CA1094702A - Process for the detoxication of waste water containing phenol, phenol derivatives, or phenol and formaldehyde (1) - Google Patents
Process for the detoxication of waste water containing phenol, phenol derivatives, or phenol and formaldehyde (1)Info
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- CA1094702A CA1094702A CA295,737A CA295737A CA1094702A CA 1094702 A CA1094702 A CA 1094702A CA 295737 A CA295737 A CA 295737A CA 1094702 A CA1094702 A CA 1094702A
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- phenol
- waste water
- formaldehyde
- salt
- iron
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
- Removal Of Specific Substances (AREA)
- Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a process for the purifi-cation of waste water containing phenol, phenol derivatives or phenol plus formaldehyde which process treats the waste water with hydrogen peroxide in the presence of metallic iron or copper.
The present invention provides a process for the purifi-cation of waste water containing phenol, phenol derivatives or phenol plus formaldehyde which process treats the waste water with hydrogen peroxide in the presence of metallic iron or copper.
Description
The present invention relates to the detoxication of - waste water, e.g. industrial effluent containing phenol, phenol ~ derivatives or phenol and formaldehyde.
Phenol-containing waste water with varying phenol con-centrations is obtained in the phenol synthesis, in coke plants and gas plants, in lignite-coking plants and last, but not least in the production of phenol-formaldehyde resins (phenolic plas-tics).
~. ~
The total removal of the toxically reacting phenol and the likewise toxically reacting formaldehyde from waste water of the industrial branch mentioned last, particularly for a subse-quent biological purification of this kind of waste water is as much as ever a very important problem, which has not yet been satisfactorily solved within a wide range of concentrations.
In the case of the phenolic plastics mentioned herein-before, for example, in the so-called "reaction water" which reacts either alkaline or acid depending on the condensation process, the content of volatile phenol can be of the order of 1700 to 15000 mg per litre, and that of free formaldehyde between 1200 and 8100 mg per litre. (F. Meinck, H. Stoof, H. Kohlschuter "Industrie-Abwasser, 4th edition, Gustav Fischer-Verlag, Stuttgart, `
1968, page 619).
A large number of processes for the purification of waste water are known. However, they are not universally appli-cable over a wide range of concentrations.
In cases of high phenol concentrations, for example, for the recovery of phenol, distillation with steam may be r suitable. Moreover several extraction processes in which an extraction of the phenol is carried out with e.g. benzene, toluene or tricrysyl phosphate is known. However, these processes have the disadvantage that certain residual components of the extracting agent get into the waste water.
109"702 Furthermore, the "de~3ree of wa<;hing out" of the diff~rent processes varies so that a total removal of the phenol is not possible.
A total dephenolization can be attained by evaporating the waste water and by burning the residues. I~owever, this process requires a high consumption of energy.
In cases of low phenol concentrations an adequate re-moval of the phenol can also be attained with the aid of special active carbons. However, the effect depends on amount, type and ~ranulation of the carbon as well as on the process (duration of r action, pH value and temperature of the waste water.) Depending on composition and concentration of the phenol-containing waste water the effect of adsorption varies greatly and at medium and high concentrations, for example, at 1000 p.p.m. and higher, said process is too costly.
Another adsorption process comprises the use of specific synthetic resins, for example, polymethacrylates and polyvinyl benzenes. Thus, for example, in a phenol-containing waste water the phenol content could be reduced from 6700 p.p.m. to approxi-mately 0.1 p.p.m. (U.S. Patents 3 663 467 and 3 531 463).
However, these adsorption processes cannot be applied to phenol-formaldehyde-containing waste water of the synthetic resin industry since, now as always, the toxically reacting formaldehyde remains in the waste water.
; In individual cases waste water rich in phenol can also be treated biologically by means of the so-called "Nocardia process". Pure cultures of these types of organism, which are related to the actinomyces, are settled in trickling-filter or activated-sludge plants. In the most favourable case a purifying effect of 99% can be attained so that even with biological degra-dation a certain residual amount remains. The effect depends largely on the other conditions. Thus, the flora is severely damaged by a phenol shock which is too severe or by other waste- P
1~94702 water toxins and possibly the ~lora is even destroyed. The pro-cess thus does not reliably detoxicate waste water. Moreover, ~ for the adaptation of such a special biological film or activated sludge N- and P- containing nutrient salts must be added (Gesundh-Ing. 81 (1960), 205 ff). These measures require the relatively costly operation of a special biological purification plant.
A well-known process is that of oxidizing the phenol by means of chlorine dioxide, which is obtained either by the r action of acids on chlorite, preferably sodium chlorite, or by reacting chlorine with sodium chlorite, for example, in a sulphuric-acid medium.
However, the latter process involves the risk that F
the phenol is chlorinated to the even more toxically reacting chloro phenols. Furthermore the reaction is not 100% efficient.
This also applies to the generation of chlorine dioxide by the action of acid on chlorite. In this case, too, an extensive oxidation can be attained. However, these kind of tests were F
performed by the applicant and the gas-chromatographical analysis of waste water thus treated have shown that after the oxidation greatly varying residual contents of phenol of the order of more L
than 10 to above 100 p.p.m. are still present. Moreover, the gas chromatograms shows extraneous peaks whicn have not yet been f ~dentified. However, it is assumed that they are intermediate oxidation products including quinones, hydroquinones or possibly even chlorinated products (see H. Thielemann, Gesundh.-Ing. 92 (1971) No. 10,297). r Corrosion problems due to intense acidification of the waste water should also be taken into account.
According to references in the literature (Klossowski, Jerzy, Gaz, Woda Tech. Sanit. (1968), 42, 197-200) phenols and its derivatives are destroyed by gaseous chlorine dioxide (generated from sodium chlorite and sulphuric acid) in amounts of only 83~.
In the acid to neutral ran~e the oxidation of phenol by chlorine dioxide results in p-benzoquinone as the final product of the phenol oxidation while in the alkaline mediurn a mixture of or~anic acids, primarily maleic acid and oxalic acid, is formed due to a high excess of chlorine dioxide (5 mg of CLO2 per 1 mg of phenol (Chemical Abstracts, 79, 23266 M).
In the USSR Patent 141,814 the purification of waste watèr of the phenol-formaldehyde-resin production is described r 10 and the formaldehyde is to be removed by treating the water with "quick lime" at room temperature or at 98C and the phenol is to be removed by oxidation either electrochemically or with ~nO2.
This process is relatively costly. By "quick lime" is meant calcium oxide.
In another process the removal of phenol, methanol and formaldehyde from waste water is carried out by means of a so-called "liquid-phase oxidation" (I.S. Stepanyan, I.A. Vinokur, G.M. Padaryan, khim. prom (1972), 6, 30/31 and Int. Chem. Eng.
12 (1972), 4, 649/6513. In this process the waste water is fed 20 into an electrically heated reactor by means of air under a pressure of 40 bars and at 200C. However, test data have only shown degrees of oxidation of approximately 95% for phenol, 77%
for methanol and 93% for formaldehyde.
In another series of tests the degrees of oxidation were only at 80% for said substances. The process is technically very expensive. Residues of the toxically reacting substances remain. r~
A process for the prepurification of waste water which contains phenol, formaldehyde and their reaction products is described in the laid-open Gerrnan Specification 2,404,264.
According to this process water-soluable aminoplast-resin precondensates or their aqueous solutions are added to the F
waste water. The reaction mixt:ure is kept in the alkaline range at boiling temperature for 2 to 8 hours and the precipitated - ~ reaction products are separated.
As is evident from the cited examples only a prepurifi-cation of this kind of waste water can be attained with this process; a complete removal of phenol and formaldehyde is impos-sible.
It has also been proposed to treat phenol-containing waste water and phenol- and formaldehyde-containing waste water r with alkali or alkaline-earth metal chlorites in the presence of specific amounts of formaldehyde (Gerrllan Patent... /Patent Application P2657 192.6).
A complete elimination of phenol and formaldehyde is achieved with this process, but the waste water thus treated is salified by the alkali or alkaline earth metal chlorites. If required, the waste water thus treated can then be subjected to an aftertreatment with active carbon.
