JP3687488B2 - Removal method of organic pollutants in sewage - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、産業排水や工業廃水などの汚水中に含まれ、ダイオキシン類に代表される有機塩素化合物などの有機汚濁物質の除去方法に関する。
【０００２】
【従来の技術】
従来、産業排水や工業廃水などの汚水の処理方法としては、浮遊物質の除去を目的とした凝集沈殿処理や濾過処理、有機汚濁物質の処理を目的とした生物処理、活性炭などを利用した高度処理などを組み合わせる。
【０００３】
しかし、このような従来の処理方法では、ダイオキシン類などの有機塩素化合物や内分泌性化学物質などの有機汚濁物質を効果的に除去することは、極めて困難であった。
【０００４】
これらの有機汚濁物質を除去する従来の方法として、オゾンと紫外線を組み合わせた処理方法があった。この処理方法では、オゾンと紫外線の反応により生成したヒドロキシルラジカルによる酸化反応と、紫外線の光化学反応とによって、有機汚濁物質が除去される。
【０００５】
【発明が解決しようとする課題】
しかし、主反応はヒドロキシルラジカルの酸化反応である。従って、紫外線の照射量は、効率よくオゾンからヒドロキシルラジカルを生成する量でよく、それ以上に紫外線を照射してもエネルギーコストが増大するだけである。さらに、紫外線による光化学反応の作用が大きくなると、脱塩素反応によって生成した塩素ラジカルにより、塩素の付加反応が起こり、副生成物が生成される恐れがある。
【０００６】
本発明は、このような従来の処理方法が抱える問題点に鑑み、紫外線の照射量を変化させることで、供給したオゾンから効率よくヒドロキシルラジカルを生成させ、汚水中の有機汚濁物質を短時間にかつ経済的に除去することができる方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するため、被処理水にオゾン接触下で、紫外線を照射する汚水処理において、紫外線照射の無い状態でかつオゾン接触下で示す酸化還元電位値を測定して基準値とし、前記基準値に対して一定範囲内の酸化還元電位値となるように、紫外線の照射条件を変化させ、溶存オゾンからヒドロキシラジカルへの変化量を制御する。
【０００８】
紫外線照射の無い状態でかつオゾン接触下で示す酸化還元電位値を測定して基準値とし、酸化還元電位値を、得られた基準値の７５〜９５％となるように、紫外線の照射条件を変化させることが望ましい。さらに、８５〜９０％となるように、紫外線の照射条件を変化させることが望ましい。
【０００９】
この方法により、被処理水中の溶存オゾンが変化して得られるヒドロキシルラジカルの量を、最適に制御することができる。
【００１０】
【発明の実施の形態】
本発明の方法では、ダイオキシン類に代表される有機塩素化合物などの有機汚濁物質を含む被処理水を、ポンプにより反応槽に導入し、この反応槽内の被処理水に、紫外線を照射しながら、オゾンと接触させる。反応槽内では、紫外線とオゾンの反応により、オゾンよりもさらに酸化力が強いヒドロキシルラジカルが生成し、ダイオキシン類に代表される有機塩素化合物などの有機汚濁物質が酸化され、分子量の小さい物質に分解除去される。
【００１１】
オゾンを混合することにより、図２に示すように、溶存オゾン濃度が高くなると酸化還元電位値は上昇する。そして、紫外線を照射すると、光化学作用により溶存オゾンは主としてヒドロキシルラジカルに変化して減少し、それとともに酸化還元電位値は低下する。
【００１２】
すなわち、酸化還元電位値を測定することにより、溶存オゾン濃度が観測できる。また、紫外線の照射によって消費される溶存オゾンの量は、紫外線照射前の酸化還元電位値に対する紫外線照射中の酸化還元電位値の率により観測できる。
【００１３】
このため、酸化還元電位値を測定し一定となるように、紫外線の照射量を変化させることにより、溶存オゾンが効果的にヒドロキシルラジカルに変化するように制御可能である。
【００１４】
具体的には、ｐＨの変化や温度変化などが酸化還元電位値に与える影響を考慮して、酸化還元電位値を、紫外線照射前でオゾンを混合したときに示す酸化還元電位値の７５〜９５％の範囲内であるように、紫外線の照射量を変化させて制御するのがよく、好ましくは８５〜９０％の範囲内であるように制御することが推奨される。
【００１５】
このとき、酸化還元電位値が、紫外線照射前でオゾンを混合したときに示す酸化還元電位値の９５％より高くなると、ヒドロキシルラジカルの生成量が不足し、有機汚濁物質の除去率は低下する。また、７５％より低くしても、有機汚濁物質の除去率の改善はほとんど見られず、処理コストの増大を招き、また、紫外線の光化学反応によって副生成物が生成し易くなる。
【００１６】
紫外線の照射量による制御は、紫外線の出力や紫外線強度、あるいは紫外線の照射時間などを変化させることで可能である。
【００１７】
酸化還元電位値を測定する方法としては、酸化還元電位電極を用いた酸化還元電位値モニターなどを使用することができる。
【００１８】
（実施例）
以下に、本発明の一実施例を具体的に説明するが、本発明はこれにより限定されない。
【００１９】
（実施例１）
産業排水を、凝集処理および生物分解処理し、有機汚濁物質としてペンタクロロベンゼンを、濃度４５μｇ／Ｌとなるように添加して被処理水を得た。被処理水のｐＨは８．３であった。
【００２０】
