DE2638516A1 - PROCESS FOR SEPARATING OIL FROM OIL-CONTAINING WASTEWATERS - Google Patents

Description

Process for separating oil from oily waste water

It is known that significant amounts of lubricants, cutting oils and cutting fluids in industrial Machining processes are applied. In the automotive industry and in similar work, these "oils", when they are used up, discharged into the company's sewage system, where they are usually combined with other sewage streams the plant come together. Simply put, these "oils" are undiluted oils made up of Rtiöl (Petroleum Oils) with an emulsifier. In practice, however, they usually contain fatty acids, surface active agents, Organic silk, antioxidants and many other additives. They can also be contaminated with synthetic oils.

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These industrial effluents usually contain from 0.05 to 4 vol. 96 oil.

With the new stringent environmental regulations, the increase in oil prices and the decrease in the oil available, it has become very important to reclaim these oils for reuse. Since the oily waste waters are usually emulsions of oil in water, recovery can be achieved using the well-known "de-emulsification-flocculation" separation process. For example, it is known to use a combination of acid-alum treatment in a process for recovering oil. At a low pH value (2-3), the aluminum complex shows a high positive value. A virtually uncharged (neutral-charged) insoluble aluminum hydroxide is formed by hydrolysis of alum at pH 6 to 7. A further increase in the pH value leads to the formation of the negatively charged aluminate and the solubility increases. The positively charged alum neutralizes the negative stabilizing charge on the oil droplets of the emulsion at a low pH value and leads to de-emulsification and coagulation. In the hydrolysis of alum provides a surface for the oil adsorption by van der Waal forces and ¹ ^ leads to flocculation. As a result, the pH of the oily waste water is kept low to facilitate the demulsification of the oil. In some cases, the oil is then flocculated and recovered by skimming. The pH is then increased to precipitate the aluminum hydroxide, with a fluffy precipitate which adsorbs the remaining oil. Alternatively, the flocculation and recovery stage can be used as a one-step process to recover the oil. However, these acid-alum treatment methods inevitably have drawbacks. For example, large amounts of acid are required

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to lower the pH of the oily wastewater «, Also special devices are required to handle the wastewater with such low pH and special metals (special metallurgy) to prevent corrosion. Also arise through a neutralization of the low pH weris an additional cost. Furthermore, large amounts of alum result in large volumes of sludge, making oil recovery difficult and waste problems arise. In addition, the oil is extremely difficult to remove from the flocculated alum or alum. Extract aluminum hydroxide.

It is therefore an object of the present invention to create a new one to develop water-soluble, cationic polymeric material suitable for the separation of oil from industrial, oily wastewater and the disadvantages associated with the known acid-alum processes to be overcome. It has now been shown that the separation of oil from oily wastewater is effective can be obtained by using a water-soluble cationic polymer obtained by polymerization an epihalohydrin with a special group of alkylene polyamines.

According to the invention, the addition of alum can be significantly reduced or completely eliminated during the separation of oil from oily wastewater by applying the invention water soluble cationic polymeric material in processes for the recovery of the oil. When a combined alum-polymer treatment should be applied the pH of the wastewater can be adjusted to ensure that the alum remains insoluble and as a coagulant aid works. A pH range of from about 5.0 to about 8.0 is considered suitable, with the preferred Range is 6.0 to 7.5. When the polymer is in

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In the absence of alum, it has been shown that the effectiveness of the polymer in separating oil from the wastewater is relatively pH-independent. To the Adjustment of the pH value of the wastewater is suitable for sulfuric acid. The basic process stages basically include the addition of acid (if necessary), the addition of polymer and the addition of alum, the order however the addition can be changed · Of course it is also possible to add the polymer and alum at the same time to admit * Research has shown that amounts of polymer in the range of approximately 0.5 to 1000 ppm are suitable, the preferred range being 5 to 750 ppm. When a combined alum-polymer treatment is used, effective amounts of alum are approximately 10 to 1000, preferably 50 to 500 ppm,

