JP4225844B2

JP4225844B2 - Muddy water treatment method

Info

Publication number: JP4225844B2
Application number: JP2003167339A
Authority: JP
Inventors: 哲夫藤井; 栄治藤井
Original assignee: 株式会社環境技術開発
Priority date: 2003-06-12
Filing date: 2003-06-12
Publication date: 2009-02-18
Anticipated expiration: 2023-06-12
Also published as: JP2005000806A

Description

【０００１】
【発明の属する技術分野】
本発明は濁水処理方法に関し、廃水、排水、汚泥処理の技術分野に属する。
【０００２】
【従来の技術】
例えばダム建設工事が施工されるとセメントを含んだアルカリ排水や濁水が発生し、また地下シールド工事が行われると多量の土砂や礫を含んだ坑内濁水が生成する。このような濁水や泥水は、水中に浮遊している不純物である懸濁成分（ＳＳ＝suspended solid）を除去して、国や県が定める所定の放流基準・排水基準を満たしたうえで、河川等に放流しなければならない。従来、このような濁水処理に用いられる凝集剤として、特許文献１〜３に開示されるように、ポリアクリルアミドと塩化カルシウムとの混合物を使用することが広く知られている。
【０００３】
【特許文献１】
特開平６−１３４４９９号公報
【特許文献２】
特開平９−２０６７５９号公報
【特許文献３】
特開平１０−３３７５７５号公報
【０００４】
【発明が解決しようとする課題】
しかし、そのようなポリアクリルアミドと塩化カルシウムとの混合物である従来の凝集剤では、例えば濁水（原水）の懸濁成分濃度（ＳＳ濃度）が１万ｐｐｍ（ｍｇ／リットル）である場合、これをＳＳ濃度が７０〜１２０ｐｐｍ程度の処理済水まで浄化するのが限度であって、近年、条例により各県でさらに厳しい排水基準が定められているなか、それよりも低いＳＳ濃度、例えばＳＳ濃度が２０〜３０ｐｐｍ程度の処理済水まで浄化することは難しいのが現状である。
【０００５】
そこで、本発明者は、上記のような現状に鑑み、たとえ濁水のＳＳ濃度が１万ｐｐｍと大量であっても、該ＳＳ濃度を２０〜３０ｐｐｍ程度まで容易に低下させることのできる濁水処理方法を開発せんと鋭意研究検討を重ねた結果、ポリアクリルアミドと塩化カルシウムとを同時に濁水に加えるのではなく、別々に加えると、懸濁成分の除去率が飛躍的に高まることを見出し、本発明を完成したものである。
【０００６】
【課題を解決するための手段】
すなわち、本願の請求項１に記載の発明は、濁水から懸濁成分を凝集して除去する濁水処理方法であって、濁水に、懸濁成分１万重量部に対し塩化カルシウムを１５〜４０重量部添加して、懸濁成分であるコロイド粒子の電荷を中和することにより該コロイド粒子を凝集させるステップと、上記コロイド粒子が凝集した濁水に、懸濁成分１万重量部に対しポリアクリルアミド系高分子凝集剤を０．０２５〜０．５重量部添加して、上記凝集したコロイド粒子を上記高分子凝集剤で捕集するステップと、上記コロイド粒子の捕集により生成した沈殿物を上澄液から除去するステップとを有することを特徴とする。
【０００８】
このように、本発明では、濁水にポリアクリルアミドと塩化カルシウムとを同時に加えるのではなく、先に塩化カルシウムを添加してから、後でポリアクリルアミド系高分子凝集剤を添加する。これにより、先に添加した塩化カルシウムのカルシウムイオン（＋電荷）によって、懸濁成分である土粒子等のコロイド粒子（−電荷）が電気的に中和され、その結果、該コロイド粒子同士が凝集して大きな径に成長する。そして、この状態でポリアクリルアミド系高分子凝集剤を添加することにより、上記の凝集した大きな径のコロイド粒子が効率よく吸着・捕集されて、大量の沈殿物が速やかに沈降する。その後、この生成・沈降した沈殿物を上澄液から除去することによって、該上澄液は、懸濁成分が大量に除去された河川等への放流が可能な処理済水となる。
