JP6296296B2 - Water treatment method - Google Patents
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本発明は、水処理方法に関する。より詳しくは、本発明は油分およびポリマー増粘剤を含む被処理水から油分を除去する水処理方法に関する。 The present invention relates to a water treatment method. More specifically, the present invention relates to a water treatment method for removing oil from water to be treated containing an oil and a polymer thickener.
油分を含む被処理水の代表例といえる石油随伴水は、石油や天然ガスの生産に伴って副次的に発生し、油分及びガス成分だけでなく、塩類、有機物、無機物、重金属類等の種々の成分を含む。石油随伴水を河川や海洋に放流することは環境負荷が大きいため望ましくなく、適切に処理されることが求められている。近年においては地層を水圧によって破砕してシェールガスを採掘することが盛んになっており、フローバック水として大量に発生する石油随伴水（単に「随伴水」と呼ばれることがある。）の効率的な処理方法が強く求められている。 Oil-associated water, which is a representative example of treated water containing oil, is generated as a result of the production of oil and natural gas, and includes not only oil and gas components but also salts, organic substances, inorganic substances, heavy metals, etc. Contains various ingredients. Discharging oil-associated water to rivers and oceans is not desirable due to the large environmental load, and is required to be treated appropriately. In recent years, shale gas has been actively mined by crushing the formation by water pressure, and the efficiency of oil-associated water (sometimes referred to simply as “associated water”) generated in large quantities as flowback water. There is a strong demand for a new treatment method.
従来、油分を含む下水道排水や工場廃水の処理技術として、簡易なＰＰＩ型オイルセパレーターを使用した比重差を利用した方式から、遠心分離を利用したハイドロサイクロン方式まで種々の処理技術が知られている。これらの中でも、簡易な装置及び操作で処理する観点から、被処理水に凝集剤を添加して油分をフロック化する凝集処理が主流である。また、凝集剤の添加に加えて、加圧ポンプによって被処理水中に微細気泡を発生させることによってフロックの回収を促進する凝集浮上処理が知られている（特許文献１参照）。従来の石油随伴水の処理においても、凝集剤によるフロック化によって油分の除去が行われている。 Conventionally, various treatment technologies from a method using a specific gravity difference using a simple PPI type oil separator to a hydrocyclone method using centrifugal separation have been known as a treatment technology for sewer wastewater and factory wastewater containing oil. . Among these, from the viewpoint of processing with a simple apparatus and operation, a flocculation process in which a flocculant is added to the water to be treated to flock the oil is the mainstream. In addition to the addition of a flocculant, a coagulation levitation process is known that promotes the recovery of flocs by generating fine bubbles in water to be treated by a pressure pump (see Patent Document 1). In the conventional treatment of oil-associated water, oil is removed by flocification with a flocculant.
しかしながら、石油やシェールガス等の採掘に使用する水にポリマー増粘剤を添加して使用するケミカル圧入法（ケミカル攻法）が近年盛んに適用されるようになったため、副次的に発生する随伴水の性質が従来とは大きく変化しており、従来と同様の凝集処理を行っても油分のフロック化が起こらず、油分を除去できないケースが出てきた。 However, since the chemical press-in method (chemical attack method) using a polymer thickener added to water used for mining oil and shale gas has been actively applied in recent years, it occurs as a secondary effect. The nature of the accompanying water has changed greatly from the conventional one, and even if the same flocculation treatment is performed, the oil content does not flock and there has been a case where the oil content cannot be removed.
本発明は、上記事情に鑑みてなされたものであり、油分及びポリマー増粘剤を含む被処理水から油分を効率的に除去することが可能な水処理方法を提供する。 This invention is made | formed in view of the said situation, and provides the water treatment method which can remove an oil component efficiently from the to-be-processed water containing an oil component and a polymer thickener.
上記の目的を達するために、本発明は以下の手段を提供している。
（１）油分及びポリマー増粘剤を含む被処理水から油分を除去する水処理方法であって、前記被処理水のＭアルカリ度を低減する工程と、前記被処理水にポリ塩化アルミニウム及び硫酸バンドのうち少なくとも何れか一方を添加して、前記被処理水中に前記油分を含むフロックを形成する工程と、を有することを特徴とする水処理方法。
（２）前記被処理水の初期のＭアルカリ度が約８０mgCaCO3/L以上であることを特徴とする上記（１）に記載の水処理方法。
（３）前記被処理水に含まれるポリマー増粘剤の濃度が５０mg/L〜５００mg/Lであることを特徴とする上記（１）又は（２）に記載の水処理方法。
（４）前記被処理水に酸を添加することにより、前記被処理水のＭアルカリ度を低減することを特徴とする上記（１）〜（３）の何れか一項に記載の水処理方法。
（５）前記被処理水のＭアルカリ度を約７０mgCaCO3/L以下に低減することを特徴とする上記（１）〜（４）の何れか一項に記載の水処理方法。
（６）Ｍアルカリ度を低減した前記被処理水に、ポリ塩化アルミニウムを５０mg/L〜１０００mg/Lの濃度となるように添加することを特徴とする上記（１）〜（５）の何れか一項に記載の水処理方法。
（７）前記ポリマー増粘剤の主成分がポリアクリルアミドであることを特徴とする上記（１）〜（６）の何れか一項に記載の水処理方法。
（８）前記被処理水の初期粘度が、０．９ｃＰ以上であることを特徴とする上記（１）〜（７）の何れか一項に記載の水処理方法。
（９）前記被処理水がエネルギー資源の採掘で発生した随伴水であることを特徴とする上記（１）〜（８）の何れか一項に記載の水処理方法。
In order to achieve the above object, the present invention provides the following means.