この被処理水に、被処理水１Ｌあたり１０ｍｇ／ｍｉｎの流量で、渦流ポンプを用いてオゾンを供給し混合させた。その混合液に、紫外線の照射条件を操作可能な装置（フリップス社製、型式ＴＵＶ１６Ｗ）を用いて紫外線を照射し、８分間循環処理した。その後、酸化還元電位電極（ＤＫＫ社製、型式６１５４：０．６５Ｗ）を接続した酸化還元電位値モニター（ＤＫＫ社製、型式ＰＨＬ２０）により、酸化還元電位値を測定した。紫外線を照射せずに処理した後述の比較例４における酸化還元電位値の９８０ｍＶ（基準値）に対して８６．７％にあたる８５０ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が３．２Ｗであった。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表１に示す。
【００２１】
（実施例２）
紫外線を照射せずに処理した後述の比較例４における酸化還元電位値の９８０ｍＶ（基準値）に対して９４．９％にあたる９３０ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が１．５Ｗであった以外は、実施例１と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表１に示す。
【００２２】
（比較例１）
紫外線を照射せずに処理した後述の比較例４における酸化還元電位値の９８０ｍＶ（基準値）に対して９９．０％にあたる９７０ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が０．９Ｗであった以外は、実施例１と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表１に示す。
【００２３】
（比較例２）
紫外線を照射せずに処理した後述の比較例４における酸化還元電位値の９８０ｍＶ（基準値）に対して７４．０％にあたる７２５ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が０．９Ｗであった以外は、実施例１と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表１に示す。
【００２４】
（比較例３）
紫外線を照射せずに処理した後述の比較例４における酸化還元電位値の９８０ｍＶ（基準値）に対して５１．０％にあたる５００ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が６．７Ｗであった以外は、実施例１と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表１に示す。
【００２５】
（比較例４）
紫外線を照射しない以外は、実施例１と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表１に示す。
【００２６】
実施例１、２ 比較例１〜４を、図１において○で示す。
【００２７】
【表１】
表１より、紫外線の照射量を変えることで、酸化還元電位値は変化することが分かる。
【００２９】
紫外線を照射せずに処理した比較例４の酸化還元電位値（９８０ｍＶ）に対し、８７％の酸化還元電位値（８５０ｍＶ）の実施例１ではペンタクロロベンゼン除去率が９９．３％であり、９５％の酸化還元電位値（９３０ｍＶ）の実施例２ではペンタクロロベンゼン除去率が９８．１％であり、ほとんど除去できたことが分かる。
【００３０】
紫外線を照射せずに処理した比較例４の酸化還元電位値（９８０ｍＶ）に対し、９５％（９３１ｍＶ）を超えた９９％の酸化還元電位値（９７０ｍＶ）の比較例１では、ペンタクロロベンゼン除去率が９２．５％と低かった。
【００３１】
また、８５％（８３３ｍＶ）未満である７４％の酸化還元電位値（７２５ｍＶ）の比較例２、および５１％の酸化還元電位値（５００ｍＶ）の比較例３では、実施例１、２に対し、紫外線の照射量を増加させているが、ペンタクロロベンゼン除去率は９８．８％、９８．２％と変化しなかった。このように、一定値以上に紫外線の照射量を増加させても、得られる効果に差はなく、経済性だけが低下することが分かる。
【００３２】
（実施例３）
産業排水を、凝集処理および生物分解処理し、有機汚濁物質としてペンタクロロベンゼンを、濃度４５μｇ／Ｌとなるように添加して被処理水を得た。被処理水のｐＨは８．３であった。
【００３３】
この被処理水に、被処理水１Ｌあたり２．０ｍｇ／ｍｉｎの流量で、渦流ポンプを用いてオゾンを供給し混合させた。その混合液に、紫外線の照射条件を制御可能な装置を用いて紫外線を照射し、２０分間循環処理した。その後、酸化還元電位電極を接続した酸化還元電位値モニターにより、酸化還元電位値を測定した。使用した装置は、実施例１と同じである。紫外線を照射せずに処理した後述の比較例８における酸化還元電位値の９００ｍＶ（基準値）に対して８６．１％にあたる７７５ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が１．５Ｗであった。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表２に示す。
【００３４】
（実施例４）
紫外線を照射せずに処理した後述の比較例８における酸化還元電位値の９００ｍＶ（基準値）に対して９４．４％にあたる８５０ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が０．９Ｗであった以外は、実施例３と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表２に示す。
【００３５】
（比較例５）
紫外線を照射せずに処理した後述の比較例８における酸化還元電位値の９００ｍＶ（基準値）に対して９８．９％にあたる８９０ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が０．３Ｗであった以外は、実施例３と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表２に示す。
