JP6826806B2 - Wastewater treatment equipment and wastewater treatment method - Google Patents

Wastewater treatment equipment and wastewater treatment method Download PDF

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JP6826806B2
JP6826806B2 JP2015068766A JP2015068766A JP6826806B2 JP 6826806 B2 JP6826806 B2 JP 6826806B2 JP 2015068766 A JP2015068766 A JP 2015068766A JP 2015068766 A JP2015068766 A JP 2015068766A JP 6826806 B2 JP6826806 B2 JP 6826806B2
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俊彦 安部
俊彦 安部
祐一 須田
祐一 須田
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Sumitomo Heavy Industries Environment Co Ltd
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Description

本発明は、排水処理装置及び排水処理方法に関する。 The present invention relates to a wastewater treatment apparatus and a wastewater treatment method.

従来、フッ素を含有する排水からフッ素を除去する排水処理装置として、排水にアルミ系無機凝集剤を混合して水酸化アルミニウム(Al2(OH)3)のフロックを生成させ、当該フロックによってフッ素を吸着し共沈させる方法が知られている(非特許文献1参照)。 Conventionally, as a wastewater treatment device for removing fluorine from wastewater containing fluorine, an aluminum-based inorganic flocculant is mixed with the wastewater to generate aluminum hydroxide (Al 2 (OH) 3 ) flocs, and the flocs are used to generate fluorine. A method of adsorbing and co-precipitating is known (see Non-Patent Document 1).

和田祐司、「フッ素含有排水の高度処理法」、科学と工業、2002年、第76巻、p.557−564Yuji Wada, "Advanced Treatment of Fluorine-Containing Wastewater", Science and Industry, 2002, Vol. 76, p. 557-564

しかしながら、上記のアルミ系無機凝集剤を用いる方法では、排水から除去できるフッ素の量が、混合するアルミ系無機凝集剤の量に対応するため、フッ素を充分に除去しようとすると大量のアルミ系無機凝集剤を使用する必要がある。また、これにより大量の余剰スラッジが発生してしまう。 However, in the method using the above-mentioned aluminum-based inorganic coagulant, the amount of fluorine that can be removed from the waste water corresponds to the amount of the mixed aluminum-based inorganic coagulant. It is necessary to use a flocculant. In addition, this causes a large amount of excess sludge.

これに対し、排水からフッ素を除去する別の方法として、排水にカルシウム系の薬剤を添加してフッ化カルシウム(CaF2)を生成させる方法がある。しかしながら、この方法では、排水がフッ素の他に硫酸マグネシウム(Mg(SO)4)等の硫酸塩を含有する場合、添加されたカルシウム系の薬剤と硫酸塩とが反応して石膏(Ca(SO)4)を生成するため、フッ化カルシウムの生成に大量のカルシウム(Ca)を必要としてしまう。従って、このような硫酸塩含有排水においてはアルミ系無機凝集剤を用いる方法を適用せざるを得ない場合があり、この場合、上述したように、大量のアルミ系無機凝集剤を使用すると共に大量の余剰スラッジが発生するという問題があった。 On the other hand, as another method for removing fluorine from wastewater, there is a method of adding a calcium-based chemical to the wastewater to generate calcium fluoride (CaF 2 ). However, in this method, when the wastewater contains sulfate such as magnesium sulfate (Mg (SO) 4 ) in addition to fluorine, the added calcium-based drug reacts with the sulfate to plaster (Ca (SO) 4 ). ) 4 ) is produced, so a large amount of calcium (Ca) is required to produce calcium fluoride. Therefore, in such sulfate-containing wastewater, a method using an aluminum-based inorganic coagulant may have to be applied. In this case, as described above, a large amount of the aluminum-based inorganic coagulant is used and a large amount is used. There was a problem that excess sludge was generated.

本発明は、上記課題を解決するために為されたものであり、硫酸塩含有排水において、アルミ系無機凝集剤の使用量を削減できると共に余剰スラッジの発生量を低減できる排水処理装置及び排水処理方法を提供することを目的とする。 The present invention has been made to solve the above problems, and is a wastewater treatment apparatus and wastewater treatment capable of reducing the amount of aluminum-based inorganic coagulant used and the amount of excess sludge generated in sulfate-containing wastewater. The purpose is to provide a method.

本発明に係る排水処理装置は、硫酸塩含有排水からフッ素を除去する排水処理装置において、硫酸塩含有排水とアルミ系無機凝集剤とを混合する混合部と、混合部で混合された混合液を固液分離する固液分離部と、固液分離部で固液分離して得た固形分を混合部に供給するための供給手段と、を備える。 The wastewater treatment apparatus according to the present invention is a wastewater treatment apparatus for removing fluorine from sulfate-containing wastewater, in which a mixing portion for mixing sulfate-containing wastewater and an aluminum-based inorganic flocculant and a mixed solution mixed in the mixing portion are mixed. A solid-liquid separation unit for solid-liquid separation and a supply means for supplying the solid content obtained by solid-liquid separation in the solid-liquid separation unit to the mixing unit are provided.

