DE1959326A1 - Clarification of industrial waste - Google Patents

Description

DR. GERHARD ÖCHUPFNER

41O2 HOMBERe (NlEDERRHEtN) BaumatraSa 31

Telephone CO 21 36) "23-2243

Telegraph θ SS 385

November 22, 1969 T 69 015

TEXACO DEVELOPMENT CORPORATION

135 East 42nd Street New York, N.Y. 10 017

UNITED STATES.

Clarification of industrial wastewater

The present invention relates to a process for the treatment of municipal and industrial wastewater, as they come from chemical plants, refineries, canning factories, paper and pulp mills.

009024/1925

9593.28

Aside from the obvious problems of air and water pollution associated with the disposal of industrial wastewater, they are common in the wastewater itself Contain substances whose recovery or return to the respective starting process is desirable. as well one would like to have the water coming from the sewage treatment in one more or less for reasons of water saving recovered form which has been cleaned and suitable for reuse. Because of the tremendous amount of it to be treated Material, the clarification processes used must be particularly economical and efficient.

The present invention enables the above objects to be achieved. It consists of a procedure for the clarification of industrial and municipal waste water, characterized in that the water-soluble and water-insoluble organic substances contained in the waste water become solid Coke are coked and optionally the coke from the Water is separated and the water is oxidized to further reduce its chemical oxygen demand. the The invention also relates to a plant for the clarification of industrial wastewater, characterized by a heat exchange device, which enables the untreated wastewater to be preheated by the treated wastewater; a coking device for receiving and coking the preheated Waste water with formation of coke and purified waste water; a separator that is in communication with the coking device and receives its contents to the To separate coke from wastewater and to purify the wastewater in this way;

0Ö9ÖU / 1Ö2S

a conduit for conveying the treated wastewater to the heat exchange device in order to increase the temperature of the treated Reduce wastewater and at the same time preheat the untreated wastewater '} and, if necessary, a device for oxidation of the treated wastewater in order to further reduce its chemical oxygen demand

Although the working principle is the same in all cases, It is clear that certain equipment and devices may be used to clarify industrial waste water of a certain origin Conditions are preferred. Thus the diagram shows «9 Fig. 1 an embodiment of the apparatus according to the invention, which is especially suitable for the treatment of municipal wastewater is · The schematic drawing Fig. 2 shows an apparatus according to the invention, which is preferably used for the treatment of liquid Outflows from a pulp mill is intended · The schematic drawing Fig. 3 shows an apparatus according to the invention, which is used for treating the sodium hydroxide solution from a Kraft pulp abrik is suitable. The schematic drawing Fig. 4 shows an apparatus according to the invention, which is used for the treatment of waste liquor from a sulphite pulp mill. The schematic drawing Fig. 5 shows an apparatus according to the invention for treating the waste liquor from a calcium-based sulfite pulp factory.

The general operating conditions of the process provide for heating to 200 to 400 ^° C. at a pressure of 20 to 250 atm for a period of 0.5 minutes to 6 hours. It is clear that for certain industrial wastewater certain values within the above In the case of biological sewage sludge, for example, coking is preferably carried out at temperatures between 200 and 370 C and a pressure which is greater than the vapor pressure of the water at the selected temperature and is generally between 20 and 250 atm a duration of 0.5 minutes to 2 hours. The waste water separated from the coke

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it will then expediently oxidize for 0.1 to 10 minutes under the above pressure and temperature conditions ^{Heat to 260 to 370 °} C. for up to 10 minutes under a pressure which is above the vapor pressure of the water at the selected temperature and is usually between 60 and 210 atm. To treat the caustic soda from Kraft pulp mills, which contains inorganic sodium salts and organic substances, the caustic is preferably used for 0.5 minutes to 6 hours under a pressure sufficient to vaporize

To prevent P of the water, ^{heat it to 230 to 370 0} C, and recover the gaseous portion formed as well as a waste water that contains practically all of the inorganic sodium salts originally present in the waste liquor. Waste liquor from pulp and paper mills can be treated by it passes for 0.5 to 20 minutes under turbulent flow conditions at temperatures between 230 and 370 ⁰ C and a pressure which is higher than the vapor pressure of the water at the selected temperature and is usually between 35 and 210 atm through a tubular heating zone. Organic waste liquor from sulfite pulp mills and canning factories is preferably ^{coked for 10 minutes to 2 hours at 200 to 320 0} C and 20 to 210 atm, followed by the

* Taking coke separate sewage for 1 minute to 1 hour is oxidized under the same conditions.

In Fig. 1, the boxes at the top represent known process steps and apparatus for wastewater treatment. The wastewater flowing in through line 5 goes through first a grate 6 which holds back bulky objects such as large pieces of wood, stones, metal and the like. Of the Sieve grate 6, the raw wastewater enters the shredder 7,

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- * -. 1359326

9: ' ■ .- ■'.

where the plague washed through the grate be reduced to a certain particle size · From the Grinder 7, the wastewater reaches the sand trap 8, where sand, gravel, glass, metal particles and the like are deposited · The wastewater then goes into the primary clarifier 9. If necessary, the wastewater can be discharged when it enters the primary clarifier Chlorine from line 11 can be added.

In many existing sewage treatment plants, the wastewater from the primary clarifier is passed through line 12 directly or after filtering off the suspended solids into rivers, lakes or sewage fields. In today's municipal sewage treatment plants, post-treatment _t, for example, an activated sludge process 13, is often used. In such cases, the sludge is separated from the waste water in the secondary clarifier 14, and the waste water is directed via line 16 to a sewage field or a pond, river, lake or the like. Part of the sludge from the secondary clarifier is returned to the activated sludge process via Leittasag 17 Ik in order to activate the bacterial flow activity again and again.

In the preferred embodiment of the invention, the sludge is withdrawn from the primary clarification tank 9 and / or the secondary clarification tank 14 and passed by means of pump 21 through line 22 and heat exchanger 23 into the tube heater or coker 24, where the suspended and dissolved organic substances are described below Way to be removed.

In the example given here, the sludge is in the heat exchanger 23 by indirect heat exchange rait hot treated wastewater is preheated and then fed into a furnace tube heater 24, where the sludge

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at a pressure between 20 and 250 atm, which is sufficient to prevent evaporation of the water, to the desired coking temperature in the range of 200 and 370 ⁰ C is heated. The heater 24, which is provided with a furnace, is two-way a tube heater of the type commonly used in mineral oil processing. The hot sludge is discharged from the heater into a coking drum 26. The coking rose is a large pressure vessel ₉ that absorbs the © rhitaten sludge for a period of 10 minutes to 1 hour and keeps it at the desired process temperature

for example 260 ° C and the process pressure of for example 58 atm · In the coking drum P ° , both the water-soluble and the water-insoluble organic components of the sludge are converted into a carbonized pesticide or coke, which by L @ it «ng 3 ^ - a «s deisa under a part of the coking drum is withdrawn *

During the coking process, the oxygen bound in the dissolved sugars ₉ acids, and other organic "oxygen compounds shower. Dehydroxylation and decarboxylation in Masser and carbon dioxide converted the same time, di @ suspended -organic Peststoffe in the mud coked and converted into one · of Fäulnisfoakterien free solid"

The practically free of suspended solids © wastewater is drawn off from the coking drum via line 27.The gas released during the coking process escapes through the pressure relief valve 30, while the fat separated from the wastewater in the coking drum 26 is drawn off through a line with control valve 33. The coke that solidifies the Matorial is deposited in the wastewater, collects in the lower part of the coking tetroramel and is continuously and periodically in the form of a white sludge lamb through line 34 and Valve 36 ± n separator 33 run @ wk

The water vapor and gases given off by the coke-containing waste water in separator 35 pass through line 37 into a suitable exhaust gas removal system. The essentially anhydrous coke is withdrawn from separator 35 through line 38. A filter or centrifuge can be built into the separator 35 to remove the water from the solid coke. The waste water from the separator is drawn off through line 41 by means of a pump 39 and combined with the waste water from the coking drum 26 in line 27. The combined waste water streams from lines 27 and 41 are used to remove the remaining organic compounds el r _; -. ft subjected to oxidation in the oxidizer. The oxidation apparatus 42 expediently consists of a pipe coil. The air required for the oxidation stage is introduced into the oxidation apparatus 42 through line 43 Ii, expediently already into line 27.

In general, the air oxidation is carried out under approximately the same temperature and pressure conditions as the coking process taking place in heater 24 and coking drum 26, ie at a temperature in the range from 200 to 370 ^° C. and a pressure in the range from 20 to 250 atm. The temperatures in the reaction zone 42 are preferably in the range from 200 to 320 ^° C., the pressures being above the vapor pressure of the water under the conditions prevailing in the reactor, ie in the range from 50 to 110 atm.

