JP5286201B2 - Bottom sediment purification method by resuspension - Google Patents

Bottom sediment purification method by resuspension Download PDF

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JP5286201B2
JP5286201B2 JP2009201665A JP2009201665A JP5286201B2 JP 5286201 B2 JP5286201 B2 JP 5286201B2 JP 2009201665 A JP2009201665 A JP 2009201665A JP 2009201665 A JP2009201665 A JP 2009201665A JP 5286201 B2 JP5286201 B2 JP 5286201B2
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正治 福江
弘次 上原
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Tokai University Educational Systems
Aomi Construction Co Ltd
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本発明は、再懸濁による底質浄化工法に関するものであり、特に、底質を再懸濁して比表面積の大きい細かい粒子を分級し、該細かい粒子に吸着した汚染物質を除去することで大掛かりな設備を不要として効率的に底質改善を行うようにした再懸濁による底質浄化工法に関するものである。   The present invention relates to a sediment purification method by resuspension, and in particular, resuspends sediment to classify fine particles having a large specific surface area, and removes contaminants adsorbed on the fine particles. The present invention relates to a bottom sediment purification method by resuspension that can efficiently improve the bottom sediment without requiring unnecessary facilities.

閉鎖水域(湖沼等)の汚染が顕在化している現状において、その対策が進まないのは社会的ニーズが無いわけではなく、技術的に効果のある工法が無いためと思われる。その証拠としては、これまで問題視されてきた多くの閉鎖水域における浄化対策が必ずしも成果を上げていないことが挙げられる。これまで行われた対策は、浚渫、覆砂、エアレーションによる好気化、菌植え付けによる有機物分解、水生植物による栄養塩吸収、貝類などによる栄養塩消費等である。これらについて、一定の効果があったとも思われるが、莫大な経費を要する工法にしては、必ずしも顕著な効果があったとは言えない。   In the current situation where pollution in closed water areas (lakes, etc.) has become apparent, the reason why countermeasures do not advance is not because there is no social need, but because there is no technically effective construction method. The proof is that the purification measures in many closed water areas, which have been regarded as problems, do not necessarily produce results. Measures taken so far include drought, sand covering, aerobic by aeration, decomposition of organic matter by planting bacteria, absorption of nutrients by aquatic plants, consumption of nutrients by shellfish and the like. Although it seems that there was a certain effect about these, it cannot necessarily be said that there was a remarkable effect for the construction method which requires a huge expense.

これに関連する従来技術として、例えば次のような浚渫底泥の処理方法が知られている。この従来技術は、浚渫底泥に対して、かかる底泥の1リットル当り、5mg/min以上の割合でオゾンを接触させることにより底泥中に含まれるフミン物質(有機物質)を分解し、この後、オゾン処理が施された底泥を固液分離し、得られた固形物を水底に戻す一方、分離液に対してはさらにオゾン処理を施し、水底ないしは水域に戻すようにしている。   As conventional techniques related to this, for example, the following method for treating dredged mud is known. This conventional technology decomposes humic substances (organic substances) contained in the bottom mud by contacting ozone with the bottom mud at a rate of 5 mg / min or more per liter of the bottom mud. Thereafter, the bottom mud that has been subjected to ozone treatment is subjected to solid-liquid separation, and the obtained solid matter is returned to the water bottom, while the separated liquid is further subjected to ozone treatment to return to the water bottom or water area.

そして、このような浚渫底泥の処理方法を行うために次のような構成の浚渫底泥の処理装置を使用している。即ち、船舶上の前後に第1と第2の2つのオゾン処理装置が設置され、該第1と第2のオゾン処理装置の間に固液分離装置が設置されている。前記各オゾン処理装置には、オゾン発生器及び攪拌機等が装備され、さらに第1のオゾン処理装置に対しては、水底から浚渫によって揚泥するための揚泥ポンプが付設されている。また、前記固液分離装置には、改質泥貯留槽と分離液槽とが併設され、該改質泥貯留槽内に改質泥攪拌機が設けられるとともに前記分離液槽上に固液分離装置本体が設置されている。この固液分離装置本体に対しては、改質泥から生じた反応処理物を交互に供給するための2基の反応槽が設けられ、さらに該2基の反応槽のそれぞれに凝集固化剤を供給するための凝集固化剤供給機が各別に設けられている(例えば、特許文献1参照)。   And in order to perform such a dredging mud processing method, the dredging mud processing apparatus of the following structures is used. That is, the first and second ozone treatment devices are installed on the front and rear of the ship, and the solid-liquid separation device is installed between the first and second ozone treatment devices. Each of the ozone treatment devices is equipped with an ozone generator, a stirrer, and the like, and further, the first ozone treatment device is provided with a mud pump for lifting mud from the bottom of the water using a dredge. Further, the solid-liquid separation device is provided with a reformed mud storage tank and a separation liquid tank, a reforming mud stirrer is provided in the reformed mud storage tank, and a solid-liquid separation device is provided on the separation liquid tank. The main body is installed. The main body of the solid-liquid separator is provided with two reaction tanks for alternately supplying reaction products generated from the modified mud, and a coagulating solidifying agent is added to each of the two reaction tanks. A coagulating solidifying agent supply machine for supplying is provided for each (see, for example, Patent Document 1).

特開2009−18223号公報JP 2009-18223 A

特許文献1に記載の従来技術においては、オゾン処理が施された底泥を固液分離し、得られた固形物(浚渫土)は水底に戻す一方、分離液に対してはさらにオゾン処理を施して水域に戻すようにしている。しかしながら、浚渫底泥の処理にかなり大掛かりな装置を必要としている。   In the prior art described in Patent Document 1, the bottom mud that has been subjected to ozone treatment is subjected to solid-liquid separation, and the obtained solid matter (soil) is returned to the bottom of the water, while the separated liquid is further subjected to ozone treatment. And return it to the water area. However, a considerably large apparatus is required for the treatment of dredged mud.

そこで、底質中の汚染物質の除去を比表面積が大きく吸着できる汚染物質の量が多い細かい粒子を除去することで効率的に底質改善を行い、底質を再懸濁し粒子の大きさによる水中での沈降速度差を用いて除去する細かい粒子の分級を行うことで大掛かりな設備を不
要とし、細かい粒子に吸着した汚染物質を除去することで底質の90%程度は元に戻すことにより経済性を有し、底質の再懸濁を基本的にはエアーを混合した水ジェットにより行うことで細かい粒子を除去した後の再堆積物はエアレーション効果により好気化の促進が行われて覆砂と同じ効果を奏するとともに水質改善(好気化)も同時に行えるようにし、浚渫に比べて再懸濁による底質の除去土量は1/10程度であることから浚渫土の処分費を大幅に低減することを可能とし、騒音や振動を伴う装置の使用を不要として無振動・低騒音にて施工を可能とするために解決すべき技術的課題が生じてくるのであり、本発明はこの課題を解決することを目的とする。
Therefore, the removal of pollutants in the sediment improves the sediment efficiently by removing fine particles with a large amount of pollutants that can adsorb a large specific surface area. By classifying fine particles to be removed using the difference in sedimentation speed in water, large-scale equipment is unnecessary, and by removing contaminants adsorbed on fine particles, about 90% of the sediment is restored. It is economical, and the bottom sediment is basically resuspended by a water jet mixed with air, and the redeposits after removal of fine particles are aerobic accelerated by the aeration effect. It has the same effect as sand and can improve water quality (aerobic) at the same time. The amount of soil removed from the bottom by resuspension is about 1/10 compared to dredging. It is possible to reduce Therefore, there is a technical problem to be solved in order to enable construction with no vibration and low noise without using a device with noise and vibration, and the present invention aims to solve this problem. And

