JP4672154B2 - Waste water treatment method and waste water treatment equipment - Google Patents

Description

【０００６】
こうしてタンク２内には、石膏と吸収剤である少量の石灰石が懸濁または溶存し、これらがスラリポンプ７により吸い出され、混合タンク８において排水処理設備２０から導出されたスラッジＤと混合される。そして、スラッジＤが混合された該スラリは、その後スラリポンプ９により真空吸引式のベルトフィルタ式濾過装置１０に送られて固液分離され、スラッジ固形分が混在した水分の少ない石膏Ｅ（通常、水分含有率：１０％程度）として採り出される。一方、真空吸引式のベルトフィルタ式濾過装置１０からの濾液Ｆは真空ポンプ１１により真空引きされる真空チャンバ１２に吸込まれ、この真空チャンバ１２を経由して濾液タンク１３に送られる。濾液タンク１３の濾液Ｆのほとんどはポンプ１４により吸い出されてスラリタンク１５に送られ、ここで原料アルカリ（石灰石など）Ｇが加えられ、吸収剤スラリとしてスラリポンプ１６により再びタンク２に供給される。なお、この脱硫装置への水の補給は図示省略されているが、例えばスラリタンク１５に不純物を含まない清浄な水を必要に応じて補給することにより行われる。一方濾液タンク１３の濾液Ｆの一部はポンプ１７により吸い出されて排水処理設備２０に送られ排水処理された後、廃液Ｈとして放水などされる。ここで、前記排水設備２０は湿式排煙排脱装置からの排水のみでなく、例えば発電所や工場等の各施設からの排水も処理する総合的な排水処理設備であっても良く、その場合のスラッジＤには各施設の排水に含まれる不純物も含むことになる。
なお、排水処理設備２０で発生するスラッジＤは排水処理設備２０より導出され、前述のように、混合タンク８において吸収塔１から抜き出されたスラリ中に混入され、副生品である石膏Ｅ中に混在することになるが、石膏の量に比べて僅かな量であるため石膏Ｅの純度は石膏ボードやセメントの材料として使用することに対して問題となるほどは低下しない。
【０００７】
しかしながら、上記従来の構成では吸収塔から抜き出した固液分離前の石膏スラリと排水処理設備２０から導出された固液分離前のスラッジＤとを予め混合タンク８で混ぜ合わせ、その後ベルトフィルタ式濾過装置１０により濾過固液分離する構成であるため混合タンク８が必要であり、さらには導出されるスラッジの量、又は成分や性状によってはその濾液Ｆ中にはスラッジＤの一部が含まれるから、スラッジＤの一部が濾液タンク１３及びポンプ１４を介して吸収塔１に戻り、脱硫装置における脱硫率が低下するなどの問題があった。すなわち、不純物除去のために排水処理設備に導出した脱硫装置における循環水の一部が再び脱硫装置におけるスラリ中に戻ることになる。このため、脱硫装置における吸収剤スラリ中の不純物濃度が設計許容値を越えてしまい、脱硫率の低下、さらには石膏生成のための前述の中和反応等が阻害され、石膏Ｅ中の不純物（未反応石灰石など）の含有量が増加して石膏の要求品質を満足できないといった不具合が生じる恐れがあった。なお、吸収塔タンク２内にアルカリ剤を投入してスラリのｐＨを高く（例えばｐＨ５以上）調整することで、不純物の悪影響が抑制できることが知られており、実際にはこのようなｐＨ調整が行われることにより脱硫率の著しい低下などの不具合が実用上なんとか回避されているのが実情であるが、この場合でも上記従来例のような構成では脱硫装置の循環水中にせっかく導出した不純物の一部が再び戻るため、アルカリ剤の投入量が増加したり不純物濃度が変動し、アルカリ剤の投入量制御が困難になるといった不具合が避けられない
【０００８】
従って、このような性能阻害を防止するためには、高品位石膏と低品位石膏の２系統の石膏回収設備を設けるなどの対策が必要であった。すなわち、図４に示すように、吸収塔から排出された脱硫石膏スラリーはベルトフィルタ式濾過装置１０ａによって濾過され高品位石膏Ｅａを回収しているが、この脱硫石膏スラリーの一部をラインＳ₂から混合タンク８に送り、排水処理設備２０からのスラッジＤと混合し、ベルトフィルタ式濾過装置１０ｂに送ってスラッジを含んだ低品位石膏Ｅｂを回収している。一方の濾過分離した後の濾液Ｆｂにも溶解した不純物が含まれているため吸収塔１へは供給せずに、濾液タンク１３ｂにて回収し、再び排水処理設備２０に送り返される。