また、本発明に係る排水処理方法は、硫酸塩含有排水からフッ素を除去する排水処理方法において、硫酸塩含有排水とアルミ系無機凝集剤とを混合部で混合し、混合部で混合された混合液を固液分離部で固液分離し、固液分離部で固液分離して得た固形分を混合部に供給する。 Further, the wastewater treatment method according to the present invention is a wastewater treatment method for removing fluorine from sulfate-containing wastewater, in which sulfate-containing wastewater and an aluminum-based inorganic flocculant are mixed in a mixing section and mixed in the mixing section. The liquid is solid-liquid separated at the solid-liquid separation unit, and the solid content obtained by solid-liquid separation at the solid-liquid separation unit is supplied to the mixing unit.

この排水処理装置及び排水処理方法によれば、混合部で硫酸塩含有排水とアルミ系無機凝集剤とが混合されると、フロックが混合液中に生成し、このフロックが混合液中のフッ素を吸着して液中から除去する。そして、固液分離部において、既にフッ素を吸着したフロックをフッ素と共に共沈させ、また、未だフッ素を吸着していないフロックも沈降させて固液分離し、これらの固液分離した固形分は混合部に供給される。その結果、未だフッ素を吸着していないフロック及び既にフッ素を吸着したが更にフッ素を吸着することができる状態のフロックが混合液中のフッ素を吸着して液中から除去する。これにより、フッ素の吸着・共沈のために使用されたアルミ系無機凝集剤を再びフッ素の吸着・共沈に活用できる。以上により、硫酸塩含有排水において、アルミ系無機凝集剤の使用量を削減できると共に、このアルミ系無機凝集剤の使用量を削減すること及び固液分離して得た固形分を混合部に供給することにより余剰スラッジの発生量を低減できる。 According to this wastewater treatment device and wastewater treatment method, when the sulfate-containing wastewater and the aluminum-based inorganic flocculant are mixed in the mixing portion, flocs are generated in the mixed solution, and the flocs generate fluorine in the mixed solution. Adsorb and remove from the liquid. Then, in the solid-liquid separation section, the flocs that have already adsorbed fluorine are coprecipitated together with fluorine, and the flocs that have not yet adsorbed fluorine are also precipitated to perform solid-liquid separation, and these solid-liquid separated solids are mixed. It is supplied to the department. As a result, the flocs that have not yet adsorbed fluorine and the flocs that have already adsorbed fluorine but can further adsorb fluorine adsorb the fluorine in the mixed liquid and remove it from the liquid. As a result, the aluminum-based inorganic flocculant used for the adsorption and coprecipitation of fluorine can be utilized again for the adsorption and coprecipitation of fluorine. As described above, in the sulfate-containing wastewater, the amount of the aluminum-based inorganic coagulant used can be reduced, the amount of the aluminum-based inorganic coagulant used can be reduced, and the solid content obtained by solid-liquid separation is supplied to the mixing section. By doing so, the amount of excess sludge generated can be reduced.

ここで、本発明に係る排水処理装置において、混合部は、pHを調整するpH調整手段を有していてもよい。この場合、pHを調整することで、硫酸塩含有排水とアルミ系無機凝集剤とが反応し、フロックを生成する最適な値とできるため、フロックを効率良く生成でき、アルミ系無機凝集剤の使用量に対して効率良くフッ素を吸着・共沈させて液中から除去できる。 Here, in the wastewater treatment apparatus according to the present invention, the mixing unit may have a pH adjusting means for adjusting the pH. In this case, by adjusting the pH, the sulfate-containing wastewater reacts with the aluminum-based inorganic flocculant to obtain the optimum value for producing flocs, so that flocs can be efficiently produced and the aluminum-based inorganic flocculants are used. Fluorine can be efficiently adsorbed and coprecipitated with respect to the amount and removed from the liquid.

本発明によれば、硫酸塩含有排水において、アルミ系無機凝集剤の使用量を削減できると共に余剰スラッジの発生量を低減できる。 According to the present invention, in the sulfate-containing wastewater, the amount of the aluminum-based inorganic flocculant used can be reduced and the amount of excess sludge generated can be reduced.

実施形態に係る排水処理装置を示す概略構成図である。It is a schematic block diagram which shows the wastewater treatment apparatus which concerns on embodiment. 変形例に係る排水処理装置を示す概略構成図である。It is a schematic block diagram which shows the wastewater treatment apparatus which concerns on the modification.

以下、本発明に係る排水処理装置及び排水処理方法の一実施形態について、図面を参照して詳細に説明する。 Hereinafter, an embodiment of the wastewater treatment apparatus and the wastewater treatment method according to the present invention will be described in detail with reference to the drawings.