(1) A water treatment method for removing oil from water to be treated containing oil and a polymer thickener, the step of reducing the M alkalinity of the water to be treated, and polyaluminum chloride and sulfuric acid in the water to be treated And a step of adding at least one of the bands to form a floc containing the oil in the water to be treated.
(2) The water treatment method according to (1) above, wherein the initial M alkalinity of the water to be treated is about 80 mg CaCO 3 / L or more.
(3) The water treatment method according to (1) or (2) above, wherein the concentration of the polymer thickener contained in the water to be treated is 50 mg / L to 500 mg / L.
(4) The water treatment method according to any one of (1) to (3), wherein the M alkalinity of the water to be treated is reduced by adding an acid to the water to be treated. .
(5) The water treatment method according to any one of (1) to (4) above, wherein the M alkalinity of the water to be treated is reduced to about 70 mg CaCO 3 / L or less.
(6) Any of (1) to (5) above, wherein polyaluminum chloride is added to the water to be treated with reduced M alkalinity so as to have a concentration of 50 mg / L to 1000 mg / L. The water treatment method according to one item.
(7) The water treatment method according to any one of (1) to (6) above, wherein a main component of the polymer thickener is polyacrylamide.
(8) The water treatment method according to any one of (1) to (7), wherein an initial viscosity of the water to be treated is 0.9 cP or more.
(9) The water treatment method according to any one of (1) to (8), wherein the water to be treated is associated water generated by mining energy resources.
本発明の水処理方法によれば、被処理水に含まれる油分をフロック化して効率的に除去することができる。従来方法と比べて被処理水のＭアルカリ度を低減するという工程は増えるが、従来方法と同様の水槽を有する施設で処理することができるため、本発明を実施するにあたって新たな設備投資はほとんど不要であるといえる。 According to the water treatment method of the present invention, the oil contained in the water to be treated can be effectively removed by flocking. Although the process of reducing the M alkalinity of the water to be treated is increased as compared with the conventional method, it can be processed in a facility having a water tank similar to the conventional method, and therefore, there is almost no new capital investment in carrying out the present invention. It can be said that it is unnecessary.
本発明にかかる水処理方法の第一実施形態は、油分及びポリマー増粘剤を含む被処理水から油分を除去する水処理方法であって、前記被処理水のＭアルカリ度を低減する工程と、前記被処理水にポリ塩化アルミニウム及び硫酸バンドのうち少なくとも何れか一方を添加して、前記被処理水中に前記油分を含むフロックを形成する工程と、を有する。 1st embodiment of the water treatment method concerning this invention is a water treatment method which removes oil from the to-be-processed water containing oil and a polymer thickener, Comprising: The process of reducing M alkalinity of the to-be-processed water, Adding at least one of polyaluminum chloride and a sulfuric acid band to the water to be treated to form a floc containing the oil in the water to be treated.
被処理水の種類は、油分及びポリマー増粘剤を含む水であれば特に制限されず、例えば、石油や天然ガス等のエネルギー資源の採掘に伴って発生する随伴水であってもよいし、工場、ガソリンスタンド、厨房、家庭等から排出される食用油、鉱物油、ガソリン等を含む排水であってもよい。 The type of water to be treated is not particularly limited as long as it contains oil and a polymer thickener, and may be, for example, accompanying water generated with the extraction of energy resources such as oil and natural gas, It may be wastewater containing edible oil, mineral oil, gasoline, etc. discharged from factories, gas stations, kitchens, homes, and the like.
被処理水に含まれる油分の種類は特に制限されない。石油随伴水や排水中に含まれる油分の種類を特定することが困難である場合もあり得るが、例えば、炭素原子数が５〜３０の炭化水素、炭素原子数が５〜２０の炭化水素等を油分の一例として挙げることができる。 The type of oil contained in the water to be treated is not particularly limited. Although it may be difficult to specify the type of oil contained in oil-associated water or wastewater, for example, hydrocarbons having 5 to 30 carbon atoms, hydrocarbons having 5 to 20 carbon atoms, etc. Can be mentioned as an example of oil.
被処理水に含まれる油分の量は特に制限されないが、水処理が必要になる濃度として、例えば、０．１mg/L以上の油分含有量が挙げられる。石油随伴水に含まれる油分の一例として、１０〜２００mg/L程度の油分含有量が挙げられる。
被処理水に含まれる油分の量が１mg/L〜１０００mg/L程度であると、本実施形態の水処理方法によって容易に油分を除去することができる。
The amount of oil contained in the water to be treated is not particularly limited, but examples of the concentration that requires water treatment include an oil content of 0.1 mg / L or more. As an example of the oil contained in the oil-associated water, an oil content of about 10 to 200 mg / L can be mentioned.
When the amount of oil contained in the water to be treated is about 1 mg / L to 1000 mg / L, the oil can be easily removed by the water treatment method of the present embodiment.
被処理水に含まれるポリマー増粘剤の種類は特に制限されないが、ケミカル圧入法に使用される、ポリアクリルアミド、ポリサッカライド（多糖類）等のポリマーが例示できる。前記ポリアクリルアミドは部分的に加水分解されていてもよい。 Although the kind of polymer thickener contained in to-be-processed water is not restrict | limited in particular, Polymers, such as polyacrylamide and a polysaccharide (polysaccharide) used for a chemical press-in method, can be illustrated. The polyacrylamide may be partially hydrolyzed.
