JP5512066B2 - Water and sea bottom purification device and water and sea bottom purification method - Google Patents

Description

  The present invention relates to a water / sea bottom purification device and a water / sea bottom purification method for producing sand-covered sand from bottom mud in a water-sea area and returning the sand to the original place to cover the sand.

  In water and sea areas such as lakes, rivers, canals, harbors, coasts, etc., especially in water areas with little water access, water algae is drastically reduced, dissolved oxygen in water is significantly reduced, and algae and other polluted organic matter that have died A large amount of sludge accumulates on the bottom of the water, and the sludge is decomposed in the absence of oxygen, generating odors and harmful substances, drowning aquatic organisms, and reducing the yield of farmed fish.

  Therefore, conventionally, in order to improve such a situation, measures have been taken to cover the bottom of the bottom by covering the bottom of the bottom with a clean sand or the like.

  However, when dripping sludge etc. on the bottom of the water, it is necessary to dehydrate / dry the drowned sludge etc. or throw it away somewhere. In addition, there is a difficult problem of securing a dumping site to throw away sludge.

  In addition, when covering sand, good quality sand must be obtained. However, obtaining high-quality sand has been very difficult in recent years due to the problem of destroying the environment of the sand collection site in addition to the problem of depletion of sand resources.

  In addition, even if it covers sand, sludge etc. exists under it, which decomposes in anoxic state, and there is a possibility that harmful substances and bad odors will leak out from here for a long time, There is a problem that sand cover is not a fundamental solution.

In addition, because sand is further layered on sludge etc., the bottom of the sand is shallow, reducing the storage capacity of the lake as a reservoir for the lake, hindering navigation of the ship, It may cause problems such as destroying the environment.
JP 05-005304 A Japanese Patent Application Laid-Open No. 06-081362

  The problem to be solved is to solve the problem that the bottom mud, which is the source of pollution in waters and marshes such as lakes, rivers, canals, harbors, and coasts, could only be handled as harmful and useless obstacles.

  The most important aspect of the present invention is to heat the bottom mud of a marine area such as lakes, rivers, canals, harbors, and coasts with high-temperature superheated steam to make mineralized sand, and to use this mineralized sand as a resource for environmental purification. Features.

  That is, the water and sea bottom purification apparatus according to the present invention includes a dredging apparatus that drowns the bottom mud in the water and sea area, and a heat treatment apparatus that exposes the mud raised by the dredging apparatus to superheated steam to convert the mud into mineralized sand. And a sand-covering device for spreading mineralized sand obtained by the heat treatment device to the bottom of the water sea area.

  Here, the dredging device, the heat treatment device, and the sand covering device may be installed on a floating body such as a work boat. Mineralized sand is sandy, granular, or flaky, mainly composed of inorganic components that remain after the removal of water and oil from the bottom mud with high-temperature superheated steam, and decomposition and removal of organic substances and harmful compounds. Or a small lump.

  Further, in the water and sea bottom purification method according to the present invention, the bottom mud in the water and sea area is dredged, the mud pulled up by the dredger is exposed to superheated steam to convert the mud into mineralized sand, and the mineralized sand is converted into the water. It covers the bottom of the sea area and covers the water area.

  Here, the mineralized sand may be appropriately crushed and used for covering sand, or may be returned to the glazed original place. When the mineralized sand is returned to the original position, the mineralized sand may be created between a plurality of areas and exchanged back to the original position.

  The temperature and contact time of the superheated steam are appropriately determined in consideration of the properties of the mud to be treated and the degree of contamination. When the heat treatment target is canal mud, the temperature of the superheated steam is preferably 350 to 600 ° C., and the contact time with the superheated steam is preferably 5 to 30 minutes.

  The present invention manufactures and covers sand using mud that can be obtained at the site where sand is covered, so that it does not incur the cost of transporting sand. This has the effect of avoiding troubles such as obstacles to other means of transportation.

  In addition, since the present invention rapidly heat-treats the bottom mud of water and marine areas such as lakes, rivers, harbors, canals, and coasts with superheated steam, it has a large surface area, and activated carbon formed by carbonization of contained organic matter It is possible to obtain mineralized sand having a high water purification capability containing such substances, and therefore, if this mineralized sand is spread over the water sea area and covered with sand, the water quality of the water sea area is further purified.

  In addition, since the present invention is covered with mineralized sand that has been treated with superheated steam and decomposed and removed harmful substances, there is no risk of harmful substances leaking from the covered sand, and the sea area is covered with sand. There is an effect that there is no risk of secondary contamination.