しかし、この場合も２系統の石膏回収設備が必要であるばかりでなく、濾液の再利用による有効活用が出来ないなどの問題点が生じる。
【０００９】
【発明が解決しようとする課題】
上記従来例のいずれの方法においても、ベルトフィルタ式濾過装置の前段にて、脱硫石膏スラリーとスラッジを含む排水とを混合させるための混合タンクが必要であり、また２系列の石膏スラリー濾過設備が必要などの設備の大型化、初期費用や運転費用が嵩む等の問題点があった。また濾過後の濾液には不純物成分が残存する結果となり、そのままでは吸収塔に戻して再利用することも出来ないため、それだけ多くの新規の水の補給が必要となり、また系外への排水量の低減が図られない等の問題点があった。
本発明は、これらの課題を解決することを目的とする。
【００１０】
【課題を解決するための手段】
上記目的を達成するため、本発明は、排水を処理する排水処理方法であって、湿式排煙脱硫装置から導出された石膏スラリーと、排水処理設備より導出されたスラッジとをベルトフィルタ式濾過装置に供給して、不純物含有石膏と濾液とに濾過分離することを特徴とする。
また、排水を処理する排水処理方法であって、湿式排煙脱硫装置から導出された石膏スラリーをベルトフィルタ式濾過装置により石膏と濾液とに濾過分離し、該ベルトフィルタ上に形成された石膏層の上に排水処理設備より導出されたスラッジを供給してスラッジ層を形成させることを特徴とする。
また、石膏スラリーをベルトフィルタ式濾過装置により石膏と濾液とに濾過分離する際に、石膏スラリーのベルトフィルタ上への供給位置を含む一定ゾーンで自然沈降により濾過し、次にベルトフィルタ上に形成された石膏層の上に排水処理設備より導出されたスラッジを供給して真空吸引濾過することを特徴とする。
また、ベルトフィルタ上に形成した不純物含有石膏又は石膏層及びスラッジ層を回収し、粉砕混合して不純物含有石膏とすることを特徴とする。
【００１１】
また、本発明は、排水を処理する排水処理装置であって、ベルトフィルタ式濾過装置と、該ベルトフィルタ式濾過装置の濾過ゾーン上に湿式排煙脱硫装置から導出された石膏スラリーを供給する石膏スラリー供給ライン及び排水処理設備より導出されたスラッジを供給するスラッジ供給ラインとを具備することを特徴とする。
また、石膏スラリー供給ラインは濾過ゾーンの上流側に、スラッジ供給ラインはその下流側に具備することを特徴とする。
また、石膏スラリー濾過ゾーンの少なくとも一部ゾーンは自然沈降濾過方式であり、他の濾過ゾーンは真空吸引濾過方式であることを特徴とする。
【００１２】
【発明の実施の形態】
以下、本発明の、実施の形態の具体例を図に基いて説明する。なお、図３に示した従来例と同様の要素には同符号を付し、共通部分の説明は省略する。
まず、第１の実施例を図１により説明する。
スラリーポンプ７により吸収塔より導出された石膏スラリーは石膏スラリー供給ラインＳより、排水処理設備２０より導出されたスラッジＤはスラッジ供給ラインＴより、ベルトフィルタ式濾過装置６０の濾過ゾーンに供給され濾過分離される。ベルトフィルター上に積層された固形分は回収されてより細かく粉砕混合されて不純物を含む低品位石膏として石膏ボードやセメントの材料などの用途として産業上有効に使用される。
ベルトフィルタを通過して濾過分離された濾液は、濾液タンク１３に集められてから吸収塔へ送られ再利用される。
なお、本第一実施例は、スラッジＤの導出量が僅かであったり、あるいはスラッジの性状や成分から濾液の中に残存する不純物濃度が許容値を超えない場合に採用できるもので、従来例にある混合槽８やスラリポンプ９などを必要としない効果がある。
【００１３】
次に、スラッジＤの導出量、性状や成分の条件等により、前記実施例では濾液の中に残存する不純物濃度が許容値を超えてしまう場合に、それを解決する第２の実施例を図２に基き説明する。
【００１４】