本実施形態の水処理方法において、ポリマー増粘剤の主成分としてポリアクリルアミドが含まれると、油分除去の効果が一層優れる場合がある。ここで、「主成分」とは、被処理水に含まれるポリマー増粘剤の総質量に対するポリアクリルアミドの含有量が５０質量％以上である場合、又は、被処理水に含まれる複数のポリマー増粘剤のうち、質量基準で、最も含有量が多いポリマー増粘剤がポリアクリルアミドである場合をいう。 In the water treatment method of this embodiment, when polyacrylamide is contained as a main component of the polymer thickener, the effect of removing oil may be further improved. Here, the “main component” means that the content of polyacrylamide with respect to the total mass of the polymer thickener contained in the water to be treated is 50% by mass or more, or a plurality of polymer increases contained in the water to be treated. Of the thickeners, the polymer thickener with the highest content on a mass basis is polyacrylamide.
ポリサッカライドの例として、食品添加物に使用される増粘多糖類を構成する、カラーギナン、キサンタンガム、ペクチン、グアーガム、タマリンドガム、アミロース、アミロペクチン、アガロース、セルロース、カルボキシメチルセルロース、プロピレングリコール等が挙げられる。 Examples of polysaccharides include carrageenan, xanthan gum, pectin, guar gum, tamarind gum, amylose, amylopectin, agarose, cellulose, carboxymethylcellulose, propylene glycol, etc., which constitute polysaccharide thickeners used in food additives.
被処理水に含まれるポリマー増粘剤を構成するポリマーの分子量は特に制限されないが、通常、５００万〜４０００万ダルトン程度の分子量であると増粘剤としての効果が高まり易い。 The molecular weight of the polymer constituting the polymer thickener contained in the water to be treated is not particularly limited, but usually the effect as a thickener tends to increase when the molecular weight is about 5 million to 40 million daltons.
被処理水に含まれるポリマー増粘剤の濃度は特に制限されないが、増粘剤としての効果を得るために、原油等を回収する場では１０００ｍｇ／Ｌ以上の濃度となっている。これが随伴水として地上に汲上げられるまでには、周辺の随伴水（地下水）により希釈されるため、被処理水のポリマー増粘剤の濃度は５００ｍｇ／Ｌ程度、もしくはそれ以下となる場合が多い。被処理水に含まれるポリマー増粘剤の濃度が５０ｍｇ／Ｌ以上であると、本実施形態による処理効果が充分に発揮され得る。 The concentration of the polymer thickener contained in the water to be treated is not particularly limited, but in order to obtain the effect as a thickener, the concentration is 1000 mg / L or more when crude oil or the like is collected. By the time it is pumped to the ground as accompanying water, it is diluted with surrounding accompanying water (groundwater), so the concentration of the polymer thickener in the water to be treated is often about 500 mg / L or less. . When the concentration of the polymer thickener contained in the water to be treated is 50 mg / L or more, the treatment effect according to the present embodiment can be sufficiently exerted.
上記濃度範囲でポリマー増粘剤を含む被処理水であると、従来方法では油分除去が困難になる場合が多いが（後述する比較例を参照）、本実施形態の水処理方法によれば、容易に油分を除去することができる（後述する実施例を参照）。 In the case of the water to be treated containing the polymer thickener in the above concentration range, it is often difficult to remove oil by the conventional method (see the comparative example described later), but according to the water treatment method of the present embodiment, The oil can be easily removed (see examples described later).
ポリマー増粘剤を含む被処理水の初期粘度は特に制限されず、例えば、０．９〜５．０ｃＰ程度の粘度の被処理水において、本実施形態の水処理方法は充分に効果が発揮され得る。ここで、初期粘度は、Ｍアルカリ度を調整する前の被処理水の粘度であり、単位ｃＰはセンチポアズを意味する。なお、１０００ｃＰは１Ｐａ・ｓ（パスカル秒）である。 The initial viscosity of the water to be treated containing the polymer thickener is not particularly limited. For example, in the water to be treated having a viscosity of about 0.9 to 5.0 cP, the water treatment method of the present embodiment is sufficiently effective. obtain. Here, the initial viscosity is the viscosity of the water to be treated before adjusting the M alkalinity, and the unit cP means centipoise. Note that 1000 cP is 1 Pa · s (Pascal second).
被処理水には、油分及びポリマー増粘剤の他に塩類、油分及びポリマー増粘剤以外の有機物、無機物、重金属類等の夾雑成分が含まれていても構わない。これらの夾雑成分が本実施形態の水処理方法による油分除去を妨げる恐れがある場合、当該夾雑成分を除くための脱塩処理等の別の処理を行ってもよいし、当該被処理水を水で希釈することにより夾雑成分による影響を低減してもよい。通常、塩類の濃度が１〜５質量％未満であれば油分除去に対する影響はみられない。 In addition to the oil and polymer thickener, the water to be treated may contain contaminants such as salts, organic substances other than the oil and polymer thickener, inorganic substances, and heavy metals. If these contaminated components may interfere with oil removal by the water treatment method of the present embodiment, another treatment such as a desalting treatment for removing the contaminated components may be performed, or the treated water You may reduce the influence by a contaminating component by diluting with. Usually, if the salt concentration is less than 1 to 5% by mass, no influence on oil removal is observed.