It is also known to remove phenol from waste water r with hydrogen peroxide, in the presence of ferric chloride. In this case the pH value of the waste water is adjusted to 2.5 - 3.5 prior to the treatment and to 10 after the treatment. After clarifying the suspension with corresponding agents, the waste water still contains 0.3 p.p.m. of phenol (Japanese Patent Application 118 8902/72-laid open under No. 77449/74~
In yet another process for the detoxication of phenol-and formaldehyde-containing waste water hydrogen peroxide is also ~
used in amounts of more than 1.5 times the COD value of the F
waste water, as well as ferrous sulphate. On adding the hydrogen peroxide and the ferrous salt the pH value of the waste water is reduced to 3-4 (Japanese Patent Application 44906/72 - laid open under No. 6763/74).
The two processes mentioned last relate to low phenol and formaldehyde contents of up to 100 p.p.m.
In order to assure complete oxidation in the case of high phenol contents, the amount of iron salts must be increased correspondingly and this results in an intolerable salt load.
Moreover, in the process mentioned last, a residual formaldehyde content of at least 50 p.p.m. remains.
Furthermore the processes mentioned hereinbefore had no detoxicating effect on waste water which contained phenol derivatives such as pyrocatechol, resorcinol, pyrogallol, cresols, f chloro phenol and hydroquinone.
The present invention eliminates essentially completely phenol, phenol derivatives or phenol plus formaldehyde from waste water even in the case of high concentrations but without loading the waste water with salt. By high concentrations are meant contents of phenol and phenol derivatives up to a maximum of 0.5%
by weight and formaldehyde contents of up to a maximum of 5% by weight since the process is not so economical at higher concen-trations.
It has now been found that waste water which contains phenol, phenol derivatives or phenol and formaldehyde can be freed, completely from these compounds by the addition of hydrogen peroxide without resulting in salt loads when the waste water is treated with hydrogen peroxide in the presence of metal-~ic iron or copper.
According to the present invention therefore there is provided a process for the purification of waste water containing phenol, phenol derivatives or phenol plus formaldehyde which r process treats the waste water with hydrogen peroxide in the presence of metallic iron or copper. Desirably the waste water is neutral or weakly acid reacting waste water.
Said metals can be put into the waste water tanks in the form of sheets, wires or yranulates. In the case of iron, which ~,094702 is particularly preferred, the metal can also be present as the reactor material, for example, as an iron reaction tank or ~ . waste-water tank or even as an iron stirrer. Copper is usually not used in this form for reasons of costs.
It has been found that an iron surface of 1 to 20 square metres per cubic metre of waste water is most favourable.
The industrial types of iron, such as crude iron, cast iron and steel, maybe used as iron (see "Ullmann", 1975, Vol. 10, page 321). The commercial types o, copper are used as copper (see, for example, "Ullmann", Enzyklopadie der Technischen Chemie, 1960, Vol. 11, page 205-206).
In contrast to said processes with hydrogen peroxide and iron salts the present process is independent of the pH
value. It can be carried out with neutral acid or alkaline waste ~ater without any difficulty.
The start of the detoxication reaction depends on the L
concentration of the phenol or phenol derivatives and of the phenol and formaldehyde on the one hand and on the metal surface available per cubic metre of waste water of the other (see Example t 1 and 2).
If the detoxication reaction does not start as fast as desired, then it is favourable to add very small amounts of activators in order to start the reaction. Halides, sulphates, nitrates but also organic salts, such as formates of alkali or alkaline earth metals, such as sodium, potassium, calcium or barium are suitable as activators. However, the corresponding salts of zinc, aluminium, nickel and manganese are also suitable.
Sodium chloride is very suitable. The activators may ~e used in amounts of 0.1 to 0.2% by weight, relative to the hydrogen peroxide used. It is possible to add them dissolved in hydrogen peroxide or in a solid form directly to the waste water. Highly dispersed silicas, which are insoluble in water, are also suitable as 1094~02 activators, likewise in the amounts mentioned above.
~ydrogen peroxide is used in amounts of 7.5 to 8 moles - ~ per mole of phenol or phenol ~erivative. In the presence of formaldehyde, 2 additional moles of hydrogen peroxide are required per mole of formaldehyde.
The detoxication is preferably carried out at room temperature or at the temperature at which the waste water is obtained.
In general, the waste water to be detoxicated can be used as such for the process. Only at phenol concentrations above 5000 p.p.m. is it advisable to dilute the waste water to phenol values below 5000 p.p.m. if a purification by means of the process according to the present invention is desired so that the reaction is not too turbulent.
The quantitative determination of phenol and possibly of derivatives thereof is carried out by means of gas chromato-graphy under the following conditions: ~
Gas chromatograph Perkin-~lmer F 7 with FID. Temperature !
of the column 180C; injection block 230C; flow approximately 24 ml per minutes; column 1 m of Poropak P, No. 85, amount of sample 1/u litre per minute; paper feed 0.5 cm per minute.
The analysis is carried out colorimetrically with the aid of the very sensitive condensation reaction between formalde- ;
hyde, acetyl acetone and arnmonia or ammonium acetate to the yellow- L
colored diacetyl-dihydro lutidine (T. Nash, Nature (London) 170 (1952), g76).
It has been found that the use of hydrogen-peroxide F
solutions in which 0.05 to a maximum 0.1~ by weight of NaCl is dissolved is the simplest and an elegant procedure. Of course the sodium chloride can also be added in a solid form to the waste water to be treated.
The procedure then is usually such that the corresponding amount of hydrogen peroxide with approximately 0.1% of activator, preferably sodium chloride is added, while stirring, to the waste water con~aining phenol, phenol derivatives or phenol and formaldehyde. Within a few minutes after the addition is com- -pleted the oxidation starts at room temperature. The oxidation is evident from the darkening of the waste water, the generation of carbon dioxide, the increase in temperature and the decrease of~the pH value to values of 2 and 1. After the completion of the entire reaction, which usually takes 30 to 60 minutes and is indicated by the abating generation of gas, the end of the temperature increase and the start of cooling, the acid-reacting waste water is neutralized. The small amount of iron ions present precipitates at the same time.
All the known alkali or alkaline earth metal hydroxides are suitable for the neutralization. However, calcium hydroxide in the form of milk of lime is preferred. ~-After the iron hydroxide precipitate and possibly the alkaline-earth metal hydroxide precipitate have settled, the virtually colorless, completely detoxicated waste water can be fed to the biological purification plant.
It is important that with the presence of metallic iron or copper and traces of salt but without the presence of hydrogen peroxide no metal ions are detached, not even after several hours.
Only after the addition of the hydrogen peroxide does a violet, partially also brownish-colored haze detach itself from the metal surface and probably accelerates the oxidation catalytically.
Thus, no minimum concentration of iron salts is re-quired as according to the Japanese patent applications mentioned hereinbefore, i.e., a concentration of iron salts which must be adapted to the phenol concentration concerned, but the lowest possible concentration of iron ions is automatically obtained irrespective of the phenol concentration present in each case.
Apart from phenol, o- and p- cresol as well as t- butyl phenol and hydroquinone can also be eliminated by means of the ~- process according to the present invention. P
The process of the present invention will be further illustrated by way of the following examples.
For this purpose synthetically produced waste water having contents of phenol, phenol derivatives and phenol plus formaldehyde bet~een 100 and 5000 p.p.m. and waste water from the ~. ~
phenolic resin industry is used.
The percentages are percent by weight.
Example 1:
To 7 waste-water samples having phenol contents of 0.5% and pH
values between 4 and 6, 0.4 ml of a 10% solution of the following salts were added per litre:
Na~l, Ca formate, MnC12, MnSO4, CuSO4, AlC13 and NiSo4.
After the addition of the salt solutions 140 to 150 ml of a 10% hydrogen peroxide solution were added to each of the waste water samples while stirring. Iron sheets having identical total surfaces (8 sq m per cu m of waste water) were suspended 20 in the samples. The sheet iron used consisted of structural ,-steel St 37. ' Shortly after the addition of the hydrogen peroxide solutions the oxidation reaction started, evident from the darkening of the solutions, the increase in temperature from 50 to 60C, the generation of carbon dioxide and the decrease of the pH value.
Within 40 to a maximum of ~0 minutes the oxidation was F
completed, the temperature dropped slowly and the pH value was between 1.~ and 1.9.
The samples were neutralized by adding a 30% milk of lir,le which precipitated.
After the lime of milk precipitate had settled, the -- 10 -- `
lOg470Z
supernatant clear waste water was analyzed in the manner described hereinbefore.
