CS216522B2 - Method of cleaning the waste waters containing dissolved organic impurities - Google Patents

Abstract

The invention concerns a process for the treatment of waste waters containing dissolved organic impurities wherein an alkali-humate- containing substance is added into the waste water, followed by the addition of a mineral acid and/or at least one salt of a two- and/or three-valent metal. The purified water and the mud obtained are separated by known techniques.

Description

(54) A method of treating waste water containing dissolved organic impurities

Process for the purification of waste water containing, among other impurities, also dissolved organic substances. Substances containing alkaline humates in an amount of 0.2 to 2.0 kg / m ^{3 of} waste water are added to the purified water, the pH of the mixture is adjusted below 4.0 by the addition of a mineral acid, preferably sulfuric, hydrochloric or phosphoric acid, and / or or by adding a divalent and / or trivalent metal salt, preferably aluminum sulphate or ferric chloride, the sludge is separated from the water by sedimentation or notation and conditioned by adding perlite in an amount of 2 to 6 kg / m 3 of sludge and / or maintained at a temperature 80 to 120 ° C for 3 to 20 minutes and filtered from the purified water.

The chemicals used for this purification process are inexpensive, the process is easy to carry out, and dissolved organic impurities are effectively removed.

The invention relates to a process for the purification of waste waters containing dissolved, organic impurities.

Waste water is traditionally cleaned with lime or acidic salt metals or a combination of lime and acidic metal salts. In - the last decade -, the. In parallel with the rapid development of industry, organic chemistry also promotes the use of organic polyelectrolytes.

Synthetic polyelectrolytes are macromolecules! organic compounds having a molecular weight of 100,000 to -10,000,000 and having anionic, cationic and. non-ionic function. ^г

Recently, numerous methods have been published using various cleaning agents for the chemical treatment of waste water. According to U.S. Pat. No. 3,171,805, an acrylamide-based polyelectrolyte having a molecular weight of > 10,000 is added to the wastewater and the sludge formed is separated from the purified water in the sedimentation vessel.

The use of the natural macromolecular compound, ligninsulfonic acid, is protected in British Patent No. 1,092,628. According to this patent, ligninsulfonic acid is added to the acidic. .waste. · The water and the sludge formed is separated from the purified water in the flotation plant.

The main shortcomings of the methods known from the state of the art are:

The prior art methods known in the art are particularly suitable for the removal of suspended floating materials; Removal of dissolved impurities is negligible even when using macromolecular polyelectrolytes.

- The main drawbacks of lignin sulphonic acid based processes are the difficulty of ensuring standard lignin sulphonic acid quality, low process efficiency, i.e. high concentration of impurities in purified water and high operating costs.

- The use of macromolecular polyelectrolytes is extremely expensive.

The invention relates to an improved process for the purification of waste water containing, among other impurities, also dissolved organic substances which it does not have. deficiencies of known methods. The process according to the invention yields high-quality purified water and easily drained sludge. Purified water is used directly or fed into the tank. The sludge is suitable for feeding purposes or for growing plants.

According to the invention, waste water containing dissolved organic impurities is treated by adding to the waste water substances containing alkaline huminates in an amount of 0.2 to 2.0 · kg / m 3 of waste water, the pH of the mixture being adjusted below 4.0 by adding mineral acid , preferably sulfuric, hydrochloric or phosphoric acid, and / or by the addition of a salt of divalent and / or trivalent metal, preferably aluminum sulphate or ferric chloride, the sludge is separated by sedimentation or flotation and conditioned by adding perlite in an amount of 2 to 6 kg / m3 of sludge ......- and / or- -se · · is maintained at a temperature of 80 to 120 degrees Celsius for 3 to 20 minutes and filtered from the purified water.