本発明は上記目的を達成するために提案されたものであり、請求項1記載の発明は、汚染された閉鎖水域で底質を再懸濁して再懸濁水の対流を生じさせ、粒径の大きさによる水中での沈降速度の差を利用して底質に含まれる粒子を閉鎖水域の下部から上部に向かって漸次小径になるように分級を行い、閉鎖水域の上部を浮遊する前記底質に含まれる粒子のうち小さい方から粒径分布と汚染状況に応じた所要%の質量を除去することにより、汚染の原因となる有害物質を80〜90%除去する再懸濁による底質浄化工法を提供する。 The present invention has been proposed to achieve the above object, and the invention according to claim 1 is characterized in that the sediment is resuspended in a contaminated closed water area to cause convection of the resuspended water , Using the difference in sedimentation speed in water depending on the size of the sediment , the particles contained in the sediment are classified so that the diameter gradually decreases from the bottom of the closed water area to the top, and the bottom floating above the closed water area Bottom sediment purification by resuspension that removes 80-90% of harmful substances causing contamination by removing the required mass according to the particle size distribution and contamination status from the smaller particles contained in the quality Provide construction methods.

この構成によれば、底質には沈降した有機物主体の細粒土が多く含まれ、これに前記細粒土よりも粗粒な砂や礫等も含まれるが、これらの粗粒には吸着物が少なく汚染も殆どない。このため、底質改善の上で問題となるのは有機物主体の細粒土といえる。この細粒土、即ち細かい粒子は比表面積(例えば1g当たりの表面積)が大きく、その分吸着できる有害物質の量が多い。また、粘土の範疇にある粘土鉱物はその表面に電荷を有しており、重金属などの陽イオンを電気的に吸着する性質を持っている。このため、一般に粘土鉱物を多く含む細粒土は多量の有害物質を含んでいる。このことから、底質から有機物を含む細かい粒子を取り除くことで底質改善を行うことが可能である。   According to this configuration, the bottom sediment contains a large amount of finely divided soil mainly composed of organic matter, including coarse sand and gravel, etc., which are adsorbed by these coarse particles. There are few things and there is almost no pollution. For this reason, it can be said that the problem of improving sediment quality is fine-grained soil mainly composed of organic matter. This fine-grained soil, that is, fine particles, has a large specific surface area (for example, a surface area per 1 g), and the amount of harmful substances that can be adsorbed is large. In addition, clay minerals in the category of clay have a charge on the surface and have the property of electrically adsorbing cations such as heavy metals. For this reason, generally, fine-grained soil containing a large amount of clay minerals contains a large amount of harmful substances. From this, it is possible to improve the bottom sediment by removing fine particles containing organic matter from the bottom sediment.

前述のように、細かい粒子は比表面積が大きいことから、ある粒径分布を有する底質について、細かい方から質量で10〜15%程度の所要%の細粒土全体の表面積は、その底質が持つ総面積の約80〜90%の表面積を占めることになる。即ち、吸着や付着が表面積に依存すると考えると、底質に含まれる粒子のうち小さい方から粒径分布と汚染状況に応じて10〜15%程度の所要%の質量を除去することで、吸着物質の80〜90%が取り除けることになる。   As described above, since the fine particles have a large specific surface area, the surface area of the entire fine-grained soil with a required percentage of about 10 to 15% by mass from the finer side of the bottom sediment having a certain particle size distribution is the bottom sediment. Occupies a surface area of about 80 to 90% of the total area. That is, assuming that adsorption and adhesion depend on the surface area, by removing the required mass of about 10-15% depending on the particle size distribution and contamination status from the smaller particles contained in the bottom sediment, 80-90% of the material will be removed.

そこで、底質にエアーを取り込んだジェット水を吹付ける等の再懸濁操作により、該底質を攪乱する。このとき、エアーリフター効果により粒径が細かい粒子や比重が小さい有機粒子は上部まで動き、大きな粒径を持つ粒子は動く高さが限られる。このような沈降速度の差を利用した分級を行い、分級された細粒分をポンプで吸い上げ、水上で濾過する等の手段により汚染の原因となる有害物質を除去する。   Therefore, the sediment is disturbed by a resuspension operation such as spraying jet water in which air is taken into the sediment. At this time, particles having a small particle diameter and organic particles having a small specific gravity move to the top due to the air lifter effect, and the moving height of particles having a large particle diameter is limited. Classification using such a difference in sedimentation speed is performed, and the classified fine particles are sucked up by a pump, and harmful substances that cause contamination are removed by means such as filtering on water.

請求項2記載の発明は、請求項1記載の発明において、上記底質に含まれる粒子のうち小さい方から除去する上記質量は、ほぼ10〜15%である再懸濁による底質浄化工法を提供する。   According to a second aspect of the present invention, in the first aspect of the present invention, the mass removal from the smaller one of the particles contained in the bottom sediment is approximately 10 to 15%. provide.

この構成によれば、底質には粒径が0.005mm程度の有機物主体の細粒土が多く含まれ、この他に該有機物主体の細粒土よも粒径の大きい砂や礫等が含まれる。細かい粒子は比表面積が大きいことから、ある粒径分布を有する底質について、質量で小さい方から10〜15%程度の有機物主体の細粒土全体の表面積は、その底質が持つ総面積の約80〜90%の表面積を占める。したがって、吸着や付着が表面積に依存すると考えると、底質に含まれる粒子のうち小さい方からほぼ10〜15%の質量を除去することで、吸着物質の80〜90%が取り除けることになる。   According to this configuration, the bottom sediment contains a large amount of organic-based fine-grained soil having a particle size of about 0.005 mm, and in addition, sand, gravel, etc. having a larger particle size than the organic-based fine-grained soil. included. Since the fine particles have a large specific surface area, the surface area of the fine-grained soil mainly composed of organic matter, which is about 10 to 15% from the smallest by mass, is the total area of the bottom sediment. Occupies a surface area of about 80-90%. Therefore, if it is considered that the adsorption and adhesion depend on the surface area, 80 to 90% of the adsorbed substance can be removed by removing approximately 10 to 15% of the mass of particles contained in the bottom sediment.

請求項3記載の発明は、請求項1又は2記載の発明において、水中で分級された細粒分をポンプで吸い上げ、水上にて砂濾過、フィルター濾過、袋濾過のうちの少なくともいずれかの濾過手段により除去すべき質量分を濾過し、濾過後の水分は上記閉鎖水域に戻す再懸濁による底質浄化工法を提供する。   The invention according to claim 3 is the invention according to claim 1 or 2, wherein the fine particles classified in water are sucked up by a pump and filtered at least one of sand filtration, filter filtration and bag filtration on water. The mass to be removed by the means is filtered, and the bottom sediment purification method is provided by resuspension in which the filtered water is returned to the closed water area.