The analysis showe~ that the phenol had been completely eliminated.
Example 2:
An alkaline reacting waste water having a pH value of 8.7 and containing 0.5~ of phenol was mixed with 4 ml of a 10%
sodium-chloride solution, relative to 1 litre of waste water, whereupon 140 ml of a 10% hydrogen peroxide solution (per litre of waste water) was added while stirring. The same iron sheets as in example 1 were suspended in the waste water.
The oxidation reaction started only after 30 to 40 minutes and was completed after a maximum of 60 minutes. The course of the oxidation with respect to discoloration, increase in temperature, generation of carbon dioxide and decrease of the pH was the same. On completion of the reaction, the strongly acid-reacting waste water, which had a pH value of 1, was neutral-ized amd treated as in example 1.
In this case, too, the phenol had been completely removed.
Example 3:
!
A waste-water sample containing 0.5% of phenol and 0.5~ of formaldehyde and having a pH value of 5.6 was mixed with 253 ml of a 10% hydrogen-peroxide solution, relative to 1 litre of waste water. 0.1% of NaCl had first been dissolved in the hydrogen-peroxide solution. The iron sheets had been suspended in the waste-water sample as in example 1. Immediately upon the r addition of the hydrogen-peroxide solution provided with sodium chloride the oxidation reaction started while stirring. The reaction was evident from the features described in the preceding examples. The reaction was completed after approximately 30 r minutes while the temperature increased to 55C and the pH value decreased to l.5. By adding milk of lime the treated waste water was neutralized and after the precipitate had settled the super-natant water assumed a yellowish-coloration.
The presence of formaldehyde had accelerated the reaction. The analysis showed that boththe phenol and the form-aldehyde had been completely eliminated.
Example ~:
~ ~ waste water sample containing 0.5% of phenol and the same amount of formaldehyde and having a pH value of 5.3 was ~ixed with 255 ml of a 10% hydrogen-peroxide solution, relative to 1 litre of waste water.
0.1% of NaCl had been dissolved in the hydrogen peroxide solution. Sheet copper (a 99.9% copper metal) had been put into the waste water, using 15 square metres of sheet copper per cubic metre of waste water.
` After adding the hydrogen-peroxide solution it took a lengthy time before the start of the reaction was noticeable t (evident from the darkening of the waste water). Compared with the reactions in the presence of metallic iron the reaction was retarded; the pH value decreased more slowly and the rise in temperature also slowed down.
Only after several hours was the reaction completed.
In all other respects, as for example, coloration, decrease in the pH value, increase in temperature, the reaction was analogous to the reactions described in the preceding examples.
The neutralization was carried out in the manner described hereinbefore. The waste water of yellowish coloration above the deposited precipitate contained neither phenol nor formaldehyde.
Example 5:
A waste-water sample containing 0.5% of phenol was F
treated with a 10% hydrogen peroxide solution (amount added: 140 ~094702 ml per litre of waste water) in the presence sheet iron and sheet copper. The metal sheets corresponded to those used in the examples 1 and 4. The initial pH value of the waste water was X
4.5. At room temperature the reaction was considerably retarded;
only after slight heating to 40C could the oxidation be completed within 70 to 80 minutes under the conditions described herein-before. The analysis showed that the neutralized waste water was free from phenol.
Example 6:
A waste-water sample containing 0.5% of phenol and having a p~ value of 6.3 was mixed with 5 g of a highly dispersed silica. Sheet iron was suspended in the waste-water sample corresponding to example 1, whereupon hydrogen peroxide was added in an amount corresponding to the phenol concentration. 140 ml of a 10% hydrogen-peroxide solution was used per litre of waste water.
After approximately 60 minutes the reaction started while the temperature rose and the pH value decreased substantial- r ly. Within further 2 hours the reaction was completed. The pH
value was 1.8. After the treatment with milk of lime, the supernatant waste water was colorless and clear. Phenol could no longer be detected.
Example 7:
A large number of waste-water samples having different contents of phenol and formaldehyde between 100 and 5000 p.p.m.
were treated in the presence of metallic iron (corresponding to .
example 1) with a 35% by weight of peroxide solution and NaCl by F
oxidation as in the preceding examples.
Some of the sodium chloride was dissolved in the peroxide solution (maximum amount 0.1~) and some of it was dissolved in the waste water. 200 mg of sodium chloride were used per litre of waste water.
In the Table hereafter the amounts of 35% by weight hydrogen-peroxide solution and sodium chloride used for the different concentrations of phenol and formaldehyde have been listed.
Table for Example 7 Elimination of Phenol and Formaldehyde from Waste Water.
Amounts of 35% by weight hydrogen-peroxide and NaCl per litre of ~aste water in the presence of metallic iron.
1) l~ydrogen-Peroxide Solution with 0.1% of NaCl.
~1aste Water ~laving Concentrations 35% by weight H2O2 NaCl of solution phenol formaldehyde ~ , ml mg 0,01 0 7'51) __ _ t~
0,5 1,0 96,5 200 0,5 0,75 81,51) 200 0,5 0,5 66,5 __ 0,5 0,25 51,5 200 0,2 0,4 38,6 200 0,2 0,3 32,6 200 0,2 0,1 20,5 200t : 0,1 0,1 ~3,51) __ 0,05 0,l 9,7 200 0,05 0,075 8,2 200 0,05 0,025 5,2 200 0Ol 0Ol 27l) r In all these cases a complete detoxication of the waste-water samples could be attained within a short time, i.e. from 30 to a maximum of 60 minutes, that is to say, faster at high phenol contents than at low ones.
Example 8:
In an iron reactor of V2~ steel having a capacity of 20 litres, waste-water samples having phenol contents of lO0 and lO00 p.p.m. and samples having phenol and formaldehyde contents of r lO0 to lO00 p.p.m. were treated with a 35% hydrogen-peroxide solution while stirring. Prior to the addition of the hydrogen peroxide solution, sodium chloride was dissolved in the waste water at a rate of 200 mg per litre of waste water. The amounts of 35r~ by weight peroxide corresponding to the concentrations of r phenol or phenol and formaldehyde are evident from Table of Example 7.
In all the mixtures the oxidation reaction proceeded according to the same pattern, which was already described in the preceding samples.
After less than 60 minutes the oxidation was completed.
The pH value of the treated waste-water samples was 2.5.
After corresponding further treatment of the waste-water samples the analysis showed that these samples were free from phenol and formaldehyde.
Example 9:
The analysis of an industrial effluent from the phenolic- .
resin industry(acid condensation with formaldehyde, novolak type) showed a phenol content of 4.5% and a total content of formalde- t hyde of 5.8~
Most of the formaldehyde was present in a combined form, merely 0.06~ thereof was free formaldehyde. The pH value of this industrial effluent was 3.
r~he effluent also contained other organic components, for example, residues of organic solvents, in addition to phenol and formaldehyde.
In order to detoxicate this waste water from phenol and formaldehyde, it was necessary to process this waste water at least ten times diluted with peroxide since otherwise the oxida-tion reaction would have been too turbulent and uncontrolled.
In a correspondingly large reactor, the entire inside ,~.
of which was provided with sheet iron, 46 litres of the original effluent were diluted with 410 litres of water. In this diluted waste water 100 g of sodium chloride were dissolved, whereupon 34.5 litres of a 35% by weight hydrogen-peroxide solution were added while stirring this amount of hydrogen-peroxide is slightly - above the amount required for phenol and formaldehyde for the F
10 oxidation since corresponding laboratory tests had shown that other organic components had to be oxidized concomitantly.
In order to prevent the reaction from becoming too turbulent, the hydrogen-peroxide solution was added in batches, i.e., in amounts of 5 to 10 litres at a time.
By means of this procedure the waste water could be completely detoxicated within 1 to 2 hours. During the treatment the temperature increased to 75C and the pH value which was 6.8 after the dilution of the original effluent dropped to 1.9.
After the addition of the first portion of hydrogen-peroxide, 20 intense foaming started due to intense generation of CO2 but it abated towards the end of the reaction.
After the oxidation reaction the treated waste was neutralized by adding a 30~ milk of lime while both lime and ferric hydroxide precipitated.
.. i The supernatant foam-free waste water, which was clear and light-colored could then be discharged.