図1は、実施形態に係る排水処理装置を示す概略構成図である。本実施形態に係る排水処理装置は、フッ素及び硫酸塩を含有する排水(以下、硫酸塩含有排水という)からフッ素を除去して所定のフッ素濃度以下とする装置であり、当該装置による処理水のフッ素濃度を、例えば放流先の水質基準で定められるフッ素濃度(一例として、15mg/l)を下回るようにするものである。なお、硫酸塩には、硫酸イオン及び硫酸化合物が含まれる。また、硫酸化合物としては、硫酸アンモニウム、硫酸ナトリウム及び硫酸マグネシウム等が該当する。 FIG. 1 is a schematic configuration diagram showing a wastewater treatment apparatus according to an embodiment. The wastewater treatment apparatus according to the present embodiment is an apparatus for removing fluorine from wastewater containing fluorine and sulfate (hereinafter referred to as sulfate-containing wastewater) to reduce the concentration to a predetermined fluorine concentration or less, and the treated water by the apparatus. The fluorine concentration is set to be lower than, for example, the fluorine concentration (15 mg / l as an example) defined by the water quality standard of the discharge destination. The sulfate salt contains a sulfate ion and a sulfuric acid compound. Further, examples of the sulfuric acid compound include ammonium sulfate, sodium sulfate and magnesium sulfate.

ここで、フッ化カルシウムの溶解度の理論値は16mg/l(25℃)でフッ素濃度としては7.8mg/lだが、硫酸塩を含む処理水のフッ素濃度としてフッ素濃度を15mg/l以下にする場合は、カルシウム系の薬剤とアルミ系無機凝集剤との併用処理が必要であり、アルミ系無機凝集剤単独で行う場合にはアルミ系無機凝集剤を大量に添加する必要があった。本発明は、アルミ系無機凝集剤を大量に添加することなくフッ素濃度を15mg/l以下にする場合に有効なものである。以下、詳説する。 Here, the theoretical value of the solubility of calcium fluoride is 16 mg / l (25 ° C.) and the fluorine concentration is 7.8 mg / l, but the fluorine concentration is set to 15 mg / l or less as the fluorine concentration of the treated water containing sulfate. In this case, it is necessary to treat the calcium-based agent and the aluminum-based inorganic flocculant in combination, and when the aluminum-based inorganic flocculant is used alone, it is necessary to add a large amount of the aluminum-based inorganic flocculant. The present invention is effective when the fluorine concentration is reduced to 15 mg / l or less without adding a large amount of an aluminum-based inorganic flocculant. The details will be described below.

図1に示すように、排水処理装置1は、主ラインL1と、主ラインL1に併設された副ラインL2と、を備えている。主ラインL1は、排水処理装置1の上流側から流入する硫酸塩含有排水からフッ素を除去し、所定のフッ素濃度以下となった処理水を下流側へ排出するためのラインであり、副ラインL2は、主ラインL1において得られた固形分の一部を主ラインL1における上流側に還流すると共に、残部を当該装置1の外部へ排出するためのラインである。この主ラインL1には、混合槽(混合部)2と、凝集槽(凝集部)3と、固液分離槽(固液分離部)4と、が上流から下流へ向かってこの順に設けられている。 As shown in FIG. 1, the wastewater treatment apparatus 1 includes a main line L1 and a sub line L2 attached to the main line L1. The main line L1 is a line for removing fluorine from the sulfate-containing wastewater flowing in from the upstream side of the wastewater treatment device 1 and discharging the treated water having a predetermined fluorine concentration or less to the downstream side, and is a sub line L2. Is a line for returning a part of the solid content obtained in the main line L1 to the upstream side in the main line L1 and discharging the rest to the outside of the device 1. The main line L1 is provided with a mixing tank (mixing section) 2, a coagulation tank (coagulation section) 3, and a solid-liquid separation tank (solid-liquid separation section) 4 in this order from upstream to downstream. There is.

混合槽2は、排水処理装置1の上流側から第1ラインL11を介して流入する硫酸塩含有排水と、無機凝集剤供給ラインL15を介して供給されるアルミ系無機凝集剤と、を混合して混合液とし、このとき生成するフロック(すなわち、凝集剤を用いて水酸化アルミニウムを含む粒子を集合させた集合体)にフッ素を吸着させるための槽である。ここで、アルミ系無機凝集剤としては、例えばポリ塩化アルミニウム(PAC)、硫酸アルミニウム(硫酸バンド)等を用いることができるが、これに限定されない。 The mixing tank 2 mixes the sulfate-containing wastewater flowing in from the upstream side of the wastewater treatment device 1 via the first line L11 and the aluminum-based inorganic coagulant supplied via the inorganic coagulant supply line L15. This is a tank for adsorbing fluorine on the flocs (that is, aggregates in which particles containing aluminum hydroxide are aggregated using a flocculant) generated at this time. Here, as the aluminum-based inorganic flocculant, for example, polyaluminum chloride (PAC), aluminum sulfate (sulfate band) and the like can be used, but the method is not limited thereto.

混合槽2は、混合槽2内でのSS濃度(すなわち、混合液中における浮遊物質の重量濃度)を測定するSS濃度センサ5を槽内に有している。 The mixing tank 2 has an SS concentration sensor 5 for measuring the SS concentration in the mixing tank 2 (that is, the weight concentration of suspended solids in the mixed solution).

