LT3619B - Method for treatment of waste water, hidrodispersion for treatment of waste water and method for its preparation - Google Patents

Abstract

The invention relates to the field of sewage water cleaning and is primarily referred to hard metal ion removal and can be used in galvanic, skin tanning, colour metallurgy and for cleaning in other fields of industry. It is suggested to use hydro-dispersion, e.g. iron (II and III) oxyhydrate electrogenerated dispersion with alkaline metal chloride additive. Iron oxyhydrate dispersion particles in a colloidal system is 5.15 μm sized, taking up 100-150 m<2>/g of comparative surface, while the hydro-dispersion density is 1.05-1.15 g/cm<3>. Such characteristics enable to achieve a necessary cleaning level when using 1-10 ml electrogenerated iron oxyhydrate dispersion for 1 litre of disposed water, when pH is 7.5-9.5.The iron oxyhydrate hydro-dispersion production method consists in dissolving an iron anode in an electrochemical water solution, where electric conductance is at least 3x10<-3> ωm<-1> cm<-1>, hydro-dispersion is blown with air during the electrolysis. The blowing method is continued until 10-20 % of dissolved iron goes over to trivalence iron status. Hydro-dispersion may be stabilised by adding 0.3 / 1.5 % material, selected from the group containing natural aluminium silicates, calcium orthophosphate and also non-organic polyelectrolytes.

Description

The invention relates to the field of wastewater treatment, in particular to the treatment of heavy metal ions; can be used for waste water treatment in galvanizing, leather processing, non-ferrous metallurgy and other industries.

There is a known method of removing contaminating ions from the aqueous medium which provides for the use of soluble iron anodes. Electrochemically generated anodes of iron ions in a separate aqueous medium with a pH of less than 2.8. Subsequently, the two media (iron ions and effluents) are mixed (U.S. Patent No. 4,693,798, 1987).

The disadvantages of this method are the relatively high consumption of the electrogenerated solution as well as the insufficient degree of purification for metals such as Co, Mn and the like.

There is a known method of purifying wastewater from heavy metal ions, which involves the gradual treatment of wastewater: first with iron (III) hydroxide and then with iron (II) hydroxide (USSR aut. No. 778 181, 1985).

This method allows to purify wastewater from various heavy metal ions, but requires separate preparation of both decontaminating reagents; in addition, it is necessary to keep in mind that ferric hydroxide is volatile and gradually oxidizes to ferric hydroxide. This method is ineffective in attempting to decontaminate metal complexes.

The disadvantages indicated in the second method can be overcome by using the hydrodispersion of the present invention as a reagent for wastewater treatment, i. electrogenerated hydrodispersion of ferric oxide hydrate with an alkali metal chloride-containing additive

20-40 g / l of complex iron (II and III) oxide hydrate, calculated as iron (II) - 30-90%, as well as 5-10 g / l of alkaline metal chloride.

There is a known method for obtaining an electrogenerated coagulant for the treatment of wastewater by electrolysis of an aqueous sodium chloride solution (having a permeability of at least 3.10 ^-3 µm cm ^-1 ) using soluble ferrous iron anodes (USSR Aut. No. 1, 675 089, 1979). This method provides for the steps of compaction of flush jr coagulant flakes but does not provide for control of the ratio of iron (II) to iron (III).

The hydrodispersion for wastewater treatment provided by the present invention bypasses the coagulant obtained in the above manner in terms of purification efficiency. The particles of dispersion of iron oxide hydrate in the colloidal system are 5-15 µm in size, occupy a reference surface of 100-150 m / g, and have a hydrodispersion density of 1.05-1.15 g / cm ³ .

The composition of the particles can be expressed by the formula:

Fe

II (4.0-4.5)

Fe

III (1.0-0.5)

O _x (OH) _n H ₂ O (2x + y = -ll-10.5; n = 65-70), i.e., the system - complex iron (II, III) oxide hydrate - particles and most of the water in the system are bound. These characteristics allow the required degree of waste water treatment to be achieved using 1-10 ml of electro-generated dispersion of iron oxide hydrate per liter of waste water at pH 7.5-9.5.

The above characteristics are obtained by the periodic blowing of the hydrodispersed air with electrochemical dissolution of the iron anodes until 10-20% of the dissolved anodic iron enters the trivalent state. Exceeding the above limits significantly narrows the comparative surface of the hydrodispersion particles, reduces its sorption capacity and its activity as a coagulant, and consequently reduces the effluent treatment efficiency. Periodic purging with air also helps to reduce the production of hydrodispersion.

In addition, in the proposed method of obtaining a hydrodispersion, an alkali metal chloride (usually sodium chloride) added to the solution prior to electrolysis to increase the electrical conductivity to a limit of at least 3.10 ³ ohm- ¹ cm ¹ is retained in the hydrodispersion, slowing it down. the aging process.

Purification of the effluent by the described hydrodispersion can be carried out in two steps: the effluent, after treatment with ferric oxide hydrate dispersion and separation of the resulting sediment (first step), and again with a new batch of hydrodispersion (second step). The resulting second stage sediment is used to treat the next batch of wastewater in the first stage.

In the case of small amounts of wastewater from various production bars, electro-generated dispersion of iron oxide hydrate can be pre-centralized and then delivered to each production bar. 0.3 to 0.1% by weight of a material selected from the group consisting of natural aluminosilicates, calcium orthophosphate, inorganic and organic polyelectrolytes are added to stabilize the hydrodispersion. Upon introduction of the stabilizer, the hydrodispersion is stabilized by the formation of monomolecular absorption layers and interparticle bonds.

After stabilization, the hydrodispersion remains active for at least 10 months.

