JP2006291568A - Water purification method for rivers - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an effective water purification method maximally utilizing the self-purification action of rivers by effectively utilizing a boundary surface by a sheet material. <P>SOLUTION: The sheet material S formed of a porous material is sunk in a river to cover the upper side of a slime layer 1 at the bottom of the river by the sheet material S. An upper side water layer 2 is separated from the lower side slime layer 1 by the sheet material S, and the the water layer 2 is maintained in an aerobic state and the slime layer 1 is maintained in an anaerobic state. The sheet material S is sunk by its own weight according to a reduction in the volume of the slime layer 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a water quality purification method for natural water areas such as rivers, lakes, and seas that purifies the polluted water quality using sheet material, and is extremely polluted and a large amount of sludge accumulates. The present invention relates to a water purification method suitable for the situation.

  For example, in a river near a city, a thick sludge layer is often deposited at the bottom of a river as a result of a large amount of domestic wastewater flowing into a place where there is little flow. In such a situation, hydrogen sulfide is generated from the sludge layer in summer, and a bad odor drifts around the river, so there is a strong demand for water purification.

  In relation to the present invention, instead of the sand covering method of spreading sand etc. on the surface of the bottom mud, a method of laying a roll-like sheet material in which clay-like silt and gypsum etc. are sandwiched between palm mats on the water bottom is known. (Patent Document 1). The silt contains ferric oxide. One end of the sheet material is fixed to the ground with an anchor or the like, and the sheet material is laid out on the bottom mud by feeding the sheet material from the roll.

JP2003-247217A (FIGS. 1 and 3)

  The first problem to be solved by the present invention is to make maximum use of the self-cleaning action of rivers and the like. That is, anaerobic reducing bacteria that decompose organic sludge are always present in the accumulated sludge, and rivers and the like originally have a self-cleaning action. Moreover, reducing bacteria are said to be three times better than aerobic oxidizing bacteria in degradability. However, reducing bacteria are active in an anaerobic environment, but the activity is inhibited in an aerobic environment, and the activity is also inhibited by an increase in the concentration of hydrogen sulfide generated by the decomposition action. The fact is that the self-cleaning action by reducing bacteria is not fully utilized. In other words, how to maintain the anaerobic environment and keep the concentration of hydrogen sulfide low is the key to quickly purifying the sludge layer using reducing bacteria.

  The second problem is workability and cost. In general, dredging of bottom mud and sludge coagulating sediment collection by adding a flocculant are difficult to implement due to high construction costs. This is even more so in situations where the degree of pollution has advanced. In this respect, the method of Patent Document 1 using a sheet material is economically superior because no dredging work is required. However, in a natural water area where the shape of the laying range is not constant, if the sheet material can be fed out only linearly from the roll, the laying work takes time and costs are increased. When sludge is accumulated in large quantities (the sludge layer may be close to 10 m), it is difficult even to drive anchors into the ground.

  There are also problems after laying. The upper part of the sludge layer that accumulates in large quantities is in a state where the boundary with the water layer is not clear and sludge particles drift in the water. Therefore, as the purification proceeds, the sludge particles aggregate and reduce the volume, and the sludge layer settles. If there is a gap between the sludge layer and the sheet material laid down and the sludge layer, the sheet material may not be fixed on the sludge layer and the sheet material may flow. In the past, this point was overlooked.

  The objective of this invention is providing the water quality purification methods, such as a river, which can solve the said subject, utilizing the characteristic of a sheet | seat material.

  In the present invention, a sheet-like sheet material S is submerged in a river or the like, and the upper surface of the bottom sludge layer 1 is covered with the sheet material S, whereby the upper water layer 2 and the lower sludge layer 1 are covered with the sheet material S. The water layer 2 is maintained in an aerobic state and the sludge layer 1 is maintained in an anaerobic state. An aerobic state and an anaerobic state here mean a state suitable for an aerobic bacterium and an anaerobic bacterium to act, respectively.