Numerous advantages can be achieved by using the method according to the invention, for example lower amounts of chemicals are required and the large amount of sludge which usually occurs in alum treatment is substantially reduced. In addition, larger amounts of acid and alkali are no longer required for pH adjustment, as in the case of the alum-acid process described above ₍ and the difficulty of handling the flaky alum (aluminum hydroxide) precipitate is eliminated »

The water-soluble cationic polymers of the invention Substances are those obtained by polymerizing an epihalohydrin with an alkylene polyamine the formula

R ₁ . H

N-R-N

R ₂ H

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in which R is a lower alkylene group with 2 to about 6 carbon atoms, for example an ethylene, propylene, isopropylene, isopentyl, hexylene group, etc .; R ^ and R ₂ each represent a lower alkyl group having about 1 to about 6 carbon atoms, for example a methyl, ethyl, propyl, isopropyl, pentyl, hexyl, isohexyl group, etc .. mean.

The molar ratios of the epihalohydrin to the alkylene polyamine are from about 0.60: 1 to about 2.7: 1, and preferably from 0.75: 1 to 1.3: 1. The polymerization is conducted at a temperature of about 60 to about 120 ⁰ C and preferably 80 to 110 ⁰ C carried out by reacting the alkylene polyamine having about 50 to about 90 mole% epihalohydrin for polymerization. The reaction can take place long enough for the reaction medium to have a relatively uniform viscosity / or, more particularly, up to. essentially all reactive sites on the epihalohydrxns had the opportunity to react. The last-mentioned condition is essentially the reason that the reaction medium finally reaches a relatively uniform viscosity. After the reaction medium has reached the relatively uniform viscosity, the remaining portion of epihalohydrin is added to the reaction medium either all at once or in individual portions and reacted until the end product has the desired viscosity. When the final viscosity of the reaction medium is reached, ie all or essentially all reactive sites of the epihalohydrin have reacted, the reaction medium is preferably stabilized by acidifying the medium to a pH of 1 to about 7 and preferably 2 to 5. A mineral acid such as hydrochloric acid , Sulfuric acid, nitric acid or phosphoric acid is preferably but not exclusively used. Strong organic acids can also be used.

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In the present specification, for the sake of convenience, the viscosity rather than the molecular weight is used as Criterion viewed as the polymerization is preferred is carried out in an aqueous medium at an alkaline pH, i.e. 7.5 to 12 and preferably 8 to 11. As a result, it is easier to use the reaction medium that the water-soluble cationic polymer contains dissolved therein, with the help of viscosity control «

Since the amount of water present in the reaction medium directly influences the viscosity of the reaction medium and thus of the end product, this factor must of course be taken into account in order to achieve the desired viscosity of the cationic polymer solutions when an aqueous solution of the cationic polymer is actually desired. The viscosities that can be achieved can vary within wide ranges. For the purposes according to the invention and especially taking into account the applicability, viscosities corresponding to approximately 10 to approximately 2000 cP at a concentration of 20% are the most favorable. The expression “corresponding” in this context means that a 35% solution with, for example, a viscosity of 300 cP can be diluted to a 20% solution with a viscosity of 75 to 100 cP. As a result, the concentration and viscosity given above for a 20% solution does not represent a limitation on viscosity, but should only be viewed as a general framework. For example, the concentrations can range from 15 to 60 % of their own specific viscosities. Thus, a 50% solution with a viscosity of 1000, which can be diluted to a 20% solution with a viscosity of 30, can also be used in the present invention.

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As stated above, the cationic polymer according to the invention can also be obtained as a liquid which consists only of a correspondingly pure polymer. In order to obtain the polymer alone, the aqueous solution can be distilled in vacuo or evaporated as a thin film to obtain a suitably pure polymer. In some cases this may involve large containers and costs in packaging and transporting low-active products (ζ · Β · 20 % polymer and 80 % water). The pure polymer can later, for example after it has arrived at the destination, be redissolved in water to a predetermined activity in order to obtain the applicable concentration.