この構成によれば、水中で沈降速度の差を利用して分級された細粒分はポンプで吸い上げられ、水上で濾過手段により濾過されて除去される。   According to this configuration, fine particles classified using the difference in sedimentation speed in water are sucked up by the pump and filtered and removed on the water by the filtering means.

請求項4記載の発明は、請求項1,2又は3記載の発明において、上記底質の再懸濁は、インジェクターによりエアーを取込んだジェット水を前記底質に吹付け該底質の攪乱を行う再懸濁による底質浄化工法を提供する。   According to a fourth aspect of the present invention, in the first, second, or third aspect of the invention, the bottom sediment re-suspension is performed by spraying jet water, which has taken in air by an injector, onto the bottom sediment. The bottom sediment purification method by resuspension is performed.

この構成によれば、再懸濁は、底質に対しエアーを取り込んだジェット水を吹付けることで該底質が攪乱され、エアーリフター効果により有機物を多く含む細粒分が上方に浮遊することで行われる。このとき、ジェット水に取り込まれたエアーは嫌気化している底質を好気化(底質改善)することにも寄与する。   According to this configuration, in the resuspension, the bottom sediment is disturbed by spraying jet water that has taken in air to the bottom sediment, and fine particles containing a large amount of organic matter float upward due to the air lifter effect. Done in At this time, the air taken into the jet water also contributes to aerobicizing (improving bottom sediment) the bottom sediment that has been anaerobic.

請求項5記載の発明は、請求項4記載の発明において、上記底質の再懸濁の際に、機械式攪拌翼による底質の攪拌を併用する再懸濁による底質浄化工法を提供する。   The invention described in claim 5 provides the bottom purification method by resuspension according to the invention described in claim 4 in which the bottom sediment is resuspended by using the mechanical stirring blade together with the bottom sediment agitation. .

この構成によれば、底質に対しエアーを取り込んだジェット水を吹付けて再懸濁を行う際に、機械式攪拌翼により底質を掘削・攪拌することで、エアーリフター効果により有機物を多く含む細粒分が、より一層効果的に上方に浮遊する。   According to this configuration, when resuspending by spraying jet water that has taken in air to the bottom sediment, the bottom sediment is excavated and stirred with a mechanical stirring blade, thereby increasing the amount of organic matter by the air lifter effect. The contained fine particles float more effectively.

請求項6記載の発明は、請求項4記載のの発明において、上記底質の再懸濁の際に、リッパーの索引による底質の攪拌を併用する再懸濁による底質浄化工法を提供する。   The invention described in claim 6 provides a bottom sediment purification method by resuspension in the invention according to claim 4 wherein the bottom sediment is resuspended together with the bottom sediment agitation by the index of the ripper. .

この構成によれば、底質に対しエアーを取り込んだジェット水を吹付けて再懸濁を行う際に、リッパーの索引により底質を掘削・攪拌することで、エアーリフター効果により有機物を多く含む細粒分が、より一層効果的に上方に浮遊する。   According to this configuration, when resuspending by spraying jet water that has taken air into the bottom material, the bottom material is excavated and stirred by the index of the ripper, so that it contains a lot of organic matter due to the air lifter effect. The fine particles float more effectively upward.

請求項1記載の発明は、粒径の大きさによる水中での沈降速度の差を利用して底質に含まれる粒子を閉鎖水域の下部から上部に向かって漸次小径になるように分級を行い、閉鎖水域の上部を浮遊する底質に含まれる粒子のうち小さい方から10〜15%程度の所要%の質量を除去することで、汚染物質の80〜90%を取り除くことができて効率的に質改善を行うことができる。底質にエアーを取り込んだジェット水を吹付ける等の再懸濁操作により該底質を攪乱して再懸濁水の対流を生じ沈降速度の差を利用し分級を行うことで、大掛かりな設備を不要として有害物質を除去することができる。細かい粒子に吸着した汚染物質を除去するのみで底質の90%程度は元に戻すことから経済的である。また、浚渫に比べて再懸濁による底質の除去土量は1/10程度であることから浚渫土の処分費を大幅に低減することができる。さらには騒音や振動を伴う装置の使用を不要として無振動・低騒音にて施工することができるという利点がある。 In the first aspect of the invention, the particles contained in the bottom sediment are classified so as to gradually become smaller in diameter from the lower part to the upper part of the closed water area using the difference in the sedimentation rate in water depending on the size of the particle diameter. Efficiently removes 80-90% of pollutants by removing the required mass of about 10-15% of the particles contained in the bottom sediment floating above the closed water area. it can be carried out sediment improvement. Large scale facilities can be constructed by classifying by utilizing the difference in sedimentation velocity by disturbing the bottom sediment by resuspension operation such as blowing jet water that has taken air into the bottom sediment and generating convection of the resuspended water. Hazardous substances can be removed as unnecessary. It is economical because only 90% of the sediment is restored by removing the contaminants adsorbed on the fine particles. Moreover, since the amount of soil removed from the bottom sediment by resuspension is about 1/10 compared to dredging, dredging disposal cost can be greatly reduced. Furthermore, there is an advantage that construction can be performed with no vibration and low noise without using a device with noise and vibration.

請求項2記載の発明は、底質には粒径が0.005mm程度の有機物主体の細粒土が多く含まれ、この細粒土は比表面積が大きいことから、ある粒径分布を有する底質について、質量で小さい方から10〜15%程度の有機物主体の細粒土全体の表面積は、その底質が持つ総面積の約80〜90%の表面積を占める。したがって、底質に含まれる粒子のうち小さい方からほぼ10〜15%の質量を除去することで、有害物質の80〜90%を取り除くことができるという利点がある。   In the second aspect of the present invention, the bottom sediment contains a large amount of fine-grained soil mainly composed of organic matter having a particle size of about 0.005 mm, and the fine-grained soil has a large specific surface area. Regarding the quality, the surface area of the entire fine-grained soil mainly composed of organic matter of about 10 to 15% from the smallest in mass occupies the surface area of about 80 to 90% of the total area of the bottom sediment. Therefore, there is an advantage that 80 to 90% of harmful substances can be removed by removing approximately 10 to 15% of the mass of particles contained in the bottom sediment.

請求項3記載の発明は、請求項1又は2記載の発明の効果に加えてさらに、水中で沈降
速度の差を利用して分級した細粒分を水上で濾過することで、大掛かりな設備を不要として有害物質を除去することができるという利点がある。
In addition to the effects of the invention described in claim 1 or 2, the invention described in claim 3 further provides a large-scale facility by filtering the fine particles classified in water using the difference in sedimentation speed in water. There is an advantage that harmful substances can be removed as unnecessary.