  The sheet material S is made of a porous material and is characterized in that the sheet material S settles under its own weight as the sludge layer 1 is reduced in volume. The sheet material S should just be porous like a filter or sponge, for example, The raw material and the magnitude | size of a hole are not specifically limited, It can select suitably within the range of technical common sense.

  Specifically, the sheet material S can include a filter medium layer 3 configured so that the average pore diameter decreases from the lower side toward the upper side, and a support 5 that supports and fixes the filter medium layer 3. For example, the filter medium layer 3 may be formed by laminating a plurality of nonwoven fabrics having different average pore diameters, and the support 5 is preferably formed of a metal whose main component is iron. Note that the main component here is iron, which includes iron as a main component as well as iron-based alloys.

  The filter medium layer 3 can contain an auxiliary material (such as iron oxide) that prevents the defective component (such as hydrogen sulfide) of the sludge layer 1 from moving to the aqueous layer 2. The auxiliary material may be included integrally with the filter medium layer 3, or a separate auxiliary material may be included in the filter medium layer 3.

  The sheet material S can be configured by connecting the panel bodies P. The dimensions and shape of the panel body P are not limited.

  If the upper water layer 2 and the lower sludge layer 1 are separated by the sheet material S and the lower sludge layer 1 is maintained in an anaerobic state, the reducing bacteria resident in the sludge are organic in the sludge. The sludge is actively decomposed, and the sludge layer 1 is efficiently purified.

  At this time, if the sheet material S is made of a porous material, the resistance of water is small, so that the sheet material S is easily sunk during laying. As it sinks and approaches the upper surface of the sludge layer 1, the sludge particles gradually clog the pores. As a result, the resistance of water increases near the sludge layer and an appropriate buoyancy is obtained, so that even the sludge layer 1 whose boundary with the water layer 2 is not clear can be stably fixed on the upper surface. Become. The sheet material S concentrates the sludge layer 1 by filtering and separating the sludge particles and the water of the sludge layer 1 as it sinks. After laying, the hydrogen sulfide, methane gas, etc. generated by the decomposing action of the reducing bacteria easily pass through the sheet material S from the holes that are not clogged and move to the water layer 2, so that the hydrogen sulfide in the sludge layer 1 The concentration does not hinder the degradation of reducing bacteria. Even after the sheet material S is fixed on the upper surface of the sludge layer, if the sheet material S settles under its own weight along with the volume reduction of the sludge layer 1, purification proceeds and the sludge layer 1 is reduced in volume. Even if the sheet material S always covers the sludge layer 1, it acts as a weight of the sludge layer 1, so that the decomposed water and gas are forced to the water layer 2 side through the sheet material S. Extrusion can further promote volume reduction and purification of the sludge layer 1.

  When the filter medium layer 3 of the sheet material S is configured so that the average pore diameter decreases from the lower side toward the upper side, as shown in FIG. 2, when the sheet material S is laid on the sludge layer 1, the sheet material Even if the sludge particles 9 enter the filter medium layer 3 from the lower side of S, the filter medium layer 3 is caught in steps according to the size of the particles, so that clogging can be well prevented. That is, even after the sheet material S is fixed on the upper surface of the sludge layer 1, there is no possibility of preventing the gas or water generated in the sludge layer 1 from moving to the water layer 2.

  Iron reacts with hydrogen sulfide generated in the sludge layer 1 and has a reducing power to decompose hydrogen sulfide. Therefore, when the support body 5 is made of a metal containing iron as a main component, the support body 5 can also have a function of preventing bad odor caused by hydrogen sulfide in addition to supporting the filter medium. In addition, after several years, since the support 5 itself is disassembled and no trace is left, there is no need to pull up the sheet material S after the purification treatment is completed.

  When the filter medium layer 3 is configured by laminating a plurality of nonwoven fabrics having different average pore diameters, the filter medium layer 3 can be formed by a simple process in which the nonwoven fabrics are bonded together. Depending on the situation of the sludge layer 1, the hole diameter and the number of stacked layers can be combined, and clogging is more effectively prevented.

