DE2950710C2 - Process for treating waste water by wet oxidation - Google Patents

Description

50

The invention relates to a process according to which ammonia or chemically oxidizable substances (hereinafter referred to as COD), suspended solids, etc., in addition to waste water containing ammonia, are subjected to wet oxidation in the presence of a catalyst in order to t n to convert nitrogen, carbon dioxide and water and thereby render the wastewater harmless.

In the context of the invention, the ammonia contained in the wastewater comprises ammonium compounds that Release ammonium ions upon dissociation in water. μ The COD comprises phenol, cyanides, thiocyanates, oils, Thiosulfuric acid, sulfurous acid, sulfides, nitric acid and the like.

The prior art on which the present invention is based is that disclosed on February 16, 1978 DE-OS 27 35 892.

If, according to this method, wastewater with a pH value of about 9 to 11.5 is fed into the reaction vessel introduces, the pH of the reaction system lowers and consequently leads to a decreased pH Efficiency of the decomposition of harmful components.

Acid liquids cause serious damage to the reaction vessel, the pipe system, of the heat exchanger etc. and require a neutralization of the wastewater before discharge. All mentioned problems of the method according to DE-OS 27 25 892 can be overcome if an alkali in supplies the reaction vessel in such an amount that the wastewater is consistently up during its oxidation a pH value of about 8 is maintained and that the purified wastewater has a pH value when it runs off from about 5 to about 8.

The invention therefore relates to a process for treating waste water containing ammonia and / or oxidizable organic and / or inorganic substances, the waste water being placed in a reaction vessel at a pH of about 8.5 to about 11.5 for the purpose of its wet oxidation introduces an oxygen-containing gas in the presence of a catalyst and keeps the waste water at a temperature of about 100 to about 370 ⁰ C and a pressure that enables the waste water to remain in the liquid state, the oxygen-containing gas has an oxygen content of about 1 to about 1, 5 times the amount theoretically required to decompose the waste water content of ammonia, organic substances and inorganic substances and the catalyst absorbed by a carrier contains at least one substance from the group iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum, copper, gold , Tungsten and its compounds which are insoluble or sparingly soluble in water, the characterized in that the reaction vessel is supplied with an alkali in such an amount that the wastewater flowing through the reaction chamber from bottom to top is always kept at a pH of about 8 for about 80% of its way, while the purified wastewater is one Has a pH of 5 to 8.

Examples of the wastewater to be treated by the process according to the invention are those which Contain ammonia and which also contain oxidizable organic and / or inorganic substances can, such as B. Gas water that is used in coke ovens, coal gasification plants and coal liquefaction plants is produced. This also includes wastewater from gas cleaning processes used in these plants, Oily wastewater, water from the activated sludge process, sedimented activated sludge, wastewater from chemical factories and oil refineries, community sewage, service water, sewage sludge, etc. Also sewage of high-temperature and / or high-pressure systems can advantageously under: r reduced costs for heating and / or compressing the wastewater.

In contrast to the method according to the invention, known methods require many procedural steps and are expensive. For example, the gas formed in coke ovens when coke is produced becomes water usually through the successive steps of the

Removal of phenol,

Pretreatment,

Removal of NH3 by abortion,

Treatment with activated sludge

5. Coagulation and sedimentation
treated, followed by the steps

6. Oxidation with chemical substance,

7. Adsorption with activated carbon

and if necessary

8. Reverse osmosis

can follow. The method according to the invention consists essentially of a single step in which the gas water from the coke oven is introduced into a reaction vessel without cooling immediately after compression and is catalytically oxidized with an oxygen-containing gas, whereby the NH ₃ and the COD components (such as. B. phenol, cyanides, thiocyanates, oils, thiosulfuric acid, sulfurous acid, sulfides, etc.), which are contained in the gas water, can all be decomposed and rendered harmless. The method according to the invention therefore offers a considerably simplified operation which can be carried out at enormously reduced overall costs (plant costs and operating costs).