The air requirement for the conversion of the remaining organic material in the wastewater of the coking zone 26 and the separator 35 depends on the effectiveness of the coking process and the chemical oxygen demand (COD) or biochemical Oxygen demand (BOD) of the wastewater. In general, 10 to 100 g of air per liter of wastewater charge is sufficient for this Oxidation of dissolved organic compounds in the wastewater from the coking process. The time required for air oxidation

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is generally between 0.1 and 10 minutes. That the Water leaving reactor 42 is passed through the heat exchanger, where it is raised to a temperature in the range of 65 to

S5 ° C is cooled. Through pressure relief valve 44 and line 46

12th
it is discharged into the sewer system.

In the following examples and throughout the description, the expression "chemical oxygen demand", abbreviated to "COD", is used in the conventional sense. It therefore refers to the entire oxidizable material that is present in the liquid in question, regardless of whether it is biodegradable or not. In the BOD tests, on the other hand, the amount of oxygen is determined which is ^{consumed during a 5-day bacterial activity at 20 °} C. in a chemically standardized and stabilized sample. Although, strictly speaking, the COD cannot be compared with the BOD, it should indicate the decrease in the BOD with sufficient accuracy to enable a comparison of the effectiveness of different treatment processes, especially with comparable wastewater samples, on this basis.

Examples 1-3

Raw sewage sludge from the primary clarifier of the municipal sewage treatment plant in Beacon (New York) was taken on different days and treated according to the method of the present invention. The operating conditions and results are given in the tables below. The raw sewage sludge was characterized by the following averages:

Raw sewage sludge

COD, g / l 60

Evaporation residue, g / l 50

Total volatile matter, g / l 33 Fixed residue, g / l 17

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Coking stage

Example no. 1 2 Operating conditions Temperature, ⁰ C
Pressure, atm
Time, h 232
33.4
2 288
77.3
2 Product analysis Dry coke

316 110.7

42.5 24.6 53.3 5.3 - - 1.3 2.5 0J4 0.4 ο! * - 0.8 32.7 64.0 36.0

% By weight of the starting material 1.57 1.60 1.11 Analysis, wt.%

Carbon hydrogen nitrogen sulfur phosphorus ash

fat

% By weight of the starting material - 0.13 0.43 carbon,% by weight - 47.0 72.0

Air oxidation level

The wastewater obtained from the above experiments was after Separation of coke and fat from air oxidation in a j Subjected to bomb. The conditions and results were as follows!

Example No. 1 2 3

Operating conditions

Temperature, ° C pressure, atm oxygen, g / l Time, h

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232 6th U) 288 4th C2) 316 5 (3) 31, 7th (1) 84, m 105, 6th C3) 34, 21 35, 4th 4th 10

1 - 359326 3 - "4.27 clear, 13th , 90 2.18 water-clear ■ - 6th .92 2.09 -, ■ 6th , 98 2.18 2.18 4th , 6 2.4 4th clear, water-clear

Treated liquid

Evaporation residue, ■ g / l Total volatile matter, g / l Fixed residue, g / l

COD, g / l

Appearance

(1) Two 2 hour oxidation periods using of 13.9 or 20.8 g / l 0 «

(2) Two 2 hour oxidation periods using 7 and 14 g / L respectively

( 3) Five 2-hour oxidation periods with 0.4, 6.4, 6.4, 6.4 or 16 g / l using chrome steel wire mesh as a catalyst.

Example 1 A

Sufficient hydrated lime was added to the treated liquid from Example 1 to raise the pH to 7.5. A green precipitate formed. The results of the lime treatment are given in the following tables.

Lime treated liquid Ca (OH) _0.1 g / l

2 '

6.25

pH '7.5

Color light as water

Smell none

Evaporation residue,% by weight 11.3 Total volatile components,% by weight Fixed residue COD, g / l

4.3 7.0

Solid precipitation

Spectrometric analysis Major fraction: calcium Smaller part: nickel, iron

Traces: silicon, manganese

Example 2 A

Waste water from the coking of Example 2 was contained in a bomb, the chrome steel wire mesh as the catalyst, air oxidation at 29o ⁰ C and atm subjected to 85, wherein two 2-hour oxidation periods of 7 and 14 g / l of oxygen were used. After the treatment, the wastewater had a COD of 1.99 g / l.

Examples 4-15

A series of tests was carried out in which the heat treatment of the sewage sludge from the primary clarification tank of the municipal sewage treatment plant in Beacon (New York) under different conditions Time and temperature conditions took place. In these tests, the sewage sludge was placed in stainless steel pipes that were immersed in a high tin metal bath. The operating conditions and results can be seen from the following tables. For Examples 4-11, tubes 19 mm in diameter and for examples 12-15, those with a diameter of 8 mm are used.

Example no. 4th 5 6th 7th Temperature, C 260 260 260 260 Time at 260 ^° C., min 1 10 . · 20 60 (1) Coke, wt.% Des Starting material '3.4. 3.8 2.8 3.9 Liquid product, COD, g / l 9.83 10.6 12.6 17.2

(1) It took 3.5 minutes to heat the material to operating temperature needed.

Example no. 8th 9 10 11th Temperature, C 285 285 285 285 Time at 285 ° C, min (1) 1 10 20th 60 Coke, wt.% Des Starting material 2.5 2.0 3.0 2.5 Liquid product, "COD, g / i 12.0 13.0 13.6 11.2

(1) It took 3.5 minutes to heat the material to operating temperature needed*

Example no. 12th 13th 14th 15th Temperature, ⁰ C 316 316 316 316 Time at 316 ° C, min 1 5 10 20th Coke, wt.% Des Starting material 2.0 ?, 2 2.7 2.9 Liquid product, COD, g / i 13.9 13.0 11.0 11.7

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Examples 16-35

Biological sludge from the treatment of refinery wastewater by means of an activated sludge process in the Puget refinery Sound from Texaco Inc. in Anacortes (Washington) was treated according to the method of the invention. The one provided Mud had a characteristic gray, slimy appearance and could be filtered through laboratory vacuum filters do not filter. This mud was in stainless steel pipes, that were immersed in a metal bath containing a lot of tin, coked. The conditions and results are in the reproduced in the following tables.

Biological sludge

Evaporation residue, g / l 60.8

Total volatile matter, g / l 39.7 Fixed residue, g / l 21.1

pH 6.9

COD, g / l 67

Example no. 16 17th 9 18th 1 19th 1 20th 21 Tube diameter, 19th 19th 2 19 ' 0 19th 5 19th 19th mm (1) Temperature, C 243 246 243 243 243 246 Time, min (2) 0.1 1 5 10 30th 60 Coke, wt.% Of Aus gang material 2.7 2, 3, 3, 3.7 4.3 COD of the liquid,
g / l 19.1 20, 18 18 21.1 21.7 Example no. 22nd 23 1 24 7th 25th 5 26th 27 Tube diameter 19th 19th 3 19th 7th 19th 4th 19th 19th mm (1) Temperature, C
Time, min (2) 260 260 260 260 260 260 Coke,% by weight of the 0.1 1 5 10 30th 60 gangsreateriale COD of the liquid, 2.7 3, 2 _f 2, 2.4 2.4 23.1 22 19th 26, 27.1 21.3

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Example no. 28 29 30th 31 32 33 Tube diameter,
ram (1)
Temperature, C
Time, min (2) 19th
288
0.1 19th
288
1 19th
288
5 19th
288
10 19th
288
30th 19th
288
60 Coke, wt.% Of Aus
gang material
COD of the liquid,
g / i 2.4
22.8 2.0
21.4 2.4
17.7 2.5
19.5 2.1
20.5 2.7
15.8 (1) Nominal size

(2) The specified time denotes the

Treatment time at the specified operating temperature; C 3,5 min were required to the raw material to heat up to operating temperature) ·

Example no. 34 35

Tube diameter, 8 8 mm (I)

Temperature, C 316 330

Time, min (2) 1 1

Pressure, atm 116 130.1

Coke, wt% of starting 2.3 2.0

materials

COD of the liquid, g / L 17.5 16.5

(1) Nominal size

(2) The specified time denotes the duration of treatment at the specified operating temperature; (It took 3.5 minutes to heat the starting material to operating temperature). j

j Example 36 j

Biological activated sludge from an oil refinery is treated according to the method according to the invention · In one operating week, an average of 400 l / min of sludge is passed through · After heat exchange With hot, clarified wastewater, the

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Sludge fed to a tube heater equipped with a furnace. The flow conditions are regulated in such a way that a turbulent flow is achieved in the tube heater and the sludge has a residence time of about 1 min at temperatures in the range from 250 to 280 ^° C. The coked liquid is then passed into a high pressure separator. Coke is continuously transferred to a blow-off tank where virtually all of the water is evaporated and dry coke is obtained. The treated, coke-free liquid from the separator is mixed with air and fed to the heated tubular oxidation reactor equipped with a furnace. The air / liquid ratio is chosen in such a way that a slight excess of oxygen over the stoichiometric requirement of the liquid measured in COD is maintained. In the present example, the COD of the liquid product averaged 16,000 mg / l (16 g / l) during a typical week of operation, and 30 kg / min of air were added to the liquid product introduced into the tubular oxidation reactor. The residence time in the tube is about 1 min at an average temperature of 270 ⁰ C. The oxidized wastewater has an average COD of 4100 mg /. 1 Every minute 37.2 kg or, on a dry basis, 28 ^ 1 kg of wet coke are obtained. The main analytical values are as follows:

Source material Oxidized coke liquid 104.4 ⁰ C - qdried COD, g / l oxygen 67.0 4.1 Carbon, wt.% - 41.2 Sulfur, wt.% - - 1.2 Nitrogen, wt.% - - 2.8 Phosphorus, wt.% - - 1.6 Silicon, wt.% - - 7.3

1-859326

The terms "evaporation residue", "total volatile constituents" and "fixed residue" used here are known to those skilled in the art (see "Standard Methods for Examination of Water" Sewage and Industrial Wastes ", 10th Edition, American Public Health Association, New York 1955) . The evaporation residue is determined by heating the sample to 103 ^° C. in an evaporation dish. The fixed residue is determined by heating the evaporation ^{residue to 600 °} C. in an evaporation dish. Total volatiles are the difference between the evaporation residue and the fixed residue.