By "alkaline huminates" is meant alkali metal salts of humic acids. Humic acids are allomelanins that are - in the soil, in coal, in peat - and are formed by the decomposition of organic substances, especially dead plants. They consist of mixtures of complex macromolecules having polymeric ... phenolic structures and also containing carboxyl, hydroxyl, amino, quinone, hydroquinone, ketone and ether groups. According to the results of the chemical analysis, humic acids contain about 54% carbon, 37% oxygen, 4% nitrogen and 5% hydrogen. The molecular weight of the humic acids strongly depends on the feedstock, the method for producing humic acids, the pH value and the storage time. Humic acids are generally isolated from the above raw materials by alkaline treatment and subsequent acidification if water-insoluble humic acids precipitate.

In particular, high molecular weight humic acids can be isolated. from coal, originating from the Eocene period, so that they precipitate · by acid after previous alkaline treatment · at low pH. The molecular weight of the humic acid obtained by precipitation at pH 6.5 is only about one-third. molecular weight of humic- · · acid · · scavenged · by precipitation at value. · PH ·· .4. - The addition of electrolytes' proteins' and fats increases the true molecular weight '. humic - - acids and fifteen times to. thirty-fold. For example, the molecular weight · -umina. - - acids. . isolated. The carbon-eocene time at pH 6.5 is 5000. · If. . .se added. 0.2. M aqueous. sodium chloride solution, - increase. is about. 75 000 ,.

Humic acids. have a wide - ranging application - including use in the pharmaceutical industry,. in agriculture and other industries.

Huminates are weak acid salts. and strong. bases, and therefore their alkaline solutions are obtained by hydrolysis.

In the process according to the invention, it is preferred. ..- huminates. potassium and / or sodium added. to the waste water in an amount of 0.2. up to 2.0 · kg of alkali metal huminate. m. ³ 'waste water.

In a preferred embodiment of the invention, the pH is adjusted to a value of less than 4 with a mineral acid, preferably sulfuric, hydrochloric and phosphoric acids.

According to another preferred embodiment of the process according to the invention, the waste water is added to the waste water

S yields a salt of a divalent and / or trivalent metal, with - preferably -. aluminum sulphate, sulphate; - ferrous and / or ferric chloride - in - an amount of - 0.2 to 1.2 kg / m ^{3 of} waste water.

The sludge is separated from the purified water by a flotation method known per se. - way. To clean ·. water is introduced air - in parallel - with. · Flaking and, if appropriate, · added; also 5 to 50 ppm of the subsidy means - and / or anion of the active polyelectrolyte.

Yet - yet - another advantageous. In the process according to the invention, perlite is added to the effluent sludge as a conditioning agent in an amount of 2 to 6 kg / m ³ - and / or - is carried out. heat conditioning at 80 to 120 ° C for 3 to 20 minutes.

Material · containing - alkaline - aluminates - is formed in - waste water · - or. - in its - share - in a manner known per se.

The process according to the invention is based on the finding that by mixing the waste water containing organic impurities with alkali, preferably with potassium huminate or sodium, under alkaline conditions, with the alkali. electronegative groups - (groups - —OH, - - OOOH, etc.) of huminates orient in the direction of electropositive groups of impurities and - create macromolecules! a compound in which the different - units - - - are linked- - - to each other by - - / - hydrogen bonds - - or - by Van-der-Wals-bonds. - - - Macromolecules - - include - - hydrated water - - and - also - dissolved - organic. -latky.,

If - the - pH - value is adjusted - to acidic or - - - - - if they are added. - salts of diphtheria and / or ^; - trivalent metals - into the system - electropropic groups of impurities, for example. - groups - - NH, - NH 2 - etc., bind protons, form serstable valence bonds and precipitate macromolecules containing - humic - acids, metal ions and impurities. The so-obtained sludge can then be separated from the purified water in a manner known per se, preferably depending on the specific weight of the impurities.

Jakožto-. - the main advantages of the - method - according to the extruded-to-be-stated :;

- Inexpensive and readily available chemicals are needed for cleaning, and huminates are easy to produce on-site alone; operating costs are low.