また、混合槽2は、混合液のpHを測定するpHセンサ6を槽内に有し、このpHセンサ6によって測定したpHに基づきpHを調整するための薬剤を当該混合槽2に供給する薬剤供給ライン(pH調整手段)L16を有している。薬剤としては、酸性薬剤(例えば、塩酸、硫酸等)、又はアルカリ性薬剤(例えば、苛性ソーダ等)が好適に用いられる。pHセンサ6としては特に限定されず、公知のものを用いることができる。 Further, the mixing tank 2 has a pH sensor 6 for measuring the pH of the mixed solution in the tank, and a chemical for supplying a chemical for adjusting the pH based on the pH measured by the pH sensor 6 to the mixing tank 2. It has a supply line (pH adjusting means) L16. As the drug, an acidic drug (for example, hydrochloric acid, sulfuric acid, etc.) or an alkaline drug (for example, caustic soda, etc.) is preferably used. The pH sensor 6 is not particularly limited, and a known pH sensor 6 can be used.

凝集槽3は、第2ラインL12を介して混合槽2から流入する混合液に、高分子凝集剤供給ラインL17を介して供給される高分子凝集剤を混合して、混合液中のフロックが沈殿し易くなるように当該フロックをより大きく形成するための槽である。高分子凝集剤としては、例えばアニオン系高分子凝集剤等を用いることができる。 In the coagulation tank 3, the polymer coagulant supplied via the polymer coagulant supply line L17 is mixed with the mixed liquid flowing from the mixing tank 2 via the second line L12, and the flocs in the mixed liquid are formed. It is a tank for forming the floc larger so that it can be easily settled. As the polymer flocculant, for example, an anionic polymer flocculant or the like can be used.

固液分離槽4は、第3ラインL13を介して凝集槽3から流入する混合液を固液分離するための槽である。固液分離槽4は、混合液を固形分と固形分以外の液とに固液分離する。すなわち、固形分とは、固液分離槽4において固液分離された混合液のうちの液以外の部分である。固形分には、フッ素を吸着していないフロック及びフッ素を吸着したフロックの両方が含まれている。固液分離槽4の底面は、例えば下方へ狭まる漏斗状をなしており、その頂点部分には固液分離槽4から固形分を排出するための排出口4aが設けられている。 The solid-liquid separation tank 4 is a tank for solid-liquid separation of the mixed liquid flowing from the coagulation tank 3 via the third line L13. The solid-liquid separation tank 4 separates the mixed liquid into a solid content and a liquid other than the solid content. That is, the solid content is a portion of the mixed liquid separated in the solid-liquid separation tank 4 other than the liquid. The solid content includes both fluorine-adsorbed flocs and fluorine-adsorbed flocs. The bottom surface of the solid-liquid separation tank 4 has, for example, a funnel shape that narrows downward, and a discharge port 4a for discharging solid content from the solid-liquid separation tank 4 is provided at the apex portion thereof.

副ラインL2は、固液分離槽4の排出口4aに接続されると共に、排出口4aとは反対側において、固形分還流ライン(供給手段)L21と余剰スラッジ排出ラインL22とに分岐している。この三つ又の分岐点には、固形分還流ラインL21又は余剰スラッジ排出ラインL22にそれぞれ流入する固形分の量を調整するため、例えば三方弁等の弁(不図示)が設けられている。 The sub line L2 is connected to the discharge port 4a of the solid-liquid separation tank 4 and is branched into a solid content reflux line (supply means) L21 and a surplus sludge discharge line L22 on the opposite side of the discharge port 4a. .. A valve (not shown) such as a three-way valve is provided at the three-pronged branch point in order to adjust the amount of solid content flowing into the solid content recirculation line L21 or the excess sludge discharge line L22, respectively.

固形分還流ラインL21は、第1ラインL11に接続され、固液分離槽4で固液分離して得た固形分の一部を、硫酸塩含有排水に合流させて混合槽2に供給するためのラインである。固形分還流ラインL21の構成は特に限定されず、あらゆる態様とすることができる。例えば、固形分還流ラインL21は、配管内を固形分が自重又はポンプ等による圧力で圧送される構成を含んでもよい。 The solid content reflux line L21 is connected to the first line L11, and a part of the solid content obtained by solid-liquid separation in the solid-liquid separation tank 4 is merged with the sulfate-containing wastewater and supplied to the mixing tank 2. Line. The configuration of the solid content reflux line L21 is not particularly limited, and any embodiment can be used. For example, the solid content reflux line L21 may include a configuration in which the solid content is pumped through the pipe by its own weight or pressure by a pump or the like.

余剰スラッジ排出ラインL22は、固液分離槽4で固液分離して得た固形分のうちの余剰スラッジ(すなわち、固形分のうち、固形分還流ラインL21を介して硫酸塩含有排水に合流され混合槽2に供給される量を超えた余剰分)を排水処理装置1の外部へ排出するためのラインである。 The surplus sludge discharge line L22 is merged with the sulfate-containing wastewater of the solid content obtained by solid-liquid separation in the solid-liquid separation tank 4 via the solid content reflux line L21. This is a line for discharging the excess amount) that exceeds the amount supplied to the mixing tank 2 to the outside of the wastewater treatment device 1.