スラリーポンプ７により吸収塔より導出された石膏スラリーはベルトフィルタ式濾過装置６０の濾過ゾーン上流側に供給され、一定の濾過ゾーンＫ₁で濾過されてベルトフィルタ上に石膏層を形成する。排水処理設備２０から導出したスラッジＤは石膏スラリの濾過ゾーンＫ₁を過ぎたベルトフィルタ上の石膏層の上に供給される。石膏層の下部は沈降速度の大きな粗い粒子により形成され層上部は細かい粒子で形成されるので、石膏層の上に供給されたスラッジは石膏層を通過し難いものとなりスラッジの層が石膏層の上部に形成される。これにより濾過分離された濾液への不純物含有量を低減することができ、吸収塔循環液として再使用し易くなる。この石膏層とスラッジ層はベルトフィルタ式濾過装置６０より回収され、粉砕混合されて不純物混入の低品位石膏となり、石膏ボードやセメントの材料などの用途として産業上有効に使用できる。
また、ベルトフィルタを通過して得られる濾液はそのまま吸収塔に供給し、再利用しても悪影響が少ないので、従来例で説明した種々の対策を講じることを必要としないで、安定した運転が可能となる。
【００１５】
ここで、通常は濾過速度を速めるためにベルトフィルタの下部より真空吸引して濾過するが、石膏層が形成する濾過ゾーンＫ₁は真空吸引をやめて石膏粒子を自然沈降させることが好ましい。すなわち、自然沈降により粗い粒子と細かい粒子の沈降速度の差がより大きくなって表層がより多くの細かい粒子により形成されるので、上記の作用がより確実なものとなる。
なお、吸収塔へ供給再利用できる良好な濾液が得られるようにスラッジＤの量、成分や性状等に応じて濾過ゾーンＫ₁やスラッジの石膏層による濾過ゾーンＫ₂、ベルトフィルタ式濾過装置６０の運転速度等を適宜設定することができる。
なお、本願発明は上記実施例に限定されるものではなく、例えば亜硫酸ガスを吸収した吸収剤スラリーを吸収塔内では積極的な酸化をせずに別置の酸化塔や槽で酸化させて石膏を形成させるものであっても良い。
【００１６】
【発明の効果】
本発明によれば、排水処理設備で発生するスラッジの固形分を石膏中に混入させて処置する構成でありながら、石膏スラリー及びスラッジを濾過して得られる濾液は不純物成分が少ないので、従来方法で必要であった特別な処理や対策を講じる必要がなく、そのまま吸収塔への供給液として再利用できることとなる。さらには、ベルトフィルタ式濾過装置の前段に従来必要であった石膏スラリーとスラッジとを混合する混合槽が不要となり、また濾過設備を２系列とすることも必要なく、設備の簡略化・小型化と設備・運転費用の低減、系外へ排出される排水量の低減などが実現できる。
【図面の簡単な説明】
【図１】本発明の、実施形態の例の構成を示す図である。
【図２】本発明の、他の実施形態の例の構成を示す図である。
【図３】従来の、排水処理の形態の例を示す図である。
【図４】従来の、他の排水処理の形態の例を示す図である。
【符号の説明】
１ 吸収塔
２ タンク
３ エアスパージャ
４、７、９、１４、１６、１７ ポンプ
５ ヘッダパイプ
６ 充填材
８ 混合タンク
１０ ベルトフィルタ式濾過装置
１１ 真空ポンプ
１２ 真空チャンバ
１３ 濾液タンク
１５ スラリタンク
２０ 排水処理設備
６１、６２ ドラム
６３ 穴あきベルト
６６ スラリ導入パン
６７ 真空パン
６８ ローラ
６９ ベルトフィルタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for treating wastewater discharged when sulfur oxides in combustion exhaust gas such as heavy oil and coal are removed by a wet flue gas desulfurization apparatus. More specifically, impurities contained in the wastewater are mixed and treated in the recovered gypsum, and some of the components can be omitted. Further, the filtrate obtained by filtration leaves harmful components as an absorption tower circulating liquid. The present invention relates to wastewater treatment that can be effectively reused.