The analysis showed that the waste water was completely free from phenol and formaldehyde.
Example 10:
~ waste-water sample containing 1000 p.p.m. of phenol and a second waste-water sample containing 1000 p.p.m. of phenol and 1000 p.p.m. of formaldehyde were treated in the presence of 10~4702 metallic sheet iron (corresponding to example 1) with the amount of a lOQo hydrogen-peroxide solution re~uired for the oxidation of phenol or ~henol plus formaldehyde. 0.1% of sodium chloride had been dissolved in the hydrogen-peroxide solution.
The oxidation proceeded in the manner described in the preceding examples. After completion of the reaction the samples were neutralized as in the preceding examples and the clear, light-colored waste water was decanted. Corresponding samples g were analyzed and the results of the analysis showed that phenol and formaldehyde were no longer present.
Apart from the analyses, the chemical and biochemical oxygen requirements were determined from the starting samples and from the sa~ples treated with hydrogen-peroxide. Furthermore, toxicity measurements, a fish test and the carbon determination were carried out.
In the starting samples, which still contained phenol and formaldehyde, the CSB was determined and in the treated waste-water samples the CSB, the BSB5, the toxicity, the fish toxicity and the TOC value were determined.
The toxicity was measured according to K. Offhaus in Sapromat and the fish toxicity with Guppys. The CSB values were measured by means of standard methods or with the method defined in the waste water control law. (~. tr - d~ ~ r~) The carbon determination was carried out with a Beckmann\ ' "Total Organic Carbon ~nalyzer".
The results are shown in the Table hereafter.
!
waste water contain- waste water containin~
ing 1000 p.p.m. of 100~ p.p.m. of phenol phenol and 1000 p.p.m. of formaldehy~ F
sample 1 sample 2 sample 3 sample 4 treated untreated treated untreated CSB (mg O2/litre) 140 2400 300 3400 ,BSB5(mg/litre) ~;
dilùted sample 33 _ 34 _ toxic inhibition in ~ 4 _ 15 _ (for 500 ml of sample in 1000 ml of mix-ture) ~4 . 160 _ TOC ~mg/litre) 50 _ 158 _ rAC (mg/litre) 34 _ 2 _ fish test:
the fish survived for 48 hours 333 ml _ 333 ml of _ f sample sample in n 1000 ml 1000 ml of ~f mixture mixture r . _ As the Table shows the CSB value could be reduced sub-stantially. The BSB5 value also is within an acceptable range.
The result of the fish test is interesting. According to this test the fish survived for 48 hours at a mixing proportion of the treated waste-water samples of 333 ml diluted in 1000 ml.
Example 11:
(Variation of the Iron Surface) .
(The type of iron used corresponded to that of example 1).
~ aste-water samples containing 5000 p.p.m., 1000 p.p.m.
and 100 p.p.m. of phenol were treated in the presence of metallic iron with the amount of a 10% hydrogen-peroxide solution required for the oxidation of the phenol. 0.1~ of sodium chloride had been dissolved in the hydrogen-chloride solution. The iron sur- r face melted by the waste-water was varied. The iron surface was in the form of a sheet as in example 1.
Thc r~sults have been listed in the Table hereafter.
Elimination of phenol from waste water with the aid of hydrogen peroxide and metallic iron.
The use of a 10% hydrogen-peroxide solution with 0.1%
of NaCl.
Influence of the metal surface on the reaction rate.
phenol content ofiron surface start of the rea~tion time the waste water %in sq m per reaction in minutes cu m of waste after water minutes 0,5 16 5 - 6 17 3'55 8 ~ 60 2 0,1 15 10 - 12 43 3,5 15 110 0,01 ` 15 25 - 30 65 r 3,5 120 220 i The Table shows that the reaction time is extended if the iron surface is reduced. Of course the reaction rate also depends on the phenol concentration.
~xample 12:
-~aste-water samples containin~ 5000 p.p.m. of phenol plus 5000 p.p.m. of formaldehyde, 1000 p.p.m. of phenol plus r 1000 p.p.m. of formaldehyde and 100 p.p.m. of phenol plus 100 p.p.m. of formaldehyde were treated - as in example 11 - in the presence of metallic iron with the amount of a 10% hydrogen-peroxide solution required for the oxidation of phenol and r formaldehyde 0.1~ of sodium chloride were dissolved in the hydrogen-peroxide solution.
As described in Example 11, the iron surface, relative to the amount of waste water to be treated, was varied in this case too.
The Table hereafter shows the result, from which it is also evident that the reaction time is extended if the iron surface is reduced:
Elimination of phenol and formaldehyde with the aid of hydrogen peroxide and metallic iron. The use of a 10%
hydrogen-peroxide solution with 0.1~ of NaCl.
Influence of the metal surface on the reaction rate.
phenol content formaldehyde¦ iron surface start of the reaction content in sq m per reaction time in cu m of after minutes % ~ waste water minutes . ~' 0,5 0,5 ~35 4 ~ 5 177 4,4 10 - 11 52 _ _ 0,1 0,1 16,5 9 ~ 9 41 3,6 13 - 14 105 i`
0,01 0,01 11 253 _ 30 11O ~' : 7 25 - 30 120-125 3,5 30 - 35 175-180 Example 13: F
Waste-water samples containing 1000 p.p.m. of pyrocate-chol, resorcinol, pyrogallol, o- and p- cresol were mixed with a 35% hydrogen-peroxide solution, in which 0.1~ of sodium chloride has been dissolved. 8 moles of hydrogen peroxide were used per mole of said phenol derivatives. The iron sheets corresponded to those of Example 1.
The oxidation reactions proceeded at standard tempera-ture, the reactions starting after approximate]y S minutes. The reaction time was 45 minutes for pyrocatechol as well as for resorcinol; for o- and p- cresol it was approximately 70 minutes and for pyrogallol more than 90 minutes.
After this time the waste-water samples were free from t said phenol derivatives. e _xample 14: r A fur'her waste--water sample containing 1000 p.p.m. of o- chloro phenol was also treated with a 35% hydrogen-peroxide solution, in which 0.1~ of sodium-chloride had been dissolved, in '~
the presence of metallic iron corresponding to Example 1. f In this case, too, the reaction proceeded analogously to that of the other phenol derivatives. After approximately 1 hour the oxidation reaction was completed and the treated waste water was from o- chloro phenol.
Example 15:
A waste-water sample containing 0.5% of hydroquinone was treated in the presence of metallic iron (corresponding to Examp]e 1) with a 10% hydrogen-peroxide solution in which 0.1 of sodium chloride had been dissolved.
8 or 10 moles o~ hydrogen peroxide were used per mole of hydroquinone.
The reaction proceeded under the conditions mentioned hereinbefore. After approximately 45 minutes the oxidation was completed and the treated waste water sample was free from hydroquinone.
Phenol-containing waste water with varying phenol con-centrations is obtained in the phenol synthesis, in coke plants and gas plants, in lignite-coking plants and last, but not least in the production of phenol-formaldehyde resins (phenolic plas-tics).
~. ~
The total removal of the toxically reacting phenol and the likewise toxically reacting formaldehyde from waste water of the industrial branch mentioned last, particularly for a subse-quent biological purification of this kind of waste water is as much as ever a very important problem, which has not yet been satisfactorily solved within a wide range of concentrations.
In the case of the phenolic plastics mentioned herein-before, for example, in the so-called "reaction water" which reacts either alkaline or acid depending on the condensation process, the content of volatile phenol can be of the order of 1700 to 15000 mg per litre, and that of free formaldehyde between 1200 and 8100 mg per litre. (F. Meinck, H. Stoof, H. Kohlschuter "Industrie-Abwasser, 4th edition, Gustav Fischer-Verlag, Stuttgart, `
1968, page 619).
A large number of processes for the purification of waste water are known. However, they are not universally appli-cable over a wide range of concentrations.
In cases of high phenol concentrations, for example, for the recovery of phenol, distillation with steam may be r suitable. Moreover several extraction processes in which an extraction of the phenol is carried out with e.g. benzene, toluene or tricrysyl phosphate is known. However, these processes have the disadvantage that certain residual components of the extracting agent get into the waste water.
109"702 Furthermore, the "de~3ree of wa<;hing out" of the diff~rent processes varies so that a total removal of the phenol is not possible.
