Note: Descriptions are shown in the official language in which they were submitted.
1094702
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
1094702
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
109470Z
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
109470Z
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
1094702
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.
109470Z
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
1094702
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
- 12 -
~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.
- 13 -
1094702
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.
- 14 -
1094702
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
- 15 -
1094702
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
- 16 -
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.
!
1094702
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.
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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
11 10 - 12 47
7 13 - 14 70
3,5 15 110
0,01 ` 15 25 - 30 65 r
11 40 - 45 100
7 55 - 60 120
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
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109470Z
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
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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.
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