【００３６】
（比較例６）
紫外線を照射せずに処理した後述の比較例８における酸化還元電位値の９００ｍＶ（基準値）に対して８３．３％にあたる７５０ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が２．２Ｗであった以外は、実施例３と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表２に示す。
【００３７】
（比較例７）
紫外線を照射せずに処理した後述の比較例８における酸化還元電位値の９００ｍＶ（基準値）に対して２４．４％にあたる２２０ｍＶで、酸化還元電位値が一定となるようにしたところ、前記装置における紫外線の出力が６．７Ｗであった以外は、実施例３と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表２に示す。
【００３８】
（比較例８）
紫外線を照射しない以外は、実施例３と同様の条件で処理を行った。このときの酸化還元電位値とペンタクロロベンゼンの除去率を表２に示す。
【００３９】
実施例３、４ 比較例５〜８を、図１において△で示す。
【００４０】
【表２】
表２より、紫外線の照射量を変えることで、酸化還元電位値は変化することが分かる。
【００４２】
紫外線を照射せずに処理した比較例８の酸化還元電位値（９００ｍＶ）に対し、８６％の酸化還元電位値（７７５ｍＶ）の実施例３ではペンタクロロベンゼン除去率が９７．４％であり、９４％の酸化還元電位値（８５０ｍＶ）の実施例４ではペンタクロロベンゼン除去率が９６．９％であり、ほとんど除去できたことが分かる。
【００４３】
紫外線を照射せずに処理した比較例８の酸化還元電位値（９００ｍＶ）に対し、９５％（８５５ｍＶ）を超えた９９％の酸化還元電位値（８９０ｍＶ）の比較例５では、ペンタクロロベンゼン除去率が７２．８％と低かった。
【００４４】
また、８５％（７６５ｍＶ）未満である８３％の酸化還元電位値（７５０ｍＶ）の比較例６、および２４％の酸化還元電位値（２２０ｍＶ）の比較例７では、実施例３、４に対し、紫外線の照射量を増加させているが、ペンタクロロベンゼン除去率は９７．２％、９７．６％と変化しなかった。このように、一定値以上に紫外線の照射量を増加させても、得られる効果に差はなく、経済性だけが低下することが分かる。
【００４５】
【発明の効果】
本発明の方法を用いれば、経済的にかつ効率的に、汚水中に微量に含まれるダイオキシン類などの有機汚濁物質を分解除去することができる。
【図面の簡単な説明】
【図１】 紫外線出力に対するペンタクロロベンゼンの除去率を示すグラフである。
【図２】 溶存オゾン濃度に対する酸化還元電位値を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for removing organic pollutants such as organic chlorine compounds typified by dioxins, which are contained in wastewater such as industrial wastewater and industrial wastewater.
[0002]
[Prior art]
Conventionally, sewage treatment methods such as industrial wastewater and industrial wastewater include coagulation sedimentation treatment and filtration treatment for the removal of suspended solids, biological treatment for treatment of organic pollutants, advanced treatment using activated carbon, etc. And so on.
[0003]
However, with such a conventional treatment method, it has been extremely difficult to effectively remove organic pollutants such as organic chlorine compounds such as dioxins and endocrine chemical substances.
[0004]
As a conventional method for removing these organic pollutants, there has been a treatment method combining ozone and ultraviolet rays. In this treatment method, organic pollutants are removed by an oxidation reaction by hydroxyl radicals generated by a reaction between ozone and ultraviolet rays and a photochemical reaction by ultraviolet rays.
[0005]
[Problems to be solved by the invention]