A total dephenolization can be attained by evaporating the waste water and by burning the residues. I~owever, this process requires a high consumption of energy.
In cases of low phenol concentrations an adequate re-moval of the phenol can also be attained with the aid of special active carbons. However, the effect depends on amount, type and ~ranulation of the carbon as well as on the process (duration of r action, pH value and temperature of the waste water.) Depending on composition and concentration of the phenol-containing waste water the effect of adsorption varies greatly and at medium and high concentrations, for example, at 1000 p.p.m. and higher, said process is too costly.
Another adsorption process comprises the use of specific synthetic resins, for example, polymethacrylates and polyvinyl benzenes. Thus, for example, in a phenol-containing waste water the phenol content could be reduced from 6700 p.p.m. to approxi-mately 0.1 p.p.m. (U.S. Patents 3 663 467 and 3 531 463).
However, these adsorption processes cannot be applied to phenol-formaldehyde-containing waste water of the synthetic resin industry since, now as always, the toxically reacting formaldehyde remains in the waste water.
; In individual cases waste water rich in phenol can also be treated biologically by means of the so-called "Nocardia process". Pure cultures of these types of organism, which are related to the actinomyces, are settled in trickling-filter or activated-sludge plants. In the most favourable case a purifying effect of 99% can be attained so that even with biological degra-dation a certain residual amount remains. The effect depends largely on the other conditions. Thus, the flora is severely damaged by a phenol shock which is too severe or by other waste- P
1~94702 water toxins and possibly the ~lora is even destroyed. The pro-cess thus does not reliably detoxicate waste water. Moreover, ~ for the adaptation of such a special biological film or activated sludge N- and P- containing nutrient salts must be added (Gesundh-Ing. 81 (1960), 205 ff). These measures require the relatively costly operation of a special biological purification plant.
A well-known process is that of oxidizing the phenol by means of chlorine dioxide, which is obtained either by the r action of acids on chlorite, preferably sodium chlorite, or by reacting chlorine with sodium chlorite, for example, in a sulphuric-acid medium.
However, the latter process involves the risk that F
the phenol is chlorinated to the even more toxically reacting chloro phenols. Furthermore the reaction is not 100% efficient.
This also applies to the generation of chlorine dioxide by the action of acid on chlorite. In this case, too, an extensive oxidation can be attained. However, these kind of tests were F
performed by the applicant and the gas-chromatographical analysis of waste water thus treated have shown that after the oxidation greatly varying residual contents of phenol of the order of more L
than 10 to above 100 p.p.m. are still present. Moreover, the gas chromatograms shows extraneous peaks whicn have not yet been f ~dentified. However, it is assumed that they are intermediate oxidation products including quinones, hydroquinones or possibly even chlorinated products (see H. Thielemann, Gesundh.-Ing. 92 (1971) No. 10,297). r Corrosion problems due to intense acidification of the waste water should also be taken into account.
According to references in the literature (Klossowski, Jerzy, Gaz, Woda Tech. Sanit. (1968), 42, 197-200) phenols and its derivatives are destroyed by gaseous chlorine dioxide (generated from sodium chlorite and sulphuric acid) in amounts of only 83~.
In the acid to neutral ran~e the oxidation of phenol by chlorine dioxide results in p-benzoquinone as the final product of the phenol oxidation while in the alkaline mediurn a mixture of or~anic acids, primarily maleic acid and oxalic acid, is formed due to a high excess of chlorine dioxide (5 mg of CLO2 per 1 mg of phenol (Chemical Abstracts, 79, 23266 M).
In the USSR Patent 141,814 the purification of waste watèr of the phenol-formaldehyde-resin production is described r 10 and the formaldehyde is to be removed by treating the water with "quick lime" at room temperature or at 98C and the phenol is to be removed by oxidation either electrochemically or with ~nO2.
This process is relatively costly. By "quick lime" is meant calcium oxide.
In another process the removal of phenol, methanol and formaldehyde from waste water is carried out by means of a so-called "liquid-phase oxidation" (I.S. Stepanyan, I.A. Vinokur, G.M. Padaryan, khim. prom (1972), 6, 30/31 and Int. Chem. Eng.
12 (1972), 4, 649/6513. In this process the waste water is fed 20 into an electrically heated reactor by means of air under a pressure of 40 bars and at 200C. However, test data have only shown degrees of oxidation of approximately 95% for phenol, 77%
for methanol and 93% for formaldehyde.
In another series of tests the degrees of oxidation were only at 80% for said substances. The process is technically very expensive. Residues of the toxically reacting substances remain. r~
A process for the prepurification of waste water which contains phenol, formaldehyde and their reaction products is described in the laid-open Gerrnan Specification 2,404,264.
According to this process water-soluable aminoplast-resin precondensates or their aqueous solutions are added to the F
waste water. The reaction mixt:ure is kept in the alkaline range at boiling temperature for 2 to 8 hours and the precipitated - ~ reaction products are separated.
As is evident from the cited examples only a prepurifi-cation of this kind of waste water can be attained with this process; a complete removal of phenol and formaldehyde is impos-sible.
It has also been proposed to treat phenol-containing waste water and phenol- and formaldehyde-containing waste water r with alkali or alkaline-earth metal chlorites in the presence of specific amounts of formaldehyde (Gerrllan Patent... /Patent Application P2657 192.6).
A complete elimination of phenol and formaldehyde is achieved with this process, but the waste water thus treated is salified by the alkali or alkaline earth metal chlorites. If required, the waste water thus treated can then be subjected to an aftertreatment with active carbon.
It is also known to remove phenol from waste water r with hydrogen peroxide, in the presence of ferric chloride. In this case the pH value of the waste water is adjusted to 2.5 - 3.5 prior to the treatment and to 10 after the treatment. After clarifying the suspension with corresponding agents, the waste water still contains 0.3 p.p.m. of phenol (Japanese Patent Application 118 8902/72-laid open under No. 77449/74~
In yet another process for the detoxication of phenol-and formaldehyde-containing waste water hydrogen peroxide is also ~
used in amounts of more than 1.5 times the COD value of the F
waste water, as well as ferrous sulphate. On adding the hydrogen peroxide and the ferrous salt the pH value of the waste water is reduced to 3-4 (Japanese Patent Application 44906/72 - laid open under No. 6763/74).
The two processes mentioned last relate to low phenol and formaldehyde contents of up to 100 p.p.m.
In order to assure complete oxidation in the case of high phenol contents, the amount of iron salts must be increased correspondingly and this results in an intolerable salt load.
Moreover, in the process mentioned last, a residual formaldehyde content of at least 50 p.p.m. remains.
Furthermore the processes mentioned hereinbefore had no detoxicating effect on waste water which contained phenol derivatives such as pyrocatechol, resorcinol, pyrogallol, cresols, f chloro phenol and hydroquinone.
The present invention eliminates essentially completely phenol, phenol derivatives or phenol plus formaldehyde from waste water even in the case of high concentrations but without loading the waste water with salt. By high concentrations are meant contents of phenol and phenol derivatives up to a maximum of 0.5%
by weight and formaldehyde contents of up to a maximum of 5% by weight since the process is not so economical at higher concen-trations.
It has now been found that waste water which contains phenol, phenol derivatives or phenol and formaldehyde can be freed, completely from these compounds by the addition of hydrogen peroxide without resulting in salt loads when the waste water is treated with hydrogen peroxide in the presence of metal-~ic iron or copper.
According to the present invention therefore there is provided a process for the purification of waste water containing phenol, phenol derivatives or phenol plus formaldehyde which r process treats the waste water with hydrogen peroxide in the presence of metallic iron or copper. Desirably the waste water is neutral or weakly acid reacting waste water.
Said metals can be put into the waste water tanks in the form of sheets, wires or yranulates. In the case of iron, which ~,094702 is particularly preferred, the metal can also be present as the reactor material, for example, as an iron reaction tank or ~ . waste-water tank or even as an iron stirrer. Copper is usually not used in this form for reasons of costs.
It has been found that an iron surface of 1 to 20 square metres per cubic metre of waste water is most favourable.
The industrial types of iron, such as crude iron, cast iron and steel, maybe used as iron (see "Ullmann", 1975, Vol. 10, page 321). The commercial types o, copper are used as copper (see, for example, "Ullmann", Enzyklopadie der Technischen Chemie, 1960, Vol. 11, page 205-206).