【０００９】
本発明では、塩化カルシウム及びポリアクリルアミド系高分子凝集剤は水溶液にして濁水に添加するとよい。その際の好ましい濃度は、例えば塩化カルシウムは３０〜４０％（重量％：以下特に断らない限り同じ）、ポリアクリルアミド系高分子凝集剤は０．０５〜０．５％等である。もちろん、濃度を濃くするほど水溶液の添加量が少なくて済むが、塩化カルシウムの濃度が４０％を超えると、低温下で塩化カルシウムの結晶が析出してしまう可能性があるし、またポリアクリルアミドの濃度が０．５％を超えると、水溶液の粘度が過度に高くなって取り扱いが困難となる可能性がある。
【００１０】
本発明では、上記各水溶液の濁水への添加量は、該濁水中のＳＳ濃度に応じて変更してよい。その際、一般に、ＳＳ濃度が高いほど添加量を多くする。例えば、濁水のＳＳ濃度が１万ｐｐｍのときは、塩化カルシウムの３０〜４０％水溶液を５０〜１００ｐｐｍ添加し、またポリアクリルアミド系高分子凝集剤の０．０５〜０．５％水溶液を５０〜１００ｐｐｍ添加する。換言すれば、ＳＳ濃度が１万ｐｐｍの濁水１トンに対し、塩化カルシウムの３０〜４０％水溶液及びポリアクリルアミド系高分子凝集剤の０．０５〜０．５％水溶液をそれぞれ５０〜１００グラムづつ添加する。これは、懸濁成分：塩化カルシウム：ポリアクリルアミド系高分子凝集剤の重量比率にすると、１万：１５〜４０：０．０２５〜０．５（＝４０万：６００〜１６００：１〜２０）である。これにより、得られる処理済水のＳＳ濃度を２０〜３０ｐｐｍ以下まで低減することが可能となる。この場合、塩化カルシウム及びポリアクリルアミド系高分子凝集剤を上記比率を超えて添加しても効果が頭打ちとなって経済的でない。
【００１１】
本発明の方法は、掘削現場でも、また濁水処理専用プラントでも適用可能である。例えば掘削現場においては、原水を沈斜池に至る流路に流しながら、その途中でＳＳ濃度を計測し、その計測結果に基いて、塩化カルシウム水溶液の添加量及びポリアクリルアミド系高分子凝集剤水溶液の添加量を決定し、その決定した添加量で塩化カルシウム水溶液及びポリアクリルアミド系高分子凝集剤水溶液を上記流れている原水にインラインで自動注水する。沈斜池に流れ込んだ原水は該沈斜池で沈殿物と上澄液とに固液分離し、上澄液のＳＳ濃度が所定の排水基準（例えば７０ｐｐｍ以下、５０ｐｐｍ以下、３０ｐｐｍ以下、２０ｐｐｍ以下等）を満たすときは、上記上澄液を放流し、満たさないときは、満たすまで上記上澄液を再び上記流路に戻して上記処理を繰り返し行う。
【００１２】
一方、濁水処理専用プラントにおいては、例えば原水槽と複数の沈殿槽とを直列に並べ、上澄液が各槽を順に移動する間に、ＳＳ濃度の計測及びそれに応じた量の塩化カルシウム水溶液の添加及びポリアクリルアミド系高分子凝集剤水溶液の添加を行う。そして、ＳＳ濃度が所定の排水基準を満たしたところで上澄液を放流すればよい。各沈殿槽に溜まった沈殿物は脱水処理し、脱水ケーキとして埋立等に供する。
【００１３】
その場合、処理対象である原水のＳＳ濃度と、放流対象である処理済水のＳＳ濃度と、塩化カルシウム水溶液（濃度既知）の添加量と、ポリアクリルアミド系高分子凝集剤水溶液（濃度既知）の添加量との関係を予め実験的に求めておいて、その特性を濁水処理システムのプログラムに入力しておけばよい。計測した原水のＳＳ濃度と、所望の排水基準を満たす処理済水のＳＳ濃度とを上記特性にあてはめることにより、塩化カルシウム水溶液（濃度既知）及びポリアクリルアミド系高分子凝集剤水溶液（濃度既知）の必要添加量が容易に決定できる。
【００１４】
【実施例】
粘土粉末を水に分散させて、ＳＳ濃度が１０００ｐｐｍ、５０００ｐｐｍ、１万ｐｐｍ、１０万ｐｐｍ、２０万ｐｐｍの濁水をそれぞれ人工的に調製した。また、塩化カルシウムの３０％水溶液及び４０％水溶液と、ポリアクリルアミドの０．０５％水溶液及び０．５％水溶液とをそれぞれ調製した。
【００１５】