In describing the preferred process for preparing the polymers of the invention, the meaning after found that "the remaining part of the epihalohydrins then either all at once or individually Portions are added and reacted. "Although both methods can be used, the addition is individual Proportions of the remainder preferred, sufficient time should elapse before adding the remaining portion (s), to allow essentially complete reaction of the reactive sites of the epihalohydrins. The most preferred method, in which the remaining portion is added in individual portions, is to to add the remaining epihalohydrin in smaller and smaller amounts and to allow it to react, each time Allow sufficient time to pass for essentially complete implementation, as evidenced by the occurrence a relatively uniform viscosity is recognizable · The addition in individual portions does not allow just better control of the final viscosity of the

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Reaction medium and the molecular weight of the resulting polymer, but also provides the highest activity of the polymer as a flocculant or coagulant by avoiding the formation of a polymeric gel that generally has no flocculation activity.

The epihalohydrin preferred according to the invention is epichlorohydrin and epibromohydrin, although epifluorohydrin can also be used. The preferred according to the invention Alkylene polyamines are any of the general formulas given above and can basically be described are considered to have at least one tertiary amino group and at least one primary amino group. Examples of suitable compounds are dimethylaminopropylamine (N, N-dimethyl-1,3-propanediamine); Diethylaminopropylamine (N, N-diethyl-1,3-propanediamine); N, N-dimethylaminoethylamine and Ν, Ν-diethylaminoethylamine.

A cationic polymer made in accordance with the present invention using equimolar amounts of epichlorohydrin and N, N-dimethyl-1,3-propanediamine presumably possesses the following structure

--CH ₂ -CH-CH ₂ -N-

OH

CH ₇

CH ₂

CH ₂

CH,

CH

CH ₂ -CH-CH ₂

N-CH ₇ -CH, CH

CH,

CH ₇ CH-CH, -

OH

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where χ is greater than y. Although it is known to be difficult, if not impossible, to get the exact chemical structure of a whole polymer chain. It is therefore considered to be more accurate to the polymer by its manufacturing process to describe.

The invention is illustrated in more detail by the following examples.

example 1

344.5 g (3.38 mol) of N, N-dimethyl-1,3-propanediamine were added to 471 g of water in a 2 l resin bottle equipped with a thermometer, reflux condenser and stirrer. To this, 275.2 g (2.97 mol) of epichlorohydrin were added dropwise over the course of 1 hour. The solution was ^{heated to 90 °} C. for 1 h. Then 29.1 g (0.31 mol) of epichlorohydrin were added at 90 ^° C. in nine, each decreasing, portions, the last portion being 0.1 g, until the desired viscosity was reached. The viscosity was determined 20 minutes after each addition of epichlorohydrin by determining the time in which a certain amount of the solution flowed through a pipette. The reaction was then terminated by reducing the pH to 2.5 by adding 530 g of an aqueous sulfuric acid solution (1: 1 w / w). The resulting solution had a solids content of 50 % and a Brookfield viscosity (spindle 2, 12 rpm) of 912 cP. Dilution to a solids content of 35 % would result in a Brookfield viscosity (spindle 1, 12 rpm) of 94 cP (molar ratio of epichlorohydrin to amine = 0.97: 1).

Example 2

229.5 g (2.25 mol) of N, N-dimethyl-1,3-propanediamine were added to 1089 g of water in a 2 l resin kettle equipped with a stirrer, condenser and thermometer, followed by 183.5 g g (1.98 mol) of epichlorohydrin were added dropwise over the course of 1 h. The solution was heated for 1 h at 90 ⁰ C and

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then epichlorohydrin was added in smaller amounts. 20 min after each addition, the change in viscosity was determined by determining the flow time for a certain amount of the solution through a pipette. After the epichlorohydrin was added, 200 g of water was added to dilute the polymer solution. A further 0.47 g of epichlorohydrin were then added in order to achieve the desired viscosity, followed by 320 g of H 1 O 4 solution (1: 2 w / w with H 2 O), which lowers the pH to approximately 2.5 and the reaction was canceled. Finally, the solution was poured into 742.5 g of water, a solids content of 20 % and a Brookfield viscosity (spindle 1, 12 rpm) of 175 cP (molar ratio of epichlorohydrin to amine = 1.08: 1) _o