According to the method according to the invention, it is also possible to treat waste liquors from paper preparation processes. According to the invention the waste liquor from a paper preparation process is treated with a hot hydrocarbon liquid, a rapid coking of the water-soluble organic substances contained in the waste liquor and a strong reduction of the COD. Apparatus suitable for this modification of the invention enables direct contact between the waste liquor and the immiscible heated hydrocarbon

so substance liquid. In this way a rapid transfer of heat is achieved in that the carbonization or coking of the organic material contained in the waste liquor after 0.5 to 10 is substantially completed min at 290 to 330 ⁰ C. The contact or mixed treatment is preferably carried out in cocurrent; however, a countercurrent method is also effective.

In Fig. 2 wood chips of suitable origin, for example Pichte, fed through line 105 to the digester 106 and there digested in a cooking liquor introduced through line 107. The schnitzel is treated in the general

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mean at temperatures between 130 and 150 ^° C. and at a pressure between 5 and 6 atm and extends over 6 to 12 hours. In the present example, a sulphite cooking liquor based on calcium is used in the cooker 106. A typical lye contains 7% by weight of SOp, of which 4.5% by weight as sulphurous acid and 2.5% by weight as calcium bisulfite. The acidic cooking liquor from the sulphite process usually also contains excess or free sulfur dioxide.

The cooker 106 is a large pressure vessel that is conveniently lined with acid-proof stones or stainless steel is. After charging the cooker with several tons of wood chips, the cooking liquor is passed through line 107 pumped in while air escapes from the top of the digester through a suitable valve 108. This valve also serves as a pressure limiter during the cooking process. Pressure relief valve.

After charging the digester with cooking liquor and wood chips, the cooking liquor is pumped by means of pump 111 through line 109 and heater 112 and then returned to the lower part of the cooker. The wood chips are gradually brought to a temperature of about 110 ^° C. by the heated cooking liquor, which generally takes 1 to 2 hours. Then the desired cooking temperature is set. During the cooking process, the liquid level in the digester is kept below the upper rim of the vessel by drawing off part of the cooking liquor through line 113 with valve 114.

After the boiling time has elapsed, the contents of the digester 106 are drained through valve 116 and line 117 into the pit 118 , where the paper pulp is separated from the waste liquor formed. The paper pulp is fed through line 119 for further processing. Before releasing the pulp from the digester into the pit, the pressure in the digester is usually released by draining it

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of gas and water vapor reduced to about 1.75 atm by valve 108. After the pressure in the digester is reduced, the drain valve 116 at the bottom of the digester is opened to allow emptying of the contents into the pit 118 to allow water vapor and gas to escape from the pulp during drainage are released, pass through line 121 into a recovery system, not shown, in which the steam condenses and sulfur dioxide is dissolved in the water and recovered for reuse in the cooking liquor · From the gas that during of the cooking process and the pressure relief escapes through the pressure relief valve 108 at the top of the cooker, is also the sulfur dioxide recovered and returned to the system with the acidic cooking liquor

It should be noted that the process of cooking and digestion the wood chips and the process of separating the pulp from the waste liquor and the recovery treatment the exhaust gases from the cooker and the drainage pit do not ice Part of the present invention are to be regarded as merely representative examples of conventional technical ones Should serve practice. The process conditions mentioned in this patent specification and compositions are basically those used in a sulfite paper making process calcium-based are typical. The detailed description given here explains a preferred embodiment of the invention Process as it is used for the treatment of waste liquor from such processes. However, it is clear that the inventive method with the same effectiveness for the treatment of waste liquors of the various other Can use paper preparation processes.

According to the present invention, the waste liquor is removed from the pit withdrawn via line 122 and by means of pump 123 via line a coking system to remove the dissolved organic Substances supplied from the waste liquor as described below. In the present example, the waste liquor is running out

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Line 124 through the heat exchanger 126, where it is liquid to be described by heat exchange with hot re-liquid Origin is preheated. The preheated waste liquor from the heat exchanger 126 is then with hot hydrocarbon liquid from line 127 intimately mixed. An intimate mixture and an adequate residence or Ensuring contact time between the hot hydrocarbon liquid and the waste liquor is appropriate Mixer 128 provided. In the present example, the mixer 128 is a simple flow mixer, consisting of one A plurality of tubes or tubes arranged in a serpentine fashion and preferably by using elbows or other sharp curves increase the turbulence. The resulting mixture of hydrocarbon liquid and heated Waste liquor is passed into the oil / water separator 129

The contact time between the hot hydrocarbon liquid and the waste liquor is from about 0.1 to 5 minutes. Temperature and volume of the through line 127, introduced hydrocarbon liquid are that the temperature of the resulting mixture 260-320 ⁰ C is chosen. In general, it is advisable to use approximately equal volumes of hydrocarbon liquid and waste liquor, although the amount of hydrocarbon liquid can vary between 0.5 and 2 parts by volume per part by volume of waste liquor. \

At the union of the hydrocarbon oil and the waste liquor there is coking of the organic compounds contained in the waste liquor. During the coking process will the bound oxygen in the sugars, acids and other organic oxygen compounds contained in the waste liquor are released as carbon dioxide and water by decarboxylation and dehydroxylation, and a water-insoluble solid coke remains. The one coming out of the mixer 128 Mixture of waste liquor and hydrocarbon liquid contains carbonized solid or coke particles

In the oil / water separator 129, the treated waste liquor, containing the coke particles produced in the process, from the hydrocarbon liquid or oil phase separated. The treated waste liquor, which contains the coke formed in the process, comes from the lower part of the oil / water separator passed through line 131 in the 'heat exchanger 126, where the heat from the hot treated waste liquor to preheat the Waste liquor from line 124 is used. The coke dispersion is extracted from the heat exchanger 126 through the reducing valve and line 133 into the pesticide separator 134 where the coke, expediently by filtration, from the treated VC ..- ~ gtuge is removed. That of the treated waste liquor separated solids or coke is withdrawn from separator 134 through line 135. That free during coking The gas being produced is discharged from the separator 134 via line 136 and subjected to a treatment for the recovery of chemicals subjected. The treated waste liquor is drawn off from the separator 134 through line 138 and by means of a pump 139 fed to the container 1.40, where it is used to replenish the cooking liquor for the process. The reducing valve 132 in Line 133 lowers the relatively high pressure of the liquor process to the relatively low pressure of digester 106, i.e., it causes a pressure reduction from about 70 to 7 atm.

Suitable chemicals for making the cooking liquor can be added to container 140 through line 141. Through A

Line 142 may introduce fresh or recovered acid into vessel 140. The way of completing the Cooking liquor as well as the composition or formula used in the manufacture of cooking liquor from the treated waste liquor is not part of the present invention. It should be clear that the treated waste liquor, although it is from soluble organic substances such as sugars, starches, lignosulfonates and the like is exempt, still contains inorganic substances. It goes without saying that if appropriate treated waste liquor with relatively low COD

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can be withdrawn from the system, for example by conduction 144 with valve 145.

The hydrocarbon liquid separated from the treated liquor and the coke in separators is extracted from the upper Part of the separator withdrawn through line 146 by means of pump 148 and fed to the oil heater 150, where the hydrocarbon liquid is brought to the temperature required to return it to the waste liquor in the mixer 128 through line 127 is desired.

The method according to the invention for treating waste liquors from paper preparation processes is illustrated in the following examples explained in more detail.

Examples 37 and 38

Leaching from an ammonia-based sulphite process working paper preparation plant (Example 37) and off a plant operating according to the Kraft process (Example 38) were each subjected to a heat treatment with equal parts by weight of η-decane for a period of one hour at a mixed temperature of 288 ° C. The coke formed in the process was recovered from the aqueous phase by filtration.

example 37 example 38 Initial water Starting water material phase material phase Type of exit materials sulfite - force - COD ₁ g / l 153.5 11.3 167.0 57.4 Sulfur, wt.% _ 0.11 0.29 0.38 Evaporation residue, g / l 114.3 - 172 -

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example Example 38 Dry coke

% By weight of the starting material
Sulfur, wt.%
Carbon, wt.%
Nitrogen, wt.%
Ash, wt.%

Pestilence

5.1
6.38

59.4
2.6
4.5

Pestilence

3.67 1.19 77.7

The properties of the n-decane feed and the recovered Oil phase are shown in the following table.