- Reaction - is - immediate, - soaking - no need - bulky stirrers, - flocculator-. - tanks - etc .: - installation - - cost - low.

—Because - - - macromolecules - composed of humic acid - and huminates and possibly containing impurities are formed in the waste water alone after acidification or after the addition of metal salt and instead of adsorption - bonds, real chemical bonds are formed, the impurity separation efficiency is high and Floating substances also remove large amounts of organic impurities.

- If the content of impurities in the water, especially in the waste water, is low for the high efficiency of the cleaning process - - - waste -. In accordance with the invention, purified water can be used. - directly go back - -do. - without the need for additional - - biology - · cleaning.

- ‘- Because! - - se- -. the process of - purifying - the water of the invention - also removes - also - most of the - dissolved - organic substances, such as phosphorus-containing compounds and nitrogen-containing compounds. which - are - responsible - for. - contamination - water, - - not required - none. tertiary processing. and - purified - water - - - can directly - - - return - -. into - - still - - water - - without- /-. danger of its eutrophication.

Optionally -se-. purified - - water can - easily - - further - - be purified on - - - any - known biological system.

The method - can - - can be successfully used - for tertiary · - - cleaning. - biologically - treated waste water.

- Separated sludge can be used as a valuable fertilizer.

The process according to the invention can be carried out in an apparatus having a preparation vessel connected by a pipeline provided with a pump 6 to a pipeline 5 on which one is - via a pipeline with a a container 2 is connected by a pump 3, via a pipeline to the pump 8 a container 7 and with which it is connected; - also - by means of a pipeline - a container 9 is connected. flotation units 4.

Further details of the method of the invention are explained in the following examples; breath; which, however, do not constitute the invention. meaning. In the examples, reference is made to Fig. 1. on which . - is - equipment. - carrying out - the process / method - according to the invention.

Example 1

Weigh brown into the preparation vessel 1. «Eoco - carbon containing 20. % water and 20% ash. - - Then - add - by weight - 20 - - ° / o ^; - solid - ground - hydroxide - - potassium - - o - maximum - - sizes -. - grains - 20 - - mm - - and - - by weight - - 250 - -% - of tap water. The components are mixed, whereby the temperature of the mixture increases from. about -18 ° C to about 60 ° C due to the - positive · - hydration heat of potassium hydroxide. The mixture is allowed to stand for 12 hours, whereupon. to three times its original volume with tap water - -k. - obtaining - an alkaline huminate solution whose - - residual carbon content is 35 - g / l.

Into the flotation unit - 4 the waste water of different - is introduced. 3. The alkaline huminate solution, which also contains undissolved carbon particles, is then introduced into line 5 via pump 6. 6. Acid. . sulfuric, '. . needed to adjust the pH to 3.0 to 3.2 is also fed from the vessel 7 to the pipe 5 through the pump 8. Immediately before. by introduction into the flotation unit 4, 15 to 30% by weight of water is introduced into line 5 ', preferably air saturated under pressure. 0.4 MPa in vessel 9.

Originated. the sludge and the purified water are separated separately. from the flotation unit 4.

According to the results obtained, the reactions occur immediately and after addition of the alkali huminates and the acid and / or salt of the divalent and / or trivalent metal. macromolecules already form a pipe length of about 20 to 30 times the diameter of the pipe at a conventional flow rate of 0.5 to 2.0 m / s. Therefore, no additional stirrers, flocculants and similar devices are required.

If wastewater from slaughterhouses having a chemical oxygen consumption of 2500 to 3500 mg / l is treated, the addition of 0.3 to 3.5 is used. 0,7 · g / l alkaline huminate and 0,6 to 1,0 g / l sulfuric acid, purified water and, where appropriate, sludge have the following characteristics:

purified water:

chemical oxygen consumption: 200 to 250 mg / l biological oxygen consumption: 60 to. 100 mg / l fat content: 6 to 10 mg / l, sludge:

amount: 3 to 4% by weight dry matter content: 5 to 6%.