The method according to the invention has the probienes overcome that were encountered in the method of the prior invention when the wastewater at a pH of about 9 to about 1.5 is supplied. The addition of an alkali alleviates the pronounced drop in the pH value, which occurs according to the state of the art occurs in the reaction vessel, thereby reducing the decomposition efficiency, the deterioration of the catalyst and damage to the reaction vessel, heat exchanger, pipe system, etc. avoided will. The inventive method has the advantage that there is a decomposition of ammonia ensures high efficiency.

While high temperature applied to the treatment of wastewater at a pH above 11 and high pressure conditions allow easy leaching of the carrier or a large nitrite and / or amount of nitrate nitrogen prevents the use of the titanium dioxide and / or the zirconium dioxide such a disadvantage for the wearer.

In addition, the combination of wet oxidation of the waste water and a reverse osmosis process is economical very advantageous because the high pressure of the water draining from the wet oxidation step is effective can be used to separate this water into a concentrate and purified water that can be used as industrial water.

If the wastewater contains an excess of suspended solids, the solids will adhere to the Parts of the treatment device, resulting in reduced efficiency, such as. B. a reduced Heat transfer coefficient at the surface of the heat exchanger, or at a lower catalytic! Activity due to the deposition of solids on the surface of the particles in the reaction vessel packed catalyst leads. Accordingly, it is preferable to partially or partially suspend solid particles entirely ans the wastewater before treatment depending on the Remove concentration and composition of solids. Alternatively, the wastewater can be used as a Zimmermann process known non-catalytic wet oxidation process for partial or total Decomposition of suspended solid particles before the process according to the invention in order to avoid the

be subjected to poisoning of the catalyst used in the process according to the invention.

The wastewater to be treated by the method according to the invention therefore has a pH of about 8.5 to about 11.5 to effectively use the COD constituents and remove ammonia. The preferred range of pH is about 9 to about 11. It is therefore Desirably, the pH of the wastewater before reacting with an alkaline substance, such as. B. Sodium hydroxide, calcium hydroxide, sodium carbonate or the like, depending on the type of waste water to adjust.

The alkaline substance is in d ^ <. Wet reaction system at the desired time and with <: a throughput required to at least about 80% of the waste water fed to the reaction vessel, which is towards the water inlet of the reaction vessel, at a pH value of about 8 permanently and the maintenance of a pH value of about 5 to 8 im to allow treated wastewater. The same

jo alkaline substances, such as those used in advance for the pH adjustment of the Waste water used are useful as alkali.

Examples of useful active ingredients of the

Catalysts are iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum, copper. Gold and

jj tungsten and compounds of these metals, which are in Are insoluble or sparingly soluble in water. These ingredients are used individually, or at least two of them can be used together. Examples of useful compounds that are insoluble in water or are sparingly soluble are the following:

1. Oxides such as Fe ₂ O ₃ , Fe ₃ O ₄ , CoO, NiO, RuO ₂ , Rh ₂ O ₃ , PdO, IrO ₂ , CuO, WO ₂ ;

2. Chlorides such as RuCl ₂ and PtCl ₂ ;

3. Sulphides, such as. B. ruthenium sulfide, rhodium sulfide.

These metals or their compounds are supported in the usual manner by a carrier, such as. B. Titanium dioxide, zirconia, alumina, silica, silica-alumina, a porous Body made of nickel, nickel-chromium, nickel-chromium-aluminum or nickel-chromium-iron etc., added used. Depending on the treatment conditions, this could be done according to the invention Process to be treated wastewater at a

5 '. pi Ϊ -value above 11 cause the carrier to detach or cause the conversion of part of the ammonia to nitric nitrogen and / or nitrate nitrogen. The amount of active ingredient to be absorbed by the carrier is from about 0.05 to about 25%, preferably about 0.5 to about 3% based on the weight of the carrier. The catalyst can be in the form of Balls, pellets, cylinders, crushed broths, Particles or in any other desired form. If the reaction vessel is for a Fixed bed is set up, the wastewater is preferably left at a space velocity of about 0.5 to about 10 h- ', preferably at about 1 to about 5 h-' based on an empty column. The for