請求項4記載の発明は、請求項1,2又は3記載の発明の効果に加えてさらに、再懸濁をエアーを取り込んだジェット水により行うことで、エアレーション効果により、有害物質を除去した後の再堆積物に対し好気化を促進させることができるという利点がある。   In addition to the effect of the invention described in claim 1, 2 or 3, the invention described in claim 4 further performs resuspension with jet water incorporating air, thereby removing harmful substances due to the aeration effect. There is an advantage that aerobicization can be promoted with respect to redeposits.

請求項5記載の発明は、請求項4記載の発明の効果に加えてさらに、機械式攪拌翼により底質を掘削・攪拌することで、有機物を多く含む細粒分を、より一層効果的に上方に浮遊させることができるという利点がある。   In addition to the effect of the invention of claim 4, the invention of claim 5 further effectively removes fine particles containing a large amount of organic matter by excavating and stirring the bottom with a mechanical stirring blade. There is an advantage that it can be floated upward.

請求項6記載の発明は、請求項4記載の発明の効果に加えてさらに、リッパーの索引により底質を掘削・攪拌することで、有機物を多く含む細粒分を、より一層効果的に上方に浮遊させることができるという利点がある。   In addition to the effect of the invention of the fourth aspect, the invention described in the sixth aspect further effectively lifts the fine particles containing a large amount of organic matter by excavating and stirring the bottom sediment using the index of the ripper. There is an advantage that it can be suspended.

図は本発明の実施例に係る再懸濁による底質浄化工法を示すものである。
再懸濁させるための粒径と上向き流速の関係を示す特性図。 再懸濁による懸濁粒子の動きを示す図。 再懸濁装置例を示す図であり、(a)は再懸濁装置としてインジェクターを用いた例を示す図、(b)は再懸濁装置としてインジェクターに機械式攪拌翼を併用した例を示す図、(c)再懸濁装置としてインジェクターにリッパーを併用した例を示す図。 再懸濁法を概略的に示す図。 再懸濁工法底質浄化船を示す図であり、(a)は側面図、(b)は平面図。 再懸濁拡散防止機構を備えた再懸濁工法底質浄化船を示す図であり、(a)は側面図、(b)は図(a)におけるA部の再懸濁拡散防止機構を詳細に示す拡大側面図。
The figure shows a bottom purification method by resuspension according to an embodiment of the present invention.
The characteristic view which shows the relationship between the particle size for resuspending, and upward flow velocity. The figure which shows the motion of the suspended particle by resuspension. It is a figure which shows the example of a resuspension apparatus, (a) shows the example which used the injector as a resuspension apparatus, (b) shows the example which used the mechanical stirring blade together with the injector as a resuspension apparatus. (C) The figure which shows the example which used the ripper together with the injector as a resuspension apparatus. The figure which shows the resuspension method schematically. It is a figure which shows a resuspension method bottom sediment purification ship, (a) is a side view, (b) is a top view. It is a figure which shows the resuspension method bottom sediment purification ship provided with the resuspension diffusion prevention mechanism, (a) is a side view, (b) is the detail of the resuspension diffusion prevention mechanism of the A section in FIG. FIG.

本発明は、底質中の汚染物質の除去を比表面積が大きく吸着できる汚染物質の量が多い細かい粒子を除去することで効率的に底質改善を行い、底質を再懸濁し粒子の大きさによる水中での沈降速度差を用いて除去する細かい粒子の分級を行うことで大掛かりな設備を不要とし、細かい粒子に吸着した汚染物質を除去することで底質の90%程度は元に戻すことにより経済性を有し、底質の再懸濁を基本的にはエアーを混合した水ジェットにより行うことで細かい粒子を除去した後の再堆積物はエアレーション効果により好気化の促進が行われて覆砂と同じ効果を奏するとともに水質改善(好気化)も同時に行えるようにし、浚渫に比べて再懸濁による底質の除去土量は1/10程度であることから浚渫土の処分費を大幅に低減することを可能とし、騒音や振動を伴う装置の使用を不要として無振動・低騒音にて施工を可能にするという目的を達成するために、汚染された閉鎖水域で底質を再懸濁して再懸濁水の対流を生じさせ、粒径の大きさによる水中での沈降速度の差を利用して底質に含まれる粒子を閉鎖水域の下部から上部に向かって漸次小径になるように分級を行い、閉鎖水域内の上部を浮遊する底質に含まれる粒子のうち小さい方から粒径分布と汚染状況に応じた所要%の質量を除去することにより、汚染の原因となる有害物質を80〜90%除去することで実現した。 The present invention is effective in improving the bottom sediment by removing fine particles with a large amount of contaminant that can adsorb large amounts of contaminants in the removal of pollutants in the bottom sediment, and resuspending the bottom sediment to increase the size of the particles. By classifying fine particles to be removed using the difference in sedimentation speed in water, large equipment is not required, and about 90% of the sediment is restored by removing contaminants adsorbed on the fine particles. The bottom sediment is basically resuspended by a water jet mixed with air, and the redeposits after removing fine particles are accelerated by aeration. In addition to having the same effect as sand-capping, water quality can be improved (aerobic) at the same time, and the amount of soil removed by resuspension is about 1/10 compared to dredging. Can be significantly reduced And, in order to achieve the objective of allowing construction with no vibration and noise of the use of the device with a noise and vibration as an unnecessary, resuspended water was resuspended sediment contaminated with closed water area convection was generated, and classified as to get smaller in diameter gradually toward the particles contained in the sediment by utilizing the difference in sedimentation rate in water depending on the size of the particle diameter from the lower closure waters in the upper, closed 80% to 90% of harmful substances causing pollution are removed by removing the required mass according to the particle size distribution and contamination status from the smaller particles contained in the sediment floating in the upper part of the water area. It was realized by doing.

以下、本発明の実施例に係る再懸濁による底質浄化工法を図1乃至図5を参照して説明する。底質とは有機物を多く含み、基本的には沈降した懸濁物質と同じ成分である。底質には懸濁物質と異なって、それより粗粒な砂や礫等も含まれ、また、一次鉱物である石英や長石粒子のように不活性のものも含まれている。しかし、これらの粗粒な粒子はどちらかといえば吸着物が少なく汚染も殆どない。このため、底質改善の上で問題となるのは有機物主体の細粒土である。   Hereinafter, a bottom purification method by resuspension according to an embodiment of the present invention will be described with reference to FIGS. Sediment contains a lot of organic matter and is basically the same component as sedimented suspended matter. Unlike suspended solids, sediments contain coarser sand and gravel, and also contain inert substances such as primary minerals such as quartz and feldspar particles. However, these coarse particles are rather less adsorbed and hardly contaminated. For this reason, it is fine-grained soil mainly composed of organic matter that becomes a problem in improving sediment quality.

細かい粒子は比表面積(例えば1g当たりの表面積)が大きく、その分吸着できる汚染物質の量が多い。例えば、砂より粘土の方がより多くの有害物質を吸着できる。同時に粘土の範疇にある粘土鉱物はその表面に電荷を有しており、重金属などの陽イオンを電気的に吸着する性質を持っている。このため、一般に粘土鉱物を多く含む細粒土の方が砂や礫より多量の有害物質を含んでいる。このことから、底質から有機物や細かい粒子を取り除くことで、底質改善を行うことが可能である。   Fine particles have a large specific surface area (for example, a surface area per 1 g), and the amount of contaminants that can be adsorbed is large. For example, clay can adsorb more harmful substances than sand. At the same time, clay minerals in the category of clay have a charge on the surface and have the property of electrically adsorbing cations such as heavy metals. For this reason, fine-grained soil containing a large amount of clay minerals generally contains more harmful substances than sand and gravel. From this, it is possible to improve the bottom sediment by removing organic substances and fine particles from the sediment.