In contrast to said processes with hydrogen peroxide and iron salts the present process is independent of the pH
value. It can be carried out with neutral acid or alkaline waste ~ater without any difficulty.
The start of the detoxication reaction depends on the L
concentration of the phenol or phenol derivatives and of the phenol and formaldehyde on the one hand and on the metal surface available per cubic metre of waste water of the other (see Example t 1 and 2).
If the detoxication reaction does not start as fast as desired, then it is favourable to add very small amounts of activators in order to start the reaction. Halides, sulphates, nitrates but also organic salts, such as formates of alkali or alkaline earth metals, such as sodium, potassium, calcium or barium are suitable as activators. However, the corresponding salts of zinc, aluminium, nickel and manganese are also suitable.
Sodium chloride is very suitable. The activators may ~e used in amounts of 0.1 to 0.2% by weight, relative to the hydrogen peroxide used. It is possible to add them dissolved in hydrogen peroxide or in a solid form directly to the waste water. Highly dispersed silicas, which are insoluble in water, are also suitable as 1094~02 activators, likewise in the amounts mentioned above.
~ydrogen peroxide is used in amounts of 7.5 to 8 moles - ~ per mole of phenol or phenol ~erivative. In the presence of formaldehyde, 2 additional moles of hydrogen peroxide are required per mole of formaldehyde.
The detoxication is preferably carried out at room temperature or at the temperature at which the waste water is obtained.
In general, the waste water to be detoxicated can be used as such for the process. Only at phenol concentrations above 5000 p.p.m. is it advisable to dilute the waste water to phenol values below 5000 p.p.m. if a purification by means of the process according to the present invention is desired so that the reaction is not too turbulent.
The quantitative determination of phenol and possibly of derivatives thereof is carried out by means of gas chromato-graphy under the following conditions: ~
Gas chromatograph Perkin-~lmer F 7 with FID. Temperature !
of the column 180C; injection block 230C; flow approximately 24 ml per minutes; column 1 m of Poropak P, No. 85, amount of sample 1/u litre per minute; paper feed 0.5 cm per minute.
The analysis is carried out colorimetrically with the aid of the very sensitive condensation reaction between formalde- ;
hyde, acetyl acetone and arnmonia or ammonium acetate to the yellow- L
colored diacetyl-dihydro lutidine (T. Nash, Nature (London) 170 (1952), g76).
It has been found that the use of hydrogen-peroxide F
solutions in which 0.05 to a maximum 0.1~ by weight of NaCl is dissolved is the simplest and an elegant procedure. Of course the sodium chloride can also be added in a solid form to the waste water to be treated.
The procedure then is usually such that the corresponding amount of hydrogen peroxide with approximately 0.1% of activator, preferably sodium chloride is added, while stirring, to the waste water con~aining phenol, phenol derivatives or phenol and formaldehyde. Within a few minutes after the addition is com- -pleted the oxidation starts at room temperature. The oxidation is evident from the darkening of the waste water, the generation of carbon dioxide, the increase in temperature and the decrease of~the pH value to values of 2 and 1. After the completion of the entire reaction, which usually takes 30 to 60 minutes and is indicated by the abating generation of gas, the end of the temperature increase and the start of cooling, the acid-reacting waste water is neutralized. The small amount of iron ions present precipitates at the same time.
All the known alkali or alkaline earth metal hydroxides are suitable for the neutralization. However, calcium hydroxide in the form of milk of lime is preferred. ~-After the iron hydroxide precipitate and possibly the alkaline-earth metal hydroxide precipitate have settled, the virtually colorless, completely detoxicated waste water can be fed to the biological purification plant.
It is important that with the presence of metallic iron or copper and traces of salt but without the presence of hydrogen peroxide no metal ions are detached, not even after several hours.
Only after the addition of the hydrogen peroxide does a violet, partially also brownish-colored haze detach itself from the metal surface and probably accelerates the oxidation catalytically.
Thus, no minimum concentration of iron salts is re-quired as according to the Japanese patent applications mentioned hereinbefore, i.e., a concentration of iron salts which must be adapted to the phenol concentration concerned, but the lowest possible concentration of iron ions is automatically obtained irrespective of the phenol concentration present in each case.
Apart from phenol, o- and p- cresol as well as t- butyl phenol and hydroquinone can also be eliminated by means of the ~- process according to the present invention. P
The process of the present invention will be further illustrated by way of the following examples.
For this purpose synthetically produced waste water having contents of phenol, phenol derivatives and phenol plus formaldehyde bet~een 100 and 5000 p.p.m. and waste water from the ~. ~
phenolic resin industry is used.
The percentages are percent by weight.
Example 1:
To 7 waste-water samples having phenol contents of 0.5% and pH
values between 4 and 6, 0.4 ml of a 10% solution of the following salts were added per litre:
Na~l, Ca formate, MnC12, MnSO4, CuSO4, AlC13 and NiSo4.
After the addition of the salt solutions 140 to 150 ml of a 10% hydrogen peroxide solution were added to each of the waste water samples while stirring. Iron sheets having identical total surfaces (8 sq m per cu m of waste water) were suspended 20 in the samples. The sheet iron used consisted of structural ,-steel St 37. ' Shortly after the addition of the hydrogen peroxide solutions the oxidation reaction started, evident from the darkening of the solutions, the increase in temperature from 50 to 60C, the generation of carbon dioxide and the decrease of the pH value.
Within 40 to a maximum of ~0 minutes the oxidation was F
completed, the temperature dropped slowly and the pH value was between 1.~ and 1.9.
The samples were neutralized by adding a 30% milk of lir,le which precipitated.
After the lime of milk precipitate had settled, the -- 10 -- `
lOg470Z
supernatant clear waste water was analyzed in the manner described hereinbefore.
The analysis showe~ that the phenol had been completely eliminated.
Example 2:
An alkaline reacting waste water having a pH value of 8.7 and containing 0.5~ of phenol was mixed with 4 ml of a 10%
sodium-chloride solution, relative to 1 litre of waste water, whereupon 140 ml of a 10% hydrogen peroxide solution (per litre of waste water) was added while stirring. The same iron sheets as in example 1 were suspended in the waste water.
The oxidation reaction started only after 30 to 40 minutes and was completed after a maximum of 60 minutes. The course of the oxidation with respect to discoloration, increase in temperature, generation of carbon dioxide and decrease of the pH was the same. On completion of the reaction, the strongly acid-reacting waste water, which had a pH value of 1, was neutral-ized amd treated as in example 1.
In this case, too, the phenol had been completely removed.
Example 3:
!
A waste-water sample containing 0.5% of phenol and 0.5~ of formaldehyde and having a pH value of 5.6 was mixed with 253 ml of a 10% hydrogen-peroxide solution, relative to 1 litre of waste water. 0.1% of NaCl had first been dissolved in the hydrogen-peroxide solution. The iron sheets had been suspended in the waste-water sample as in example 1. Immediately upon the r addition of the hydrogen-peroxide solution provided with sodium chloride the oxidation reaction started while stirring. The reaction was evident from the features described in the preceding examples. The reaction was completed after approximately 30 r minutes while the temperature increased to 55C and the pH value decreased to l.5. By adding milk of lime the treated waste water was neutralized and after the precipitate had settled the super-natant water assumed a yellowish-coloration.
The presence of formaldehyde had accelerated the reaction. The analysis showed that boththe phenol and the form-aldehyde had been completely eliminated.
Example ~:
~ ~ waste water sample containing 0.5% of phenol and the same amount of formaldehyde and having a pH value of 5.3 was ~ixed with 255 ml of a 10% hydrogen-peroxide solution, relative to 1 litre of waste water.
0.1% of NaCl had been dissolved in the hydrogen peroxide solution. Sheet copper (a 99.9% copper metal) had been put into the waste water, using 15 square metres of sheet copper per cubic metre of waste water.
` After adding the hydrogen-peroxide solution it took a lengthy time before the start of the reaction was noticeable t (evident from the darkening of the waste water). Compared with the reactions in the presence of metallic iron the reaction was retarded; the pH value decreased more slowly and the rise in temperature also slowed down.
Only after several hours was the reaction completed.
In all other respects, as for example, coloration, decrease in the pH value, increase in temperature, the reaction was analogous to the reactions described in the preceding examples.