The solid bed of useful grains or pieces of the captured catalyst usually have a dimension of about 3 to about 50 mm. preferably from about 5 to about 25 mm. In the case of fluidized beds, the catalyst taken up by the support is preferably used, suspended in the wastewater like a slurry, in such an amount that a fluidized bed is formed within the reaction vessel, specifically in an amount of usually about 0.1 to about 20% by weight , preferably about 0.5 to about · <· (OGew.%., based on the suspension obtained. For the practical operation of the fluidized bed your reaction vessel resulting in, preferably in the captured from the support catalyst in the effluent suspended to. separates the catalyst · .om treated water resulting from the reaction by sedimentation, centrifugation or a similar suitable process and re-uses the separated catalyst to facilitate the separation of the catalyst from the treated water, the catalyst which can be used for the fluidized bed has a particle size of advantageously about 0.1 5 to about 0.5 mm.

Examples of useful oxygen-containing gases are I lift, oxygen-enriched air. Oxygen, oxygen-containing exhaust gases, etc. The oxygen-containing exhaust gases are those that have a lower oxygen concentration in air and one or more substances from the hydrogen cyanide group. Hydrogen sulfide. NH _:. Sulfur dioxide, organic sulfur compounds. Contain nitrogen oxides, hydrocarbons, etc., such as /. Fl a waste gas from the regenerator of the redox-Fn'.schwt.'felungsver Procedure meant. The use of such oxygen-containing waste gases is advantageous in that the harmful components of the gas can be rendered harmless together with those contained in the waste water. The feed throughput of the oxygen-containing gas can be determined from the theoretical amount of Siiuerstoff, which is necessary for the oxidation of the organic and / or inorganic substances in the wastewater and for the decomposition of the NHi to nitrogen. In general, the oxygen ^{ring r} j, ■: <■ ι- e; ner amount from about 1 to about 1.5 times. ■. "- /. ^ SWise from about 1.05 to about 1.2 times: ·:"r-eo-e'ischen amount of oxygen supplied. If the: ■.! Hvii'jte amount of oxygen is insufficient when using the acidic ■ -.i <"'*" ih.i! Tig-jn exhaust gas. the gas is supplemented with oxygen by supplying air, oxygen-enriched air or oxygen directly. The oxygen-ringed gas can be supplied to the reaction vessel at a single level or at two or more levels via branched lines the gas flowing out of the reaction vessel, if it is economical and advantageous for operation, for reuse: ■ - be recycled.

The reaction is up to about 37o ¹ C. preferably at a temperature of usually about 100 about 200 C. to about 300 "C, the reaction pressure should therefore only be such that the effluent at -.. * ■ DZ certain temperature of at least its liquid phase may be maintained, although higher temperatures will result in more effective removal of the ammonia.

This results from the wet oxidation treatment5 Enduring wastewater has a pH value of around 5 to around 8. It looks almost colorless and can be whatever it is. discharged or reused. However, if the wastewater contains high concentrations of sodium sulfate and other substances derived from sulfur compounds, so it can be fed directly into a reverse osmosis unit. The purified water can e.g. B. as Part of the scrubbing liquid can be reused for gas cleaning, while sodium sulfate and the like. Useful substances can easily be obtained from the concentrate.

The invention is explained in more detail with reference to the exemplary embodiments illustrated in the drawing; in it shows

F i ii. 1 is a flow diagram illustrating an embodiment of the method according to the invention in which a fixed bed is used;

Figure 2 is a flow chart for illustrative purposes another embodiment of the invention Process in which a fluidized bed is used and the collected catalyst for reuse is returned.

in Figures i and 2, like parts are like Ikvugs numbers designated.

According to FIG. 1, waste water is from a container I. fed through an I .line 2 to a pump 3 through which the water is compressed to a certain pressure level. The water is then passed through a pipe 4. a heat exchanger 5 and a line 6 promoted, mixed with an oxygen-containing gas and through a line 11 into a with a catalyst filled reaction vessel 12 introduced. As already mentioned, the pH value of the wastewater is determined by a Alkali ie adjusted according to the type of sewage. The alkali can add to the water in one or more parts of the container 1. of the lines 2. 4, 6 and 11 are added.