上記調製した５種のＳＳ濃度の濁水と、２種の濃度の塩化カルシウム水溶液及びポリアクリルアミド水溶液とを種々組み合わせて濁水処理を行った。すなわち、先に濁水に塩化カルシウム水溶液を添加し、攪拌して放置した後、次にポリアクリルアミド水溶液を添加し、攪拌して放置し、得られた上澄液のＳＳ濃度を濁度センサで測定した。濁水への塩化カルシウム水溶液及びポリアクリルアミド水溶液の添加量は、１０ｐｐｍ、５０ｐｐｍ、１００ｐｐｍ、１０００ｐｐｍとした。表１に、種々の組合せのうち代表的・特徴的なものの結果を示す。なお、表中、ポリアクリルアミドをＰＡＡと記している。
【００１６】
【表１】

【００１７】
本実施例において、濁水の懸濁成分：塩化カルシウム：ポリアクリルアミドの重量比率のうち、塩化カルシウム及びポリアクリルアミドの比率が最も小さいのは、ＳＳ濃度が２０万ｐｐｍの濁水に、塩化カルシウムの３０％水溶液を１０ｐｐｍ添加し、ポリアクリルアミドの０．０５％水溶液を１０ｐｐｍ添加した場合であって、２０万：３：０．００５（＝１万：０．１５：０．０００２５）となる（実験番号１７）。逆に、塩化カルシウム及びポリアクリルアミドの比率が最も大きいのは、ＳＳ濃度が１０００ｐｐｍの濁水に、塩化カルシウムの４０％水溶液を１０００ｐｐｍ添加し、ポリアクリルアミドの０．５％水溶液を１０００ｐｐｍ添加した場合であって、１０００：４００：５（＝１万：４０００：５０）となる（実験番号４）。
【００１８】
そして、特に、懸濁成分：塩化カルシウム：ポリアクリルアミドの重量比率が、１万：１５以上：０．０２５以上のときに、上澄液のＳＳ濃度が２０ｐｐｍ以下となって、良好な結果が得られた（実験番号１〜４、６〜８、１０〜１２、１６、２０）。ただし、同重量比率が、１万：４０超：０．５超となっても、上澄液のＳＳ濃度はそれ以上にはあまり効果的に低下しなかった（実験番号２〜４、７、８、１２）。なお、表１の重量比率の欄において、「○」は、塩化カルシウムの重量比率が上記「１５〜４０」の範囲内にあること、及びポリアクリルアミドの重量比率が上記「０．０２５〜０．５」の範囲内にあることを示し、「△」は、該範囲を超えていること示し、「×」は、該範囲未満であることを示す。
【００１９】
また、従来の１液型処理液として、塩化カルシウム３９％、ポリアクリルアミド１％、水６０％からなる混合水溶液を調製し、同様に濁水処理を行った。すなわち、上記調製した各濁水にこの従来型の１液処理液を１０ｐｐｍ、５０ｐｐｍ、１００ｐｐｍ又は１０００ｐｐｍ添加し、攪拌して放置した後、得られた上澄液のＳＳ濃度を濁度センサで測定した。この場合、濁水の懸濁成分：塩化カルシウム：ポリアクリルアミドの重量比率のうち、塩化カルシウム及びポリアクリルアミドの比率が最も小さいのは、ＳＳ濃度が２０万ｐｐｍの濁水にこの１液処理液を１０ｐｐｍ添加した場合であって、２０万：３．９：０．１（＝１万：０．１９５：０．００５）となる。逆に、塩化カルシウム及びポリアクリルアミドの比率が最も大きいのは、ＳＳ濃度が１０００ｐｐｍの濁水にこの１液処理液を１０００ｐｐｍ添加した場合であって、１０００：３９０：１０（＝１万：３９００：１００）となる。
【００２０】
そして、ＳＳ濃度が１０００ｐｐｍの濁水にこの１液処理液を１００ｐｐｍ以上添加したときに（懸濁成分：塩化カルシウム：ポリアクリルアミドの重量比率＝１万：３９０以上：１０以上）、上澄液のＳＳ濃度が７０ｐｐｍ程度となって、例えば本発明に係る上記実験番号５、９、１５、１９（懸濁成分：塩化カルシウム：ポリアクリルアミドの重量比率＝１万：２〜６：０．００５〜０．０５）等とほぼ同程度の懸濁成分の除去効果が観察された。このことから、本発明の方法によれば、従来の１液型処理液を使う方法に比べて、懸濁成分の除去効果が飛躍的に高まる結果、塩化カルシウム及びポリアクリルアミドの使用量が少なくて済み、コスト的にも有利であることがわかった。
【００２１】
ここで、上記従来型の１液混合水溶液は、ポリアクリルアミドを１％含むが、その粘度は、ポリアクリルアミドの１％単独水溶液よりもはるかに低いものであった。これは、１液混合水溶液中ではポリアクリルアミドと塩化カルシウムとが電気的に結合し、その結果、ポリアクリルアミドの高分子鎖構造が開いたり延びたりするためであると考えられる。したがって、従来、塩化カルシウムとポリアクリルアミドとを１液に溶解して同時に濁水に添加する方法は、ポリアクリルアミドの高分子機能、すなわちミクロフロックの架橋吸着機能・捕獲機能を阻害・損減する不利な方法であると考察される。