ここで、粒子を取り除くことで、この粒子への吸着・付着物質を取り除く場合、効果的な方法は細かい粒子から取り除くことである。これは、細かい粒子ほど、前述のように比表面積が大きいためである。比表面積は1m3当たり又は1g当たりの全表面積で表す。この比表面積は粒子の大きさと形状で決まる。粒子が球の場合、粒径が半分になれば、面積は2倍、体積は1/8になる。したがって、比表面積は16倍になる。 Here, when removing the adsorbed / adhering substances on the particles by removing the particles, an effective method is to remove the particles from the fine particles. This is because fine particles have a larger specific surface area as described above. The specific surface area is expressed as the total surface area per 1 m 3 or 1 g. This specific surface area is determined by the size and shape of the particles. When the particle is a sphere, if the particle size is halved, the area is doubled and the volume is 1/8. Therefore, the specific surface area is 16 times.

したがって、代表的な粒径として、砂、:シルト:粘土=1:0.01:0.001(mm)とすれば、その比表面積は砂の場合を1とすれば、砂、:シルト:粘土の比表面積の比は1:100:1000となる。これより、ある粒径分布を有する底質について、細かい方から質量で10〜15%程度の細粒土全体の表面積は、その底質が持つ総面積の約80〜90%の表面積を占めることになる。即ち、吸着や付着が表面積に依存すると考えると、底質に含まれる粒子のうち小さい方から粒径分布と汚染状況に応じて10〜15%程度の質量を除去することで、吸着物質の80〜90%が取り除けることになる。   Therefore, if the typical particle size is sand, silt: clay = 1: 0.01: 0.001 (mm), the specific surface area is 1 in the case of sand, sand: silt: The specific surface area ratio of the clay is 1: 100: 1000. From this, about the bottom sediment which has a certain particle size distribution, the surface area of the whole fine-grained soil of about 10-15% by mass from the finer side occupies the surface area of about 80-90% of the total area of the bottom sediment. become. That is, assuming that the adsorption and adhesion depend on the surface area, the mass of about 10 to 15% is removed from the smaller one of the particles contained in the bottom sediment according to the particle size distribution and the contamination status, so that ~ 90% will be removed.

そこで、底質に含まれる粒子のうち小さい方からほぼ10〜15%の質量を除去する手段として、底質部を再懸濁により浮遊させ除去対象の粒径を分級する。この分級の原理を説明する。底質に堆積している粒子の比重は、閉鎖水域における海水の比重1.03以上でなければならない。実際、普通の無機粒子の比重は約2.6であり、有機物が混じることでその値が下がり、砂鉄など重鉱物が混入すると高くなる。粒子が流体中を沈降する速度は、比重、流体の粘性係数(温度依存)、粒子の大きさと形などに関係する。   Therefore, as a means for removing approximately 10 to 15% of the mass contained in the bottom sediment, the bottom sediment is suspended by resuspension to classify the particle size to be removed. The principle of this classification will be explained. The specific gravity of the particles deposited in the sediment should be 1.03 or higher for the seawater in the closed water area. Actually, the specific gravity of ordinary inorganic particles is about 2.6, the value decreases when organic substances are mixed, and increases when heavy minerals such as iron sand are mixed. The speed at which particles settle in the fluid is related to specific gravity, fluid viscosity coefficient (temperature dependence), particle size and shape, and the like.

沈降速度vを表す式は、理想的な条件下(例えば、粒子は球と仮定)で、ストークスの法則として知られている。一つの粒子に作用する重力fは、   The equation representing the settling velocity v is known as Stokes' law under ideal conditions (for example, assuming that the particles are spheres). Gravity f acting on one particle is

ここに、Gsは粒子比重、ρwは水の密度、gnは重力加速度、dは粒子直径である。一方、その粒子が流体中を沈降するとき受ける抵抗Rは、 Here, the G s is the particle density, [rho w density of water, is g n is the gravitational acceleration, d is the particle diameter. On the other hand, the resistance R received when the particles settle in the fluid is

ここに、ηは水の粘性係数、vは沈降速度である。もし、この粒子が上向きのVupの流速の場にあるとすれば、抵抗力R´は、 Here, η is the viscosity coefficient of water, and v is the sedimentation velocity. If this particle is in an upward V up flow field, the resistance R ′ is

ある粒径の粒子が懸濁したまま沈降しないと考えると、次の条件となる。 Considering that particles of a certain particle size do not settle while suspended, the following conditions are satisfied.

したがって、沈降・堆積しない粒径範囲は次のようになる。   Therefore, the particle size range where no sedimentation / deposition occurs is as follows.

つまり、Vupより大きな上向きの流れがあるところでは、沈降しない又は上向きに動く粒子が存在する。これから、Gs=2.65、水の粘性係数=0.000188Pa・m、重力加速度gn=9.8m/s2、海水の密度ρw=1030kg/m3を用いて計算すると、得られる粒径dと上向き流速Vupの関係は図1のようになる。即ち、両対数の関係を取れば直線によって沈降領域と懸濁領域とが分けられる。この図1の特性から、粒径dが0.005mm程度の有機物主体の細粒土には、0.01(cm/s)を超えた上向き流速Vupが生じて浮遊することが分かる。なお、図1の特性計算では、粒子は無機物と仮定してある。もし、有機物とするなら、Gs<2.0にする必要がある。これからも分かるように、底質を再懸濁させておいて、有機物を含む細かい粒子を分級により除去することが可能である。 That is, where there is an upward flow greater than V up , there are particles that do not settle or move upward. From this, it is obtained by calculating using G s = 2.65, water viscosity coefficient = 0.000188 Pa · m, gravity acceleration g n = 9.8 m / s 2 , and seawater density ρ w = 1030 kg / m 3. The relationship between the particle diameter d and the upward flow velocity V up is as shown in FIG. That is, if the logarithmic relationship is taken, the sedimentation area and the suspension area are separated by a straight line. From the characteristics shown in FIG. 1, it is understood that an upward flow velocity V up exceeding 0.01 (cm / s) is generated and floats in an organic-based fine-grained soil having a particle diameter d of about 0.005 mm. In the characteristic calculation of FIG. 1, the particles are assumed to be inorganic. If it is organic, it is necessary to set G s <2.0. As can be seen, it is possible to resuspend the sediment and remove fine particles containing organic substances by classification.

