three months later, 44.9% of the initial value of dioxins was decomposed.

  The present invention has been described above with reference to various embodiments. However, the present invention is not limited to the above embodiments, and can be applied to other embodiments within the scope of the invention described in the claims. It is.

  INDUSTRIAL APPLICABILITY The present invention can be used for purification of soil or ash contaminated with organochlorine compounds such as dioxins.

It is drawing which shows the outline | summary of a sediment purification process. It is drawing which shows the outline | summary of the first half process of a sediment purification process.

Explanation of symbols

10 High-concentration dredger 11 Grab dredger 12 Backhoe dredger 20 Pneumatic ship 21 Pump pump ship 30 Mud pit 31 Mud tank 40 Pump 50 Packed bottom

Claims (6)

A dredging process for dredging sediments contaminated with organochlorine compounds;
An addition mixing step of adding and mixing microorganisms capable of decomposing organochlorine compounds to the dredged sediment;
A bagging step of filling the obtained mixture into a bag having air permeability and water permeability;
A standing step of standing the bag after filling;
A method for purifying contaminated sediment, comprising:   The method for purifying contaminated sediment according to claim 1, wherein the adding and mixing step is performed by adding the microorganisms to the sediment and then transferring it by a pneumatic feeding method.   The method for purifying contaminated sediment according to claim 1 or 2, further comprising a wastewater treatment step of treating wastewater that has oozed from the bag in the stationary step.   The method for purifying contaminated sediment according to any one of claims 1 to 3, further comprising a sand-covering step of laying the bag on the bottom of the water following the stationary step.   The method for purifying contaminated sediment according to any one of claims 1 to 4, wherein a biological organic substance and / or a biodegradable plastic is added together with the microorganism.   The method for purifying contaminated sediment according to any one of claims 1 to 5, wherein the microorganism is a group of microorganisms containing an anaerobic microorganism and an aerobic microorganism.

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