API density
Aniline point, ⁰ C ( ⁰ F
Sulfur, wt.%

ASTM distillation,
Start of boiling

5%
10
50
90
95
End of boiling

Residue, wt.%

η-decane loading Example 37 Oil phase

Example oil phase

61.0 60.7 60.9 76.64 (169.9) 76.42 (169.5) 76.42 (169.5 <0.005 0.023 -

169.4 169.4 169.4 169.4 336
336
336
336

169.4C336
169.4 (336
172.7 (343

1.2 168.2
169 * 4
169.9
169.9

334; 336!

337

169.9 (33?

169.9 (537 177 (350

f 3

example

Waste liquor from a Kraft process was as in Example 37 a heat treatment with equal parts by weight of kerosene for the Subjected for 1 hour at an equilibrium temperature of the mixture of 288 ° C. The results are given below

Ausqanqsmaterial water phase

COD, g / L 153.5

Sulfur, wt.% -

Evaporation residue, g / l 172

48.9 0.38 9

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Dry coke ■% by weight of the starting material carbon,% by weight ash,% by weight

Ausqanqsmaterial

Water phase

3.78 62.4 16.3

The properties of the kerosene charge and the recovered Oil phase can be seen from the following list.

Keresinbe- Oil phase sendunq 44.4 180.3 40 (137.1) 43.7 (143.9) 58 ^ 3 183.7 328) 62.1 (321) 164.5 189.1 356) 160.5 (344 195.2 363) 173.2 350 201.8 372 177 359 208.4 384 181.4 370 216 395 188 380 223.8 408 193 390 210 420 199 403 232.6 435 205.7 417 252.9 213.9 433 263.3 222.7 455 97.5 234.8 475 1.0 245.8 490 1.5 254 98.0 410) 0.5 451) 1.5 488) example 506)

API density ₀ aniline point, ⁰ C (

ASTM distillation

Onset of boiling, ⁰ C 5%

10

40

60

70

80

90

95

End of boiling Yield % Loss % Residue %

Sulphite waste liquor from an ammonia-based sulphite process is according to the invention with an average throughput of 45000 kg / h treated. Dissolved organic material is practically completely removed from the waste liquor by coking the waste liquor in the presence of high-quality paraffinic kerosene. The analyzes of the starting liquor and the kerosene used are shown below.

009824 / 1Ö2S

- BT- API density Sulphite waste liquor 41.9 19th - Color number, Saybolt Kineroa; before viscosity at 100 ⁰ F cSt 25+ Kerosene Sulfur, wt.% _ API seal. 0.05 Piano point, day, 'C (F) COD, g / l 58.8 Smoke point Evaporation residue, g / l +30 ASTM distillation. Total volatile matter, g / l Initial boiling point, ⁰ C ( ⁰ F) Fixed residue »g / l 169.3 (138) 10% Carbon, wt.% 179.8 95% Nitrogen, wt.% 240.8 End of boiling Sulfur, wt.% 268.2 (336 (355 0.967 (465 3.7 (514 153.5 114.25 112.086 2.164 5.0 0.32 0.34

The sulphite waste liquor, which is passed through in an amount of 45,000 kg / h, is quickly preheated to around 245 ° C. under turbulent flow conditions. The preheated liquid is intimately mixed with paraffinic kerosene heated to 373 ° C and supplied in an amount of 72,000 kg / h.The system is kept at a pressure of 91 atm -Inch pipes of 132 mm inner diameter mixed together. About half of the hot kerosene and the preheated waste liquor are passed through each of the two pipes. When flowing through the pipes under turbulent flow conditions, the waste liquor and the hot kerosene are brought into intimate contact with one another and the sulphite waste liquor is heated, the organic substances being coked. ^{The mixture reaches a temperature of about 300 °} C. during the 5.5 seconds contact time in the pipes.

009824/1925

Am

The fluids from the two 6-inch pipes go into one Separator where a practically complete separation of the two immiscible liquid phases, namely the aqueous phase and the Oil phase, takes place · The gas formed in the process is taken from the upper part of the separator · The oil phase is withdrawn from the separator and returned to the process. The lower liquid or water phase, which contains the coke, is drained, cooled to about 200 ° C and centrifuged. The liquid recovered from the centrifuge is recycled and concentrated for reuse in the sulphite process. The coke is dried and used for the recovery of Heat and SO «burned.

Typical results after one hour of testing are given below.

Product " Gas Dry Water

Coke phase

Weight, kg 356 2297 42

Product analysis gas analysis

Dimethyl sulfide, 0.1 mole percent

Methyl mercaptan, mole percent 1.5

CO ", mole% 96.3

Hydrogen, mole percent 1.5

Methane, mole percent 0.4

Ethane, mole percent 0.2

Dry coke

Carbon, wt% 61.9

Sulfur, weight percent 6.2

Nitrogen, weight percent 3.1

Ash, wt% 5.2

Upper calorific value, kcal / kg 6 105

Treated waste liquor

COD, g / L 12.72

Evaporation residue, g / l 14.72

Volatile components, total, g / l 13.05

Fixed residue, g / l 1.67

Nitrogen, wt% 0.16

Sulfur, weight percent 0.1

009324/1925

Example 41

Ammonia-based sulphite waste liquor accumulates every hour in an average amount of 23,600 liters. By coking the waste liquor in the presence of a paraffinic mineral oil distillate, the organic substances are largely removed from the waste liquor The analysis data of the sulphite waste liquor and the mineral oil distillate are given below.

Mineral oil distillate

API density
Sulfur, wt.% F1 flash point, day, <aniline point, C ASTM distillation

Start of boiling,

10%

95 End of boiling

COD, g / l

Dissolved contaminants, density, 20 ⁰ C carbon,% by weight sulfur,% by weight nitrogen,% by weight

166

169.3

171

204

232

44, 4th (140} 0, 01 (158) 60 71 330 336 340 400 450

Sulphite waste liquor

Weight%

20? ■ 13.5
l _s 05 7.5
0.76 0.32

The sulphite liquor has after the removal of the paper pulp a temperature of about 93 ° C. The waste liquor obtained in an amount of 23,600 kg / h is immediately combined with 101,000 kg / h of mineral oil distillate, preheated to 377 ° C is injected into 10.50 m long 10 inch (254 mm diameter) pipe. The system will kept under a pressure of about 75 atm, so that essentially is working in the liquid phase · The flow is

5. The total contact time turbulent {N _R ■ 20 χ 10) undy is about 7.5 see · under

under these conditions the sulphite waste liquor is heated to 285 ° C, extensive coking with minimal gel formation

009824/1926

of the organic matter takes place · The liquids from the reactor tube go into a separator, where an extensive Separation of the two immiscible liquid phases under minor Gas formation takes place · The lower water phase, which contains the coked organic material, is caused by heat exchange cooled to about 150 ° C and filtered. A coke-free liquid and a wet coke are obtained. The liquid After appropriate reinforcement, it goes back into the paper preparation process as a lye · The coke is used to obtain Burned sulfur dioxide · The hydrocarbon phase is returned to the heater for reuse in the process.

Typical mean result values are given below «

Ablaugebe sendunq

Gas formation

Water phase

kg / h

23 470 141 19 5 6? (1) The wet coke contains 35% by weight of water

Dry Coke (1)

2,040

Methyl mercaptan
Carbon dioxide
hydrogen
carbon

Product analysis Gas analysis

1.3 mole% 97.0 mole%

1.0 mole%

0.7 mol%

Carbon, wt.%
Sulfur, wt.%
Nitrogen, wt.%
Upper calorific value, kcal / kg

CODj g / l

Nitrogen, wt.%
Sulfur, wt.%

Dry coke

63.7

6.1

3.2 6 100

Clarified waste liquor

17.8 0.2 0.3

009814/1925

Is it the industrial wastewater to be treated? to caustic soda ("black lye") from a plant for the production of Kraft paper, so results after separation of the coke an aqueous liquid, the so-called "green liquor", which is fed back into the process. The modification of the process can be carried out in an apparatus shown in FIG.

In Fig. 3, wood chips of suitable origin are fed through line 205 to a cooker 206 where they are cooked in cooking liquor introduced through line 207-. In allgemel α --erden the chips 2 to 5 hours at a temperature in the range of 170 to 180 ⁰ C and a pressure of 7 b, is 9 atm with a 12.5% solution of sodium hydroxide, sodium sulfide and sodium carbonate treated. A typical composition of the solids contained in the solution is 58.6% by weight sodium hydroxide, 27.1% by weight sodium sulfide and 14.3% by weight sodium carbonate. Sodium hydroxide and sodium sulfide are the active chemical reagents; the carbonate is inactive and represents the equilibrium residue between lime and sodium carbonate in the formation of sodium hydroxide. Various types of wood such as hemlock, Douglas fir, silver fir and pine are suitable for the wood chips.