この底質を再懸濁により浮遊させ除去対象の粒子を分級する原理を図2に示す。この図2から、上向き流速Vupの上向き噴流により比重が小さい有機物粒子を含む粒径が細かい粒子は上部まで動き、大きな粒径を持つ粒子は動く高さが限られる。すなわち、粒径の大きさによる水中での沈降速度の差に起因して、粒子の粒径が下部から上部に向かって徐々に小さくなるように分級される。したがって、上部から排出される水には有機物粒子を含む細かい粒子が存在する。それらの粒子の除去には、後述するようにフィルター等による除去が相応しい。なお、この細かい粒子より大径の大きな粒子は、閉鎖水域から外部に排出されることなく閉鎖水域内に留まるようになっている。 The principle of classifying the particles to be removed by suspending the sediment by resuspension is shown in FIG. From FIG. 2, fine particles including organic particles having a small specific gravity move to the top due to the upward jet of upward flow velocity Vup, and the moving height of particles having a large particle size is limited. That is, the particles are classified so that the particle size of the particles gradually decreases from the lower part toward the upper part due to the difference in the sedimentation speed in water depending on the size of the particle diameter. Therefore, fine particles including organic particles are present in the water discharged from the top. For the removal of these particles, it is appropriate to remove them with a filter or the like as will be described later. It should be noted that particles having a diameter larger than the fine particles remain in the closed water area without being discharged from the closed water area to the outside.

上記の底質を再懸濁する方法を図3の(a)、(b)、(c)を用いて説明する。底質の堆積物を再懸濁させ、上方に浮遊した有機物を含む細かい粒子を除去できる装置であるなら、どのようなものでも適用できる。再懸濁には空気又は水噴射が適用できるであろうし、また、それを上層へ移動させるには上向き流又は泡沫などの適用が考えられる。   A method for resuspending the sediment will be described with reference to FIGS. 3 (a), (b), and (c). Any device that can resuspend sediment sediment and remove fine particles including organic matter suspended above can be applied. Air or water jets could be applied for resuspension and applications such as upward flow or foam could be considered to move it up.

図3(a)は、再懸濁装置としてインジェクター(Injector)を用いた例を示している。この例では、シルトフェンス1で囲った閉鎖水域の底質2に対しインジェクター3によりエアーを取り込んだジェット水を吹付けることで該底質2が攪乱され、エアーリフター効果により有機物を多く含む細粒分が上方に浮遊することで再懸濁が行われる。このとき、ジェット水に取り込まれたエアーは嫌気化している底質2を好気化(底質改善)することにも寄与する。なお、この例では、インジェクター3におけるジェット水出口に図示しないキャビテーションノズルを取付けることで、底質2に対する掘削効果が向上して一層効果的に再懸濁を行わせることができる。   FIG. 3A shows an example in which an injector is used as a resuspension device. In this example, the bottom sediment 2 in the closed water area surrounded by the silt fence 1 is disturbed by spraying the jet water that has taken in air by the injector 3, and the fine granule that contains a large amount of organic matter by the air lifter effect. Resuspension takes place as the minutes float upwards. At this time, the air taken into the jet water also contributes to aerobic bottom sediment improvement (bottom quality improvement). In this example, by attaching a cavitation nozzle (not shown) to the jet water outlet of the injector 3, the excavation effect on the bottom sediment 2 is improved and resuspension can be performed more effectively.

図3(b)は、再懸濁装置として、上記図3(a)のインジェクター3に機械式攪拌翼4を併用した例を示している。この併用例では、底質2に対しインジェクター3によりエアーを取り込んだジェット水を吹付けて再懸濁を行う際に、機械式攪拌翼4により底質を掘削・攪拌することで、エアーリフター効果により有機物を含む細粒分が、より一層効果
的に上方に浮遊する。
FIG.3 (b) has shown the example which used the mechanical stirring blade 4 together with the injector 3 of the said Fig.3 (a) as a resuspension apparatus. In this combination example, when the bottom water 2 is resuspended by spraying jet water taken in by the injector 3, the bottom material is excavated and stirred by the mechanical stirring blade 4, thereby providing an air lifter effect. As a result, fine particles containing organic substances float more effectively.

図3(c)は、再懸濁装置として、上記図3(a)のインジェクター3にリッパー5を併用した例を示している。この併用例では、底質2に対しインジェクター3によりエアーを取り込んだジェット水を吹付けて再懸濁を行う際に、リッパー5の索引により底質2を掘削・攪拌することで、エアーリフター効果により有機物を含む細粒分が、より一層効果的に上方に浮遊する。   FIG.3 (c) has shown the example which used the ripper 5 together with the injector 3 of the said Fig.3 (a) as a resuspension apparatus. In this combined example, when the bottom water 2 is resuspended by spraying the jet water in which air is taken in by the injector 3, the bottom 2 is excavated and stirred by the index of the ripper 5, and the air lifter effect is obtained. As a result, fine particles containing organic substances float more effectively.

図4は、上記再懸濁装置による再懸濁法を概略的に示している。台船6上に濾過手段としての砂濾過槽7及びポンプ8等が設置されている。図の例では、砂濾過槽7が適用されているが、濾過には、該砂濾過の他にフィルター濾過、袋濾過等も適用可能である。また、砂濾過槽7の濾過面積は、濾過対象水域の大きさ、工期、濾過手段の設置面積等から決定される。なお、濾過という概念から離れれば、有機物を含む細粒分の濾過には、遠心分離器やフィルタープレス等の機械式濾過も適用可能である。   FIG. 4 schematically shows a resuspension method using the resuspension apparatus. A sand filtration tank 7 and a pump 8 are installed on the carriage 6 as filtration means. In the example shown in the figure, the sand filtration tank 7 is applied. For filtration, filter filtration, bag filtration, and the like can be applied in addition to the sand filtration. Moreover, the filtration area of the sand filtration tank 7 is determined from the size of the filtration target water area, the construction period, the installation area of the filtration means, and the like. In addition, if it leaves | separates from the concept of filtration, mechanical filtration, such as a centrifuge and a filter press, is also applicable to filtration of the fine particle containing an organic substance.

そして、前記インジェクターによりエアーを取り込んだジェット水が底質2に吹付けられて該底質2が攪乱され、エアーリフター効果により有機物を多く含む細粒分が上方に浮遊する。該有機物を多く含む細粒分は沈降速度の差を利用して水中で分級され、ポンプ8で台船6上に吸い上げられた後、砂濾過槽7で濾過されて除去される。また濾過後の水分は閉鎖水域に戻される。   And the jet water which took in the air with the said injector is sprayed on the bottom sediment 2, the bottom sediment 2 is disturbed, and the fine particle part which contains many organic substances floats upwards by the air lifter effect. The fine particles containing a large amount of the organic matter are classified in water using the difference in sedimentation speed, sucked up by the pump 8 onto the barge 6, and then filtered and removed by the sand filtration tank 7. The filtered water is returned to the closed water area.

このとき、細粒分を除去した後の再堆積物はエアレーション効果による好気化の促進が行われ、また底質改善と同時に水質改善(好気化)も同時に行われる。さらに、閉鎖水域において、栄養塩であるリンはリン酸イオンとして懸濁物質(細粒分)に付着している。したがって再懸濁法により懸濁物質を除去する際にリンの除去も可能である。   At this time, the redeposit after removing the fine particles is promoted to aerobic by the aeration effect, and at the same time the water quality is improved (aerobic) simultaneously with the bottom quality improvement. Furthermore, in the closed water area, phosphorus, which is a nutrient salt, adheres to the suspended substance (fine particles) as phosphate ions. Therefore, it is possible to remove phosphorus when removing suspended substances by the resuspension method.