[0002]
[Prior art]
As a flue gas desulfurization device that removes sulfur oxides in exhaust gas generated by burning heavy oil, coal, etc. in thermal power plants, etc., exhaust gas and absorbent slurry (made of calcium compounds such as limestone) in an absorption tower A wet flue gas desulfurization apparatus that produces gypsum as a by-product by absorbing sulfur dioxide gas in exhaust gas into an absorbent slurry, oxidizing the slurry after contact, and solid-liquid separation is widely used.
In this desulfurization device, the filtrate (main component is water) generated when gypsum is separated is circulated and used as the liquid constituting the absorbent slurry, but the combustion contained in the exhaust gas is merely circulated and used. Impurities such as ash and chlorine accumulate in large amounts in this circulating water, hindering absorption reactions and gypsum formation reactions. For this reason, a part of the filtrate is usually discharged to a wastewater treatment facility and treated for wastewater (e.g., water discharge), and the deficiency of the liquid constituting the absorbent slurry is used as make-up water as an impurity. Clean water without water is supplied.
[0003]
By the way, in order to clear wastewater standards in wastewater treatment facilities, wastewater treatment including removal of harmful substances, COD treatment or decomposition, absorption, pH adjustment, etc. is performed, but at this time a considerable amount of sludge is generated, This processing has been a problem because of the cost. That is, this sludge is formed in Mg (OH) ₂ or CaSO ₄ .2H ₂ O (gypsum) produced by the reaction of MgSO ₄ contained in the filtrate with a neutralizing agent {Ca (OH) ₂ } or the like, or in the filtrate. Fe (OH) ₃ and Al (OH) ₃ that are precipitated when Fe, Al, etc. contained are adjusted from acidic to alkaline, are solid components and are not necessarily harmful, but are discarded as they are That is not allowed by law. For this reason, in the initial stage, the sludge was discarded by special solidification. However, since it is disadvantageous in terms of equipment cost and operation cost to perform the solidification treatment, in recent years, this sludge is mixed with gypsum slurry derived from the absorption tower of the desulfurization device in a tank and filtered with a filtration device, A method is adopted in which sludge is mixed in byproduct gypsum.
[0004]
An example of the configuration of the smoke emission processing system employing this conventional method will be described below with reference to FIG.
The desulfurization apparatus in this example includes an arm-rotating air sparger 3 that blows air C as fine bubbles into the slurry while stirring the slurry in the tank 2 of the absorption tower 1. The absorbed absorbent slurry and air C are efficiently brought into contact with each other to oxidize the entire amount to obtain gypsum. That is, in this desulfurization apparatus, the untreated flue gas A is guided to the flue gas introduction part 1a of the absorption tower 1 and is brought into contact with the absorbent slurry injected from the header pipe 5 by the circulation pump 4 so as to sulfite gas in the untreated flue gas A. Is absorbed and removed as processed smoke B from the smoke exhausting part 1b. The absorbent slurry injected from the header pipe 5 and flowing down through the filler 6 while absorbing sulfurous acid gas is oxidized in contact with a large number of bubbles blown in the tank 2 while being stirred by the air sparger 3, Furthermore, a neutralization reaction is caused to form gypsum. In this case, a method is also known in which an absorbent slurry that has absorbed sulfurous acid gas is led out from an absorption tower and oxidized in a separate oxidation tower or tank to form gypsum.
The main reactions occurring during these treatments are the following reaction formulas (1) to (3).
