DE294957C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

The purification of waste water of organic origin is primarily a matter of the precipitation of the dissolved colloids contaminating them.

It is already known for this purpose the waste water between suitable electrodes electrolysis and thereby the elimination of solid matter to cause you to get small amounts of

ίο adding precipitants. Are iron or Similar to aluminum electrodes, new colloids are formed as a result of electrolysis Iron hydroxide or aluminum hydroxide, which however with opposite electrical Charge than the colloids of organic origin are afflicted. Because colloids of opposite When the charge precipitates, the colloids or coagulation occur as a result the so-called breaking of the brine.

Thorough experiments have shown that this process does not always go smoothly; it so-called protective colloids often occur in the colloids of organic origin, which the Prevent flocculation by metal hydroxides.

The brine runs unchanged from the electrolytic cell without causing it to break would have come. This condition can occur suddenly after a long period of perfect operation. The flocculation suddenly breaks despite the fact that the metal in question continues to dissolve.

Further experiments have shown that the addition of electrolytes, which on and. exert a precipitating effect for oneself, also fails here, insofar as the concentration of the electrolyte in question is below a certain threshold value, the application of which, however, makes the electrolytic flocculation no longer worthwhile. Only one salt, the aluminum sulfate Al ₂ (SO ₄ ) ₃ , is an exception. Its use in an amount which ^{corresponds approximately to only 1} Z ₃ to ¹ Z _{4 of} the threshold value or that amount which is required for the direct precipitation of the colloids enables the protective colloids to be rendered harmless and the metal hydroxides to precipitate them smoothly. As a result, the use of the electrolytic process remains profitable and feasible.

An embodiment of the new method and its result is shown below specified experiment explained in more detail:

The subject of the experiment was wastewater from a municipal sewage treatment plant, _{neutralized with a little milk of lime (20 mg Ca (OH) 2} per 1 liter). An addition of 10 mg aluminum sulfate Al ₂ (SO ₄ ) ₃ to 1 liter was added to this waste water.

The organic matter calculated from the oxygen consumption was 1280 mg to 11 = 100 percent in the original wastewater, after the above addition 1248 mg to 11 = 97.5 percent; accordingly, 2 ¹ ₂ percent of the organic matter was excreted as a result of the addition.

After 3 hours, the methylene blue sample showed complete, and with the addition of almost complete

coloring; the wastewater had lost almost nothing of its putrefactive properties as a result of the addition.

The same wastewater with the same addition of aluminum sulfate was in one Test cell electrolyzed.

Cell output: 0.0061 1 in ι sec. = 21.9 1 in ■ '■ ι hours,

- Amperage: 0.42 amp. At 11.6 volt terminal voltage,

Surface of the electrodes: 0.0923 qm,
0.42

Current density:

= 4.55 amps on 1 square meter,

050923
Current path in the electrolyte = 5 cm,

Electromotive force of polarization for the test cell, from 5 unit cells consisting = 5 volts,

Voltage drop on 1 cm current path in

Electrolytes:

= 1.32 volts,

Labor consumption on 1 cbm:
0.42 x 11.6

1000 x 0.0219

= 0.223 Kwst.

After the electrolytic treatment, a strong one appeared in the treated wastewater flaky discharge of brownish color, and sat down after standing for some time a strong sediment from, while the untreated water after long standing retained its dirty gray color and formed only very little sediment. That treated Water could be filtered very easily in a folded filter.

In the filtrate from this experiment, the organic matter came from the consumption of oxygen determined; Oxygen consumption of 27.2 mg = 537 mg per liter = 42 percent.

The methylene blue sample showed no discoloration after 3 hours, the waste water showed none Putability was more likely, and the filtrate was crystal clear in appearance.

The same wastewater was then with and without the addition of aluminum sulfate Addition of hydrated lime under the same conditions and current ratios in the test cell electrolyzed. After this, the flocculation did not occur even after standing for a long time, the treated wastewater showed the same dirty gray coloration as the original sewage, and the methylene blue sample did not show any reduction in putability. The treated water was in A pleated filter just like the original wastewater cannot be filtered because of immediate clogging of the filter occurred.

Experiments with the addition of other falling salts in the same low concentration yielded same negative result.

Claims (1)

Patent claim: Process for purifying waste water containing organic substances by means of an electric current with the addition of precipitating salts as electrolytes, characterized in that aluminum sulfate is added to the waste water as electrolyte in an ^{amount corresponding to about 1} Z ₃ to ^x / ₄ of the amount required to precipitate the colloids .