The oxygen-containing gas. which is pressurized by a compressor 7. is conveyed through a line 8, a humidifier 9 and a line 10, mixed with the waste water, as mentioned above, and introduced through the line 11 into the reaction vessel 12. It is preferable, but not critical, to use the humidifier 9, which serves to avoid evaporation of the water in the reaction vessel and to achieve an improved heat recovery efficiency, but if an oxygen-containing exhaust gas is used as the oxygen source, the humidifier is not used in order to avoid the transfer of harmful components from the exhaust gas to the treated water. For an improved liquid-gas contact efficiency and an increased reaction efficiency in the reaction vessel 12, it is advantageous to finely subdivide the gas bubbles in the flow of the mixed water and gas. Processes for subdividing such bubbles are, for. B. in JP-OS 49 873/1974 and 49 874/1974 disclosed, to which reference is hereby made. The oxygen-containing gas to the waste water can also be introduced or added at the outlet of the pump 3 is partially divided directly into the reaction vessel 12 at a single level or on two or more levels. If necessary , the waste water can be heated in the line 6 or in a lower part of the reaction vessel 12. However, if the required amount of heat can be supplied by the heat of reaction, the waste water does not need to be heated.

An alkali, which is usually in the form of an aqueous solution, is introduced from an alkali container 21 through a line 22, a pump 23 and a line 24 into the reaction vessel 12 at such a rate that the reaction space of

Wastewater flowing through the bottom upwards about 80% of its way continuously at a pH value of at least about 8 and allowing this to flow out of the reaction vessel through conduit 13 leaking water always maintains a pH of about 5 to about 8. As the pH of the wastewater drops, while the water inside the reaction vessel

12 rises as the reaction proceeds, the pH value of the water is adjusted to one by known means Plurality of levels measured at equal intervals over the distance of about 80% of the Total length of the reaction vessel from its bottom are arranged so that the alkali on each Level is fed where there is a decrease in pH on about 8 has been detected. Depending on the reaction conditions, the line 24 in a plurality of pipes for supplying the alkali at two or more levels with the progress of the Rcakti "ti be branched.

Niichuciii ua · * wastewater irtii the oxygen in the gas has reacted in the reaction vessel 12 under the specified conditions. the mixture obtained runs out of the upper part of the reaction vessel 12 through a conduit

13 out and is a separation drum 14 for gas and Liquid supplied.

That flowing out of the separating drum 14 treated water can be fed to the humidifier 9 through a line 15. The rest of the Humidification: 9 withdrawn treated water is fed via a line 16 to a cooler 17, cooled and relaxed and left alone to atmospheric pressure. The treated water can internally at increased pressure from the cooler 17 via a line ι H in an I mkehmsmoseeinheit 25 are introduced to to obtain purified water from a line 2fi and a concentrate from a line 27: n

Since \ us the separating drum 14 is escaping gas passed through a line 19 to the heat exchanger 5, in the·; the gas gives off heat to the wastewater, then on the atmospheric pressure is released and discharged through a line 20. Alternatively, the dated Reaction vessel 12 withdrawn liquid-gas mixture passed directly to the heat exchanger 5 and then in the separation drum 14 into a gas and a liquid be separated.

If the ingredients of the concentrate from the Line 27 are further decomposable, the concentrate can be conveyed into the container 1 and again the wet oxidation be subjected.