The neutralization was carried out in the manner described hereinbefore. The waste water of yellowish coloration above the deposited precipitate contained neither phenol nor formaldehyde.
Example 5:
A waste-water sample containing 0.5% of phenol was F
treated with a 10% hydrogen peroxide solution (amount added: 140 ~094702 ml per litre of waste water) in the presence sheet iron and sheet copper. The metal sheets corresponded to those used in the examples 1 and 4. The initial pH value of the waste water was X
4.5. At room temperature the reaction was considerably retarded;
only after slight heating to 40C could the oxidation be completed within 70 to 80 minutes under the conditions described herein-before. The analysis showed that the neutralized waste water was free from phenol.
Example 6:
A waste-water sample containing 0.5% of phenol and having a p~ value of 6.3 was mixed with 5 g of a highly dispersed silica. Sheet iron was suspended in the waste-water sample corresponding to example 1, whereupon hydrogen peroxide was added in an amount corresponding to the phenol concentration. 140 ml of a 10% hydrogen-peroxide solution was used per litre of waste water.
After approximately 60 minutes the reaction started while the temperature rose and the pH value decreased substantial- r ly. Within further 2 hours the reaction was completed. The pH
value was 1.8. After the treatment with milk of lime, the supernatant waste water was colorless and clear. Phenol could no longer be detected.
Example 7:
A large number of waste-water samples having different contents of phenol and formaldehyde between 100 and 5000 p.p.m.
were treated in the presence of metallic iron (corresponding to .
example 1) with a 35% by weight of peroxide solution and NaCl by F
oxidation as in the preceding examples.
Some of the sodium chloride was dissolved in the peroxide solution (maximum amount 0.1~) and some of it was dissolved in the waste water. 200 mg of sodium chloride were used per litre of waste water.
In the Table hereafter the amounts of 35% by weight hydrogen-peroxide solution and sodium chloride used for the different concentrations of phenol and formaldehyde have been listed.
Table for Example 7 Elimination of Phenol and Formaldehyde from Waste Water.
Amounts of 35% by weight hydrogen-peroxide and NaCl per litre of ~aste water in the presence of metallic iron.
1) l~ydrogen-Peroxide Solution with 0.1% of NaCl.
~1aste Water ~laving Concentrations 35% by weight H2O2 NaCl of solution phenol formaldehyde ~ , ml mg 0,01 0 7'51) __ _ t~
0,5 1,0 96,5 200 0,5 0,75 81,51) 200 0,5 0,5 66,5 __ 0,5 0,25 51,5 200 0,2 0,4 38,6 200 0,2 0,3 32,6 200 0,2 0,1 20,5 200t : 0,1 0,1 ~3,51) __ 0,05 0,l 9,7 200 0,05 0,075 8,2 200 0,05 0,025 5,2 200 0Ol 0Ol 27l) r In all these cases a complete detoxication of the waste-water samples could be attained within a short time, i.e. from 30 to a maximum of 60 minutes, that is to say, faster at high phenol contents than at low ones.
Example 8:
In an iron reactor of V2~ steel having a capacity of 20 litres, waste-water samples having phenol contents of lO0 and lO00 p.p.m. and samples having phenol and formaldehyde contents of r lO0 to lO00 p.p.m. were treated with a 35% hydrogen-peroxide solution while stirring. Prior to the addition of the hydrogen peroxide solution, sodium chloride was dissolved in the waste water at a rate of 200 mg per litre of waste water. The amounts of 35r~ by weight peroxide corresponding to the concentrations of r phenol or phenol and formaldehyde are evident from Table of Example 7.
In all the mixtures the oxidation reaction proceeded according to the same pattern, which was already described in the preceding samples.
After less than 60 minutes the oxidation was completed.
The pH value of the treated waste-water samples was 2.5.
After corresponding further treatment of the waste-water samples the analysis showed that these samples were free from phenol and formaldehyde.
Example 9:
The analysis of an industrial effluent from the phenolic- .
resin industry(acid condensation with formaldehyde, novolak type) showed a phenol content of 4.5% and a total content of formalde- t hyde of 5.8~
Most of the formaldehyde was present in a combined form, merely 0.06~ thereof was free formaldehyde. The pH value of this industrial effluent was 3.
r~he effluent also contained other organic components, for example, residues of organic solvents, in addition to phenol and formaldehyde.
In order to detoxicate this waste water from phenol and formaldehyde, it was necessary to process this waste water at least ten times diluted with peroxide since otherwise the oxida-tion reaction would have been too turbulent and uncontrolled.
In a correspondingly large reactor, the entire inside ,~.
of which was provided with sheet iron, 46 litres of the original effluent were diluted with 410 litres of water. In this diluted waste water 100 g of sodium chloride were dissolved, whereupon 34.5 litres of a 35% by weight hydrogen-peroxide solution were added while stirring this amount of hydrogen-peroxide is slightly - above the amount required for phenol and formaldehyde for the F
10 oxidation since corresponding laboratory tests had shown that other organic components had to be oxidized concomitantly.
In order to prevent the reaction from becoming too turbulent, the hydrogen-peroxide solution was added in batches, i.e., in amounts of 5 to 10 litres at a time.
By means of this procedure the waste water could be completely detoxicated within 1 to 2 hours. During the treatment the temperature increased to 75C and the pH value which was 6.8 after the dilution of the original effluent dropped to 1.9.
After the addition of the first portion of hydrogen-peroxide, 20 intense foaming started due to intense generation of CO2 but it abated towards the end of the reaction.
After the oxidation reaction the treated waste was neutralized by adding a 30~ milk of lime while both lime and ferric hydroxide precipitated.
.. i The supernatant foam-free waste water, which was clear and light-colored could then be discharged.
The analysis showed that the waste water was completely free from phenol and formaldehyde.
Example 10:
~ waste-water sample containing 1000 p.p.m. of phenol and a second waste-water sample containing 1000 p.p.m. of phenol and 1000 p.p.m. of formaldehyde were treated in the presence of 10~4702 metallic sheet iron (corresponding to example 1) with the amount of a lOQo hydrogen-peroxide solution re~uired for the oxidation of phenol or ~henol plus formaldehyde. 0.1% of sodium chloride had been dissolved in the hydrogen-peroxide solution.
The oxidation proceeded in the manner described in the preceding examples. After completion of the reaction the samples were neutralized as in the preceding examples and the clear, light-colored waste water was decanted. Corresponding samples g were analyzed and the results of the analysis showed that phenol and formaldehyde were no longer present.
Apart from the analyses, the chemical and biochemical oxygen requirements were determined from the starting samples and from the sa~ples treated with hydrogen-peroxide. Furthermore, toxicity measurements, a fish test and the carbon determination were carried out.
In the starting samples, which still contained phenol and formaldehyde, the CSB was determined and in the treated waste-water samples the CSB, the BSB5, the toxicity, the fish toxicity and the TOC value were determined.
The toxicity was measured according to K. Offhaus in Sapromat and the fish toxicity with Guppys. The CSB values were measured by means of standard methods or with the method defined in the waste water control law. (~. tr - d~ ~ r~) The carbon determination was carried out with a Beckmann\ ' "Total Organic Carbon ~nalyzer".
The results are shown in the Table hereafter.
!
waste water contain- waste water containin~
ing 1000 p.p.m. of 100~ p.p.m. of phenol phenol and 1000 p.p.m. of formaldehy~ F
sample 1 sample 2 sample 3 sample 4 treated untreated treated untreated CSB (mg O2/litre) 140 2400 300 3400 ,BSB5(mg/litre) ~;
dilùted sample 33 _ 34 _ toxic inhibition in ~ 4 _ 15 _ (for 500 ml of sample in 1000 ml of mix-ture) ~4 . 160 _ TOC ~mg/litre) 50 _ 158 _ rAC (mg/litre) 34 _ 2 _ fish test:
the fish survived for 48 hours 333 ml _ 333 ml of _ f sample sample in n 1000 ml 1000 ml of ~f mixture mixture r . _ As the Table shows the CSB value could be reduced sub-stantially. The BSB5 value also is within an acceptable range.
The result of the fish test is interesting. According to this test the fish survived for 48 hours at a mixing proportion of the treated waste-water samples of 333 ml diluted in 1000 ml.
Example 11:
(Variation of the Iron Surface) .
(The type of iron used corresponded to that of example 1).