本実施形態の水処理方法においては、被処理水のＭアルカリ度を低減する前処理工程を行う。ここで、「Ｍアルカリ度」とは、被処理水に含まれる炭酸(H2CO3)、炭酸イオン(CO3 2-)、炭酸水素イオン(HCO3 -)、水酸化イオン(OH-)などの酸を消費する成分の濃度を炭酸カルシウム(CaCO3)の濃度で表した値（単位：mgCaCO3/L）である。 In the water treatment method of the present embodiment, a pretreatment step for reducing the M alkalinity of the water to be treated is performed. Here, “M alkalinity” means carbonic acid (H 2 CO 3 ), carbonate ion (CO 3 2− ), hydrogen carbonate ion (HCO 3 − ), hydroxide ion (OH − ) contained in the water to be treated. This is a value (unit: mgCaCO 3 / L) in which the concentration of an acid consuming component such as calcium carbonate (CaCO 3 ) is expressed.
被処理水の初期のＭアルカリ度は、ポリマー増粘剤及び含まれ得る夾雑成分の影響によって、１００mgCaCO3/L以上であることが多く、１５０〜１６００mgCaCO3/Lの範囲であることが多い。本実施形態の水処理方法においては、夾雑成分の濃度にもよるが、被処理水のＭアルカリ度を、１００mgCaCO3/L以下に低減することが好ましく、７０mgCaCO3/L以下に低減することがより好ましく、０mgCaCO3/Lに低減することが更に好ましい。被処理水のＭアルカリ度の下限値は特に制限されず、０mgCaCO3/Lにまで低減させてもよい。 The initial M alkalinity of the water to be treated is often 100 mgCaCO 3 / L or more and often in the range of 150 to 1600 mgCaCO 3 / L due to the influence of the polymer thickener and impurities that may be contained. In the water treatment method of this embodiment, depending on the concentration of the impurity component, a M alkalinity of the water to be treated, it is preferable to reduce below 100mgCaCO 3 / L, be reduced to less 70mgCaCO 3 / L More preferably, it is more preferable to reduce to 0 mg CaCO 3 / L. The lower limit value of the M alkalinity of the water to be treated is not particularly limited, and may be reduced to 0 mg CaCO 3 / L.
被処理水のＭアルカリ度を低減させる方法としては、例えば、酸を添加する方法、曝気する方法が挙げられる。これらの方法のうち酸を添加する方法が容易かつ効果的であるため好ましい。曝気することによって被処理水から炭酸を抜くことによってもＭアルカリ度を低減することは可能であるが、油分が揮発して爆発や火災が起こることや、装置の酸化や腐食を避けるために窒素ガスを使用することが望ましい。窒素ガスで曝気する場合、被処理水を大量に処理することが現実的には難しくなることがある。一方、酸を添加して被処理水を撹拌することによりＭアルカリ度を低減する場合には、大量の被処理水を一括して処理することができる。 Examples of the method for reducing the M alkalinity of the water to be treated include a method of adding an acid and a method of aeration. Of these methods, the method of adding an acid is preferable because it is easy and effective. It is possible to reduce the M alkalinity by removing carbonic acid from the water to be treated by aeration, but nitrogen is used to avoid explosion and fire due to oil volatilization and oxidation and corrosion of the equipment. It is desirable to use gas. In the case of aeration with nitrogen gas, it may be difficult in practice to treat a large amount of water to be treated. On the other hand, when M alkalinity is reduced by adding acid and stirring the water to be treated, a large amount of water to be treated can be treated at once.
添加する酸の種類は特に制限されず、例えば、塩酸、硫酸、リン酸、ホウ酸等の無機酸、酢酸、ギ酸、シュウ酸等の有機酸が挙げられる。これらの酸のうち、被処理水を自然環境に返送する最終処分において環境負荷が比較的少ない無機酸が好ましく、塩酸がより好ましい。 The kind of acid to be added is not particularly limited, and examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and boric acid, and organic acids such as acetic acid, formic acid and oxalic acid. Among these acids, an inorganic acid having a relatively low environmental load in the final disposal for returning the water to be treated to the natural environment is preferable, and hydrochloric acid is more preferable.
添加する酸の量は特に制限されず、酸を被処理水に添加して撹拌するとともに、当該被処理水のＭアルカリ度を測定し、目的の値にまで低減するために必要な量を徐々に添加する方法が好ましい。酸を大過剰に添加すると被処理水のｐＨが極端に低下して、被処理水の取り扱いが難しくなる場合があるので、必要最小量の酸を添加することが好ましい。必要最小量の酸を徐々に添加した場合、酸は被処理水に含まれる炭酸、炭酸イオン、炭酸水素イオン、水酸化イオンによって消費されるため、被処理水のｐＨの低下は抑制される傾向がある。したがって、Ｍアルカリ度を低減するための酸の添加は、被処理水のｐＨを低下させる目的で酸を滴下することとはその意義が異なる。 The amount of the acid to be added is not particularly limited, and the acid is added to the water to be treated and stirred, and the M alkalinity of the water to be treated is measured, and the amount necessary for reducing to the target value gradually. The method of adding to is preferable. When the acid is added in a large excess, the pH of the water to be treated is extremely lowered, and it may be difficult to handle the water to be treated. Therefore, it is preferable to add a minimum amount of acid. When the necessary minimum amount of acid is gradually added, the acid is consumed by carbonic acid, carbonate ion, hydrogen carbonate ion, and hydroxide ion contained in the water to be treated, so that the decrease in pH of the water to be treated tends to be suppressed. There is. Accordingly, the addition of an acid for reducing the M alkalinity is different in significance from dropping an acid for the purpose of lowering the pH of water to be treated.