[0005]

[0006]
In this way, a small amount of limestone, which is gypsum and absorbent, is suspended or dissolved in the tank 2, and these are sucked out by the slurry pump 7 and mixed with the sludge D led out from the wastewater treatment facility 20 in the mixing tank 8. The The slurry mixed with the sludge D is then sent to the vacuum suction belt filter type filtration device 10 by the slurry pump 9 for solid-liquid separation. Water content: about 10%). On the other hand, the filtrate F from the vacuum suction type belt filter type filtration device 10 is sucked into the vacuum chamber 12 evacuated by the vacuum pump 11, and is sent to the filtrate tank 13 through the vacuum chamber 12. Most of the filtrate F in the filtrate tank 13 is sucked out by the pump 14 and sent to the slurry tank 15, where raw material alkali (limestone or the like) G is added, and is supplied again to the tank 2 by the slurry pump 16 as an absorbent slurry. The Although replenishment of water to the desulfurization apparatus is omitted, for example, it is performed by replenishing the slurry tank 15 with clean water not containing impurities as necessary. On the other hand, a part of the filtrate F in the filtrate tank 13 is sucked out by the pump 17, sent to the waste water treatment facility 20 and subjected to waste water treatment, and then discharged as waste liquid H. Here, the drainage facility 20 may be a comprehensive wastewater treatment facility that treats not only the wastewater from the wet type flue gas exhausting device but also the wastewater from each facility such as a power plant or a factory. The sludge D also contains impurities contained in the wastewater of each facility.
The sludge D generated in the wastewater treatment facility 20 is derived from the wastewater treatment facility 20 and mixed in the slurry extracted from the absorption tower 1 in the mixing tank 8 as described above, and gypsum E as a by-product. However, the purity of gypsum E is not so low as to be problematic for use as a material for gypsum board or cement.
[0007]
However, in the above-described conventional configuration, the gypsum slurry before solid-liquid separation extracted from the absorption tower and the sludge D before solid-liquid separation derived from the wastewater treatment facility 20 are mixed in advance in the mixing tank 8, and then filtered by a belt filter. Since the apparatus 10 is configured to separate the solid and liquid by filtration, the mixing tank 8 is necessary. Furthermore, depending on the amount of sludge to be derived, or depending on the components and properties, the filtrate F contains a part of the sludge D. A part of the sludge D returns to the absorption tower 1 through the filtrate tank 13 and the pump 14, and there is a problem that the desulfurization rate in the desulfurization apparatus is lowered. That is, a part of the circulating water in the desulfurization apparatus led out to the wastewater treatment facility for removing impurities returns again into the slurry in the desulfurization apparatus. For this reason, the impurity concentration in the absorbent slurry in the desulfurization apparatus exceeds the design allowable value, the desulfurization rate is lowered, and further, the above-described neutralization reaction for generating gypsum is hindered, and the impurities in gypsum E ( The content of unreacted limestone and the like) may increase, and there may be a problem that the required quality of gypsum cannot be satisfied. In addition, it is known that an adverse effect of impurities can be suppressed by introducing an alkali agent into the absorption tower tank 2 and adjusting the pH of the slurry to be high (for example, pH 5 or more). In practice, problems such as a significant decrease in the desulfurization rate have been avoided in practice, but even in this case, in the configuration as in the above-described conventional example, one of the impurities led out in the circulating water of the desulfurization unit has been used. Since the part returns again, it is unavoidable that the amount of alkali agent input increases or the concentration of impurities fluctuates, making it difficult to control the amount of alkali agent input.
Therefore, in order to prevent such a performance hindrance, it has been necessary to take measures such as providing two types of gypsum recovery facilities of high-grade gypsum and low-grade gypsum. That is, as shown in FIG. 4, desulfurization gypsum slurry discharged from the absorption tower is being recovered high quality gypsum Ea is filtered by a belt filter type filtration apparatus 10a, the line S ₂ a part of the desulfurization gypsum slurry To the mixing tank 8, mixed with the sludge D from the waste water treatment facility 20, and sent to the belt filter type filtration device 10b to collect the low-grade gypsum Eb containing the sludge. One of the filtrates Fb after separation by filtration also contains dissolved impurities, so that they are not supplied to the absorption tower 1 but are collected in the filtrate tank 13b and sent back to the wastewater treatment facility 20 again.
However, in this case as well, two types of gypsum recovery equipment are required, and problems such as the inability to effectively utilize the filtrate by reuse are caused.