図5の(a)、(b)は、再懸濁工法底質浄化船9の構成例を示している。台船6の長手方向中央部からやや一方に偏った位置に砂濾過槽7が設置され、該砂濾過槽7の側部位置にポンプ8が設置されている。台船6の前部にインジェクター3が突き出して設けられ、台船6の前方側スペース位置に高圧エアーを送り出すコンプレッサ10、ジェット水を送り出すタービンポンプ11、砂濾過槽7用の砂を水底から吸い上げるサンドポンプ12及び動力源である電力を発生する発電機13等が設置されている。   (A), (b) of FIG. 5 has shown the structural example of the resuspension method bottom sediment purification ship 9. FIG. A sand filtration tank 7 is installed at a position slightly deviated from the longitudinal center of the trolley 6, and a pump 8 is installed at a side position of the sand filtration tank 7. The injector 3 protrudes from the front of the trolley 6 and sucks up the sand for the compressor 10 that sends high-pressure air to the front space of the trolley 6, the turbine pump 11 that sends jet water, and the sand filtration tank 7 from the bottom of the water. A sand pump 12 and a generator 13 for generating electric power as a power source are installed.

前記コンプレッサ10からの高圧エアーと前記タービンポンプ11からのジェット水とで、再懸濁時にインジェクター3から底質に対して吹付けるためのエアーを取り込んだジェット水が作り出される。沈降速度の差を利用して水中で分級されポンプ8で吸い上げられた有機物を多く含む細粒分は砂濾過槽7にシャワーリングされて濾過され除去される。また濾過後の水分は排水管14を介して閉鎖水域に戻される。   The high-pressure air from the compressor 10 and the jet water from the turbine pump 11 produce jet water that takes in air to be sprayed from the injector 3 to the bottom during resuspension. Fine particles containing a large amount of organic matter classified in water using the difference in sedimentation speed and sucked up by the pump 8 are showered in the sand filtration tank 7 and filtered and removed. Further, the filtered water is returned to the closed water area via the drain pipe 14.

図6の(a)、(b)は、再懸濁拡散防止機構を備えた再懸濁工法底質浄化船15の構成例を示している。該再懸濁工法底質浄化船15は、有害物質であるダイオキシン、水銀、PCB等が含まれる底質部を周囲への再懸濁物質の拡散を防止しつつ再懸濁して底質浄化工法を実行する場合に使用されるものであり、台船16上には、前記図5に示した再懸濁工法底質浄化船9における各設備とほぼ同様の機能を有する各設備が設置されている。そして、台船16の前部に、図6(b)にその詳細を示すような再懸濁拡散防止機構17が設けられている。   (A), (b) of FIG. 6 has shown the structural example of the resuspension method bottom sediment purification ship 15 provided with the resuspension diffusion prevention mechanism. The resuspension method bottom sediment purification ship 15 resuspends the bottom sediment containing harmful substances such as dioxin, mercury, PCB and the like while preventing the resuspension material from diffusing to the surroundings. Each equipment having almost the same function as each equipment in the resuspension method bottom sediment purification ship 9 shown in FIG. 5 is installed on the carriage 16. Yes. A resuspension / diffusion prevention mechanism 17 whose details are shown in FIG. 6B is provided at the front of the carriage 16.

該再懸濁拡散防止機構17は、底質2に対向する下方に所要の内容積を持つフード状の再懸濁拡散防止ケーシング18が設けられ、その天井側に複数個のエアー海水ジェット注入ノズル19が取付けられている。該再懸濁拡散防止ケーシング18の上部には再懸濁水
誘導ケーシング20が接続されており、該再懸濁水誘導ケーシング20内で沈降速度の差を利用した分級が行われる。再懸濁水誘導ケーシング20の側方には細粒分回収ケーシング21が平行して立設され、該再懸濁水誘導ケーシング20と細粒分回収ケーシング21とは再懸濁水の上昇速度を調整するための2個の開閉弁22a,22bで連結されている。各開閉弁22a,22bには、それぞれ開閉板23a,23bが傾動可能に内装されている。また、細粒分回収ケーシング21の内底部にはポンプ24が装備され、該ポンプ24で細粒分回収ケーシング21内に回収された細粒分が細粒分回収管25を介して台船16上に吸い上げられる。
The resuspension / diffusion prevention mechanism 17 is provided with a hood-like resuspension / diffusion prevention casing 18 having a required internal volume below the bottom sediment 2, and a plurality of air seawater jet injection nozzles on the ceiling side thereof. 19 is attached. A resuspension water induction casing 20 is connected to the upper part of the resuspension diffusion prevention casing 18, and classification is performed in the resuspension water induction casing 20 using a difference in sedimentation speed. A fine particle collection casing 21 is erected in parallel to the side of the resuspension water induction casing 20, and the resuspension water induction casing 20 and the fine particle collection casing 21 adjust the rising speed of the resuspension water. Are connected by two on-off valves 22a and 22b. Each on-off valve 22a, 22b is provided with an on-off plate 23a, 23b so as to be tiltable. In addition, a pump 24 is provided on the inner bottom portion of the fine particle collection casing 21, and the fine particles collected in the fine particle collection casing 21 by the pump 24 are connected to the carriage 16 via the fine particle collection pipe 25. Sucked up.

そして、ダイオキシン、水銀、PCB等の有害物質が含まれる底質2の再懸濁工法による浄化の際は、再懸濁拡散防止ケーシング18内下方の底質2に対し、複数個のエアー海水ジェット注入ノズル19からエアーを混合した海水ジェットが吹付けられて該底質2が攪乱されて再懸濁される。このとき、再懸濁拡散防止ケーシング18により、ケーシング外への再懸濁物質の拡散が防止されて周囲への拡散が顕著に低減する。再懸濁拡散防止ケーシング18内の再懸濁水は、再懸濁水誘導ケーシング20内を上昇して分級が行われ、分級された細粒分は開閉弁22a又は22bを介して細粒分回収ケーシング21内に移行する。この後、細粒分はポンプ24で台船16上に吸い上げられ、前記と同様にして、有害物質を含む細粒分は濾過されて除去される。   When purifying the bottom sediment 2 containing harmful substances such as dioxin, mercury, and PCB by the resuspension method, a plurality of air seawater jets are applied to the bottom sediment 2 below the resuspension diffusion prevention casing 18. A seawater jet mixed with air is blown from the injection nozzle 19 to disturb the bottom sediment 2 and resuspend it. At this time, the resuspension diffusion prevention casing 18 prevents the resuspension substance from diffusing out of the casing, and the diffusion to the surroundings is significantly reduced. The resuspended water in the resuspension / diffusion prevention casing 18 rises in the resuspended water induction casing 20 and is classified, and the classified fine particles are collected through the on-off valve 22a or 22b. 21. Thereafter, the fine particles are sucked onto the carriage 16 by the pump 24, and the fine particles containing harmful substances are filtered and removed in the same manner as described above.