  When the filter medium layer 3 includes an auxiliary material that prevents the defective component of the sludge layer 1 from moving to the aqueous layer 2, contamination of the aqueous layer 2 due to the defective component of the sludge layer 1 can be prevented. In particular, it is effective that the filter medium layer 3 is composed of a nonwoven fabric and the fiber contains an auxiliary material, for example, iron oxide. That is, since the fibers constituting the nonwoven fabric are intertwined in a complicated manner and have a very large surface area per unit volume, the iron oxide can be efficiently brought into contact with the hydrogen sulfide passing through the filter medium layer 3, and the hydrogen sulfide is reliably decomposed. It is because generation | occurrence | production of a bad smell can be prevented.

  When the sheet material S is configured by connecting the panel bodies P, the sheet material S is easily transported, and the sheet material S is appropriately connected at the site according to the laying range, and then laid down by sunk sequentially from the connected place. Can go. Construction work is rarely limited by the size and shape of the laying range.

  The present invention can be applied to all natural water areas such as rivers, lakes, and seas. Here, as shown in FIG. 3A, the best mode is shown by taking a river as an example. In the figure, reference numeral 1 is a sludge layer deposited on the riverbed, and reference numeral 2 is an upper water layer. The water purification method of the present invention uses the sheet material S.

  As shown in FIG. 1, the sheet material S is composed of a rectangular thin plate-like panel body P, and is arranged on the lower surface side of the filter material layer 3 and a filter material layer 3 configured by laminating a plurality of non-woven fabrics vertically. And a metal support 5 for supporting and fixing the filter medium layer 3.

  The filter medium layer 3 was composed of three layers of nonwoven fabric. Each non-woven fabric constituting the filter medium layer 3 has a different average pore diameter, and the average pore diameter decreases from the lower side toward the upper side. The first layer 3a having a larger average pore diameter and the average than the first layer 3a. The second layer 3b has a small hole diameter, and the third layer 3c has a smaller average hole diameter than the second layer 3b. Adjacent non-woven fabrics are fixed in close contact by bonding with an adhesive or welding of non-woven fabrics.

  The fiber which comprises a nonwoven fabric contains iron oxide. That is, each non-woven fabric is immersed in an iron oxide aqueous solution in advance and then dried, so that the iron oxide is infiltrated into the fibers constituting the non-woven fabric, or the iron oxide is adhered to the outer surface of the fibers constituting the non-woven fabric. It is. Scattered inside the filter medium layer 3 are activated carbon and zeolite particles 6.

  An iron wire mesh 5 as a support is attached to the lower side of the filter medium layer 3, that is, the lower surface of the first layer 3 a so as to be in close contact with the filter medium layer 3. An average pore diameter of the wire mesh 5 is at least larger than the average pore diameter of the first layer 3a of the filter medium layer 3. The main purpose of the wire mesh 5 is to support and fix the filter medium layer 3, but it also serves as a heavy stone that decomposes hydrogen sulfide and sinks the sheet material S.

  Next, a method for carrying out the present invention will be described with reference to FIG. A required amount of the panel body P constituting the sheet material S is conveyed by a truck or the like in accordance with the laying site. As shown in FIG. 3A, the panel body P is connected to the ends of the adjacent panel bodies P by inserting and fixing a temporary fixing member 7 such as a wire or a string into the hole of the sheet material S, for example. However, as shown in FIG. 3 (b), it is submerged in water one by one to cover the sludge layer 1 on the bottom of the river. At this time, since the sheet material S is porous and has little resistance to water, the sheet material S easily sinks into a predetermined position. Once the sheet material S sinks and is fixed on the sludge layer 1, there is no possibility that the sheet material S is integrated with the sludge layer 1 and misaligned. This also helps to reduce the work load.

  FIG. 2 shows a conceptual diagram in a state in which the sheet material S sinks to the riverbed and is fixed on the sludge layer 1. When the sheet material S sinks and reaches the upper portion of the sludge layer 1, sludge particles 9 enter the filter material layer 3 from the lower side of the sheet material S. At this time, the large and small sludge particles 9 are caught on the filter medium layer 3 in a stepwise manner according to the size thereof, so that they are not completely clogged. The sludge layer 1 and the water layer 2 communicate with each other through the holes that are not clogged, and a large amount of water in the sludge layer 1 moves to the water layer 2 through the sheet layer, and the sludge layer 1 is concentrated. . In a state where the water layer 2 and the sludge layer 1 are separated from each other vertically, the sheet material S adheres to the top surface of the sludge layer 1 and is fixed.