続いて、排水処理装置1の動作について説明する。 Subsequently, the operation of the wastewater treatment device 1 will be described.

まず、硫酸塩含有排水が排水処理装置1の上流側から第1ラインL11を通じて混合槽2に流入すると共に、混合槽2にはアルミ系無機凝集剤が無機凝集剤供給ラインL15を介して供給される。そして、混合槽2において硫酸塩含有排水とアルミ系無機凝集剤とが混合されて混合液とされ、これにより、水酸化アルミニウムを含むフロックが混合液中に生成し、このフロックが混合液中のフッ素を吸着する。 First, the sulfate-containing wastewater flows into the mixing tank 2 from the upstream side of the wastewater treatment device 1 through the first line L11, and the aluminum-based inorganic coagulant is supplied to the mixing tank 2 via the inorganic coagulant supply line L15. To. Then, in the mixing tank 2, the sulfate-containing wastewater and the aluminum-based inorganic flocculant are mixed to form a mixed solution, whereby flocs containing aluminum hydroxide are generated in the mixed solution, and the flocs are formed in the mixed solution. Adsorbs fluorine.

ここで、SS濃度センサ5によって混合槽2内でのSS濃度が測定されることにより、アルミ系無機凝集剤の添加量をより適正に判断することができる。これにより、一例として、混合槽2内でのSS濃度が5000〜8000mg/lとなるようにアルミ系無機凝集剤を混合槽2に供給することによって、アルミ系無機凝集剤の添加量をフロックが生成する最適な値とできる。その結果、混合液中にフロックが効率良く生成し、混合液中のフッ素がより多く吸着される。 Here, by measuring the SS concentration in the mixing tank 2 with the SS concentration sensor 5, the amount of the aluminum-based inorganic flocculant added can be determined more appropriately. As a result, as an example, by supplying the aluminum-based inorganic coagulant to the mixing tank 2 so that the SS concentration in the mixing tank 2 becomes 5000 to 8000 mg / l, the amount of the aluminum-based inorganic coagulant added can be increased by Flock. It can be the optimum value to generate. As a result, flocs are efficiently generated in the mixed solution, and more fluorine in the mixed solution is adsorbed.

また、pHセンサ6によって混合液のpHが測定され、測定されたpHに基づいて、混合液のpHが中性又は弱酸性(例えばpHが5以上8以下、特に好ましくは6.5以上7.0以下)となるように、薬剤供給ラインL16を介して混合槽2に酸性薬剤又はアルカリ性薬剤が供給される。具体的には、測定されたpHが所定値より低く酸性寄りの場合、薬剤供給ラインL16から混合槽2にアルカリ性薬剤が供給される。一方、測定されたpHが所定値より高くアルカリ性寄りの場合、薬剤供給ラインL16から混合槽2に酸性薬剤が供給される。混合液のpHを上記範囲内の中性又は弱酸性とすることで、混合液中にフロックが効率良く生成し、その結果、混合液中のフッ素がより多く吸着される。 Further, the pH of the mixed solution is measured by the pH sensor 6, and the pH of the mixed solution is neutral or weakly acidic (for example, the pH is 5 or more and 8 or less, particularly preferably 6.5 or more and 7.) based on the measured pH. The acidic agent or alkaline agent is supplied to the mixing tank 2 via the agent supply line L16 so as to be 0 or less). Specifically, when the measured pH is lower than a predetermined value and is closer to acidity, the alkaline drug is supplied from the drug supply line L16 to the mixing tank 2. On the other hand, when the measured pH is higher than a predetermined value and is closer to alkaline, the acidic drug is supplied from the drug supply line L16 to the mixing tank 2. By setting the pH of the mixed solution to neutral or weakly acidic within the above range, flocs are efficiently generated in the mixed solution, and as a result, more fluorine in the mixed solution is adsorbed.

次いで、混合液が第2ラインL12を通じて凝集槽3に流入すると共に、凝集槽3には高分子凝集剤が高分子凝集剤供給ラインL17を介して供給される。そして、高分子凝集剤の混合により、混合液中のフロックがより大きく形成され(粗大フロック)、その結果、当該フロックが沈殿し易くなる。 Next, the mixed solution flows into the coagulation tank 3 through the second line L12, and the polymer coagulant is supplied to the coagulation tank 3 via the polymer coagulant supply line L17. Then, by mixing the polymer flocculant, the flocs in the mixed solution are formed larger (coarse flocs), and as a result, the flocs are easily precipitated.

次いで、混合液が第3ラインL13を介して固液分離槽4に流入すると共に、固形分と固形分以外の液とに固液分離される。このとき、固形分には、フッ素を吸着していないフロック及びフッ素を吸着したフロックの両方が含まれている。ここで、フッ素を吸着したフロックが固液分離されて沈殿することでフッ素が共沈される。沈殿した固形分は、排出口4aから副ラインL2へ排出される。 Next, the mixed liquid flows into the solid-liquid separation tank 4 via the third line L13, and is solid-liquid separated into a solid content and a liquid other than the solid content. At this time, the solid content includes both flocs that do not adsorb fluorine and flocs that have adsorbed fluorine. Here, fluorine is coprecipitated by solid-liquid separation and precipitation of flocs that have adsorbed fluorine. The precipitated solid content is discharged from the discharge port 4a to the sub line L2.