After the cooking time has elapsed, the contents of the digester 206 are emptied into the separator system 208, where the pulp by means of Filtration is separated from the black liquor and removed through line 209 from the separator. Gas and steam, which are released as a result of the pressure relief when emptying the cooker from the black liquor and the paper pulp are sent via line 211 for further processing. The process of opening and cooking the wood chips and separating the pulp from the black liquor of the digester effluent does not form part of the present invention, but is typical of a conventional way of working.

009824/1925

β «»

According to the present invention, the black liquor leaving the separator 208 through line 212 is ^{heated to a temperature in the range from 200 to 370 °} C., in the present example to 330 ° C., with the exclusion of air. This is achieved in the present example by first sending the black liquor through a heat exchanger 213, where it is preheated with hot reflux liquid from a source to be described, and then feeding it to a heater 214 provided with a furnace, where the temperature of the black liquor Lye to the desired coking temperature, ZeB. 330 ⁰ C, is increased. The hot black liquor is then directed into a coking drum 216 which is in the form of a large pressure vessel _; and the heated black liquor holds for a period of 2 to 6 hours at the desired processing temperature of, for example, 330 ° C. and the desired pressure of, for example, 160 atm. In the coking drum, the organic constituents of the black liquor are decomposed and dehydrated to a carbonized solid or coke, which is drawn off from the lowest part of the coking drum via line 217 after the coking time has expired. During the coking process, the bound oxygen in the sugars, acids and other organic oxygen compounds is converted _{into water and CO 2 by dehydroxylation and decarboxylation.}

In the process a small amount of gas is released, which is continuously released from the top of the drum 216 via line 218 or can be drained intermittently · One of carbonized Solids-free aqueous solution of sodium hydroxide, Sodium sulfide and sodium carbonate are added through line 219 withdrawn from the coking drum and used to preheat the Black liquor coming from separator 208 is passed through heat exchanger 213 and through line 221 to the white liquor preparation system fed. For the preparation of white liquor is

009824/1925

the return liquid coming from the coking drum 216 with suitable chemical reagents, namely calcium oxide, Calcium carbonate and sodium hydroxide, which are fed in through line 223, mixed »If necessary, make up water to be initiated through line 224 »

As can be seen from the figure, the coking zone can be continuous operated, the black liquor being continuously supplied and that of organic substances largely freed aqueous waste liquor is continuously withdrawn · The gas produced as a by-product can continuously or periodically withdrawn from the coking zone. The resulting gas volume is small, but the gaseous one Process products contain a substantial proportion (typically 7 to 8% by volume) of dimethyl sulfide, which is considered valuable By-product of the process can be recovered. The coke can be released from the coking zone intermittently as required can be removed, the liquid removed with the coke can be removed in a suitable manner, e.g. by filtration (not shown), separated from the coke and fed back into the process.

The following examples explain the process according to the invention with regard to its application to the clarification of black liquor from the Kraft process of paper preparation. The treated black liquor contained 17.2% total dissolved solids.

Example no. 42 43 44 45 46 47

Process facilities :

Temperature, ⁰ C 232 260 288 316 330 343

Pressure, atm 31.6 56.2 90 137 158 183

Time, h 6 6 6 2 6 2

Product liquid :

% dissolved solids 14.4 12.4 11.3 9.5 10.6 9.9

Oew.% Of feed 98.4 9S ₉ O 98.0 98.2 96 _$ 6 98.2

009824/1121

In a series of experiments, the black liquor was used at different. Time and temperature conditions coked. The amount of coke removed is a measure of that Effectiveness of the coking process

Example No, 48 49 50 51 52

Procedural conditions ;

Temperature, ^OC 288 288 288 316 316

Pressure, atm ——— —-—— autogenous—- ■ -

Time at temperature,

min 1 5 120 1 5

Spreading on

dry coke CD,

Weight% of the feed 0.68 1.82 3.88 2.73 3.41

(1) On a hot plate to an approximately constant weight dried.

The coke produced in the process has a calorific value of about 7,200 kcal / kg. The coke can be burned to generate heat for the process and to recover the chemicals it contains, or it can be used as a soil improver. However, it can also be further carbonized by heating in order to obtain a high-quality coke for metallurgical purposes, or it can be processed into good quality activated carbon by heating and partial oxidation. Activated carbon is used for the fine cleaning of wastewater streams. ■ ■ '■■ ·. "'.: '■'■" ■■■ '■ ·''. ·

The compositions of the black liquor, the process coke, and the clarified waste liquor are shown in Table I. The values refer to 1000 kg of starting liquor for 6 hours at 33O ⁰ C and was treated atm 158.2 (Example 5).

TABLE I.

Weight, kg black
Lye Clarified
AbIauge coke total weight 1000 914 52 Organic
Solids 170 _ Sodium (as NaOH) 34.2 29.8 1.5 sulfur 2.9 0.14 0.5

The cooking liquor is made by adding lime and salt cake to the reflux liquor, using coke from the salt cake reduction process. * In a typical case in which the black liquor contains around 30 % wash water, the treated liquid is first freed of excess water by evaporation and then processed into cooking liquor by adding chemicals.In this example, part of the coke (10, 3%) for a reaction with the salt cake (Na ₃ SO ₄ ). The sodium sulfide formed is used to reprocess the cooking liquor. The remaining coke is burned to generate process heat and recover chemicals. 1.27 kg of sodium sulfide and 1.75 kg of sodium carbonate are obtained from the 52 kg of coke that are obtained in accordance with Table I when 1000 kg of black liquor are processed. For every 1000 kg of black liquor treated, 4.8 kg of the coke formed are used for the reaction with 28.4 kg of sodium sulphate (Na ₂ SO ₄ ), whereby 15.5 kg of sodium sulphide are obtained for reprocessing the cooking liquor.

In addition, based on 1000 kg, 5.6 kg of sodium carbonate and 42.3 kg of lime (Ca (OH) ₂ ) are added to the treated reflux liquid in order to provide the sodium hydroxide required for the cooking liquor. That in the reaction between sodium carbonate

009824/1926.

^ - 1959328

Calcium carbonate and lime is obtained by filtration of the processed cooking liquor separated »

The chemicals used to make the cooking liquor from the clarifying liquid of 1000 kg of black liquor are required are listed in Table II.

TABLE II

Chem ikalie ^ _f Weight kg sodium sulfate CNa ₂ SO ₄₎ 28.4

Sodium carbonate (Na ₂ CO ₃ ) 5.6

Lime (Ca (OH)) 42.3

Table III shows the typical composition of the non-condensable fraction nes gas which flows out under the above coking and the above * composition of the black liquor from the coke drum.

TABLE III component

Dimethyl sulfide carbon dioxide hydrogen sulfide methane
Hydrogen inert gas

From the above gas, dimethyl sulfide can be obtained as a by-product of the Procedure can be won

The method according to the invention can also be used for clarification organic waste water from canning factories and from sulphite processes used in paper preparation «. Fig «4 shows an apparatus for such a treatment «Als B @ i * The game here was the sewage treatment from a Sul £ itsell fabric plant chosen

In Fig 4 there are woodcuts! suitable origin, -ζ · Β · spruce, introduced through line 305 into the cooker 306, where they are cooked in a Kcehlauge introduced through line 307. In general, the schnitzel is treated for 6 to 12 hours at a temperature in the range from 130 to 150 ^° C. and a pressure in the range from 5 to 7 atm with a cooking liquor which typically contains 7% SO ", of which 4, 5% by weight in sulphurous acid and 2.5% by weight in calcium bisulphite. The acidic cooking liquor usually also contains excess or free sulfur dioxide is.

After loading the cooker with several tons. Holsschnitzeln the cooking acid is pumped in via line 307, while aas the top of the cooker through a suitable valve 308 Air escapes. Valve 308 also serves as an overpressure'bssw. * Pressure relief valve during the cooking process »-When the cooker is loaded with cooking liquor, the cooking liquor is conveyed via line 309 by means of pump 311 into the heater 312, where it is usually heated with the aid of steam and then Returned to the lower part of the 3Ö6 cooker · The wood chips are gradually heated to around 110 ° C, usually within 1 to 2 hours. The process temperature is then set »

During the cooking process, the liquid level in the Cooker held under the top of the jar by placing draws off part of the Koelilauge via line 313 and valve 314 »

At the end of the cooking time, the contents of the digester 306 are discharged via valve 316 and line 317 into the pit 318 where the Paper pulp separated from the waste liquor and carried out by conducting 319 is forwarded for further processing · After the wedding, printing is usually done by Ab

.009824 / 1925

Gas and vapor reduced to about 1 _s 8 atm by valve 20B. Then the drain valve 316 at the bottom of the cooker is opened and the contents are ^{emptied through line 317 into the pit 31.8 1} * water vapor and gas ₅ which are discharged during starting. entweichst the pulp, through line 321 .zugeführt a recovery system * Here is water vapor are condensed and dissolved sulfur dioxide in water and srarückgewonnen »Gases _g which are during the Kochprosesses from the pressure relief valve 308 top of the digester escape ₃ are also for the recovery of sulfur dioxide The sulfur dioxide is returned to the system with the ssivren cooking liquid. The process of cooking and digesting the wood chips as well as the process of separating the pulp from the waste liquor and recovering the exhaust gases from the digester do not form. Rather, they are part of the present invention as an example of a conventional technical working method. ”In a preferred one. Embodiment of the present invention is the waste liquor from the ^; Pit 318 withdrawn through line 322 and a Vsrkofeings- and Oxidat ions sys tesa for the removal of the dissolved organic substances ₈ q & m & ß the following description, quoted through line 324 through line 324