«IUS.II HSII) ί. II1JII! , IIL), I! I; II I 11.11 I, m YUKIJ! , 11.11 ·· I I / 1

The invention is illustrated by the following examples. The tests were performed under static conditions using a laboratory reactor of 1.0 L capacity. The contact time between the effluent and the coagulant (iron (II, III) oxyhydrate hydrodis5 persia) was 30 min.

The results are shown in the tables (analyzes by atomic absorption spectroscopy).

Sample numbers I-IV by purification in a known manner.

Pavyz- jio No. Pollutants, Concentrated its initial mg / 1 Coagulant (hydrodispersion) dose in mg Fe / l or ml Residual pollutant concentrations in mg / l T X Cr ^VI 62.4 Coagulant 0 Zn ²⁺ 41.8 300 mg / L C Cu ² 18, 9 or 10 ml 0 7 4. Ni 28.2 0 II Complexes with ethical Coagulant flying amino tetra 300 mg / L acetate or 10 ml Zn ²⁺ 41.8 12.5 Cu ²⁺ 18.9 5.7 Ni ² 28.2 8.5 III Complexes with wine same with acid Zn ²⁺ 41.8 8.4 Cu ²⁺ 18, 9 3.9 IV Pb ²⁺ 15.2. same 5.1 Cd ²ⁱ 8.1 3.7

II, 1,

1 2 3 4 Examples numbers V-XI, cleaning proposed way V Cr ^VI 60.0 hydrodispers ij a, 0 Zn ²⁺ 60.0 stabilized 0 Cu ²⁺ 27.0 cic orthophosphate 0 Ni ²⁺ 35, 2 (newly manufactured) 300 mg / 1 or 10 ml 0

VI Complexes with eth- flying amino tetra acetate hydrodispersion, stabilized with calcium orthophosphate Zn ²⁺ Cu ²⁺ Ni ²⁺ 35.0 2i; o 22.0 (newly manufactured) 300 mg / 1 or 10 ml 0 0 0 VII Complexes with men- hydrodispersion, from acid passed for 10 months Zn ²⁺ 30.0 after stabilizer- 0 Cu ²⁺ 20.0 calcium calcium or- administration of 300 mg / l of phosphate or 10 ml 0 VIII Pb ²⁺ 35.0 same 0 Cd ²⁺ 18.2 0 IX Cr ^VI 60.0 hydrodispersion, 0 Zn ²⁺ 60.0 stabilized 0 sodium carboxy Cu ²⁺ 27.0 methylcellulose 0 Ni ²⁺ 35.2 salt 300 mg / L 0

or 10 ml

III UI JHBIH

Complexes with ethical That's it by itself- flying amino tetra hell 10 months acetate Zn ²⁺ 15.0 0 . Pb ²⁺ 12.0 0 Cd ²⁺ 10, 5 0

Hlll Iii: I II U K. I. I

Claims (10)

DEFINITION OF INVENTION A process for treating wastewater, comprising treating the wastewater with iron (II, III) oxide hydrate, precipitation precipitation and separating the precipitate by simultaneously introducing ferric oxide hydrates in the form of an electrogenerated hydrodispersion containing g / l. of complex iron (II, III) oxyhydrate, converted to iron (II) (80-90%) 20 - 40, alkali metal chloride 5-10. 2. A process according to claim 1, wherein the electrogenerated iron (II, III) hydrodispersion of iron (II, III) is pre-prepared and centrally stabilized by adding 0.3 to 1.5% of a calcium selected from the group consisting of aluminosilicates. orthophosphate, inorganic and organic polyelectrolytes, and delivers stabilized hydrodispersion to waste water treatment sites. 3. The process according to claim 1 or 2, wherein the electrogenerated iron (II, III) hydrodispersion of iron (II, III) is introduced into the effluent in a volume of 1 to 10 ml per liter of effluent at pH 7.5 to 9.5. 4. The process of claim 3, wherein the wastewater is treated in two steps: treating the wastewater by separating off the precipitate obtained by treating it in the first stage, treating with a new portion of an electrogenerated ferric oxide hydrate dispersion, and treating the precipitate obtained in the second stage. for processing in the first step. III JI U.I 5. Hydrodispersion for wastewater treatment consisting of hydrogel dispersion of electrogenerated iron oxide hydrate, characterized in that it contains, in g / l of complex iron (II, III) oxyhydrate, expressed as iron (II) 80 - 90% of 20 - 40 alkali metal chloride 5-10. 6. Hydrodispersion of ferric oxide hydrate according to To claim 5, characterized in that the iron (II, III) oksihidrato particles are 5-15 μπι size, having 100 - 150 m / g specific surface area and hidrodispersijos density 1.05 to 1.15 g / cm ^J. 7. Hydrodispersion of ferric oxide hydrate according to 6. The method of claim 6 further comprising 0.3-1.5% of a stabilizer selected from the group consisting of natural aluminosilicates, calcium orthophosphate, and inorganic and organic polyelectrolytes. 8. Iron oksihidrato hidrodispersijos for cleaning waste water, the method based on the iron anode, usually made of metal waste electrochemical dissolution in a water solution in which the electrical conductivity of less than 3.10 cm ³ om ^{1 x} bes.iskiriantis that electrolytically - the hydrodispersion is purged with air. 9. The method of claim 8, wherein the air purge is effected until 10-20% of the dissolved anodic iron enters the trivalent iron state. ! I, L U III Hl EN 3,619 B ac The process according to claim S, characterized in that the hydrodispersion of iron: oxyhydrate. for purification of wastewater. ,, stabilizes by adding 0.3 to 1.5% of substances, selected from the group consisting of: - natural aluminous silicates, calcium arto ± 0s-f: atas, and inorganic, and organic polyelectrons ...