However, the main reaction is an oxidation reaction of hydroxyl radical. Therefore, the irradiation amount of ultraviolet rays may be an amount that efficiently generates hydroxyl radicals from ozone. Even if ultraviolet rays are irradiated beyond that, only the energy cost increases. Furthermore, when the action of the photochemical reaction due to ultraviolet rays is increased, there is a possibility that a chlorine addition reaction occurs due to chlorine radicals generated by the dechlorination reaction and a by-product is generated.
[0006]
In view of the problems of the conventional treatment method, the present invention efficiently generates hydroxyl radicals from the supplied ozone by changing the irradiation amount of ultraviolet rays, and in a short time removes organic pollutants in sewage. And it aims at providing the method which can be removed economically.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, in the sewage treatment in which the water to be treated is irradiated with ultraviolet rays in contact with ozone, the oxidation-reduction potential value shown in the absence of ultraviolet irradiation and in contact with ozone is used as a reference value, and the reference The irradiation condition of ultraviolet rays is changed so that the redox potential value is within a certain range with respect to the value, and the amount of change from dissolved ozone to hydroxy radical is controlled.
[0008]
Measure the irradiation conditions of ultraviolet rays so that the oxidation-reduction potential value measured in the absence of ultraviolet irradiation and under ozone contact is used as a reference value, and the oxidation-reduction potential value is 75 to 95% of the obtained reference value. It is desirable to change . Furthermore, it is desirable to change the irradiation condition of ultraviolet rays so that it may become 85 to 90%.
[0009]
By this method, the amount of hydroxyl radicals obtained by changing the dissolved ozone in the water to be treated can be optimally controlled.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the method of the present invention, water to be treated containing organic pollutants such as organic chlorine compounds typified by dioxins is introduced into a reaction tank by a pump, and the water to be treated in the reaction tank is irradiated with ultraviolet rays. Contact with ozone. In the reaction tank, the reaction between ultraviolet rays and ozone generates hydroxyl radicals that have stronger oxidizing power than ozone, and organic pollutants such as organic chlorine compounds typified by dioxins are oxidized and decomposed into low molecular weight substances. Removed.