一方、固形分以外の液は、所定のフッ素濃度(一例として、15mg/l)以下までフッ素が除去された処理水として、固液分離槽4から第4ラインL14を通じて排水処理装置1の後段へ排出される。 On the other hand, the liquid other than the solid content is treated water from which fluorine has been removed to a predetermined fluorine concentration (for example, 15 mg / l) or less, from the solid-liquid separation tank 4 to the subsequent stage of the wastewater treatment device 1 through the fourth line L14. It is discharged.

副ラインL2に流入した固形分のうちの一部は、固形分還流ラインL21を通じて第1ラインL11に供給され、第1ラインL11を通じて混合槽2に供給される。一方、固形分のうちの残部は、余剰スラッジとして余剰スラッジ排出ラインL22を通じて排出される。 A part of the solid content that has flowed into the sub line L2 is supplied to the first line L11 through the solid content reflux line L21, and is supplied to the mixing tank 2 through the first line L11. On the other hand, the remaining solid content is discharged as surplus sludge through the surplus sludge discharge line L22.

混合槽2に供給された固形分のうち、未だフッ素を吸着していないフロック及び既にフッ素を吸着したが更にフッ素を吸着することができる状態のフロックが、混合液中のフッ素を吸着する。そして、前述したのと同様に、このフロックが固液分離槽4において固液分離されて沈殿することで、混合液中のフッ素を共沈させて液中から除去し、この一連の動作が繰り返される。 Of the solids supplied to the mixing tank 2, the flocs that have not yet adsorbed fluorine and the flocs that have already adsorbed fluorine but can further adsorb fluorine adsorb the fluorine in the mixture. Then, as described above, the flocs are solid-liquid separated and precipitated in the solid-liquid separation tank 4, so that fluorine in the mixed solution is coprecipitated and removed from the solution, and this series of operations is repeated. Is done.

以上、説明したように、本実施形態に係る排水処理装置1及び排水処理方法によれば、混合槽2で硫酸塩含有排水とアルミ系無機凝集剤とを混合することにより、フロックが混合液中に生成し、このフロックが混合液中のフッ素を吸着して液中から除去する。そして、固液分離槽4において、既にフッ素を吸着したフロックをフッ素と共に共沈させ、また、未だフッ素を吸着していないフロックも沈降させて固液分離し、これらの固液分離した固形分を混合槽2に供給する。その結果、未だフッ素を吸着していないフロック及び既にフッ素を吸着したが更にフッ素を吸着することができる状態のフロックが混合液中のフッ素を吸着して液中から除去する。これにより、フッ素の吸着・共沈のために使用されたアルミ系無機凝集剤を再びフッ素の吸着・共沈に活用できる。以上により、硫酸塩含有排水において、アルミ系無機凝集剤の使用量を削減できると共に、このアルミ系無機凝集剤の使用量を削減すること及び固液分離して得た固形分を混合槽2に供給することにより余剰スラッジの発生量を低減できる。 As described above, according to the wastewater treatment apparatus 1 and the wastewater treatment method according to the present embodiment, by mixing the sulfate-containing wastewater and the aluminum-based inorganic flocculant in the mixing tank 2, flocs are contained in the mixed liquid. This floc adsorbs fluorine in the mixed solution and removes it from the solution. Then, in the solid-liquid separation tank 4, the flocs that have already adsorbed fluorine are coprecipitated together with fluorine, and the flocs that have not yet adsorbed fluorine are also precipitated to undergo solid-liquid separation, and these solid-liquid separated solids are separated. It is supplied to the mixing tank 2. As a result, the flocs that have not yet adsorbed fluorine and the flocs that have already adsorbed fluorine but can further adsorb fluorine adsorb the fluorine in the mixed liquid and remove it from the liquid. As a result, the aluminum-based inorganic flocculant used for the adsorption and coprecipitation of fluorine can be utilized again for the adsorption and coprecipitation of fluorine. As described above, the amount of the aluminum-based inorganic coagulant used in the sulfate-containing wastewater can be reduced, the amount of the aluminum-based inorganic coagulant used can be reduced, and the solid content obtained by solid-liquid separation can be transferred to the mixing tank 2. By supplying it, the amount of excess sludge generated can be reduced.