In the present example, the waste liquor is first conducted from line 322 by means of pumps 323 through the Srftitser 324, where it is preheated by heat exchange with hot return fluid from a source that is still too bssGh & sihendsn * The preheated waste liquor is then fed into a heater 326 equipped with a furnace ₉ ws. The temperature of the Äblätag® to the desired VerkoteuysgstaKiporatnr isa range vc-. ~> 200 to 35G ^G C. increased viirdc thereby - ^ ird d, sr pressure av, f a value. kept in the range of 20 to 250 atm sufficient mm an evaporator «ng the water su verhissdersi" the hot liquor -schfe intestine into a separator 327 "This is a great DruekgefSß _s claö .sich dasu is ^ .dl © erhitafce Ablaug® voraufspeise SO tois 2 hours on EQS ' G

vou to hold, for example, 260 ⁰ C and the desired pressure of for example 53 atm "During the coking process, the organic components of the waste liquor in a carbonized Peststoff or coke are converted ·

Bound oxygen in the sugars, acids and other organic oxygen compounds is caused by decarboxylation and dehydroxylation is released as carbon dioxide and water. The gas evolved during the coking process will run out drained from separator 327 through pressure relief valve 330 and processed for the recovery of sulfur compounds

The coca or solid carbonized material settles out of the aqueous liquid and collects in the lower part of the separator 327, from which it is continuous as an aqueous sludge or is intermittently emptied through valve 331 in pit 332 · water vapor and gases emanating from the coke-containing drain discharged into pit 332 go through line 333 to a suitable gas recovery system · An aqueous liquid is withdrawn from the top of separator 327 through line 334, mixed with air from line 335, and introduced as a mixture into a tubular reactor 336, in which the remaining organic compounds in the aqueous Liquid to be oxidized

The aqueous liquid separated from the coke in pit 332 is fed into the reactor through line 338 by means of pump 339 where the remaining organic compounds are removed by oxidation with air

In general, the air oxidation is carried out under approximately the same temperature and pressure conditions as the coking process taking place in heater 326 and separator 327, ie at a temperature in the range from 200 to 340 ^° C. and a pressure in the range from 20 to 250 atm. The preferred temperature

009824 / 192S

in the reaction zone is between 288 and 343 ° C; the prints are higher than the vapor pressure of the water under the prevailing Conditions. The amount of air required for the reaction with the remaining organic material in the wastewater from the coking process depends on the effectiveness of the coking process and the final COD value required for the cooled wastewater. In general, 10 to 100 g of air are sufficient per liter of wastewater feed for the removal of the dissolved organic compounds from the aqueous discharge of the coking process. The time required for air oxidation is generally between 0.5 and 10 minutes.

The clarified wastewater exiting reactor 336 is passed through heat exchanger 324. By indirect heat exchange with the waste liquor, which was separated from the paper pulp in pit 318 and brought in through line 322, it is cooled here to a temperature of about 150 ° C., for example. At the same time the waste liquor is heated to about 230 ⁰ C. The clarified wastewater is then further cooled in cooler 341 and fed to a suitable wastewater disposal system through line 342 or returned to the system for reuse.

For treating wastewater from canning factories, the Waste water is fed to the system through line 322.

EXAMPLES

The following examples serve to further illustrate the process according to the invention for clarifying waste liquors from sulphite paper processing plants. In Examples 53 up to 63, waste liquor was produced from an ammonia-based sulphite pulp process of the Pa. Rayonier Inc. in batches treated at different temperature and pressure conditions. In all cases the pressure was set sufficiently high to boil the water at treatment temperature

009824/1925

to prevent. The waste liquor had the following properties:

Sulphite waste liquor

Carbon, wt.% Solved % By weight of the liquid 7.4 Pests Sulfur, wt.% Analysis, wt.% 0.81 13.5 Nitrogen, wt.% carbon 0.35 Carbon dioxide, wt.% sulfur 0.5 51.4 Chemical oxygen hydrogen 5 4 need, g / l nitrogen 210 5.6 pH Carbon dioxide 1 2.8 1.9

The operating conditions under which the above described Waste sulphite liquor has been treated, and the results are in Table 4 reproduced:

0Ö9824 / 132S

TABEL
Examples 4th
53-59 55 56 57 58 0
8th
1 59 ,1
, 4
, 7 Examples No. 53 54 Procedural conditions 232
35.2
2 260
58.0
2 288
73.8
2 316
134
2 343
183
2 Temperature, ⁰ C
Pressure, atm
Time, h 177 204
8.79 21.
2 2 1 Product liquid 88.6
1.8
10.4 89.0
1.4
9.3 87.2
1.4
15.9
3 88
0,
14, 88
0
14th % By weight of the charge
Dissolved pesticides,%
COD, g / l O ₉
DH * 98.9 87,
12.6 2,
204.0 20, 0
5
8th

coke

% By weight of the charge. 0 , 0 10.2 8.6 8.6 96.3 9.4 8.9 8.2 80.2 Analysis, wt.% - 8.2 carbon - 57.7 66.5 62.3 1.8 60.6 65.6 71.1 .. 3.0 φ sulfur - 6.9 5.3 6.0 1.5 6.8 5.4 4.6 5.8 hydrogen _ 5.0 4.0 4.1 3.9 3.6 3.5 2.2 nitrogen - 3.0 3.0 2.7 _. 2.7 3.1 3.1 0.6 Carbon dioxide - 0.4 1.0 0.3 1.0 1.5 1.5 - ■ Ash ρ - 3.3 5.7 9.6 8.0 5.0 4.3 - Surface m / g _ 86 9 27 170 186 228 Calorific value kcal / kg (xlOOO) - 5.7 6.4 6.1 5.8 - ..; 6.4. density - 1,426 1.404 - 1.526 1.517 Product gas 18.5 - Analysis, Mo1% 4.9 - Carbon dioxide 99 , 0 92.4 91.6 14.3 95.9 85.5 ■■ - Hydrogen sulfide 0 , 4 5.5 4.5 9 »5 - 0.7 - hydrogen 0 , 3 1.5 1.7 0.6 2.4 6.1 - Methyl mercaptan - 0.4 2.0 1.5 5.1 methane ■ - 1.4 ^; Ethan ■. "■■. .. - _ - - 0.5 · ■! . Oxygen. '■ .- .. ■■ .. 0 » ³ 0.2 0.2 0.1 0.2 £ dimethyl sulfide - 0.1 0.5. Dissolved pests in the product liquid ! Analysis, wt% carbon _ 27.1 23.1 18.6 hydrogen 5 , 3 5.5 4.3 ■ -. Sulfur ' 6th , 7 13.2 - 13.3 16.0 nitrogen 3 f ° 7.4 - 7.6 9.4 Carbon dioxide 1 3 1.8 - 0.9 0.7

1959328

Example 60 '

Product liquid from Example 53 was brought into contact with air at 288 ° C. and 10 5.5 atm for 1 hour. 29 liters of air per liter of liquid were used. The treatment with air decreased the dissolved solids content from 1.4 to 1.1 % , the CQD value decreased from 15.9 g to 4.7 g oxygen per liter and the pH value increased from 3 to 5 . As can be seen from the above examples, the process according to the invention resulted in a reduction in the COD value of 92.4 % through the coking treatment alone and by 97.7 % through the combination of the coking treatment with air oxidation.

Examples 61-63

At temperatures of preferably 260 and 288 C, tests were carried out carried out to determine the influence of the heating time on the extent of COD reduction. After adding 2 parts by weight of water per part by weight of treated liquor, the solid residue was removed from the treated liquor by filtration Lye removes «The treatment conditions and results are shown in Table 5.

Table 5

Example no. 61 62 63 Temperature, ⁰ C, 260 288 288 Pressure, atm 58 74 74 Time, min 20th 10 20th Treated liquid COD, g / l 16,080 18,780 17,130 Decrease % 92.3 90.1 91.9 Example 64

An ammonia-based sulfite waste liquor obtained from Boise Cascade was prepared in a manner similar to Example 57 described, coked. The treated sewage sludge was

009824/1925

19533-26

mixed with an equal volume of water and placed under vacuum filtered. Analysis values and yield structure are shown in Table 6.

Tabel Volatile inventory g / L 112.086 6th Treated coke feed parts in total, Waste liquor Fixed back 2.164 Wt.% Of Be stood, g / l .% 5.0 52 6th dispatch 100 Carbon, wt £ 0.32 6.9 - COD, g / l 153.5 Nitrogen, wt 0.34 Evaporation Sulfur, wt.% - 6.174 - residue, g / l 114.25 Ash, wt.% - PH 4,582 - 1,592 - - 63 0.075 - - 2.1 _ 5.58 3, 9 -

So the COD of the liquid was reduced by 95%. That Liquid product was then at 288 ° C with 15.0 normal liters Treated air per liter of liquid. As a result of this treatment, the COD was reduced to 193 mg / l (0.193 g / l) - i.e. by more than 99.5% - reduced. The pH of the product was 1.