[0011]
By mixing ozone, as shown in FIG. 2, when the concentration of dissolved ozone increases, the oxidation-reduction potential value increases. When ultraviolet rays are irradiated, dissolved ozone is reduced mainly by hydroxyl radicals due to photochemical action, and at the same time, the oxidation-reduction potential value decreases.
[0012]
That is, the dissolved ozone concentration can be observed by measuring the redox potential value. Further, the amount of dissolved ozone consumed by ultraviolet irradiation can be observed by the ratio of the oxidation-reduction potential value during ultraviolet irradiation to the oxidation-reduction potential value before ultraviolet irradiation.
[0013]
For this reason, it is possible to control so that dissolved ozone is effectively changed to hydroxyl radicals by measuring the oxidation-reduction potential value and changing the irradiation amount of ultraviolet rays so as to be constant.
[0014]
Specifically, taking into consideration the influence of pH change, temperature change, etc. on the oxidation-reduction potential value, the oxidation-reduction potential value is 75 to 95 of the oxidation-reduction potential value shown when ozone is mixed before ultraviolet irradiation. It is recommended that the amount of UV irradiation be controlled so as to be within the range of%, and it is recommended to control within the range of 85 to 90%.
[0015]
At this time, if the oxidation-reduction potential value is higher than 95% of the oxidation-reduction potential value shown when ozone is mixed before the ultraviolet irradiation, the amount of hydroxyl radicals generated becomes insufficient, and the organic pollutant removal rate decreases. Moreover, even if it is made lower than 75%, the improvement rate of removal of organic pollutants is hardly seen, resulting in an increase in processing costs, and by-products are easily generated by the photochemical reaction of ultraviolet rays.
[0016]
Control by the irradiation amount of ultraviolet rays can be performed by changing the output of ultraviolet rays, the intensity of ultraviolet rays, or the irradiation time of ultraviolet rays.
[0017]
As a method for measuring the oxidation-reduction potential value, an oxidation-reduction potential value monitor using an oxidation-reduction potential electrode can be used.
[0018]
(Example)
Hereinafter, an embodiment of the present invention will be described in detail, but the present invention is not limited thereto.
[0019]
(Example 1)
Industrial wastewater was subjected to agglomeration treatment and biodegradation treatment, and pentachlorobenzene was added as an organic pollutant to a concentration of 45 μg / L to obtain treated water. The pH of the water to be treated was 8.3.
[0020]
To this water to be treated, ozone was supplied and mixed using a vortex pump at a flow rate of 10 mg / min per liter of water to be treated. The mixed solution was irradiated with ultraviolet rays using a device capable of operating ultraviolet irradiation conditions (manufactured by Flipx Corporation, model TUV16W) and circulated for 8 minutes. Thereafter, the oxidation-reduction potential value was measured by an oxidation-reduction potential value monitor (DKK, model PHL20) connected with an oxidation-reduction potential electrode (DKK, model 6154: 0.65 W). When the oxidation-reduction potential value was made constant at 850 mV corresponding to 86.7% with respect to 980 mV (reference value) of the oxidation-reduction potential value in Comparative Example 4 described later treated without being irradiated with ultraviolet rays, the apparatus The output of ultraviolet rays at 3.2 was 3.2 W. Table 1 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0021]
(Example 2)