上述したように、本実施例に係る再懸濁による底質浄化工法においては、底質2に含まれる粒子のうち小さい方からほぼ10〜15%の質量を除去することで、汚染物質の80〜90%を取り除くことができて効率的に低質改善を行うことができる。   As described above, in the sediment purification method by resuspension according to the present embodiment, 80% of the pollutant is removed by removing approximately 10 to 15% of the mass of particles contained in the sediment 2 from the smaller one. ˜90% can be removed and low quality improvement can be made efficiently.

底質2に対しインジェクター3によりエアーを取り込んだジェット水を吹付ける再懸濁操作により該底質2を攪乱し沈降速度の差を利用した分級を行うことで、大掛かりな設備を不要として有害物質を除去することができる。   By suspending the bottom sediment 2 by resuspension operation in which jet water that has taken in air by the injector 3 is sprayed on the bottom sediment 2 and classifying it using the difference in sedimentation velocity, a large-scale facility is not required and harmful substances Can be removed.

細かい粒子に吸着した汚染物質を除去するのみで底質2の90%程度は元に戻すことから経済的である。   It is economical because only 90% of the bottom sediment 2 is restored by removing the contaminants adsorbed on the fine particles.

浚渫に比べて再懸濁による底質2の除去土量は1/10程度であることから浚渫土の処分費を大幅に低減することができる。   Compared with dredging, the amount of soil removed from sediment 2 by resuspension is about 1/10, so dredging costs for dredging can be greatly reduced.

騒音や振動を伴う装置の使用を不要として無振動・低騒音にて施工することができる。   Construction is possible with no vibration and low noise, eliminating the need to use equipment with noise and vibration.

再懸濁をエアーを取り込んだジェット水により行うことで、エアレーション効果により、有害物質を除去した後の再堆積物に対し好気化を促進させることができる。   By performing resuspension with jet water that has taken in air, aerobicization can be promoted for the redeposits after removal of harmful substances due to the aeration effect.

なお、本発明は、本発明の精神を逸脱しない限り種々の改変をなすことができ、そして、本発明が該改変されたものにも及ぶことは当然である。   The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

底質を再懸濁して比表面積の大きい細かい粒子を分級し、該細かい粒子に吸着した汚染物質を除去することで大掛かりな設備を不要として効率的に底質改善を行うことが不可欠な港湾等の底質浄化にも適用可能である。   Ports where it is indispensable to improve the sediment efficiently without reusing the large amount of equipment by resuspending the sediment and classifying fine particles with a large specific surface area and removing contaminants adsorbed on the fine particles It can also be applied to bottom sediment purification.

1 シルトフェンス
2 底質
3 インジェクター
4 機械式攪拌翼
5 リッパー
6 台船
7 砂濾過槽
8 ポンプ
9 再懸濁工法底質浄化船
10 コンプレッサ
11 タービンポンプ
12 サンドポンプ
13 発電機
14 排水管
15 再懸濁拡散防止機構を備えた再懸濁工法底質浄化船
16 台船
17 再懸濁拡散防止機構
18 再懸濁拡散防止ケーシング
19 エアー海水ジェット注入ノズル
20 再懸濁水誘導ケーシング
21 細粒分回収ケーシング
22a,22b 開閉弁
23a,23b 開閉板
24 ポンプ
25 細粒分回収管
DESCRIPTION OF SYMBOLS 1 Silt fence 2 Sediment 3 Injector 4 Mechanical stirring blade 5 Ripper 6 Cargo ship 7 Sand filter tank 8 Pump 9 Resuspension method bottom sediment purification ship 10 Compressor 11 Turbine pump 12 Sand pump 13 Generator 14 Drain pipe 15 Re-hanging Resuspension method bottom sediment purification ship with turbidity diffusion prevention mechanism 16 Cargo ship 17 Resuspension diffusion prevention mechanism 18 Resuspension diffusion prevention casing 19 Air seawater jet injection nozzle 20 Resuspension water induction casing 21 Fine particle recovery casing 22a, 22b Open / close valve 23a, 23b Open / close plate 24 Pump 25 Fine grain collection tube

Claims (6)

汚染された閉鎖水域で底質を再懸濁して再懸濁水の対流を生じさせ、粒径の大きさによる水中での沈降速度の差を利用して前記底質に含まれる粒子を閉鎖水域の下部から上部に向かって漸次小径になるように分級を行い、前記閉鎖水域の上部を浮遊する前記底質に含まれる粒子のうち小さい方から粒径分布と汚染状況に応じた所要%の質量を除去することにより、汚染の原因となる有害物質を80〜90%除去することを特徴とする再懸濁による底質浄化工法。 The bottom sediment is resuspended in the contaminated closed water area to cause convection of the resuspended water , and the particles contained in the bottom sediment are removed from the closed water area by utilizing the difference in the sedimentation rate in water depending on the size of the particle size. Classification is performed so that the diameter gradually decreases from the lower part to the upper part, and the required mass according to the particle size distribution and the contamination state from the smaller of the particles contained in the sediment floating in the upper part of the closed water area The bottom sediment purification method by resuspension is characterized by removing 80 to 90% of harmful substances that cause contamination by removing water. 上記底質に含まれる粒子のうち小さい方から除去する上記質量は、ほぼ10〜15%であることを特徴とする請求項1記載の再懸濁による底質浄化工法。   2. The bottom sediment purification method by resuspension according to claim 1, wherein the mass removed from the smaller one of the particles contained in the bottom sediment is approximately 10 to 15%. 水中で分級された細粒分をポンプで吸い上げ、水上にて砂濾過、フィルター濾過、袋濾過のうちの少なくともいずれかの濾過手段により除去すべき質量分を濾過し、濾過後の水分は上記閉鎖水域に戻すことを特徴とする請求項1又は2記載の再懸濁による底質浄化工法。   The fine particles classified in water are sucked up with a pump, and the mass to be removed is filtered by at least one of sand filtration, filter filtration, and bag filtration on the water, and the filtered water is closed as described above. 3. The bottom sediment purification method by resuspension according to claim 1 or 2, wherein the method is returned to the water area. 上記底質の再懸濁は、インジェクターによりエアーを取込んだジェット水を前記底質に吹付け該底質の攪乱を行うことを特徴とする請求項1,2又は3記載の再懸濁による底質浄化工法。   The resuspension of the bottom is performed by resuspension according to claim 1, 2 or 3, wherein jet water taken in by an injector is sprayed on the bottom to disturb the bottom. Bottom sediment purification method. 上記底質の再懸濁の際に、機械式攪拌翼による底質の攪拌を併用することを特徴とする請求項4記載の再懸濁による底質浄化工法。   5. The bottom sediment purification method by resuspension according to claim 4, wherein the bottom sediment is resuspended together with bottom sediment agitation with a mechanical stirring blade. 上記底質の再懸濁の際に、リッパーの索引による底質の攪拌を併用することを特徴とする請求項4記載の再懸濁による底質浄化工法。   5. The bottom sediment purification method by resuspension according to claim 4, wherein the bottom sediment is resuspended together with stirring of the bottom sediment by an index of a ripper.
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