  The implementation work is completed by laying the sheet material S over the entire upper surface of the sludge layer 1. Just leave it alone. In this state, the water layer 2 is blocked by the sheet material S and the amount of organic sludge is reduced. As a result, oxygen consumption is reduced and the aerobic state is obtained. In the sludge layer 1, the sheet material S is pressed from above, so that water, oxygen, etc. in the sludge layer 1 are pushed out to the water layer 2 side through the sheet layer and become more anaerobic. As a result, the action of decomposing organic sludge of reducing bacteria is activated. When the decomposing action of reducing bacteria becomes active, the amount of generated hydrogen sulfide increases, but the generated hydrogen sulfide is also pushed out to the aqueous layer 2 side through the sheet material S, so that the decomposing action of reducing bacteria is not hindered. The purification of the sludge layer 1 is further promoted. When the hydrogen sulfide also passes through the sheet material S, it reacts with the iron contained in the wire mesh and the filter medium layer 3 and is decomposed, so that no bad odor is generated. Defective components such as nitrogen and phosphorus in the sludge layer 1 are adsorbed by the activated carbon and zeolite particles 6 in the filter medium layer 3.

  As time passes, the sludge layer 1 is purified and volume-reduced as shown in FIG. Accordingly, the sheet material S also settles under its own weight, so that the sludge layer 1 is always maintained in a constant anaerobic state. As a result, the period for purification can be shortened. Eventually, although it takes many years, the sheet material S itself is also decomposed so that there is no trace, and a purified water layer 2 and a purified sludge reduced sludge layer 1 remain.

  The support 5 may be attached to the upper surface or the middle of the filter medium layer 3. The support 5 is not limited to a wire mesh, and may be a punching metal or an expanded metal. The rigidity of the support body 5 is not necessarily required. For example, a plurality of metal wires may be attached to support the panel body P. After laying the sheet material S, a step of spreading an iron composition such as steel slag or foundry sand from the top may be provided. In this case, the iron composition plays the role of weight and hydrogen sulfide adsorption on the sheet material S. Further, if a step of adding reducing bacteria to the sludge layer 1 is provided before laying the sheet material S, purification can be performed more effectively. By incorporating an air generation mechanism inside the sheet material S, for example, air is sent from the compressor to the air generation mechanism via a pipe or the like, and bubbling is performed using the porous structure of the sheet material S, thereby the water layer 2 A step of maintaining a more aerobic state may be provided. When there are a lot of fine sludge particles 9 that float, in order to prevent the sheet material S from being clogged while reaching the riverbed, a water-soluble temporary sheet having a small average pore diameter is provided below the sheet material S. Materials can also be attached.

Side view showing a panel body of sheet material and partially enlarged view thereof Conceptual diagram for explaining the function of sheet material Conceptual diagram for explaining water purification method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sludge layer 2 Water layer 3 Filter material layer 5 Support body S Sheet material P Panel body

Claims (4)

By submerging the porous sheet material (S) in the river and covering the upper surface of the bottom sludge layer (1) with the sheet material (S), Each of the sludge layer (1) in an anaerobic state,
A water purification method for rivers and the like, characterized in that the sheet material (S) settles under its own weight as the sludge layer (1) is reduced in volume.   The sheet material (S) includes a filter medium layer (3) configured such that the average pore diameter decreases from the lower side toward the upper side, and a support (5) for supporting and fixing the filter medium layer (3). Item 1. A water purification method for rivers or the like according to item 1.   The water purification method for a river or the like according to claim 2, wherein the filter medium layer (3) includes an auxiliary material that prevents a defective component of the sludge layer (1) from moving to the water layer (2).   The water purification method for a river or the like according to any one of claims 1 to 3, wherein the sheet material (S) is configured by connecting the panel bodies (P).

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