When the oxidation-reduction potential value was made constant at 930 mV, which is 94.9% with respect to 980 mV (reference value) of the oxidation-reduction potential value in Comparative Example 4 to be described later processed without irradiating ultraviolet rays, the apparatus The treatment was performed under the same conditions as in Example 1 except that the output of ultraviolet rays at 1.5 was 1.5 W. Table 1 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0022]
(Comparative Example 1)
When the oxidation-reduction potential value was made constant at 970 mV, which is 99.0% with respect to 980 mV (reference value) of the oxidation-reduction potential value in Comparative Example 4 to be described later treated without irradiating ultraviolet rays, the apparatus The treatment was performed under the same conditions as in Example 1 except that the ultraviolet light output at was 0.9 W. Table 1 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0023]
(Comparative Example 2)
When the oxidation-reduction potential value was made constant at 725 mV, which is 74.0% with respect to 980 mV (reference value) of the oxidation-reduction potential value in Comparative Example 4 to be described later processed without irradiating ultraviolet rays, the apparatus The treatment was performed under the same conditions as in Example 1 except that the ultraviolet light output at was 0.9 W. Table 1 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0024]
(Comparative Example 3)
When the oxidation-reduction potential value was made constant at 500 mV corresponding to 51.0% with respect to 980 mV (reference value) of the oxidation-reduction potential value in Comparative Example 4 described later treated without irradiating ultraviolet rays, the apparatus The treatment was performed under the same conditions as in Example 1 except that the output of ultraviolet rays at 6.7 was 6.7 W. Table 1 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0025]
(Comparative Example 4)
The treatment was performed under the same conditions as in Example 1 except that ultraviolet rays were not irradiated. Table 1 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0026]
Examples 1 and 2 Comparative Examples 1 to 4 are indicated by ◯ in FIG.
[0027]
[Table 1]
From Table 1, it can be seen that the oxidation-reduction potential value changes by changing the irradiation amount of ultraviolet rays.
[0029]
In Example 1, which had a redox potential value (850 mV) of 87% compared to the redox potential value (980 mV) of Comparative Example 4 treated without being irradiated with ultraviolet rays, the pentachlorobenzene removal rate was 99.3%, 95 In Example 2 having an oxidation-reduction potential value of 930% (930 mV), the pentachlorobenzene removal rate was 98.1%, and it can be seen that the removal was almost complete.
[0030]
In Comparative Example 1, which has a redox potential value (970 mV) of 99% exceeding 95% (931 mV) compared to the redox potential value (980 mV) of Comparative Example 4 that was treated without being irradiated with ultraviolet rays, the removal rate of pentachlorobenzene was Was as low as 92.5%.
[0031]
In Comparative Example 2 having a redox potential value of 74% (725 mV) of less than 85% (833 mV) and Comparative Example 3 having a redox potential value of 51% (500 mV), Although the irradiation amount of ultraviolet rays was increased, the removal rate of pentachlorobenzene did not change to 98.8% and 98.2%. Thus, it can be seen that even if the irradiation amount of ultraviolet rays is increased to a certain value or more, there is no difference in the obtained effect and only the economic efficiency is lowered.
[0032]
(Example 3)
Industrial wastewater was subjected to agglomeration treatment and biodegradation treatment, and pentachlorobenzene was added as an organic pollutant to a concentration of 45 μg / L to obtain treated water. The pH of the water to be treated was 8.3.
