Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
  • C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/78—Compounds containing aluminium, with or without oxygen or hydrogen, and containing two or more other elements
  • C01F7/784—Layered double hydroxide, e.g. comprising nitrate, sulfate or carbonate ions as intercalating anions
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/78—Compounds containing aluminium, with or without oxygen or hydrogen, and containing two or more other elements
  • C01F7/784—Layered double hydroxide, e.g. comprising nitrate, sulfate or carbonate ions as intercalating anions
  • C01F7/785—Hydrotalcite
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G49/00—Compounds of iron
  • C01G49/009—Compounds containing iron, with or without oxygen or hydrogen, and containing two or more other elements
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/20—Two-dimensional structures
  • C01P2002/22—Two-dimensional structures layered hydroxide-type, e.g. of the hydrotalcite-type
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer

Definitions

• the present invention relates to precipitants or flocculants for wastewater treatment, with which in particular laundry wastewater can be cleaned.
• the invention further relates to methods using these agents.
• the object of the invention is to provide a new precipitant or flocculant for waste water treatment, in particular for laundry waste water.
• REPLACEMENT BL Another object of the invention is to provide a wastewater treatment process using these precipitants or flocculants.
• Freshly precipitated cationic layer compounds of the general composition are used for this
• A stands for one equivalent of an acid and x is between 0.01 and 0.5 and n is between 0 and 20, which are in a special form described below.
• REPLACEMENT LEAF Waste water ingredients are removed.
• the ability to separate the dirt flakes is usually favored by the addition of flocculation aids (organic polymers of different charge states).
• FR-A-24 66 438 claims a process for cleaning laundry wastewater by adding aluminum sulfate in the same amount to the solids content of the wastewater.
• comparative example 3 shows, although favorable turbidity values and low total solids values are obtained, the filtered wash liquor appears to the eye as whitish-cloudy. The pH in the acidic range is also unfavorable for recycling the wash liquor.
• a similar process uses polymeric aluminum salts, such as basic polychlorosulfates of aluminum, in conjunction with iron salts (EP-A-0 261 019).
• the present invention has the task of effectively removing preferably negatively charged wastewater constituents, such as occur particularly in laundry wastewater (e.g. anionic surfactants and builder substances, but also the dirt particles negatively charged at normal pH values of washing liquors).
• Layer compounds with a positive layer charge are suitable as reagents. Such compounds are known under the name “double layer hydroxides” in the literature (e.g. R. Allmann, “double layer structures with brucite-like layers", Chimia 2_4_ / 99-108 (1970)).
• M (II) for a divalent metal ion
• M (III) for a trivalent metal ion
• Acid and x are between 0.01 and 0.5 and n are between 0 and 20.
• REPLACEMENT BLA can clean wastewater containing phat by means of the sorption and exchange properties of this compound.
• the present invention was therefore based on the object of providing a novel precipitant or flocculant for wastewater treatment, but in particular for treating laundry wastewater, with the aid of which the wastewater can be cleaned better and which is almost completely optically clear Lead solutions.
• the present invention relates to precipitants or flocculants for wastewater treatment, consisting of double-layer hydroxides of the general composition
• M (III) represents at least one trivalent metal ion and A represents an equivalent of one or more mono- or polybasic acids, x is between 0.01 and 0.5 and n is between 0 and 20, which is characterized in that it has a minimum content of 30% by weight of hydrophilic solvents and thereby preventing the agglomeration of the primary particles into secondary particles which do not disintegrate in water to such an extent that their average particle diameter in an aqueous suspension is less than 2 ⁇ m and no particles with a particle diameter of more than 10 ⁇ m are available and can be obtained by
• the average particle diameter in the aqueous suspension is measured in a manner known to the person skilled in the art by means of a Coulter Counter from Coulter Electronic Ltd., England, using 1% by weight aqueous
• REPLACEMENT LEAF sodium chloride solution as an electrolyte The measurement conditions mentioned are explained in the manual for this device.
• the procedure for the preparation of the precipitants or flocculants according to the invention is that the starting materials are continuously fed to a reaction site, so that an excess of one of the components is avoided during the reaction.
• the precipitation reaction carried out continuously is known for the production of composition hydroxides which are used, for example, as acid binders, as described in claim 4 of DE-OS 20 61 156.
• An alternative to this embodiment for this combination of the starting materials, namely pumping the solutions of the starting materials together through a Y-tube, is described in EP-A-0 207 811, which relates to mixed metal hydroxides, which act as gelling agents for drilling fluids and the like be used.