酸を添加して所定のＭアルカリ度に達した被処理水のｐＨは特に制限されないが、油分のフロック化を妨げず、被処理水の取り扱いが容易なｐＨ範囲として、ｐＨ６．５〜８．０の範囲であることが好ましい。ｐＨの調整方法は特に制限されず、例えば、塩酸又は水酸化ナトリウム水溶液の滴下する公知方法によって調整することができる。 The pH of the water to be treated that has reached a predetermined M alkalinity by adding an acid is not particularly limited, but the pH range of 6.5 to 8. A range of 0 is preferred. The pH adjustment method is not particularly limited, and can be adjusted by, for example, a known method in which hydrochloric acid or an aqueous sodium hydroxide solution is dropped.
被処理水のＭアルカリ度は公知の測定器、測定試薬で測定することができる。例えば、（株）共立理化学研究所製のドロップ・テスト（品番：ＷＡＤ−ＡＬ−Ｍ）を使用した滴定分析によって、被処理水のＭアルカリ度を簡易に測定することができる。 The M alkalinity of the water to be treated can be measured with a known measuring instrument and measuring reagent. For example, the M alkalinity of water to be treated can be easily measured by titration analysis using a drop test (product number: WAD-AL-M) manufactured by Kyoritsu Riken.
被処理水のＭアルカリ度を低減する工程において、被処理水の温度は調整してもよいし、調整しなくてもよい。被処理水のＭアルカリ度を低減する際の被処理水の温度は特に制限されず、通常、屋外環境そのままの４〜５０℃でも行うことができる。 In the step of reducing the M alkalinity of the water to be treated, the temperature of the water to be treated may or may not be adjusted. The temperature of the water to be treated at the time of reducing the M alkalinity of the water to be treated is not particularly limited, and can be usually performed even at 4 to 50 ° C. in the outdoor environment.
被処理水のＭアルカリ度を低減した後、凝集剤として、ポリ塩化アルミニウム及び硫酸バンドのうち少なくとも何れか一方を添加することによって、当該被処理水に含まれる油分をフロック化することができる。通常、油分のフロック化に伴って、当該被処理水の濁度を低下させることもできる。 After reducing the M alkalinity of the water to be treated, the oil contained in the water to be treated can be flocked by adding at least one of polyaluminum chloride and sulfuric acid band as a flocculant. Usually, the turbidity of the to-be-processed water can also be reduced with the flocking of oil.
ポリ塩化アルミニウム（ＰＡＣ）の添加量としては、油分含有量や塩類濃度等の水質の違いによって最適値も異なるが、前述した油分含有量及び塩類濃度の範囲であれば、５０mg/L〜１０００mg/Lが好ましく１００mg/L〜１０００mg/Lがより好ましく、２００mg/L〜４００mg/Lが更に好ましく、２５０mg/L〜４００mg/Lが特に好ましく、３００mg/L〜４００mg/Lが最も好ましい。
上記範囲の下限値以上を添加することによって油分を短い時間で効率的にフロック化し、更に濁度を低下させることができる。一方、上記範囲の上限値を超えて添加しても、油分のフロック化及び濁度の低下に対する寄与は殆ど見られない。
The amount of polyaluminum chloride (PAC) added varies depending on the water content such as oil content and salt concentration, and the optimum value varies depending on the water content and salt concentration, but 50 mg / L to 1000 mg / L is preferably 100 mg / L to 1000 mg / L, more preferably 200 mg / L to 400 mg / L, particularly preferably 250 mg / L to 400 mg / L, and most preferably 300 mg / L to 400 mg / L.
By adding more than the lower limit of the above range, the oil content can be efficiently flocked in a short time, and the turbidity can be further reduced. On the other hand, even if the addition exceeds the upper limit of the above range, there is hardly any contribution to the flocculation of oil and a decrease in turbidity.
硫酸バンド（硫酸アルミニウム）の添加量としては、油分含有量によって最適値も多少異なるが、前述した油分含有量の範囲であれば、１００mg/L〜１０００mg/Lが好ましく、２００mg/L〜４００mg/Lがより好ましく、２５０mg/L〜４００mg/Lが更に好ましく、３００mg/L〜４００mg/Lが特に好ましい。
上記範囲の下限値以上を添加することによって油分を短い時間で効率的にフロック化し、更に濁度を低下させることができる。一方、上記範囲の上限値を超えて添加しても、油分のフロック化及び濁度の低下に対する寄与は殆ど見られない。
The amount of sulfuric acid band (aluminum sulfate) added varies somewhat depending on the oil content, but is preferably 100 mg / L to 1000 mg / L, and 200 mg / L to 400 mg / L within the range of the oil content described above. L is more preferable, 250 mg / L to 400 mg / L is still more preferable, and 300 mg / L to 400 mg / L is particularly preferable.
By adding more than the lower limit of the above range, the oil content can be efficiently flocked in a short time, and the turbidity can be further reduced. On the other hand, even if the addition exceeds the upper limit of the above range, there is hardly any contribution to the flocculation of oil and a decrease in turbidity.
本実施形態の水処理方法で使用する凝集剤として、比較的低濃度で優れた油分除去率及び濁度低下率を示すことから、ＰＡＣを使用することが好ましい。ＰＡＣと共に硫酸バンドを併用することも好ましい。また、本実施形態の水処理方法で使用する凝集剤として、ＰＡＣと硫酸バンド以外の公知の凝集剤を併用しても構わない。 As the flocculant used in the water treatment method of the present embodiment, it is preferable to use PAC because it exhibits an excellent oil removal rate and turbidity reduction rate at a relatively low concentration. It is also preferable to use a sulfate band together with PAC. Moreover, you may use together well-known flocculants other than PAC and a sulfate band as a flocculant used with the water treatment method of this embodiment.