According to FIG. 2 wastewater is passed from a container 1 into a mixing container 34 in which the water is mixed with a catalyst from a container 32 through a line 33 to form a pulp. The cloudiness is compressed by a pump 3 to a certain pressure level and then in the same Way as in Fig. 1 through a line 4, a heat exchanger 5 and lines 6, 11 in a none Reaction vessel 31 containing catalyst is introduced. An oxygen-containing gas can usually be fed into the Reaction vessel can be fed in the same manner as in FIG. To the turbidity to a greater extent to fluidize, a part of the gas can be branched off directly from the line 10 through at least one Line are introduced into the reaction vessel 31. As in the exemplary embodiment according to FIG. 1 becomes a aqueous alkali solution from an alkali tank 21 through a line 22. a pump 23 and a line 24 to the reaction vessel 31 with a suitable one Throughput supplied to about 80% of the wastewater introduced into the reaction vessel adjacent to keep the waste water inlet of the reaction vessel at a pH value of about 8 at all times and to close it > i-r-possible that the treated water a Maintains pH from about 5 to about 8.

The high pressure treated water containing the catalyst is through a line 13, a separation drum 14, a line 15, a humidifier Mi ter 9, a line 16, a cooler 17 and a line 18 to one Separator 28 for liquids and solids such as a filter press. The separated liquid is drawn off from the system after expansion to atmospheric pressure or, alternatively, introduced through a line 29 directly into a reverse osmosis unit 25, in which the liquid is converted into purified, water flowing out of a line 26 is separated from a concentrate flowing out of a line 27. The catalyst captured in the separator 28 is returned through a line 30 to the container 32 and used again in the case of FIG. 1, the humidifier 9 is not used.

The following examples serve to provide a better understanding of the invention.

Example I.

The process according to the invention is carried out continuously h for 4000 h in the in F i g. 1 through the VVVise illustrated; ''leads.

A gas water (pH about 9.5) obtained from a coke oven becomes the lower part of a. cylindrical stainless steel reaction vessel with a space velocity of 0.99 h (based on an empty column) fed. The mass velocity of the liquid is 3.45 t / m ^: h. Air is drawn into the lower part of the reaction vessel with a volume of space

μ speed of 50.8 h ^: (based on an empty column under normal conditions) introduced. The reaction vessel is taken up with a catalyst in the form of pellets with a diameter of 5 mm from 2.0% by weight on n-alumina

·. Ruthenium filled as a metal-metal oxide mixture. The inside of the reaction vessel is kept at a temperature of 250 ^° C. and a pressure of 75 bar, while a 48% strength aqueous sodium hydroxide solution is poured into the reaction vessel at a throughput

-r-, which is required. in order to keep the part of the water which fills the reaction vessel up to 80% of its length from the bottom at a pH value of at least 8.5 permanently and to enable the water resulting from the wet oxdation to have a pH value of about 7 , 5 retains. The liquid-gas mixture originating from the catalytic reaction is continuously withdrawn from the upper part of the reaction vessel and then introduced into a separation drum (liquid-gas separator) in order to separate it into a liquid and gas, which are indirectly cooled or from the System are discharged.

The gas phase obtained 4000 h after the start of the process was found to contain. 2j ppm NH ₃ and 0.03 ppm nitrogen oxides, the

it remainder made up of nitrogen. Oxygen and carbon dioxide existed, whereas neither sulfur oxides nor hydrogen sulfide nor hydrogen cyanide were detected.

Table 1 shows the nature of the liquid

Phase and clic amount of dissolved catalyst support based on the determination after 4000 h is the beginning of the procedure.

After the lapse of 4,000 hours, the reaction vessel was vertically divided into two, and its inner surface was checked with the naked eye, but essentially no corrosion was found.

Example 2

The same procedure as in Example I is repeated with the exception that the titanium dioxide is used as the catalyst is used in place of valumina.

The gas phase obtained 4000 hours after the start of the process contained 0.5 ppm NlI ₁ and 0.01 ppm nitrogen oxides, while the remainder consisted of nitrogen, oxygen and carbon dioxide, whereas neither carbon dioxide nor hydrogen sulfide nor hydrogen cyanide were detected.

Table 1 shows the nature of the liquid phase and the amount of catalyst support dissolved out as determined at the end of 4000 hours from the start of the procedure.

After the mentioned time of 4000 h, the essentially no corrosion on the inner surface of the reaction vessel.