【００２２】
【発明の効果】
以上のように、本発明によれば、懸濁成分の除去率が飛躍的に高まる結果、ＳＳ濃度が１万ｐｐｍと極めて高い原水でも、ＳＳ濃度が２０〜３０ｐｐｍと極めて低い処理済水に容易に転換することができ、年々厳しくなる各地の排水基準をクリアすることができる。本発明は、ダム建設工事や地下シールド工事等で排出される、廃水、濁水、汚泥等の処理技術分野において幅広い産業上の利用可能性を有する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a muddy water treatment method and belongs to the technical fields of wastewater, drainage, and sludge treatment.
[0002]
[Prior art]
For example, when dam construction work is performed, alkaline drainage and turbid water containing cement are generated, and when underground shield work is performed, turbid water in the mine containing a large amount of earth and sand and gravel is generated. Such muddy water and muddy water removes suspended solids (SS = suspended solid), which are impurities suspended in water, and meet the specified discharge and drainage standards set by the national and prefectural governments. It must be released to etc. Conventionally, as a flocculant used for such turbid water treatment, it is widely known to use a mixture of polyacrylamide and calcium chloride as disclosed in Patent Documents 1 to 3.
[0003]
[Patent Document 1]
JP-A-6-134499 [Patent Document 2]
JP-A-9-206759 [Patent Document 3]
JP-A-10-337575 [0004]
[Problems to be solved by the invention]
However, in the conventional flocculant which is a mixture of such polyacrylamide and calcium chloride, for example, when the suspended component concentration (SS concentration) of turbid water (raw water) is 10,000 ppm (mg / liter), The limit is to purify the treated water with an SS concentration of about 70 to 120 ppm, and in recent years, stricter drainage standards have been established in each prefecture by regulations, and SS concentration lower than that, for example, SS concentration is At present, it is difficult to purify even treated water of about 20 to 30 ppm.