Examples 65-69

Waste water from canneries were artificially imitated by tomato, potato skins or orange peel ± n a Waring blender with water behandelte.Die obtained aqueous slurry was subjected to treatment according to the inventive method. Process conditions and test results are given in Table 7

009824/1925

Tabel 7th 66 67 68 69 Example no. 65 orange
9.6
122 potato
4.21
39.7 potato
3.1
33.5 tomato
1.02
12.3 Waste material
Solids, wt.%
COD, g / l orange
10.8
100 Coking conditions 288
77
2 232
30th
2 288
76
2 343
155
2 Temperature, ⁰ C
Pressure, atm
Time, h 204
21
2 Clarified wastewater 88.5
0.44
26.9 97.0
1.16
14.8 98.0
0.66
10.3 96.0
0.35
9.0 % By weight of the charge
Dissolved solids, wt
COD, g / l 89.7
.% 2.08
29.2

coke

% By weight of the charge

4.1

1.7

0.9

Analysis, wt.% 61.7 72.6 72.3 63.8 - 9, 17th carbon 6.1 6.2 5.8 5.9 '- O" hydrogen 1.3 1.63 3.91 3.56 St. nitrogen 0.13 0.17 0.06 0.28 - phosphorus 0.22 0.10 0.21 0.35 - potassium 0.6 0 | 9 _ - Carbon oxide 3.1 2.48 0.27 12.6 ash 5.7 7.3 '- - - 0 Calorific value kcal / kg (x 1000) 13th Oxidationsbedinqunqen 288 23 * 288 288 2 Temperature, ⁰ C _ 70 127 120 Pressure, atm (D - 2 2 - Time, h Product liquid - 4.2 4.0 pH _ 0.33 0.34 0.26 Dissolved solids, wt.% - 4J ₂ 5.2 0.8 COD, g / l

(1) The oxidation tests would be carried out in a bomb carried out; the specified pressure is the observed maximum pressure

009824/1925

The high ash content found in the coke from Example 68 is believed to be due to the presence of inorganic ones Material, e.g. sand or dirt, in the potato peels.

In the above examples and throughout the description, the term "chemical oxygen demand", abbreviated to "COD", is used in the usual sense not. In contrast, the BOD value denotes the amount of oxygen that is ^{consumed during a 5-day bacterial activity at 20 °} C. in a chemically standardized and stabilized sample. Strictly speaking, the COD is not comparable to the BOD, but it should represent a sufficient guide for the reduction of the BOD in order to provide the basis for a comparison of the effectiveness of different treatment methods, especially with comparable waste samples.

Waste liquors from pulp and paper mills can also be coked in a tubular reactor. If the turbulence in the tubular reactor is sufficiently great, the coke particles formed during the heat treatment are uniformly dispersed and distributed in the waste water, and coke build-up on the reactor walls is largely avoided. In this process, the coking is essentially completed in 0.5 to 10 minutes at 316 ° C. In a preferred embodiment of the invention, the outlet temperature of the treated liquid is maintained in the range of about 288 to 343 ° C. when it leaves the tubular coking zone ^{the treated wastewater is kept at a temperature of over 200 °} C. for a certain time, for example for 1 min, in order to achieve practically complete carbonization of the organic compounds it contains to form water-insoluble solid or coke,

009824 / 192S

The flow of the liquid in the tubular reactor can be laminar or turbulent. For a given reactor design, the type of flow depends on that flowing through the reactor Amount of liquid. A turbulent flow is most appropriate for coking, as it causes coke to build up on the reactor walls largely prevented and thus ensures a long service life of the tubular reactor. A useful ratio for characterizing the type of flow in a pipe is Reynolds number. It is defined as follows:

Re, u

In it are:

. Ne Reynold's number D m Inside diameter of pipe, feet (ft)

V * «Mean linear velocity, feet each Second (ft / sec)

ο * density of the liquid, pounds per cubic foot (lb / cu ft)

, including viscosity of fluid, pounds / feet / '■ Second (Ib / Cft) (see))

Reynolds are preferably used in the tubular reactor Numbers in excess of 4000 maintained. The tubular reactor expediently has an internal diameter of 13 mm up to 1016 mm (1/2 to 4 inches). The length of the reactor tube is preferably chosen so that the mean residence time of the liquid in the tube is at least 1 min. The pressure itself is not critical in the heating stage. The correlation between temperature and pressure in terms of evaporation of the Water is known. It is generally advantageous to work in the heating stage so that the pressure at the outlet of the tubular reactor close to or only slightly higher than the evaporation temperature of water at the reactor outlet. For the sake of heat saving it is generally advisable to set the pressure at the outlet of the tubular heating zone above the vapor pressure of water at the outlet temperature to keep the heating zone.

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To better illustrate the method according to the invention The attached Fig. 5 is used, which shows a preferred embodiment of the invention for treating the waste liquor based on calcium working sulfite pulp plant schematically represents.

In the figure, wood chips of suitable origin, for example pine, are fed through line 405 to the cooker 406, where they are cooked in cooking liquor brought in through line 407. In general, the chips are treated for 6 to 12 hours at a temperature in the range from 130 to 150 ^° C. and at a pressure in the range from 5 to 7 atm. In the present example, a sulphite cooking liquor based on calcium is used in the cooker 406, which typically contains 7% by weight SCU, of which 4.5 % is bound in sulphurous acid and 2.5% in calcium bisulphite. The acidic cooking liquor usually contains excess or unbound sulfur dioxide.

The cooker 406 is a large pressure vessel that is expediently lined with acid-resistant stones or stainless steel. After several tons of wood chips have been charged to the digester, cooking acid is pumped in through the line while air is vented from the top of the digester through a suitable valve 408. The valve 408 also serves as a pressure relief and pressure relief valve during the cooking process. When the cooker is loaded with cooking liquor, this is fed by pump 411 through line 409 into heater 412 and then returned to the lower part of the cooker.The wood chips are usually ^{heated gradually to around 110 °} G for 1 to 2 hours * Then it is heated the process temperature set.

During the cooking process, the liquid level in the Cooker held under the top of the jar by placing withdraws part of the cooking liquor through line 413 and valve 414 «

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After the cooking time has elapsed, the pressure in the cooker is reduced Relief of gas and water vapor reduced through valve 408, expediently to about 1.75 atm. Opening the drain valve 416 at the bottom of the digester will let the reactor contents through Line 417 emptied in pit 418. Gas and water vapor that are released from the pulp during emptying go through line 421 into a recovery system in which the Water vapor condenses and sulfur dioxide is dissolved in water and recovered. The gases released during the cooking process Exhaust from the pressure relief valve 408 at the top of the cooker are also treated for the recovery of sulfur dioxide, which along with the acidic cooking liquor is fed back into the system. The pulp obtained as the product of the process is emptied through line 419 and fed to further processing.

The process of cooking and disrupting the wood chips Production of the paper pulp, the separation of the paper pulp from the waste liquor and the recovery of the exhaust gases from the kitchen drain does not form part of the present invention, but rather intended as a representative example of a conventional technical The practice described here serves to link the process of the invention to the large-scale industrial To show paper preparation processes · waste liquors from cellulose Abriken the cooking liquids other than those in this one Use calcium-based sulphite waste liquor mentioned in the example * can also be * to act

In a preferred embodiment of the present invention waste liquor is withdrawn from pit 418 through line 422 and by means of pump 423 through line 424 to heat exchanger 426 fed, where the waste liquor by heat exchange with hot, coke-free liquid brought in through line 432 from separator 431 is heated. The waste liquor from the heat exchanger

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passes through line 427 into tubular reactor 429 heated by furnace 428, in tubular reaction zone 429 the waste liquor to the desired coking temperature, expediently heated to 288 C, at a pressure of, for example, 75 atm, which is sufficient to evaporate the Water to prevent. When the waste liquor passes through the tubular heated reactor zone, the temperature for a Period of time, which is usually in the range of 1 to 10 minutes, is kept above 200.degree. C., so that a large part of the in the Water-soluble organic substances contained in waste liquor precipitates in the form of water-insoluble solids

Without wishing to limit the present invention in any way, the following explanation is given of one possible mechanism given for the relatively quick response obtained:

The highly turbulent flow of the liquid through the tubular carbonization zone causes a very rapid transfer of heat into the liquid; at the same time, the coke particles formed are suspended in the liquid and passed through the reactor or the coking zone 429 without any accumulation of solids on the walls of the tubular coking zone.

The treated waste liquor is at the outlet of the coking zone 429 withdrawn and passed through line 430 into the separator 431. This can consist of a filter, a cyclone separator, a settling tank or a centrifuge and causes a Separation of the luggage from the liquid · The largely Coke-free, treated liquor is passed through line 432 into heat exchanger 426, where its heat content through heat exchange is lowered with untreated waste liquor. The cooled, coke-free liquid from the heat exchanger goes in line 433 and can be disposed of as relatively low COD wastewater; but preferably it is served with fresh sour cooking

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liquid and other suitable chemical reagents, e.g. calcium oxide, calcium carbonate and calcium hydroxide, mixed and fed through line 441 to the additional liquor container 443.