Example 3

To 1089 g H ₂ O in a 2 1 four-neck resin flask equipped with thermometer, reflux condenser and stirrer were placed 229.5 g (2.25 mol) of N, N-dimethyl-1,3-propanediamine and then 133 , 5 g (1.44 mol) of epichlorohydrin were added dropwise within 1 h. The solution was heated 1 h at 90 ° C and then epichlorohydrin in eight decreasing proportions at 90 ⁰ C was added. After each addition of epichlorohydrin, the solution was stirred for 20 minutes and the viscosity was determined by measuring the time it took a certain amount of the solution to pass through a 10 ml pipette. When the desired viscosity was reached, for which 100.3 g (1.0 mol) of epichlorohydrin were required, 227 g of sulfuric acid _{solution (1: 2 w / w) and 91.7.5 g of H 2} O were added and the solution was filtered, to remove some insoluble gel »The final solids content was 20 % with a Brookfield viscosity (spindle 2, 12 rpm) of 2100 cP (molar ratio of epichlorohydrin to amine = 1.12: 1).

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Example 4

To 51.0 g (0.50 mol) of N, N-dimethyl-1,3-propanediamine in 638 g of water, 40.3 g (0.435 mol) of epichlorohydrin (EPI) was added at a rate such that the temperature did not exceed 90 ⁰ C rose. The resulting solution was ^{heated to 90 °} C. for 1 h. 35.4 g (0.38 mol) of EPI were then added in small portions in order to increase the viscosity, the solution being ^{heated to 90 °} C. for 20 minutes after each addition. The viscous solution was then diluted with 445 grams of water and 6.4 grams of concentrated sulfuric acid added to reduce the pH to 6.5. Then 50.1 g (0.54 mol) of EPI were added again in small portions, stirring at 90 ° C. for 20 minutes between the individual additions and then 510 g of water. Additional amounts of EPI gave no sign of reaction or viscosity increase. The resulting solution had a pH of 6.0 and a viscosity (Brookfield, spindle 2, 12 rpm) of 890 cP and a solids content of 10.3% (molar ratio EPI to amine = 2.7: 1).

Example 5

To 1854.3 kg (4088 lbs) of water in a 7570 l (2000 gal.) Reactor was added 806.7 kg (1778.4 lbs) of epichlorohydrin at a rate of about 6.8 to 7.6 l (1.8 to 2.0 gal.) Per min. The resulting solution was ^{heated to 90 °} C. (194 ^° F.) for 1 hour, epichlorohydrin was then added at 90 ^° C. in decreasing proportions, finally in an amount of 1.8 kg (4 lbs ) _{ until the desired viscosity was achieved. The viscosity was measured 20 minutes after each addition of epichlorohydrin by taking a sample and determining the Brookfield viscosity with a No. 2 spindle at 20 rpm. The polymer was then diluted with 3443.7 kg (7592 lbs) of water. The reaction

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was stopped by the slow addition of 437.7 kg (965 lbs) 93.2% H ^ O ^ solution until the pH was lowered to 5.0 +1.0. The resulting solution had a viscosity of 1000;
Solids content of 50 %.

a viscosity of 1000 + 200 cP at 30 ° C and one

Products of this invention have been thoroughly tested for their entemulgierende and flocculating action in various industrial plants, various oily wastewater systems represented _β According to the test method has been the effectiveness of treatment determined by visual inspection of the waste water. The test results that were obtained clearly show not only the effectiveness of the polymer according to the invention for oil-water separation, but also the advantages mentioned above over the known processes. All amounts given for the polymer are based on the product.

Example 6

The oily wastewater in this application contained rapid and lubricating oils that have been used in the manufacture of automobiles. The initial pH before the Treatment was approximately 9.0.

Treatment with only one inorganic coagulant (alum in an optimal amount of 600 ppm) resulted in adequate oil-water separation. However, a large volume of sludge was formed.

With the simultaneous use of 25 ppm (product) of an inventive prepared according to Example 5 Po ^ mers, the optimal amount of alum was reduced to half, i.e. 300 ppm, and thus the sludge volume was also reduced.