[0005]
Therefore, in view of the current situation as described above, the present inventor is able to easily reduce the SS concentration to about 20 to 30 ppm even if the SS concentration of muddy water is as large as 10,000 ppm. As a result of extensive research and development, we have found that the removal rate of suspended components increases dramatically when polyacrylamide and calcium chloride are added separately to turbid water separately, but not separately. It has been completed.
[0006]
[Means for Solving the Problems]
That is, the invention described in claim 1 of the present application is a turbid water treatment method for removing by agglomerating suspended component from turbid water, 15 to 40 weight calcium chloride to the turbid water, suspended components 10,000 parts by weight parts were added, and the step of coagulating the colloidal particles by neutralizing the charge of the colloidal particles are suspended component, the turbid water the colloidal particles are aggregated, polyacrylamide to suspension components 10,000 parts 0.025 to 0.5 parts by weight of a polymer flocculant is added, and the aggregated colloidal particles are collected by the polymer flocculant, and the precipitate generated by the collection of the colloidal particles is supernatant. Removing from the liquid.
[0008]
As described above, in the present invention, polyacrylamide and calcium chloride are not added to muddy water at the same time, but calcium chloride is added first, and then a polyacrylamide polymer flocculant is added later. As a result, colloidal particles (-charge) such as soil particles as suspension components are electrically neutralized by the calcium ions (+ charge) of calcium chloride added earlier, and as a result, the colloidal particles aggregate together. And grow to a large diameter. Then, by adding a polyacrylamide polymer flocculant in this state, the agglomerated large-diameter colloidal particles are efficiently adsorbed and collected, and a large amount of sediment settles quickly. Thereafter, by removing the generated and settled precipitate from the supernatant, the supernatant becomes treated water that can be discharged into a river or the like from which a large amount of suspended components have been removed.
[0009]
In the present invention, the calcium chloride and the polyacrylamide polymer flocculant may be added as an aqueous solution to turbid water. The preferred concentration in that case is, for example, 30-40% for calcium chloride (% by weight: the same unless otherwise specified), and 0.05-0.5% for the polyacrylamide polymer flocculant. Of course, the higher the concentration, the smaller the amount of aqueous solution added. However, if the concentration of calcium chloride exceeds 40%, crystals of calcium chloride may precipitate at low temperatures. When the concentration exceeds 0.5%, the viscosity of the aqueous solution may become excessively high and handling may become difficult.
[0010]
In this invention, you may change the addition amount to said muddy water of said each aqueous solution according to SS density | concentration in this muddy water. At that time, generally, the higher the SS concentration, the larger the addition amount. For example, when the SS concentration of turbid water is 10,000 ppm, 50 to 100 ppm of a 30 to 40% aqueous solution of calcium chloride is added, and a 0.05 to 0.5% aqueous solution of a polyacrylamide polymer flocculant is added to 50 to 50 ppm. Add 100 ppm. In other words, 50 to 100 grams of 30 to 40% aqueous solution of calcium chloride and 0.05 to 0.5% aqueous solution of polyacrylamide polymer flocculant are added to 1 ton of muddy water with an SS concentration of 10,000 ppm. Added. This is 10,000: 15-40: 0.025-0.5 (= 400,000: 600-1600: 1-20) when the weight ratio of suspension component: calcium chloride: polyacrylamide polymer flocculant is used. It is. Thereby, it becomes possible to reduce the SS concentration of the treated water obtained to 20-30 ppm or less. In this case, even if calcium chloride and polyacrylamide polymer flocculant are added in excess of the above ratio, the effect reaches a peak and is not economical.