Ｍアルカリ度を低減した被処理水に所定濃度でＰＡＣ及び／又は硫酸バンドを添加した後、穏やかに撹拌することによって、油分のフロック化を促進することができる。凝集剤の添加後、数十秒〜数十分以内、又は数十分〜数時間以内に油分を含むフロックが形成し、濁度も低下する。フロックの平均的な直径は５ｍｍ以上になり得る。 After adding PAC and / or a sulfuric acid band at a predetermined concentration to the water to be treated with reduced M alkalinity, flocking of the oil can be promoted by gently stirring. After the addition of the flocculant, flocs containing oil are formed within several tens of seconds to several tens of minutes, or within several tens of minutes to several hours, and the turbidity also decreases. The average diameter of the floc can be 5 mm or more.
形成されたフロックを被処理水から除去する方法は特に制限されず、公知の方法が適用できる。例えば、フロックを沈殿させて回収してもよいし、水槽の壁や底にスカムとして吸着させて回収してもよいし、被処理水の上部に浮上させて回収してもよい。 A method for removing the formed floc from the water to be treated is not particularly limited, and a known method can be applied. For example, the flocs may be precipitated and collected, or collected by being adsorbed as scum on the wall or bottom of the water tank, or may be collected by floating on the top of the water to be treated.
油分が除去された被処理水をさらにアンスラサイト、活性炭等と接触させて、フロック化せずに被処理水に残留した有機物質、無機物質等を吸着することによって、より高度に精製された水を得ることができる。 More highly purified water by contacting the treated water from which oil has been removed with anthracite, activated carbon, etc., and adsorbing organic and inorganic substances remaining in the treated water without flocking Can be obtained.
［比較例１］
産油国においてケミカル圧入法による石油採掘に使用された、ポリマー増粘剤としてポリアクリルアミドを５００ｍｇ／Ｌの濃度で含む石油随伴水（Ａ）を試験液として、種々の濃度になるようにＰＡＣ又は硫酸バンドを添加した各試験液における、フロックの形成を調べた。
その結果、図１Ａの写真（上）に示すように、０〜２００ｍｇ／ＬでＰＡＣを添加した試験液ではフロックが形成されず、石油等の含有物による濁りが観察された。一方、図１Ａの写真（下）に示すように、０〜２００ｍｇ／Ｌで硫酸バンドを添加した試験液では、０〜１２５ｍｇ／Ｌの範囲ではフロックが形成されず、１５０〜２００ｍｇ／Ｌの範囲でフロックが形成された。フロックが形成された試験液においては、フロックが沈殿し、溶液の濁度が低下した（透明度が増した）。
比較例１の結果から、ポリマー増粘剤が含まれる随伴水において、ＰＡＣによる油分の凝集効果が発揮され難いことが分かった。
[Comparative Example 1]
In oil-producing countries, PAC or sulfuric acid was used in petroleum-related water (A) containing polyacrylamide at a concentration of 500 mg / L as a polymer thickener and used as a test solution in various oil concentrations. The formation of floc was examined in each test solution to which the band was added.
As a result, as shown in the photograph (upper) of FIG. 1A, flocs were not formed in the test solution to which PAC was added at 0 to 200 mg / L, and turbidity due to inclusions such as petroleum was observed. On the other hand, as shown in the photograph (bottom) of FIG. 1A, in the test solution to which a sulfate band was added at 0 to 200 mg / L, floc was not formed in the range of 0 to 125 mg / L, and the range of 150 to 200 mg / L. The flock was formed. In the test solution in which flocs were formed, flocs precipitated and the turbidity of the solution decreased (transparency increased).
From the results of Comparative Example 1, it was found that the effect of agglomeration of oil by PAC is hardly exhibited in the accompanying water containing the polymer thickener.
［比較例２］
ポリマー増粘剤が含まれない石油随伴水を試験液として使用し、比較例１と同様にＰＡＣ又は硫酸バンドを０〜３５０ｍｇ／Ｌの濃度で添加した結果、図１Ｂに示すように、硫酸バンドよりもＰＡＣの凝集効果が高かった。このことから、ポリマー増粘剤が含まれる随伴水（比較例１）の処理方法は、ポリマー増粘剤が含まれない随伴水（比較例２）の処理方法とは区別して考える必要があることが分かる。
[Comparative Example 2]
As a result of adding PAC or sulfuric acid band at a concentration of 0 to 350 mg / L in the same manner as in Comparative Example 1 using petroleum-associated water not containing a polymer thickener as a test solution, as shown in FIG. The aggregation effect of PAC was higher than that of PAC. From this, it is necessary to consider the treatment method of the accompanying water (Comparative Example 1) containing the polymer thickener separately from the treatment method of the accompanying water (Comparative Example 2) not containing the polymer thickener. I understand.
［比較例３］
前記石油随伴水（Ａ）を試験液として、２５０，３００，３５０，４００ｍｇ／Ｌの各濃度でＰＡＣ又は硫酸バンドを添加した各試験液における、濁度（ＦＴＵ）を調べた。
その結果、図２のグラフに示すように、２５０ｍｇ／Ｌで添加した場合はいずれの凝集剤を添加した場合にも濁度が１００以上（グラフの欄外）であったが、ＰＡＣを添加した試験液よりも硫酸バンドを添加した試験液の方が低い濁度を示していた。また、３００ｍｇ／Ｌで添加した場合はＰＡＣ添加の方が低い濁度を示し、３５０ｍｇ／Ｌで添加した場合は硫酸バンド添加の方が低い濁度を示し、４００ｍｇ／Ｌで添加した場合はいずれの凝集剤を添加した場合も、濁度はほぼゼロになった。
比較例３の結果から、ポリマー増粘剤が含まれる随伴水において、３００ｍｇ／Ｌ以上でＰＡＣ及び硫酸バンドを添加した場合には、いずれの凝集剤を添加した場合にも目視でも確認できる程度に濁度の低下が起こることが分かった。
[Comparative Example 3]
Using the petroleum-associated water (A) as a test solution, turbidity (FTU) was examined in each test solution to which PAC or sulfuric acid band was added at respective concentrations of 250, 300, 350, and 400 mg / L.