[0033]
Ozone was supplied to the water to be treated at a flow rate of 2.0 mg / min per liter of water to be treated using a vortex pump and mixed. The mixed solution was irradiated with ultraviolet rays using a device capable of controlling the irradiation conditions of ultraviolet rays and circulated for 20 minutes. Thereafter, the oxidation-reduction potential value was measured by an oxidation-reduction potential value monitor connected to the oxidation-reduction potential electrode. The apparatus used is the same as in Example 1. When the oxidation-reduction potential value was made constant at 775 mV corresponding to 86.1% with respect to 900 mV (reference value) of the oxidation-reduction potential value in Comparative Example 8 to be described later treated without irradiating ultraviolet rays, the apparatus The output of ultraviolet rays at 1.5 was 1.5 W. Table 2 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0034]
(Example 4)
When the oxidation-reduction potential value was made constant at 850 mV, which is 94.4% with respect to 900 mV (reference value) of the oxidation-reduction potential value in Comparative Example 8 to be described later treated without being irradiated with ultraviolet rays, the apparatus The treatment was performed under the same conditions as in Example 3, except that the output of ultraviolet rays at 0.9 was 0.9 W. Table 2 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0035]
(Comparative Example 5)
When the oxidation-reduction potential value was made constant at 890 mV corresponding to 98.9% with respect to 900 mV (reference value) of the oxidation-reduction potential value in Comparative Example 8 described later treated without irradiating ultraviolet rays, the apparatus The treatment was performed under the same conditions as in Example 3 except that the output of ultraviolet rays at 0.3 was 0.3 W. Table 2 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0036]
(Comparative Example 6)
When the oxidation-reduction potential value was made constant at 750 mV, which is 83.3% with respect to 900 mV (reference value) of the oxidation-reduction potential value in Comparative Example 8 to be described later treated without being irradiated with ultraviolet rays, the apparatus The treatment was performed under the same conditions as in Example 3 except that the output of ultraviolet rays at 2.2 was 2.2 W. Table 2 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0037]
(Comparative Example 7)
When the oxidation-reduction potential value was made constant at 220 mV, which is 24.4% with respect to 900 mV (reference value) of the oxidation-reduction potential value in Comparative Example 8 to be described later treated without being irradiated with ultraviolet rays, the apparatus The treatment was performed under the same conditions as in Example 3 except that the output of ultraviolet rays at 6.7 was 6.7 W. Table 2 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0038]
(Comparative Example 8)
The treatment was performed under the same conditions as in Example 3 except that ultraviolet rays were not irradiated. Table 2 shows the oxidation-reduction potential value and the removal rate of pentachlorobenzene.
[0039]
Examples 3 and 4 Comparative Examples 5 to 8 are indicated by Δ in FIG.
[0040]
[Table 2]
From Table 2, it can be seen that the oxidation-reduction potential value changes by changing the irradiation amount of ultraviolet rays.
[0042]
Compared to the oxidation-reduction potential value (900 mV) of Comparative Example 8 treated without irradiating ultraviolet rays, the removal rate of pentachlorobenzene was 97.4% in Example 3 having an oxidation-reduction potential value (775 mV) of 86%, 94 In Example 4 having a redox potential value of 850% (850 mV), the removal rate of pentachlorobenzene was 96.9%, which indicates that the removal was almost complete.
[0043]
With respect to the redox potential value (900 mV) of Comparative Example 8 treated without being irradiated with ultraviolet rays, the removal rate of pentachlorobenzene in Comparative Example 5 having a redox potential value of 99% (890 mV) exceeding 95% (855 mV) Was as low as 72.8%.
[0044]
In Comparative Example 6 having an oxidation-reduction potential value (750 mV) of 83% that is less than 85% (765 mV) and Comparative Example 7 having an oxidation-reduction potential value (220 mV) of 24%, Although the amount of ultraviolet irradiation was increased, the removal rate of pentachlorobenzene did not change to 97.2% and 97.6%. Thus, it can be seen that there is no difference in the effect obtained even if the irradiation amount of ultraviolet rays is increased to a certain value or more, and only the economical efficiency is lowered.
[0045]
【The invention's effect】
By using the method of the present invention, it is possible to decompose and remove organic pollutants such as dioxins contained in a trace amount economically and efficiently.
[Brief description of the drawings]
FIG. 1 is a graph showing the removal rate of pentachlorobenzene with respect to ultraviolet output.
FIG. 2 is a graph showing a redox potential value with respect to a dissolved ozone concentration.
Claims (3)
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| JP2000146316A JP3687488B2 (en) | 2000-05-18 | 2000-05-18 | Removal method of organic pollutants in sewage |
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| JP3687488B2 true JP3687488B2 (en) | 2005-08-24 |
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