The product coke from the separator 431 goes through conduit into a discharge container 435, in which the hot coke finally is dried by evaporation of the water remaining in it after separation. Generally enough the heat content of the coke to that required for drying To deliver heat. Gas and water vapor escape through line 436.

The dried coke is sent to storage through line 437.

Examples 70-75

A waste liquor from a Kraft process was invented treated in a series of experiments in a stainless steel tube with an inner diameter of 21 mm, with a metal bath, consisting of solder with high tin content, served as a heat transfer medium. The COD of the waste liquor used was 175.6 g oxygen per liter. The COD reduction is obtained from a comparison of this value with the Values of the treated liquid products B according to the following Table clearly.

Example no . 70 71 72 73 74 Operating conditions

Pressure, atm 49.2 73.8 110.7 105.5 130.1 16.9

Temperature, ° C 260 288 316 316 330 Time, min (1) 10 10 1 5 1

Product liquidity

COD, g / l 134.5 90.9 62.3 53.0 59.1 un

changes

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(1) The specified time is the treatment time at the specified temperature. (The loading. had to be heated for 3.5 minutes to reach the specified operating temperature).

Substances that contributed to the high COD of the waste liquor were as easily filterable coke particles from the treated Liquid removed. The value of using higher temperatures becomes clear from the above examples *

Examples 76-78

A sulphite liquor was coked in a series of experiments in a stainless steel pipe with an inner diameter of 13 mm, a metal bath consisting of high tin solder served as the heat transfer medium. The sulfite waste liquor had the following properties:

COD, g / l 153.5 Evaporation residue, g / l 114.25 Total volatile components g / i 112.086 Fixed residue, g / l 2.164 Carbon, wt.% 5.0 Nitrogen, wt.% 0.32 Sulfur, wt.% 0.34

The effectiveness of the coking process in removing substances that contribute to the high COD levels is off can be seen in the following list:

Example No « 76 77 78 Operating conditions Pressure, atm
Temperature, C
Time, min (1) 73.8
288
1 73.8
288
30th 16.9
204
20th Product liquid COD, g / l 15.1 15.9 No coke

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(1) The specified time is the treatment time at the specified temperature. (The batch had to be heated for 3.5 minutes to reach the specified operating temperature).

Example 79

An ammonia-based SuIf iti-Zel Istoff treatment plant has an hourly accumulation of an average of 000 kg sulphite waste liquor with the following properties!

Ammonia-based sulphite waste liquor

Λ C ·> C

COD, g / l g / l 153.5 Evaporation residue, g / l 114.25 Total volatile components 112.09 Fixed residue, g / l 2.16 Carbon, wt.% 5.0 Nitrogen, wt.% 0.32 Sulfur, wt.% 0.34

The waste liquor from the pulp production process is supplied with a temperature of about 93 ° C and then heated by heat exchange with Niedrigdruckdarapf and treated hot (285 ° C) liquid from the coke / liquid separator of the present process to a temperature in the range 200-210 ⁰ C. . The hot liquid from the heat exchanger is then passed through 4 three-inch noble; Steel pipes are pumped, which are housed in a heater provided with a furnace. Here the temperature of the waste liquor is increased to 288 ° C and kept for a period of one minute essentially at the coking temperature of 288 ° C. The heater provided with a furnace is from of conventional design, except that the tubes of the Verkokungsabschnitts against the open flame of the forehearth shielded. the Verkokungsabschnitt consists of four 60 dreizölllgen m long (75 mm) stainless steel tubes to each other by _t

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Double elbows are connected. At an hourly .Accumulation of 45,000 kg (100,000 lbs) of waste liquor is calculated | the Reynolds number with N_ »6.8-10, this value is far within the turbulent flow area. The Verr dwell time at the coking temperature of about 288 ° C is 1 minute. The outlet of the tubular coking zone consists of a slurry of coke particles, from which easily separates the liquid in a cyclone separator can be. -

The process can withstand loading fluctuations of, + 15% and Fluctuations in the total solids content of the waste liquor approximately cope with the same order of magnitude. Typical product yields and ^ compositions made under the above operating conditions are shown in the following table.

Analysis of the coke products

product Treated Wet coke Drier Product- from the coke liquid cyclone Yield in% by weight the loading 84.8 15.2 6.9 COD, g / l 10.9 - analysis Evaporation residue, g / l 14.9 - - Volatiles total, g / l 12.3 - -

Fixed residue, g / l 1.56

pH 3.9

Nitrogen, wt% 0.18

Carbon, wt.%

Sulfur, wt%

Ash, wt.% -

3.6 62.9 5.67 3.3

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Claims (1)

EXPECTATIONS Process for the treatment of industrial and municipal wastewater, characterized in that the waste water is exposed to coking conditions in order to remove the water-soluble and water-insoluble organic substances contained therein solid coke to coke, and that optionally the coke separated from the so treated wastewater and this is oxidized to further the chemical oxygen demand of the water to lower. ?. A method according to claim 1, characterized in that the waste water is carbonized 0.5 minutes to 6 hours at a temperature of 200 to 400 ⁰ G, especially 200 to 37Q ° E, under i a pressure of 20 to 250 atm. 3. The method according to any one of claims 1 and 2, characterized in that that sewer sewage sludge is coked for 0.5 minutes to 2 hours, and that this clarified Waste water is oxidized for 0.1 to 10 minutes. 4. The method according to any one of the preceding claims, characterized characterized in that biological sewage sludge from an oil refinery is clarified. 5- The method according to claim 1, characterized in that ^; Black liquor from Kraft paper mills is heated to 230 to 330 0} and introduced into the middle part of a vertical, cylindrical coking zone in which there is coke and; Form gas that the gas is taken from the uppermost part and the coke \ from the lower part of the coking zone, [and that waste water containing soluble inorganic salts from the \ black liquor is taken from the upper part of the coking \ zone at one The point between the entry of the untreated wastewater and the exit of the gas is deducted. : ■ '.- ■ 009824/1925 6. The method according to any one of claims 1 and 2, characterized in that, that waste liquor from pulp and paper mills through direct contact with hot hydrocarbon liquid is heated to coking temperature. 7. Method according to one of Claims 1 and 2, characterized in that that the wastewater under turbulent flow conditions, by a Reynolds' number of about 2000, is passed through a tubular heating zone. . 8. The method according to any one of claims 1 and 2, characterized in that that the clarified wastewater is conducted so that an indirect heat exchange with the wastewater to be coked takes place and it then drains into a sewage disposal system. 9. Method according to one of Claims 1 and 2, characterized in that that waste liquor "from a sulphite pulp process, which comes from the wood derived vegetable organic matter contains in dissolved form, is clarified. 10. The method according to any one of claims 1 and 2, characterized in that that waste water from canning plants, which contains carbohydrates, is "clarified". 11. The method according to claim 1, characterized in that black liquor from Kraft paper mills, the inorganic sodium salts and organic substances of wood contains in dissolved form, at temperatures between 230 and 370 ⁰ C with the exclusion of oxygen at a pressure sufficient to evaporate the To prevent water, is coked for 0.5 minutes to 6 hours, forming a granular solid coke, and that the coke is separated from the remaining aqueous solution and the treated aqueous solution, which is largely freed from organic matter and practical 009824/1925 the total inorganic sodium salts from the black Contains lye, is recovered. 12. The method according to claim 11, characterized in that a gaseous fraction produced during the "coking of the Organic matter contained in the black liquor was formed from the aqueous solution as a product of the process is recovered. 13. The method according to any one of the preceding claims, characterized characterized in that the wastewater is continuously in a relatively large-volume coking zone with a such a flow rate is introduced that the through f Average residence time of the wastewater in the coking zone at elevated temperature and pressure is between 1 and hours, and that the treated wastewater is continuous is withdrawn from the coking zone. 14-, method according to any one of the preceding claims, characterized in that the untreated wastewater before Coking is preheated by heat exchange with the treated wastewater. 15. Plant for the treatment of industrial wastewater according to a of the preceding claims, characterized by: a heat exchange device that preheats the untreated wastewater made possible by the treated; = a coking device for receiving and coking the preheated wastewater with the formation of coke and treated wastewater \ a separation device, which is in communication with the charring device and receives its contents, around the To separate coke from the wastewater to obtain purified wastewater; 009824/1925 a line for conveying the treated wastewater to the heat exchange device in order to increase the temperature of the
to lower treated wastewater and at the same time that
preheat untreated wastewater. 16. Plant according to claim Vp for the treatment of waste liquors from pulp and paper mills, characterized in that
that the coking device contains a tubular heater which creates turbulent flow conditions for the waste liquors during coking. 17. Plant according to claim 15 * characterized by a device to oxidize the treated wastewater in order to further reduce its chemical oxygen demand. 009824/1925