As a result, as shown in the graph of FIG. 2, when added at 250 mg / L, the turbidity was 100 or more (outside of the graph) when any flocculant was added. The test solution to which the sulfuric acid band was added showed lower turbidity than the solution. When added at 300 mg / L, PAC addition shows lower turbidity, when added at 350 mg / L, sulfuric acid band shows lower turbidity, and when added at 400 mg / L, either Even when the flocculant was added, the turbidity was almost zero.
From the results of Comparative Example 3, in the accompanying water containing the polymer thickener, when PAC and sulfuric acid band are added at 300 mg / L or more, even when any flocculant is added, it can be visually confirmed. It was found that a decrease in turbidity occurred.
［比較例４］
前記石油随伴水（Ａ）を試験液として、２５０，３００，３５０，４００ｍｇ／Ｌの各濃度でＰＡＣ又は硫酸バンドを添加した各試験液における、油分除去率（％）を調べた。
その結果、図３のグラフに示すように、２５０ｍｇ／Ｌで添加した場合はＰＡＣを添加した試験液よりも硫酸バンドを添加した試験液の方が明らかに高い油分除去率を示していた。また、３００ｍｇ／Ｌで添加した場合はいずれの凝集剤を添加した場合も同等の高い油分除去率を示し、３５０，４００ｍｇ／Ｌで添加した場合はいずれの凝集剤を添加した場合も、ほぼ完全に油分が除去された。
比較例４の結果から、ポリマー増粘剤が含まれる随伴水において、３００ｍｇ／Ｌ以下でＰＡＣを添加した場合には、硫酸バンドと比べて油分除去効果が発揮され難いことが分かった。
[Comparative Example 4]
Using oil-associated water (A) as a test solution, the oil removal rate (%) in each test solution to which PAC or sulfuric acid band was added at each concentration of 250, 300, 350, and 400 mg / L was examined.
As a result, as shown in the graph of FIG. 3, when 250 mg / L was added, the test liquid to which the sulfuric acid band was added showed a clearly higher oil removal rate than the test liquid to which PAC was added. Also, when added at 300 mg / L, the same high oil removal rate is exhibited when any flocculant is added, and when added at 350,400 mg / L, almost any flocculant is added. The oil was removed.
From the results of Comparative Example 4, it was found that when PAC was added at 300 mg / L or less in the accompanying water containing the polymer thickener, the oil removing effect was hardly exhibited as compared with the sulfuric acid band.
［実施例１］
前記石油随伴水（Ａ）のＭアルカリ度及びｐＨを測定したところ、１４５mgCaCO3/L、
ｐＨ＝８．２であった。この石油随伴液に塩酸を滴下することにより、Ｍアルカリ度を７０mgCaCO3/Lへ低下させた石油随伴水（Ｂ）を試験液として使用した。石油随伴水（Ｂ）のｐＨは７．６であった。この試験液に、２５０，３００，３５０，４００ｍｇ／Ｌの各濃度でＰＡＣ又は硫酸バンドを添加した各試験液における、濁度（ＦＴＵ）を調べた。
その結果、図４のグラフに示すように、２５０ｍｇ／Ｌで添加した場合には両者共に８０ＦＴＵ付近まで濁度が低下しており、３００ｍｇ／Ｌ以上で添加した場合には明らかにＰＡＣ添加の方が濁度の低下が促進された。
実施例１と比較例３の結果を比較すると、被処理水である石油随伴水のＭアルカリ度を予め低減しておくことにより、ＰＡＣ及び硫酸バンドの何れを添加した場合にも低濃度の添加で濁度の低下が促進され、特にＰＡＣ添加の場合に濁度低下の格別顕著な促進効果が見られた。また、Ｍアルカリ度を低減した被処理水においては、硫酸バンドとＰＡＣの効果の発現率が逆転することが分かった。
[Example 1]
When the M alkalinity and pH of the water associated with petroleum (A) were measured, 145 mg CaCO 3 / L,
The pH was 8.2. By adding hydrochloric acid dropwise to the petroleum-associated liquid, petroleum-associated water (B) having an M alkalinity reduced to 70 mg CaCO 3 / L was used as a test liquid. The pH of petroleum-associated water (B) was 7.6. Turbidity (FTU) in each test solution in which PAC or a sulfuric acid band was added to this test solution at respective concentrations of 250, 300, 350, and 400 mg / L was examined.
As a result, as shown in the graph of FIG. 4, when both were added at 250 mg / L, the turbidity decreased to about 80 FTU in both cases, and clearly when PAC was added at 300 mg / L or more. However, the decrease in turbidity was promoted.
When the results of Example 1 and Comparative Example 3 are compared, the M alkalinity of petroleum-associated water, which is the water to be treated, is reduced in advance, so that a low concentration is added when either PAC or sulfuric acid band is added. Acceleration of turbidity reduction was observed, and in particular, when PAC was added, a particularly remarkable acceleration effect of turbidity reduction was observed. Moreover, in the to-be-processed water which reduced M alkalinity, it turned out that the expression rate of the effect of a sulfuric acid band and PAC is reversed.