~ aste-water samples containing 5000 p.p.m., 1000 p.p.m.
and 100 p.p.m. of phenol were treated in the presence of metallic iron with the amount of a 10% hydrogen-peroxide solution required for the oxidation of the phenol. 0.1~ of sodium chloride had been dissolved in the hydrogen-chloride solution. The iron sur- r face melted by the waste-water was varied. The iron surface was in the form of a sheet as in example 1.
Thc r~sults have been listed in the Table hereafter.
Elimination of phenol from waste water with the aid of hydrogen peroxide and metallic iron.
The use of a 10% hydrogen-peroxide solution with 0.1%
of NaCl.
Influence of the metal surface on the reaction rate.
phenol content ofiron surface start of the rea~tion time the waste water %in sq m per reaction in minutes cu m of waste after water minutes 0,5 16 5 - 6 17 3'55 8 ~ 60 2 0,1 15 10 - 12 43 3,5 15 110 0,01 ` 15 25 - 30 65 r 3,5 120 220 i The Table shows that the reaction time is extended if the iron surface is reduced. Of course the reaction rate also depends on the phenol concentration.
~xample 12:
-~aste-water samples containin~ 5000 p.p.m. of phenol plus 5000 p.p.m. of formaldehyde, 1000 p.p.m. of phenol plus r 1000 p.p.m. of formaldehyde and 100 p.p.m. of phenol plus 100 p.p.m. of formaldehyde were treated - as in example 11 - in the presence of metallic iron with the amount of a 10% hydrogen-peroxide solution required for the oxidation of phenol and r formaldehyde 0.1~ of sodium chloride were dissolved in the hydrogen-peroxide solution.
As described in Example 11, the iron surface, relative to the amount of waste water to be treated, was varied in this case too.
The Table hereafter shows the result, from which it is also evident that the reaction time is extended if the iron surface is reduced:
Elimination of phenol and formaldehyde with the aid of hydrogen peroxide and metallic iron. The use of a 10%
hydrogen-peroxide solution with 0.1~ of NaCl.
Influence of the metal surface on the reaction rate.
phenol content formaldehyde¦ iron surface start of the reaction content in sq m per reaction time in cu m of after minutes % ~ waste water minutes . ~' 0,5 0,5 ~35 4 ~ 5 177 4,4 10 - 11 52 _ _ 0,1 0,1 16,5 9 ~ 9 41 3,6 13 - 14 105 i`
0,01 0,01 11 253 _ 30 11O ~' : 7 25 - 30 120-125 3,5 30 - 35 175-180 Example 13: F
Waste-water samples containing 1000 p.p.m. of pyrocate-chol, resorcinol, pyrogallol, o- and p- cresol were mixed with a 35% hydrogen-peroxide solution, in which 0.1~ of sodium chloride has been dissolved. 8 moles of hydrogen peroxide were used per mole of said phenol derivatives. The iron sheets corresponded to those of Example 1.
The oxidation reactions proceeded at standard tempera-ture, the reactions starting after approximate]y S minutes. The reaction time was 45 minutes for pyrocatechol as well as for resorcinol; for o- and p- cresol it was approximately 70 minutes and for pyrogallol more than 90 minutes.
After this time the waste-water samples were free from t said phenol derivatives. e _xample 14: r A fur'her waste--water sample containing 1000 p.p.m. of o- chloro phenol was also treated with a 35% hydrogen-peroxide solution, in which 0.1~ of sodium-chloride had been dissolved, in '~
the presence of metallic iron corresponding to Example 1. f In this case, too, the reaction proceeded analogously to that of the other phenol derivatives. After approximately 1 hour the oxidation reaction was completed and the treated waste water was from o- chloro phenol.
Example 15:
A waste-water sample containing 0.5% of hydroquinone was treated in the presence of metallic iron (corresponding to Examp]e 1) with a 10% hydrogen-peroxide solution in which 0.1 of sodium chloride had been dissolved.
8 or 10 moles o~ hydrogen peroxide were used per mole of hydroquinone.
The reaction proceeded under the conditions mentioned hereinbefore. After approximately 45 minutes the oxidation was completed and the treated waste water sample was free from hydroquinone.
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process of purifying waste water containing (1) phenol, (2) a substitute phenol or (3) phenol + formaldehyde comprising treating the waste water with hydrogen peroxide in the presence of either (a) metallic iron under acid conditions and an activator which is a salt of an alkali metal, a salt of an alkaline earth metal, a zinc salt, an aluminum salt, a nickel salt or a manganese salt or is insoluble silica or (b) metallic copper and an activator which is a salt of an alkali metal, a salt of an alkaline earth metal, a zinc an aluminum salt, or a manganese salt or is insoluble silica.
2. A process according to claim 1, in which the metal is present in the form of sheets, wires or granulates during the purification.
3. A process according to claim 1, in which the puri-fication is carried out in an iron tank.
4. A process according to claim 1, 2 or 3 in which the purification is carried out in the presence of an iron stirrer.
5. A process according to claim 1, 2 or 3 in which an iron surface of 1 to 20 square metres is used per cubic metre of waste water.
6. A process according to claim 1, 2 or 3 in which V2A
steel is used as metallic iron.
steel is used as metallic iron.
7. A process as claimed in claim 1, 2 or 3 in which halides, sulphates, organic salts of alkaline earth or alkali metals are added as activators.
8. A process as claimed in claim 1, 2 or 3 in which sodium chloride or insoluble silicas are added as activators.
9. A process as claimed in claim 1, 2 or 3 in which 0.1 to 0.2% of activators are added.
10. A process as claimed in claim 1, 2 or 3 in which the hydrogen peroxide is added in amounts from 7.5 to 8.0 moles per mole of phenol or phenol derivative.
11. A process as claimed in claim 1, 2 or 3 in which the hydrogen peroxide is added in amounts from 9.5 to 10.0 moles per mole of phenol and formaldehyde.
12. A process as claimed in claim 1, 2 or 3 in which the waste water has a maximum phenol content of 5000 p.p.m.
13. A process as claimed in claim 1, 2 or 3 in which the waste water is neutral or weakly acid reacting.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19772703268 DE2703268C2 (en) | 1977-01-27 | 1977-01-27 | Process for the detoxification of waste water containing phenol, phenol derivatives or phenol and formaldehyde |
| DEP2703268.4 | 1977-01-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1094702A true CA1094702A (en) | 1981-01-27 |
Family
ID=5999652
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA295,737A Expired CA1094702A (en) | 1977-01-27 | 1978-01-26 | Process for the detoxication of waste water containing phenol, phenol derivatives, or phenol and formaldehyde (1) |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5745389A (en) |
| BE (1) | BE863321A (en) |
| CA (1) | CA1094702A (en) |
| DE (1) | DE2703268C2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2835496A1 (en) * | 1978-08-12 | 1980-02-21 | Bayer Ag | METHOD FOR CHEMICAL-BIOLOGICAL TREATMENT OF WASTEWATER |
| DE2927911A1 (en) * | 1979-07-11 | 1981-01-29 | Bayer Ag | WATER TREATMENT METHOD |
| DE3932174A1 (en) * | 1989-09-27 | 1991-04-11 | Degussa | METHOD FOR REDUCING THE AOX CONTENT IN WATER |
| EP0544924A4 (en) * | 1991-06-25 | 1993-11-03 | Nippon Steel Corporation | Method and device for treating waste water containing organic chlorine compounds |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA646440A (en) * | 1962-08-07 | M. Hill John | Method of removing phenols from waste streams | |
| SU141814A1 (en) * | 1960-12-15 | 1961-11-30 | П.М. Богатырев | The method of complex wastewater treatment from formaldehyde and phenol in the production of phenol-formaldehyde resins |
-
1977
- 1977-01-27 DE DE19772703268 patent/DE2703268C2/en not_active Expired
-
1978
- 1978-01-25 BE BE6046329A patent/BE863321A/en not_active IP Right Cessation
- 1978-01-26 CA CA295,737A patent/CA1094702A/en not_active Expired
-
1981
- 1981-07-06 JP JP10457181A patent/JPS5745389A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2703268C2 (en) | 1985-10-03 |
| DE2703268A1 (en) | 1978-08-10 |
| BE863321A (en) | 1978-07-25 |
| JPS5742390B2 (en) | 1982-09-08 |
| JPS5745389A (en) | 1982-03-15 |
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