When processing · sewage sludge having a chemical oxygen demand of 12,000 to 16,000 mg / l, · adding 1 to 1.2 g / l of alkaline huminate and 1.2 to 1.5 g / l of sulfuric acid, · the purified water obtained has a chemical oxygen demand of 1200 to 1500 mg / l, and the sludge obtained 14 to 18% by volume contains 5 to 6% dry matter.

Example 1 a d 2

The process described in Example 1 is repeated, but aluminum sulphate or ferric chloride from vessel 7 is introduced into line 5 and 10 to 30% of air-saturated water at 0.4 MPa is added to the waste water to obtain these results:

A. Waste water:

chemical oxygen demand:

400 to 600 mg / l phosphorus content: 7 to 15 mg / l nitrogen content: 30 to 50 mg / l solid floating substance: 100 to 250 mg / l

Reagents:

0.2 · to 0.6 g / l. alkaline huminates

0.1 to 0.4 g / l of aluminum sulfate

Purified water:

chemical. oxygen consumption: 60 to 70 mg / l phosphorus content: 0,3 to 0,5 mg / l nitrogen content: 8 to 10 mg / l solid floating substance: 10 to 25 mg / l

B. Waste water: chemical slaughterhouse waste water. oxygen consumption: 3500 mg / l nitrogen content: 20 to 30 mg / l phosphorus content: 30 to 40 mg / l

Reagents:

0.6 to 1.0 g / l of alkaline huminate

0.18 to 1.2 g / l of ferrous sulfate and ferric chloride

Purified ^water:! chemical oxygen demand:

200 to 300 mg / l nitrogen content: 20 to 30 mg / l phosphorus content: 0.1 to 0.5 mg / l

Example 1 a. d 3

The process described in Example 1, obtained, was repeated. the sludge is brought to a boil by steaming under thermal conditioning. Allow to stand for 5 minutes, then cool to 40 ° C and filter. with disc vacuum filter. The filter capacity is over 30 kg / m ³ per hour and the sludge cake contains 22-28%. dry matter.

Sludge cake can be used as fertilizer and. gives the same results as the alkaline huminate from which it was obtained.

Example 4

The method described in Example 3 is repeated. however, 5 to 6 g / l of perlite is added as conditioning agent and the filtration is performed at a rate of 50 to 60 kg / m ² per hour, with the dry matter content of the cake rising above 30 why.

Example. 5

0.2 kg / m &^lt; ³ > of sodium huminate and 0.2 kg / m ^{< 3 >} of aluminum sulphate are added to the biologically treated waste water in the plant of FIG. The sludge is separated from the purified water by sedimentation. Presented. Some characteristics of the initial wastewater and purified water:

Wastewater

Purified water

chemical oxygen demand 70 mg / l 24 mg / l nitrogen content 27 mg / l 5 mg / l phosphorus content 6 mg / l 0.4 mg / l solid floating substances 70 mg / l 25 mg / l

Claims (2)

OBJECT OF THE INVENTION Process for treating waste water containing dissolved organic impurities, characterized in that substances containing alkaline huminates in an amount of 0.2 to 2.0 kg / m ^{3 of} waste water are added to the waste water, the pH of the mixture is adjusted below 4.0 by adding mineral acids, preferably sulfuric, hydrochloric or phosphoric acids, and / or by adding a divalent and / or trivalent metal salt, preferably aluminum sulfate or ferric chloride, the sludge is separated from the water by sedimentation or flotation and conditioned by adding perlite in an amount of 2 up to 6 kg / m ^{3 of} sludge and / or maintained at 80 to 120 ° C for 3 to 20 minutes and filtered from the purified water. 2. A process according to claim 1, characterized in that, in the case of separation of the sludge by flotation from the purified water, air is introduced simultaneously with the formation of sludge flakes and at the same time 5 to 50 mg / l of anionic polyelectrolyte are added.