［実施例２］
実施例１でＭアルカリ度を低減した石油随伴水（Ｂ）を試験液として使用した。この試験液に、２５０，３００，３５０，４００ｍｇ／Ｌの各濃度でＰＡＣ又は硫酸バンドを添加した各試験液における、油分除去率（％）を調べた。
その結果、図５のグラフに示すように、２５０ｍｇ／Ｌ以上で添加した場合には明らかにＰＡＣ添加の方が油分除去を促進していた。
実施例２と比較例４の結果を比較すると、被処理水である石油随伴水のＭアルカリ度を予め低減しておくことにより、ＰＡＣ及び硫酸バンドの何れを添加した場合にも低濃度の添加で濁度の低下が促進され、特にＰＡＣ添加による油分除去が格別顕著に促進されることが分かった。また、Ｍアルカリ度を低減した被処理水においては、硫酸バンドとＰＡＣの効果の発現率が逆転することが分かった。
[Example 2]
Petroleum-associated water (B) having a reduced M alkalinity in Example 1 was used as a test solution. The oil removal rate (%) in each test solution in which PAC or sulfuric acid band was added to this test solution at respective concentrations of 250, 300, 350, and 400 mg / L was examined.
As a result, as shown in the graph of FIG. 5, when adding at 250 mg / L or more, PAC addition clearly promoted oil removal.
Comparing the results of Example 2 and Comparative Example 4, the addition of a low concentration was achieved when either PAC or sulfuric acid band was added by previously reducing the M alkalinity of petroleum-associated water as the water to be treated. It was found that the decrease in turbidity was promoted by the addition of PAC, and particularly the oil removal by PAC addition was promoted remarkably. Moreover, in the to-be-processed water which reduced M alkalinity, it turned out that the expression rate of the effect of a sulfuric acid band and PAC is reversed.
＜濁度の測定方法＞
被処理水の濁度の測定は、デジタル濁度計（型番：HI 93703；ハンナ インスツルメンツ・ジャパン社製）を使用して行った。
<Measurement method of turbidity>
The turbidity of water to be treated was measured using a digital turbidimeter (model number: HI 93703; manufactured by Hanna Instruments Japan).
＜油分除去率の測定方法＞
被処理水の油分濃度の測定は、まず抽出溶媒（型番：H-997；堀場製作所社製）と被処理水を混合して激しく撹拌することによって、抽出溶媒中に抽出された油分量をフーリエ変換赤外分光光度計（型番：FTIR-8400、島津製作所社製）を使用して測定することによって行った。FTIRによる油分濃度の測定においては、Ａ重油を標準物質として作成した検量線を使用した。検量線の作成は「廃棄物の処理及び清掃に関する法律施行令第六条第一項第四号に規定する海洋投入処分を行うことができる産業廃棄物に含まれる油分の検定方法（平四環庁告四五・平五環庁告一〇〇・平七環庁告八六・一部改正）」に準拠して行った。
<Measurement method of oil removal rate>
The oil concentration of the water to be treated is measured by first mixing the extraction solvent (model number: H-997; manufactured by Horiba Seisakusho Co., Ltd.) and the water to be treated, and stirring vigorously. The measurement was performed by using a conversion infrared spectrophotometer (model number: FTIR-8400, manufactured by Shimadzu Corporation). In the measurement of the oil concentration by FTIR, a calibration curve prepared using A heavy oil as a standard substance was used. The calibration curve is created by the “Testing Method for Oil Contained in Industrial Waste that can be Disposed into the Ocean as stipulated in Article 6, Paragraph 1, Item 4 of the Law Enforcement Ordinance on Waste Disposal and Cleaning ( “Announcement of the Government of Japan 45 / Heigokan”, “Heisei 7”
＜Ｍアルカリ度の測定方法＞
被処理水の油分濃度の測定は、簡易測定キット（型番：WAD-AL-M；共立理化学研究所社製）を使用して行った。本簡易測定キットの測定精度が充分に高いことを、予めＭアルカリ度が分かっている標準液で確認した。
<Measurement method of M alkalinity>
The oil concentration of the water to be treated was measured using a simple measurement kit (model number: WAD-AL-M; manufactured by Kyoritsu Riken). It was confirmed with a standard solution whose M alkalinity was known in advance that the measurement accuracy of this simple measurement kit was sufficiently high.
以上で説明した各実施形態における各構成及びそれらの組み合わせ等は一例であり、本発明の趣旨を逸脱しない範囲で、構成の付加、省略、置換、およびその他の変更が可能である。 The configurations and combinations thereof in the embodiments described above are examples, and the addition, omission, replacement, and other modifications of the configurations can be made without departing from the spirit of the present invention.
本発明は、石油、シェールガス等の資源採掘にともなって生じる随伴水の処理等に広く適用できる。 The present invention can be widely applied to the treatment of accompanying water that occurs with the extraction of resources such as petroleum and shale gas.
Claims (9)
前記被処理水のＭアルカリ度を低減する工程と、
前記被処理水にポリ塩化アルミニウム及び硫酸バンドのうち少なくとも何れか一方を添加して、前記被処理水中に前記油分を含むフロックを形成する工程と、を有することを特徴とする水処理方法。 A water treatment method for removing oil from water to be treated containing oil and a polymer thickener,
Reducing the M alkalinity of the water to be treated;
And a step of adding at least one of polyaluminum chloride and a sulfuric acid band to the water to be treated to form a floc containing the oil in the water to be treated.
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