Comparative example I

Waste water is supplied continuously for 4000 hours in the same manner as in Example I with the exception treated so that the 48% sodium hydroxide solution is not supplied to the reaction vessel.

The gas phase obtained 4000 h after the start of the process was found to contain 5.0 ppm NH) and 0.6 ppm nitrogen oxides, while the remainder is nitrogen, oxygen and carbon dioxide existed, whereas neither sulfur oxides nor hydrogen sulfide nor hydrogen cyanide were detected.

Table I shows the nature of the liquid Phase and the amount of catalyst support dissolved out as determined after 4000 h had elapsed since the beginning of the procedure.

After 4,000 hours had passed, the reaction vessel was vertically divided into two and checked its inner surface visible to the naked eye, with corrosion scars found on various parts. Microscopic observation indicated that some of the scars became transcrystalline cracks became.

I alvlle I

ι ppm ι

200 (10

(iesanii-NII, 2S2O

CiSt. *) 2SK)

CiSB. **) 15950

CiOK *** l 1410

Concentration of the out
dissolved Al or Ti
SO ₄ - concentrate ion

*) (ies.imtslickstoff.

Example I.
(iük ilc.
hehanilellen
Water
I ppm)

2H.9

10.4
46.0
25.0

7.5
0.9

1500

Example Γ

liütcilcs Bcsci

Ivhiiiulelien I "··!

Water

ι ppm)

at least 15.0

99

99

99
99

9X..1

nothing
recorded
I 500

\ erjleich-neis
(iiitc iIl'n
heh.iiulellen
Water
ι ppm ι

pid I
Hcei

ι ", .ι

at least

99

99

99

99

9K.fi

4S.0

45.il

Γ5.4

4! .O

2.s

19.0
134 (1

at least

99

9S.3

98.4

9X.9

9 ". I

"ι (all organic carbon.

Due to the concentration of the dissolved Al given in Table 1, the ratio is the Amount of the dissolved carrier to the originally used carrier amount in Example 1 0.96% and in Comparative Example 1 21.3%.

Example 3

The method according to the invention is carried out in the method shown in FIG. 2 illustrated manner of handling a obtained from a coke oven and phenol, ammonium thiocyanate, Ammonium thiosulfate, ammonium nitrite. Ammonium nitrate, ammonium carbonate and ammonia containing gas water carried out in combination with wastewater resulting from a coke oven gas cleaning process yielded and hydrogen cyanide, hydrogen sulfide, NH3 and a very small amount of naphthalene using a ratio of 2 parts of the former to 1 part of the latter. A particulate

A shaped catalyst with a particle size of 0.15 to 0.3 mm from 5% by weight of ruthenium taken up on aluminum oxide is mixed with the mixed waste water to produce a slurry containing 10% by weight of the catalyst. The slurry is brought to a pH of 103 and then introduced into a cylindrical stainless steel reaction vessel at a space velocity of 1 ^ 51 h ~ '(based on an empty column) and at a mass velocity of 4.53 t / m ² · h. Air is introduced into the reaction vessel at a space velocity of 57.8 h ~> (based on an empty column, under normal conditions)

The inside of the reaction vessel is at a temperature of 250 ° C and a pressure of 60 bar held while a 48% aqueous sodium hydroxide solution with a in the reaction vessel Throughput that is needed to Wastewater leaving the reaction vessel from its bottom

Lis ILUS 80% of its length filled, always be kept at a pH of at least 8.5 to facilitate 'ind that the pH of the wet oxidation Anyone resulting water: holding of about 7.8. The liquid-gas mixture originating from the catalytic wet oxidation reaction is continuously withdrawn from the upper part of the reaction vessel, indirectly cooled and introduced into a separation drum, in which the mixture is separated into a liquid and a gas. The separated gas is expanded to atmospheric pressure and released into the atmosphere. The liquid phase is let down to atmospheric pressure, fed to a separator and separated there into the catalyst and the treated water. According to the findings, the separated gas phase contains 3 ppm NH ₁ and 0.05 ppm nitrogen oxides, the remainder being nitrogen. Oxygen and carbon dioxide exist, whereas neither

Sulfur oxides nor hydrogen sulfide were detected.