  Moreover, since this invention procures in the place which covers sand covering material, there exists an effect that the problem that a water bottom becomes shallow by covering sand does not generate | occur | produce.

  In addition, the present invention heats the bottom mud with superheated steam and cools and collects all the steam containing the distillate component, or heats the distillate component at 800 ° C. or higher with a superheater. There is an effect that there is little generation of odors.

  The purpose of purifying the bottom mud of waters and marshes such as lakes, rivers, canals, harbors, and coasts was realized only at the site without procuring materials from others.

  FIG. 1 is an explanatory view of a water and sea bottom purification apparatus according to one embodiment of the present invention. In the figure, reference numeral 10 denotes a work ship. The work ship 10 has a dredging device 12 dredging bottom mud in the water and sea, and the mud obtained by the dredging device 12 is heat-treated with superheated steam and converted to mineralized sand. A heat treatment apparatus 14 and a sand covering apparatus 16 that covers the mineralized sand obtained by the heat treatment apparatus 14 on the bottom of the water sea area are installed.

  As shown in FIG. 1, the dredging device 12 can use a pump type that pumps up mud on the bottom of the water onto the ship, but uses a power shovel to pull up the mud on the bottom of the ship. You may do it.

  As shown in FIG. 2, the heat treatment device 14 is provided in a sealed injection furnace 18 into which superheated steam is blown, a mud storage device 20 provided above the injection furnace 18, and a lower portion of the injection furnace 18. And a discharge duct 22.

  A superheated steam generator is connected to the injection furnace 18 via a superheated steam supply pipe 24. The superheated steam generator includes a boiler 28 that converts water in the water tank 26 into steam, and a superheater 30 that converts steam generated from the boiler 28 into superheated steam.

  A continuous supply device 32 for continuously supplying the mud of the mud storage device 20 to the injection furnace 18 is provided between the mud storage device 20 and the injection furnace 18, and the injection furnace 18 is provided between the injection furnace 18 and the discharge duct 22. A continuous discharge device 34 for continuously discharging the mineralized sand to the discharge duct 22 side is provided.

  Water and seabed purification is performed according to the process shown in FIG. 3 using this water and seabed purification apparatus. That is, first, the dredging device 12 is used to dredge the bottom mud of the water and sea area. This dredging provides mud that is the raw material for the sand cover. The division ratio and amount of dredged bottom mud are appropriately determined by the degree of organic matter contamination of the whole bottom mud. In addition, when the organic matter contamination degree of sediment bottom mud is low, a part of the sediment bottom mud may be dredged and covered with mineral sand according to the present invention.

  Next, the trapped mud is put into the heat treatment apparatus 14 and heat-treated with superheated steam. Oil and other volatile components contained in the mud are distilled from the mud together with the superheated steam, organic substances are carbonized, and harmful substances such as PCBs and dioxins are decomposed and detoxified by the superheated steam. The mud loses moisture by this treatment and becomes flaky or granular sand.

  Next, the flaky or granular sand is spread by the sand covering device 16 in a plane with a predetermined thickness at the original position in the water and sea area (the original position where the mud was removed).

  Next, specific experimental examples of the present invention will be described in more detail. First, the mud (raw mud) at the bottom of the brackish water canal was collected, and 2 kg of this mud was converted to 10 ° C. superheated steam at 500 ° C. with a steam generation rate of 20 L / hour using the superheated steam treatment test apparatus configured as shown in FIG. For a minute. The mud became flaky sand (mineralized sand) by superheated steam.

  Next, ignition loss (g / 100g) of raw mud and mineralized sand, organic carbon (g / 100g), nitrogen content (mg / g / dry), phosphorus content (mg / g / dry), sulfurization When the product (mg / g / dry), chemical oxygen demand (COD) (mg / g / dry), and oil (g / 100 g) were analyzed, they were as shown in Table 1.

  The analysis method is JISSM8819 for organic carbon, and “Sediment Survey Method and Explanation” for the loss on ignition, nitrogen content, phosphorus content, sulfide content, and chemical oxygen demand. The water quality management section, published by the Japan Environmental Measurement and Analysis Association, revised in August, 1993, 4th edition), for oil, "Sewage test method first volume 1997 edition" (Ministry of Construction, Urban Bureau, Sewerage Department, Ministry of Health and Welfare) Supervised by the Department of Public Health, Water Environment Department, issued by the Japan Sewerage Association, second printed in September 1997).