[0009]
[Problems to be solved by the invention]
In any of the above-described conventional methods, a mixing tank for mixing desulfurized gypsum slurry and wastewater containing sludge is required in the preceding stage of the belt filter type filtration device, and two series of gypsum slurry filtration facilities are provided. There were problems such as an increase in the size of necessary equipment and increased initial and operating costs. In addition, impurity components remain in the filtrate after filtration, and as it is, it cannot be returned to the absorption tower and reused, so that it is necessary to replenish new water, and the amount of drainage to the outside of the system. There was a problem that the reduction could not be achieved.
The present invention aims to solve these problems.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a wastewater treatment method for treating wastewater, wherein a gypsum slurry derived from a wet flue gas desulfurization device and sludge derived from a wastewater treatment facility are converted into a belt filter type filtration device. And is separated by filtration into an impurity-containing gypsum and a filtrate.
Also, a wastewater treatment method for treating wastewater, wherein a gypsum slurry derived from a wet flue gas desulfurization apparatus is filtered and separated into gypsum and filtrate by a belt filter type filtration device, and a gypsum layer formed on the belt filter The sludge derived from the waste water treatment facility is supplied on the top to form a sludge layer.
In addition, when the gypsum slurry is filtered and separated into gypsum and filtrate by a belt filter type filtration device, it is filtered by natural sedimentation in a fixed zone including the supply position of the gypsum slurry onto the belt filter, and then formed on the belt filter. The sludge derived from the waste water treatment facility is supplied onto the gypsum layer thus formed, and vacuum suction filtration is performed.
In addition, the impurity-containing gypsum or gypsum layer and sludge layer formed on the belt filter are collected and pulverized and mixed to form an impurity-containing gypsum.
[0011]
The present invention also relates to a wastewater treatment apparatus for treating wastewater, and a gypsum slurry for supplying a gypsum slurry derived from a wet flue gas desulfurization apparatus onto a belt filter type filtration apparatus and a filtration zone of the belt filter type filtration apparatus. And a sludge supply line for supplying sludge derived from the slurry supply line and the waste water treatment facility.
The gypsum slurry supply line is provided upstream of the filtration zone, and the sludge supply line is provided downstream thereof.
Further, at least a part of the gypsum slurry filtration zone is a natural sedimentation filtration system, and the other filtration zones are a vacuum suction filtration system.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. Elements similar to those of the conventional example shown in FIG. 3 are denoted by the same reference numerals, and description of common portions is omitted.
First, a first embodiment will be described with reference to FIG.
The gypsum slurry derived from the absorption tower by the slurry pump 7 is supplied from the gypsum slurry supply line S, and the sludge D derived from the waste water treatment facility 20 is supplied from the sludge supply line T to the filtration zone of the belt filter type filtration device 60 and filtered. To be separated. The solid content laminated on the belt filter is recovered, finely pulverized and mixed, and effectively used industrially as a gypsum board or cement material as a low-grade gypsum containing impurities.
The filtrate filtered and separated through the belt filter is collected in the filtrate tank 13 and then sent to the absorption tower for reuse.
The first embodiment can be adopted when the amount of sludge D derived is small or the concentration of impurities remaining in the filtrate from the sludge properties and components does not exceed the allowable value. There is an effect that the mixing tank 8 and the slurry pump 9 are not required.
[0013]
Next, in the above embodiment, when the concentration of impurities remaining in the filtrate exceeds the allowable value due to the derived amount of sludge D, properties, component conditions, and the like, the second embodiment is used to solve the problem. Explanation will be made based on 2.
[0014]
The gypsum slurry led out from the absorption tower by the slurry pump 7 is supplied to the upstream side of the filtration zone of the belt filter type filtration device 60 and is filtered through a fixed filtration zone K ₁ to form a gypsum layer on the belt filter. Sludge D derived from a wastewater treatment facility 20 is supplied onto the plaster layer on the belt filter past the filtration zone K ₁ of the gypsum slurry. Since the lower part of the gypsum layer is formed by coarse particles with a high sedimentation rate and the upper part is formed by fine particles, the sludge supplied on the gypsum layer is difficult to pass through the gypsum layer, and the sludge layer becomes a part of the gypsum layer. Formed on top. As a result, the impurity content in the filtrate separated by filtration can be reduced, and it can be easily reused as the absorption tower circulating liquid. The gypsum layer and the sludge layer are collected from the belt filter type filtration device 60 and pulverized and mixed to become low-grade gypsum mixed with impurities, which can be effectively used industrially as a gypsum board or cement material.