Table 2 shows the nature of the blended Wastewater and treated water.

Example 4

Waste water is treated in the same manner as in Example 3 with the exception that zirconia is used as a carrier instead of the Λ-alumina.

It is found that the gas phase contains 2.1 ppm NH) and 0.08 ppm nitrogen oxides, while the remainder consists of Nitrogen. Oxygen and carbon dioxide exist, whereas neither sulfur oxides nor hydrogen sulfide exist hydrogen cyanide can still be detected.

Table 2 shows the nature of the treated Water.

('line tics Ik ¹ I-PK ¹ I ■ Hl-nCIII'HUIÜ Ik'ispiL-l 4 H: I. JsL ¹ IIhJlIIIl! konibiniLTlL'ii (inc lIl-n η ι ". ι <ΐinc lIl's ,. 1 Ahua-sLTs MuIHIl ¹ IIl- treated (ppm I W .InslTs Water \\ ι ppm ι w en igNiL-ns I ppm ι W. enigsleiis C SB. 3,500 ίο at least 2 s enigsleiis Oesanite-Nll, 4000 4th <■) <■) λ 5 >) ' ) L), s ".Il Nitrate and nitrite JOO 1; fi.O W. Stiekstoff at least on the one hand CiSB. 12 700 ι> , S. <■) ' ) ¹ Xi. 3 i) ■ ".9 OK.*) I 700 I (i5 L) N. 3 Vs W.
I) CiOK. 1 100 I ¹ » at least 2 ;, enigsleiis
t) CiSt. 3,500 IS -). s SO ₄ 105 1046 145 (1 Concentration of the her 1.0 nothing triggered Al or Zr erf: il! (

*) Total cabbage.

Example 5

The method according to the invention is carried out in the same embodiment as in FIG. 1, except that the humidifier 9 is not used.

A gas water obtained from a coke oven is adjusted to pH 11.0 with a sodium hydroxide solution and then introduced into the lower part of a reaction vessel at a space velocity of 039 h- '(based on an empty column). The mass velocity of the water is 3.45 t / m ² - h. 2 g / Nm ³ hydrogen sulfide, 4 g / Nm ³ NH ₃ and 0.1 g / Nm ³ hydrogen cyanide-containing air is in the lower part of the reaction vessel with a space velocity of 44.4 h ~ ^! (based on an empty column, under normal conditions). The reaction vessel is charged with a catalyst in the form of spheres with a diameter of about 6 mm made from 2.0% by weight of palladium absorbed on -aluminium oxide as a metal-metal oxide mixture

The inside of the reaction vessel is held bar at a temperature of 250 ⁰ C and a pressure of 55, while \ ktionsgefäß in the Re. A 48% aqueous Natriumhydroxi solution at a rate introduces needed, the part of the water, which fills the reaction vessel from its bottom up to 80% of its length, always to be kept at a pH value of at least 8.5 and to enable the water resulting from the wet oxidation to maintain a pH value of about 7.6 . The liquid-gas mixture resulting from the catalytic reaction is continuously withdrawn from the upper part of the reaction vessel and then passed into a separation drum. The gas phase obtained 4000 hours from the start of the process contains, it is found, 3.5 ppm NH ₃ and 0.05 ppm nitrogen oxides, the remainder being nitrogen, oxygen and carbon dioxide, but neither sulfur oxides nor hydrogen sulfide nor hydrogen cyanide were detected. The following Table 3 shows the nature of the treated water obtained 4000 hours after the start of the treatment.

Table 3

COD.
Gesami-NH:

nitrate
GSB.

GOK

GSt.

concentration of the extracted Al

Ciülc the Güie des Elimination Ciasnüssmkeu treat (%) ι ppm ι Water (ppm! 40 (10 10 at least 99 5 (100 2.5 Wenasia 99 60 0.8 98.7 16000 20th least of all 99 2200 175 92.0 1,500 15th 99 4700 4th who i asten s 99

1.2

Example 6

The inventive method is in the same type of execution. as illustrated in Fig. 2, performed except that the humidifier 9 is not used.