  From the results of this analysis, it can be seen that mineralized sand is significantly purified compared to raw mud, such as 91.5% of sulfides and 97% of COD, and the oil content is below the detection limit. all right.

  It is considered that the remarkable decrease in the COD value suggests that the impact on the water environment caused by sludge is reduced by the superheated steam treatment. Therefore, in order to follow the impact on oxygen consumption of raw mud and superheated steam-treated mud over time, the amount of BOD was examined using an Okura Electric Co., Ltd. (type OM3100A) coulometer (automatic recording aerobic microbial respirometer). It was. In the survey, SS (amount of suspended solids) was set to 1000 mg / L, and the double dilution water of seawater (pH: 8.0, EC: 20.2 mS / cm) was used as the liquid according to the specific gravity of the target brackish water canal. used. FIG. 4 shows changes in BOD over time of raw mud and superheated steam-treated mud.

  According to this, the BOD value of raw mud increased at an almost constant oxygen consumption rate until 790 hours, and finally reached a plateau at 37 mg / L. On the other hand, the superheated steam-treated mud had a low oxygen consumption rate and reached a plateau of 5 mg / L in 400 hours.

  Combined with the results of the COD values shown in Table 1 above, the impact of superheated steam-treated mud on oxygen consumption in environmental water is expected to be significantly reduced.

  The situation of dissolved oxygen in the water quality is important for the biological environment. Naturally, the growth of aquatic organisms becomes difficult if the dissolved oxygen decreases, and the generation of hydrogen sulfide and methane that are toxic to organisms under hypoxic conditions can be considered. For this reason, the impact of sludge containing a large amount of organic matter on oxygen consumption becomes an important issue for both bottom sediment and water quality.

  As described above, since the BOD of the mud subjected to the superheated steam treatment is remarkably reduced as compared with the raw mud not subjected to the superheated steam, the present treatment method using the superheated steam treatment is effective for the oil and sulfide. It is thought that the impact on the biological environment will be greatly reduced more than the reduction.

It is explanatory drawing of the water seabed purification apparatus which concerns on one Example of this invention. It is explanatory drawing of the heat processing apparatus using superheated steam. It is process drawing of the water seabed purification method which concerns on one Example of this invention. It is a graph which shows a time-dependent change of BOD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Work ship 12 Dredging apparatus 14 Heat processing apparatus 16 Sand covering apparatus 18 Injection furnace 20 Mud storage apparatus 22 Discharge duct 24 Superheated steam supply pipe 26 Water tank 28 Boiler 30 Superheater 32 Continuous supply apparatus 34 Continuous discharge apparatus

Claims (4)

A dredging device that drowns the bottom mud of water and sea that contains organic matter and is contaminated with oil, and the earth and sand composed of the bottom mud pulled up by the dredging device is exposed to superheated steam at 450 to 500 ° C. to make the soil inorganic A heat treatment device for converting to fossil sand, a sand covering device for spreading the mineralized sand obtained by the heat treatment device to the bottom of the water seabed, and cooling the superheated steam discharged from the heat treatment device to An oil recovery device that recovers the oil contained in the oil, and a superheater that superheats steam after recovering the oil and supplies superheated steam to the heat treatment device. A water-sea-bottom purification device , wherein the oil recovery device, the superheater, and the heat treatment device are circulated in this order .   The water-sea-bottom purification apparatus according to claim 1, wherein the obtained mineralized sand is mineralized sand containing activated carbon-like substance and having high water purification capability. The dredging process of dredging the bottom mud of the water and sea that is contaminated with oil containing organic matter, and the earth and sand consisting of the bottom mud pulled up by the dredging is exposed to superheated steam at 450 to 500 ° C. to mineralize the earth and sand A mineralization step for converting to sand, a step for covering the water and seabed by spreading the mineralized sand on the bottom of the water and the bottom of the water, and cooling the superheated steam that has been exposed to the earth and sand to the superheated steam. An oil recovery step for recovering the contained oil, and a steam superheating step for heating the steam after recovering the oil to superheated steam to expose the earth and sand composed of the bottom mud, and the water vapor is the mineralization step The method for purifying water and sea bottom is characterized by circulating through the oil recovery step, the steam superheating step, and the mineralization step in this order .   The method of claim 3, wherein the obtained mineralized sand is mineralized sand containing activated carbon-like substance and having a high water purification capability.

Images