特に、排水処理装置1及び排水処理方法は、流入水のフッ素濃度が高い場合に有効で、このような硫酸塩含有排水において一層顕著な効果を奏する。一般に高濃度のフッ素を含有する排水からフッ素を除去する別の方法として、フッ素を含有する排水にカルシウム系の薬剤を添加してフッ化カルシウム(CaF2)を生成させることが知られている。しかしながら、硫酸塩含有排水においては、カルシウム系の薬剤を添加するとカルシウム系の薬剤が硫酸塩と反応して石膏(Ca(SO)4)を生成してしまい、フッ化カルシウムの生成が阻害されるという問題がある。これに対し、本実施形態によれば、硫酸塩含有排水に対して石膏を生成させることなく効果的にフッ素を除去することができる。 In particular, the wastewater treatment apparatus 1 and the wastewater treatment method are effective when the fluorine concentration of the inflow water is high, and are more remarkable in such sulfate-containing wastewater. It is generally known that as another method for removing fluorine from wastewater containing a high concentration of fluorine, calcium fluoride-based chemicals are added to the wastewater containing fluorine to generate calcium fluoride (CaF 2 ). However, in sulfate-containing wastewater, when a calcium-based drug is added, the calcium-based drug reacts with the sulfate to produce gypsum (Ca (SO) 4 ), which inhibits the production of calcium fluoride. There is a problem. On the other hand, according to the present embodiment, fluorine can be effectively removed from the sulfate-containing wastewater without producing gypsum.

また、本実施形態に係る排水処理装置1では、混合槽2が、pHを調整するために酸性薬剤又はアルカリ性薬剤を供給する薬剤供給ラインL16を有している。これにより、pHを調整することで、硫酸塩含有排水とアルミ系無機凝集剤とが反応し、フロックを生成する最適な値とできるため、フロックを効率良く生成でき、アルミ系無機凝集剤の使用量に対して効率良くフッ素を吸着・共沈させて液中から除去できる。 Further, in the wastewater treatment apparatus 1 according to the present embodiment, the mixing tank 2 has a chemical supply line L16 for supplying an acidic chemical or an alkaline chemical in order to adjust the pH. As a result, by adjusting the pH, the sulfate-containing wastewater reacts with the aluminum-based inorganic flocculant to obtain the optimum value for producing flocs, so that flocs can be efficiently produced, and the use of aluminum-based inorganic flocculants. Fluorine can be efficiently adsorbed and coprecipitated with respect to the amount and removed from the liquid.

なお、本発明に係る排水処理装置1及び排水処理方法は、上記実施形態に限定されない。例えば、上記実施形態ではアルミ系無機凝集剤によりフッ素を含有する硫酸塩含有排水からフッ素を除去するが、例えばヒ素、ホウ素又はセレンを含有する硫酸塩含有排水から、アルミ系無機凝集剤によりそれぞれヒ素、ホウ素又はセレンを除去する構成としてもよい。これらの場合であっても、上記実施形態と同様の構成を有する排水処理装置及び同様の工程を有する排水処理方法によって同様の作用効果が得られる。 The wastewater treatment device 1 and the wastewater treatment method according to the present invention are not limited to the above-described embodiment. For example, in the above embodiment, fluorine is removed from the sulfate-containing wastewater containing fluorine by an aluminum-based inorganic flocculant. For example, arsenic is removed from the sulfate-containing wastewater containing arsenic, boron or selenium by an aluminum-based inorganic flocculant. , Boron or selenium may be removed. Even in these cases, the same effect can be obtained by the wastewater treatment apparatus having the same configuration as the above embodiment and the wastewater treatment method having the same steps.

また、上記実施形態では、アルミ系無機凝集剤の添加量をより適正に判断できるように、SS濃度センサ5によって混合槽2内でのSS濃度を測定している。しかしながら、SS濃度センサ5に代えて、水酸化アルミニウム濃度を測定する水酸化アルミニウム濃度センサを混合槽2に設けてもよい。この場合、一例として、混合槽2内での水酸化アルミニウム濃度が3000〜5000mg/lとなるようにアルミ系無機凝集剤を混合槽2に供給することにより、アルミ系無機凝集剤の添加量をフロックが生成する最適な値とできる。その結果、混合液中にフロックが効率良く生成し、混合液中のフッ素がより多く吸着される。 Further, in the above embodiment, the SS concentration in the mixing tank 2 is measured by the SS concentration sensor 5 so that the amount of the aluminum-based inorganic flocculant added can be determined more appropriately. However, instead of the SS concentration sensor 5, an aluminum hydroxide concentration sensor for measuring the aluminum hydroxide concentration may be provided in the mixing tank 2. In this case, as an example, the amount of the aluminum-based inorganic coagulant added can be increased by supplying the aluminum-based inorganic coagulant to the mixing tank 2 so that the concentration of aluminum hydroxide in the mixing tank 2 is 3000 to 5000 mg / l. It can be the optimum value generated by the floc. As a result, flocs are efficiently generated in the mixed solution, and more fluorine in the mixed solution is adsorbed.

また、上記実施形態において、無機凝集剤供給ラインL15は混合槽2へ直接接続されているが、混合槽2より上流である第1ラインL11へ接続されていてもよい。この場合であっても、第1ラインL11に供給されたアルミ系無機凝集剤は、第1ラインL11を通じて混合槽2に供給される。 Further, in the above embodiment, the inorganic flocculant supply line L15 is directly connected to the mixing tank 2, but may be connected to the first line L11 upstream of the mixing tank 2. Even in this case, the aluminum-based inorganic flocculant supplied to the first line L11 is supplied to the mixing tank 2 through the first line L11.