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In all treatments, the pH of the oily wastewater was first adjusted to approximately with 10% HpSOA 7.0 set.

Some results of this treatment are given in the following Table 1, with treatment only with Alum is compared to treatment with alum and polymer in relation to flocculation (floc formation). The flocculation received a digit between 1 to 6, with the lower digits providing better flocculation mean.

Tabel 1 Outflow 2 Alum-
(ppm) polymer
(ppm) 6th 2 200 - 5 1 400 - 1 600 - 2 800 - 3 1000 - 4th 1200 - 5 - 500 5 - 1000 2 300 25th 2 300 50 400 80 100 250 100 500

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Example 7

Oily wastewater from an oil company API separator was treated with alum and a liquid cationic polymer prepared according to Example 5. The pH was adjusted to 9.0 to 7.3 with 760 ppm H _{2 SO ^.} An optimal amount of about 75 ppm alum resulted in good oil-water separation. However, a large volume of sludge was formed.

The alum could be completely replaced by less than 5 ppm of the polymer according to the invention. Such replacement resulted in a similarly good oil-water separation, but a lower sludge volume ₀ The settling rate of the flocculant precipitate (floe settling rate) was low, but could by adding 0.2 ppm of a commercially available high molecular weight acrylamide / sodium acrylate / copolymer containing 10 wt .-% sodium acrylate can be significantly improved after adding the liquid cationic polymer. Of course, a larger amount (a host) of commercially available high molecular weight acrylamide polymers could be used successfully. The liquid cationic polymer treatment was successfully carried out without any initial pH adjustment in the oily waste water.

Example 8

In this application example, the oily wastewater from a transmission and machining system was a larger automobile factory. Due to the return of acidic water from an oil-cooking process the pH of the oily wastewater was approximately 4. An adjustment of the pH with the help of lime was used to achieve a pH of 7.0, to optimize the effectiveness of alum.

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In the treatment program, 450 ppm of lime were added first, followed by 200 ppm of alum. A corresponding Clarification gave good breakdown of the oil-water emulsion and excellent clarity of the draining liquid * However, a large volume of sludge became formed what turned out to be a big problem with the batch wise Working in the treatment facility proved.

It was found that a liquid cationic polymer prepared according to Example 5 could replace the alum in an amount of 5 to 10 ppm. This application had the distinct advantage that the accumulation of sludge in the tanks was substantially reduced and, as a result, several batches were treated with the same amount of sludge. could become.

The results of this treatment are given in Table 2 below, which compares the amount of alum with the amount of polymer indicating the flocculation activity and clarity of the draining liquid visually were observed.

Table 2 Alum Polymer Lime · Observations

(ppm) (ppm) (ppm) ■

100 - 250 only slight flocculation activity

200 - 250 "

300 - 250 "

10 250 "

20 250 ".

30 250 V

²⁰⁰ - 450 good flocculation activity,

satisfactory clarity

5 450- best flocculation activity,

clear

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Table 2 (cont.)

Alum polymer _c lime observations

(ppm) (ppm) (ppm)

jQ 450 good flocculation activity,

satisfactory clarity

15 450 "

- ■ 20 450 "

Example 9

A liquid cationic polymer, which had been prepared according to Example 5, was used to separate Oil-water tested in the oily waste water of an automobile manufacturing plant. The initial pH of the wastewater was 7.0. At an amount of 750 ppm of the product, the polymer only led to a slight flocculation, but good oil separation. Good flocculation occurred at an amount of 500 ppm. The application of either Alum or acid to help break the emulsion was not required.

Example 10

A plant for the treatment of oily wastewater with a very low activity shows the successful application of a liquid cationic polymer which had been prepared according to Example 5. as a de-emulsifying agent.

Preliminary tests (Jar test studies) showed that an optimal amount of 200 ppm leads to a thick voluminous slowly settling flocculent precipitation, which reduced the already low capacity of the treatment plant (132 300 or 35,000 gal. per day) was further reduced.