[0011]
The method of the present invention can be applied at an excavation site or a plant dedicated to muddy water treatment. For example, at an excavation site, the SS concentration is measured in the middle of flowing raw water through a channel leading to a sinking basin. Based on the measurement result, the amount of calcium chloride aqueous solution added and the polyacrylamide polymer flocculant aqueous solution are measured. Then, the calcium chloride aqueous solution and the polyacrylamide polymer flocculant aqueous solution are automatically poured into the flowing raw water in-line with the determined addition amount. The raw water that has flowed into the sedimentation basin is separated into solid and liquid in the sedimentation basin, and the SS concentration of the supernatant is a predetermined drainage standard (for example, 70 ppm or less, 50 ppm or less, 30 ppm or less, 20 ppm or less). Etc.), the above-mentioned supernatant is discharged, and when it is not filled, the above-mentioned supernatant is returned again to the above-mentioned flow path until it is filled, and the above process is repeated.
[0012]
On the other hand, in a plant exclusively for muddy water treatment, for example, a raw water tank and a plurality of precipitation tanks are arranged in series, and while the supernatant liquid moves in each tank in order, the measurement of SS concentration and the amount of calcium chloride aqueous solution corresponding thereto are measured. Addition and addition of polyacrylamide polymer flocculant aqueous solution. And what is necessary is just to discharge a supernatant liquid, when SS density | concentration satisfy | fills the predetermined | prescribed drainage standard. The sediment accumulated in each sedimentation tank is dehydrated and used for landfill as a dehydrated cake.
[0013]
In that case, the SS concentration of the raw water to be treated, the SS concentration of the treated water to be discharged, the addition amount of the calcium chloride aqueous solution (concentration known), and the polyacrylamide polymer flocculant aqueous solution (concentration known) What is necessary is just to obtain | require experimentally the relationship with addition amount beforehand, and to input the characteristic into the program of a muddy water processing system. By applying the measured SS concentration of raw water and the SS concentration of treated water that satisfies the desired drainage standard to the above characteristics, calcium chloride aqueous solution (concentration known) and polyacrylamide polymer flocculant aqueous solution (concentration known) The required amount can be easily determined.
[0014]
【Example】
Clay powder was dispersed in water, and muddy waters with SS concentrations of 1000 ppm, 5000 ppm, 10,000 ppm, 100,000 ppm, and 200,000 ppm were artificially prepared. In addition, 30% aqueous solution and 40% aqueous solution of calcium chloride and 0.05% aqueous solution and 0.5% aqueous solution of polyacrylamide were prepared, respectively.
[0015]
The turbid water treatment was carried out by variously combining the five types of turbid water with the SS concentration prepared above, two aqueous calcium chloride solutions and an aqueous polyacrylamide solution. That is, first add calcium chloride aqueous solution to turbid water and stir to stand, then add polyacrylamide aqueous solution and stir to stand, and measure the SS concentration of the obtained supernatant with a turbidity sensor did. The amount of calcium chloride aqueous solution and polyacrylamide aqueous solution added to the muddy water was 10 ppm, 50 ppm, 100 ppm, and 1000 ppm. Table 1 shows representative and characteristic results of various combinations. In the table, polyacrylamide is referred to as PAA.
[0016]
[Table 1]

[0017]
In this embodiment, the ratio of calcium chloride and polyacrylamide is the smallest among the weight ratio of suspended components: calcium chloride: polyacrylamide in turbid water, in turbid water having an SS concentration of 200,000 ppm, and 30% of calcium chloride. When 10 ppm of the aqueous solution was added and 10 ppm of the 0.05% aqueous solution of polyacrylamide was added, the result was 200,000: 3: 0.005 (= 10,000: 0.15: 0.00025) (Experiment No. 17 ). Conversely, the ratio of calcium chloride and polyacrylamide is greatest when 1000 ppm of a 40% aqueous solution of calcium chloride and 1000 ppm of a 0.5% aqueous solution of polyacrylamide are added to turbid water with an SS concentration of 1000 ppm. Thus, 1000: 400: 5 (= 10,000: 4000: 50) (Experiment No. 4).