また、固液分離槽4は、遠心分離機を有し、遠心分離によって固液分離を行うこととしてもよい。 Further, the solid-liquid separation tank 4 may have a centrifuge and perform solid-liquid separation by centrifugation.

また、固形分還流ラインL21としては、配管等の設備を用いず、人力によって固形分を混合槽2に供給する構成としてもよい。 Further, the solid content reflux line L21 may be configured to manually supply the solid content to the mixing tank 2 without using equipment such as piping.

また、上記実施形態において、固形分還流ラインL21は固形分を第1ラインL11に供給するが、混合槽2に直接供給してもよい。 Further, in the above embodiment, the solid content reflux line L21 supplies the solid content to the first line L11, but the solid content may be directly supplied to the mixing tank 2.

また、図2に示されるように、混合槽2を無くし、第1ラインL11と第2ラインL12とを接続して第5ラインL18とすると共に、この第5ラインL18に無機凝集剤供給ラインL15を接続し、第5ラインL18と無機凝集剤供給ラインL15との接続点から凝集槽3までのラインを、硫酸塩含有排水(すなわち、フッ素及び硫酸塩を含有する排水)とアルミ系無機凝集剤とを混合する混合部としてもよい。なお、混合部には、当該混合部内での混合液のSS濃度を測定するSS濃度センサ5が設けられていてもよい。また、混合部には、当該混合部内での混合液のpHを測定するpHセンサ6が設けられていてもよく、更に、このpHセンサ6によって測定したpHに基づきpHを調整するための薬剤を当該混合部に供給する薬剤供給ラインL16が接続されていてもよい。 Further, as shown in FIG. 2, the mixing tank 2 is eliminated, and the first line L11 and the second line L12 are connected to form the fifth line L18, and the fifth line L18 is connected to the inorganic flocculant supply line L15. The line from the connection point between the fifth line L18 and the inorganic coagulant supply line L15 to the coagulation tank 3 is connected to the sulfate-containing wastewater (that is, the wastewater containing fluorine and sulfate) and the aluminum-based inorganic coagulant. May be used as a mixing unit for mixing and. The mixing section may be provided with an SS concentration sensor 5 for measuring the SS concentration of the mixed solution in the mixing section. Further, the mixing section may be provided with a pH sensor 6 for measuring the pH of the mixed solution in the mixing section, and further, a drug for adjusting the pH based on the pH measured by the pH sensor 6 may be provided. The drug supply line L16 to be supplied to the mixing unit may be connected.

1…排水処理装置、2…混合槽(混合部)、4…固液分離槽(固液分離部)、L21…固形分還流ライン(供給手段)。 1 ... Wastewater treatment device, 2 ... Mixing tank (mixing unit), 4 ... Solid-liquid separation tank (solid-liquid separation unit), L21 ... Solid content reflux line (supply means).

Claims (3)

硫酸塩含有排水からフッ素を除去する排水処理装置において、
前記硫酸塩含有排水とアルミ系無機凝集剤とを混合する混合部と、
前記混合部で混合された混合液中のフッ素をアルミ系無機凝集剤によって共沈させることにより固液分離する固液分離部と、
前記固液分離部で固液分離して得た固形分を、フッ素を吸着していないフロック及びフッ素を吸着したフロックが含まれている状態で、前記混合部に供給するための供給手段と、
を備える排水処理装置。
In a wastewater treatment device that removes fluorine from sulfate-containing wastewater
A mixing portion that mixes the sulfate-containing wastewater and an aluminum-based inorganic flocculant, and
A solid-liquid separation unit that separates solid-liquid by co-precipitating fluorine in the mixed liquid mixed in the mixing unit with an aluminum-based inorganic flocculant.
A supply means for supplying the solid content obtained by solid-liquid separation in the solid-liquid separation unit to the mixing unit in a state containing flocs that do not adsorb fluorine and flocs that adsorb fluorine .
Wastewater treatment equipment equipped with.
前記混合部は、pHを調整するpH調整手段を有する請求項1に記載の排水処理装置。 The wastewater treatment apparatus according to claim 1, wherein the mixing unit has a pH adjusting means for adjusting the pH. 硫酸塩含有排水からフッ素を除去する排水処理方法において、
前記硫酸塩含有排水とアルミ系無機凝集剤とを混合部で混合し、
前記混合部で混合された混合液中のフッ素をアルミ系無機凝集剤によって共沈させることにより固液分離部で固液分離し、
前記固液分離部で固液分離して得た固形分を、フッ素を吸着していないフロック及びフッ素を吸着したフロックが含まれている状態で、前記混合部に供給する排水処理方法。
In a wastewater treatment method that removes fluorine from sulfate-containing wastewater,
The sulfate-containing wastewater and the aluminum-based inorganic flocculant are mixed in the mixing section, and then
Fluorine in the mixed solution mixed in the mixing section is coprecipitated with an aluminum-based inorganic flocculant to separate the solid and liquid in the solid-liquid separation section.
A wastewater treatment method in which the solid content obtained by solid-liquid separation in the solid-liquid separation unit is supplied to the mixing unit in a state of containing flocs that do not adsorb fluorine and flocs that adsorb fluorine .
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