In addition, the filtrate obtained by passing through the belt filter is supplied to the absorption tower as it is, and since there is little adverse effect even if it is reused, it is not necessary to take various measures described in the conventional example, and stable operation is possible. It becomes possible.
[0015]
Here, in order to increase the filtration speed, filtration is generally performed by vacuum suction from the lower part of the belt filter. However, it is preferable that the filtration zone K ₁ formed by the gypsum layer stops the vacuum suction to allow the gypsum particles to spontaneously settle. That is, since the difference in sedimentation speed between coarse particles and fine particles becomes larger due to natural sedimentation, and the surface layer is formed with more fine particles, the above-described action becomes more reliable.
It should be noted that the filtration zone K ₁ , the filtration zone K ₂ by the gypsum layer of the sludge, the belt filter type filtration device 60 according to the amount of sludge D, components and properties so as to obtain a good filtrate that can be supplied and reused to the absorption tower. It is possible to appropriately set the operation speed of the vehicle.
The invention of the present application is not limited to the above-described embodiment. For example, an absorbent slurry that has absorbed sulfurous acid gas is oxidized in a separate oxidation tower or tank without being actively oxidized in the absorption tower. May be formed.
[0016]
【The invention's effect】
According to the present invention, the solid content of sludge generated in the wastewater treatment facility is treated by mixing it in gypsum, and the filtrate obtained by filtering the gypsum slurry and sludge has few impurity components. Therefore, it is not necessary to take special treatments and countermeasures that are necessary in this case, and it can be reused as the feed liquid to the absorption tower. In addition, a mixing tank for mixing gypsum slurry and sludge, which was conventionally required before the belt filter type filtration device, is no longer necessary, and there is no need for two lines of filtration equipment, simplifying and downsizing the equipment. It is possible to reduce equipment and operating costs, and reduce the amount of wastewater discharged outside the system.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of an example of an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of an example of another embodiment of the present invention.
FIG. 3 is a diagram showing an example of a conventional wastewater treatment mode.
FIG. 4 is a diagram showing an example of another conventional wastewater treatment mode.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Absorption tower 2 Tank 3 Air sparger 4, 7, 9, 14, 16, 17 Pump 5 Header pipe 6 Filler 8 Mixing tank 10 Belt filter type filtration apparatus 11 Vacuum pump 12 Vacuum chamber 13 Filtrate tank 15 Slurry tank 20 Waste water treatment Equipment 61, 62 Drum 63 Perforated belt 66 Slurry introduction pan 67 Vacuum pan 68 Roller 69 Belt filter

Claims (3)

A wastewater treatment method for treating wastewater, wherein a gypsum slurry derived from a wet flue gas desulfurization apparatus is filtered and separated into gypsum and filtrate by a belt filter type filtration device, and the gypsum layer formed on the belt filter is filtered. A wastewater treatment method characterized by supplying sludge derived from wastewater treatment equipment to form a sludge layer ,
When the gypsum slurry is filtered and separated into gypsum and filtrate by a belt filter type filtration device, the gypsum slurry is filtered by natural sedimentation in a certain zone including the supply position of the gypsum slurry onto the belt filter, and then formed on the belt filter. A wastewater treatment method in which sludge derived from wastewater treatment equipment is supplied onto a gypsum layer and vacuum suction filtered . The wastewater treatment method according to claim 1, wherein the impurity-containing gypsum or the gypsum layer and the sludge layer formed on the belt filter are collected and pulverized and mixed to obtain the impurity-containing gypsum. A wastewater treatment device for treating wastewater, a belt filter type filtration device, a gypsum slurry supply line for supplying gypsum slurry derived from a wet flue gas desulfurization device onto a filtration zone of the belt filter type filtration device, and wastewater treatment A wastewater treatment apparatus comprising a sludge supply line for supplying sludge derived from equipment ,
The gypsum slurry supply line is provided upstream of the filtration zone, and the sludge supply line is provided downstream thereof. At least a part of the gypsum slurry filtration zone is a natural sedimentation filtration system, and the other filtration zones are a vacuum suction filtration system. Some wastewater treatment equipment .

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