With a gas-water (pH 92) obtained from a coke oven, a particle-shaped catalyst with a particle size of 0.15 to 0.3 mm composed of 5% by weight of ruthenium absorbed on titanium dioxide as a metal-metal oxide mixture is mixed to produce a pulp which is introduced into a cylindrical stainless steel reaction vessel with a space velocity of 1.51 h "^; (based on an empty column) and a mass velocity of 4.53 t / m ² · h. Air containing 5 g / Nm ^{3 of} hydrogen sulfide is introduced into the reaction vessel with a Space velocity of 72.4 h- ^: (based on an empty column, under normal conditions) introduced.

The interior of the reaction vessel is kept at a temperature of 250 ⁰ C and a pressure of 60 bar, while an aqueous sodium hydro-

Table 4

Oxide solution is introduced into the reaction vessel at a throughput that is required by the reaction vessel to keep filling v / ater at a pH of at least 8.5 and to allow the water to be removed from the Water resulting from wet oxidation retains a pH of about 6.5 from the catalytic wet oxidation reaction originating liquid-gas mixture is continuous from the top of the reaction vessel withdrawn, indirectly cooled and introduced into a separation drum, in which the mixture is divided into a liquid and a gas is separated. The separated gas is a.ul Atmospheric pressure relaxed and then drained. The liquid phase is expanded to atmospheric pressure, in a separator is introduced and separated into the catalyst and treated water. It is found that the separated gas phase contains 1.0 ppm NH3 and 0.02 ppm nitrogen oxides, the remainder being nitrogen Oxygen and carbon dioxide exist, whereas neither sulfur oxides nor hydrogen sulfide are detected.

Table 4 shows the nature of the wastewater and the treated water.

(SB.

Total NH.

X it rat- and Niint-Sticksi.oH "

(iSB.

Gk

GOk

GSt.

(inte of Goodness of the ■ - - Elimination (', iNflii- ^ iukeit treated ("ή) ι ppm I Water (ppm) 400 (1 at least 99 5,000 0.3 least:. 99 300 0.Λ at least 99 UiOOO 20th at least 99 2,200 120 94.5 1> ll'l 15th 99 4 "I) II 19th at least 99

Claims (6)

Patent claims: 1. A method for treating wastewater containing ammonia and / or oxidizable organic and / or inorganic substances, wherein the wastewater is at a pH of about 8.5 to about 11.5 in a reaction vessel for the purpose of its wet oxidation with an oxygen-containing gas introduces the presence of a catalyst and the wastewater at a temperature of about 100 to about 370 ⁰ C and a pressure that allows the wastewater to remain in the liquid state, the oxygen-containing gas has an oxygen content of about 1 to about 1.5 times the amount theoretically contains the amount required to decompose the waste water content of ammonia, organic substances and inorganic substances and the catalyst absorbed by a carrier contains at least one substance from the group iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium. Contains platinum, 3n copper, gold, tungsten and their water-insoluble or sparingly soluble compounds, characterized in that an alkali is fed to the reaction vessel in such an amount that the waste water flowing through the reaction chamber from bottom to top is about 80% of its way is always kept at a pH of about 8, while the treated wastewater has a pH of 5 to 8. 2. The method according to claim 1, characterized in that the wet oxidation of the waste water carried out in a reaction vessel of the fixed bed type. 3. Procedure natii Ansj.uch 1, characterized in that that the wet oxidation of the waste water in a reaction vessel 'es fluidized bed type performs. 4. The method according to claim 1, characterized in that that the catalytic wet oxidation a non-catalytic wet oxidation, which the Carpenter process corresponds, upstream. 5. The method according to claim 1, characterized in that one is used as the oxygen-containing gas Oxygen-containing exhaust gas is used. 6. The method according to claim 1, characterized in that one is through the wet oxidation introduces resulting water into a reverse osmosis unit.