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However, replacing the alum with 20 ppm of the polymer resulted in a denser, faster settling flake Precipitation, which indirectly contributed to increasing the capacity of the facility. Both treatments (alum and Polymer) led to a good oil-water separation and a clear drainage stream containing only 30 ppm oil compared to an initial oil content of 150 ppm.

Example 11

The application of two liquid cationic polymers to the treatment of oily wastewater in a large automotive plant has been very successful. The first polymer was a commercial polyamine product (hereinafter referred to as commercial product A). The second polymer was produced according to Example 5. It was observed that 80 % of the time the wastewater entering the treatment plant had a pH greater than 9.0. Acid was used to adjust the pH to approximately 7.0 prior to treatment with the chemicals. 20 % of the time the wastewater had a pH of 7.0 and did not require any acid adjustment. In each case, 500 ppm of commercial product A was added at pH 7.0. Good oil / water separation was obtained.

The use of the polymer according to the invention at a pH of 7.0 of the waste water resulted in an amount of 500 ppm to a low oil-water separation. It required alum "^ to increase the clarification activity. If that However, wastewater treated with the polymer at pH still 9.0 or above yielded 350 ppm excellent separation of the oil and clarity of the effluent.

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The results of these treatments are as follows Table 3, the clearing activity being observed visually.

Table 3;

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Table 3 treatment

Amount (ppm)

Commercial product A, 2cm- ³ 10% H ₂ S0 _{Zf 100}

ι «200

co commercial product A

For example, 2cm ³ 10% H ₂ SO ₄

Example 5

300

500

• 500

200, 225, 275,300 350 450 500

400 • 700

Observations

no activity
low activity

activity

large flocculation

good flocculation, good clarity

no activity
good activity

very good activity

stronger activity than an equal amount of commercial product A and 1000 ppm commercial product A

overdosed, no activity

ro

CD OO CO

cn

Claims (10)

Claims (Λ 4 process for separating oil from oily wastewater, characterized in that the wastewater is treated with a water-soluble cationic polymer which has been obtained by polymerizing an epihalohydrin with an alkylene amine of the formula R ₁ ^ H N-R-N ^R 2. ^H in which R is a lower alkylene group having 2 to about carbon atoms and R ^ and R _{2 are} each a lower alkyl group having 1 to about 6 carbon atoms. 2. The method according to claim 1, characterized in that a polymer is used in which the ratio of epihalohydrin to polyamine is about 0.60: 1 to about 2.7: 1. 3. The method according to claim 1 or 2, characterized in that a polymer is used which has been prepared by reacting the alkylenepolyamine with 50 to 90 % of the amount of epihalohydrin to be polymerized, the reaction 'has led until the medium has an im possessed substantially the same viscosity, and the remaining portion of epihalohydrin added in individual portions and at one 709810/1045 1A-48 394 - ζ - U Polymerization temperature of about 60 to about 120 ⁰ C has worked _o 4. The method according to any one of claims 1 to 3, characterized in that a polymer is used which has been produced by polymerization in an aqueous alkaline solution and subsequent acidification of the reaction medium after conversion of the last added amount of epihalohydrin. 5. The method according to any one of claims 1 to 4, characterized in that a polymer is used in its production epichlorohydrin as. Epihalohydrin and dimethylaminopropylamine, diethylaminopropylamine, Ν, Ν-dimethylaminoethylamine and / or Ν, Ν-diethylaminoethylamine has been used as an alkyl polyamine. 6. The method according to claim 5, characterized in that the alkylene polyamine is _{0 dimethylaminopropylamine} 7. The method according to any one of claims 1 to 6, characterized in that the pH of the oil-containing Adjust the wastewater to 5.0 to 8.0 before treatment with the polymer and the wastewater at the same time with Alum treats. 8. The method according to claim 7, characterized in that the pH r value is adjusted to 6.0 to 7.5. 9. The method according to any one of claims Ibis 8, characterized characterized that one.dem oily wastewater in addition, an anionic acrylamide polymer is added. - 3 -709810/1045 1A-48 394 10. Application of the method according to one of claims 1 to 9 to a waste water containing hydrocarbon oils. 709810/1045