• the primary particle collective of the precipitant or flocculant according to the invention is also essential to keep the primary particle collective of the precipitant or flocculant according to the invention stable in agglomeration until use.
• This state is generally achieved according to the invention in that the drying of the suspension present after the precipitation is ended after attaining a pasty state with at least 30% by weight of residual hydrophilic solvents. It can be assumed that the particularly fine-particle primary particles obtained by the special precipitation process are kept in a dispersed state while they agglomerate during drying to secondary particles which no longer disintegrate.
• This agglomeration effect is also described in the above-mentioned EP-A-0 207 811, where the addition of glycerol or other polyols is recommended to avoid it.
• a disadvantage of this procedure is that large amounts of fresh process water are required to prepare the starting material solutions, which is technically complex and leads to problems at the latest when the precipitants or flocculants according to the invention and the process used with them Water shortage areas are to be used. Accordingly, it is particularly preferred to generate the double-layer hydroxide directly in the waste water to be treated.
• the required amounts of starting materials for water-soluble salts with di- and trivalent metal ions, preferably with magnesium and aluminum ions are dissolved in the minimal amount of water and this concentrated solution is added to the waste water to be treated (Example 5).
• the solid water-soluble salts can also be dissolved directly in the waste water volume (Examples 3 and 4).
• a pH of between 8 and 12 is optionally adjusted with lye, for example sodium hydroxide solution, pH values around 11 resulting in a clearer pure water phase, but with
• REPLACEMENT LEAF increased electrolyte content. At pH values around 9, a slight turbidity remains after the precipitation has been separated off, but the content of dissolved / dispersed constituents in the purified water is lower than at higher pH values.
• the precipitates formed during the treatment can be separated off using conventional methods such as sedimentation, flotation, filtration or centrifugation. The same applies to further dewatering of the sludge obtained, for which e.g. a chamber filter press can be used.
• the pure water obtained is completely clear to slightly cloudy and has an electrolyte content of between about 6 and about 24 g / l.
• this electrolyte content proves to be disruptive due to the salting-up effect in a largely closed water cycle, it can be processed according to the methods known from the prior art, e.g. by reverse osmosis or electrodialysis.
• the pH value which is in the alkaline range due to the electrolyte content, is in principle favorable for reuse as a wash liquor.
• the method according to the invention represents an inexpensive and effective alternative for the required pretreatment.
• used washing liquor (waste water from the washing cycle, blue wash) from a large commercial laundry was used.
• 500 ml of the wash liquor were mixed with the indicated amount of reagent at room temperature with stirring using a magnetic stirrer and stirred for five minutes.
• 2 ppm of a strongly anionic flocculant were subsequently used
• the two solutions are pumped together with peristaltic pumps through the two legs of a Y-shaped tube into a beaker, the hydrotalcite precipitate formed is suctioned off and washed with demineralized water.
• 16 g (corresponding to 4 g hydrotalcite) of the pasty product with a solids content of 25% by weight are stirred into the wash liquor.
• the precipitant or flocculant hydrotalcite is precipitated directly into the wash liquor.
• 250 ml of reagent solutions I and II from Example 1 are pumped through, the two legs of a Y-shaped tube in 500 ml of wash liquor.
• the mixture obtained (1,000 ml) is divided into two, the one half immediately and the second half after adding Ferrocryl.
• the precipitant or flocculant is produced directly in the wash liquor: 1.73 g aluminum nitrate nonahydrate and 2.27 g magnesium nitrate hexahydrate are dissolved in 500 ml wash liquor and the pH is adjusted to 9 with sodium hydroxide solution.
• Example 3 As described in Example 3, a precipitant or flocculant is produced, but 2.27 g of calcium nitrate tetrahydrate are used instead of the magnesium nitrate.
• the precipitant or flocculant was produced in a new wash liquor and the starting materials dissolved in a small volume of water were added: 500 ml wash liquor was stirred without stirring with a solution of 0.65 g aluminum nitrate nonahydrate and 0.85 g magnesium nitrate hexahydrate in 5 ml deionized water. After a waiting time of 5 minutes, the mixture was gently stirred and filtered.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)

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• 1988
  • 1988-11-14 DE DE3838532A patent/DE3838532A1/de not_active Withdrawn
• 1989
  • 1989-11-06 EP EP89912981A patent/EP0442951A1/de active Pending
  • 1989-11-06 JP JP2500154A patent/JPH04501529A/ja active Pending
  • 1989-11-06 EP EP89120479A patent/EP0369275A1/de not_active Withdrawn
  • 1989-11-06 WO PCT/EP1989/001324 patent/WO1990005706A1/de not_active Ceased
  • 1989-11-06 AU AU46344/89A patent/AU627806B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

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