[0018]
In particular, when the weight ratio of suspended component: calcium chloride: polyacrylamide is 10,000: 15 or more: 0.025 or more, the SS concentration of the supernatant is 20 ppm or less, and good results are obtained. (Experiment Nos. 1-4, 6-8, 10-12, 16, 20). However, even when the same weight ratio was over 10,000: 40: 0.5, the SS concentration of the supernatant liquid did not decrease much more effectively (experiment numbers 2-4, 7, 8, 12). In the column of weight ratio in Table 1, “◯” indicates that the weight ratio of calcium chloride is in the range of “15 to 40”, and the weight ratio of polyacrylamide is “0.025 to 0.00. “Δ” indicates that it is within the range, “Δ” indicates that the range is exceeded, and “x” indicates that it is less than the range.
[0019]
Further, as a conventional one-pack type treatment solution, a mixed aqueous solution consisting of 39% calcium chloride, 1% polyacrylamide and 60% water was prepared, and similarly treated with muddy water. That is, 10 ppm, 50 ppm, 100 ppm, or 1000 ppm of this conventional one-component treatment solution was added to each of the turbid water prepared above, and the mixture was allowed to stand with stirring, and then the SS concentration of the obtained supernatant was measured with a turbidity sensor. . In this case, the ratio of calcium chloride and polyacrylamide is the smallest among the weight ratios of suspended components: calcium chloride: polyacrylamide in turbid water. 10 ppm of this one-component treatment solution is added to turbid water with an SS concentration of 200,000 ppm. In this case, 200,000: 3.9: 0.1 (= 10,000: 0.195: 0.005). On the contrary, the ratio of calcium chloride and polyacrylamide is largest when 1000 ppm of this one-component treatment liquid is added to turbid water having an SS concentration of 1000 ppm, and 1000: 390: 10 (= 10,000: 3900: 100). )
[0020]
When 100 ppm or more of this one-liquid treatment liquid is added to turbid water with an SS concentration of 1000 ppm (suspension component: calcium chloride: polyacrylamide weight ratio = 10,000: 390 or more: 10 or more), SS of the supernatant liquid The concentration is about 70 ppm. For example, the experiment numbers 5, 9, 15, 19 according to the present invention (suspension component: calcium chloride: polyacrylamide weight ratio = 10,000: 2-6: 0.005-0. 05) etc., and the removal effect of suspended components was observed. Therefore, according to the method of the present invention, the effect of removing suspended components is dramatically increased as compared with the conventional method using a one-pack type processing solution, resulting in less use of calcium chloride and polyacrylamide. It turned out to be advantageous in terms of cost.
[0021]
Here, the conventional one-component mixed aqueous solution contains 1% polyacrylamide, but its viscosity is much lower than that of a single aqueous solution of polyacrylamide alone. This is considered to be because polyacrylamide and calcium chloride are electrically bonded in a one-component mixed aqueous solution, and as a result, the polymer chain structure of polyacrylamide opens and extends. Therefore, the conventional method of dissolving calcium chloride and polyacrylamide in one solution and simultaneously adding them to turbid water is disadvantageous in that it inhibits or reduces the polymer function of polyacrylamide, that is, the cross-linking adsorption function / capturing function of micro flocs. It is considered a method.
[0022]
【The invention's effect】
As described above, according to the present invention, as a result of the drastic increase in the removal rate of suspended components, even raw water having an extremely high SS concentration of 10,000 ppm can be easily treated water having an extremely low SS concentration of 20 to 30 ppm. It is possible to switch to, and clear the drainage standards of various places that become stricter year by year. The present invention has wide industrial applicability in the field of treatment technology of waste water, muddy water, sludge, etc. discharged in dam construction work and underground shield work.

Claims

A method for treating turbid water by agglomerating and removing suspended components from turbid water, wherein 15 to 40 parts by weight of calcium chloride is added to 10,000 parts by weight of suspended components in turbid water, and colloidal particles as suspended components are added. A step of aggregating the colloidal particles by neutralizing the charge, and 0.025 to 0.5 weight of a polyacrylamide polymer flocculant per 10,000 parts by weight of the suspended component in the turbid water in which the colloidal particles are agglomerated parts is added, characterized in that a step of removing the steps of collecting the flocculated colloidal particles in the polymer flocculant, the precipitate formed by collection of the colloidal particles from the supernatant Muddy water treatment method.