MXPA00011143A - Method for treating waters, soils, sediments and/or sludges - Google Patents

Abstract

The invention relates to a method for treating waters, such as standing, flowing and waste waters, soils, sediments and/or sludges. The invention is characterized in that the waters or sediments are treated with alkaline-earth peroxides.

Description

PROCESS FOR TREATING WATERS, SOILS, SEDIMENTS AND / OR HUNDREDS FIELD OF THE INVENTION The present invention relates to a process for treating water, such as standing and running water, wastewater, soil sediments and / or silt.

BACKGROUND OF THE INVENTION Aqueous bodies, soils, sediments and / or silt always comprise a certain proportion of organic material. Especially in the case of water, ie water bodies as well as waste water, the content of organic compound, inter alia, determines the water quality. The organic matter first increases the values of COD and BOD and second leads in the course of time the formation of detritus, ie the formation of silt and, in the extreme case, to accretion or organic growth. The high values of COD and BOD mean that material is present, which has a high oxygen demand and leads to an oxygen deficiency for microorganisms and other life forms, and finally to death. The degraded material is present in the water as additional organic matter, for example as suspended particles, which are accompanied by an additional decrease in water quality. To prevent accretion or organic growth, in aqueous bodies, particularly in ponds, the formed sediments must be removed mechanically at regular intervals. However, this mechanical removal of the silt requires an adequate particle size. The suspended particles generally can not be removed. Also, the contamination of waters, soils, sediments and / or silt damages the activity of the microorganisms that live in them, which in turn leads to an interference with the natural balance. An additional problem, especially in the case of aqueous bodies inland, is the phosphate content, which is responsible for the eutrophication of aqueous bodies. The reduction in the concentration of phosphate in eutrophied aqueous bodies is generally the key to a successful remedy, ie the improvement of water quality and its possibilities of use. Therefore, for more than two decades attempts have been made and are being made with varying degrees of success in decreasing the concentration of phosphate in particular in lakes and effluents from wastewater treatment plants. The established processes use salts of iron and aluminum salts as precipitants. Recent developments are developed with the optimization of the elimination of biological phosphate and the technological control of the precipitation of biogenic calcite and the washing of deposits of chalk or lacustrine tisa as potential methods of ecotechnological remedy of aqueous bodies. The known processes for phosphate removal, however, have the disadvantage that the precipitation of the phosphate proceeds only incompletely and is also sometimes technically complex. Adding Al compounds or Fe compounds, in addition, aluminum ions and iron ions are also introduced into the water, which do not always have beneficial consequences on water quality. In the prior art it is known how to treat water contaminated with a mixture of Ca (OH) 2 and H202 In such processes, the existing phosphate is precipitated as calcium acid phosphate (Brushit), whose solubility product depends on The pH is formed in a state of equilibrium with the existing components in the aqueous environment, and in some cases even hydrogen phosphate redissolves, which does not allow the permanent binding of the mineral phosphate in the treated systems and does not ensure oxygen balanced environment that can be tolerated by the aqueous organisms and inhabitants of the sediment.

BRIEF DESCRIPTION OF THE INVENTION The object underlying the present invention is thus to provide a process for treating waters, soils, sediments and / or silt, which allows the organic matter that is present as a sky or suspended matter to be degraded and This way reduce the content of substances that consume oxygen and simultaneously improve the nitrification and enzymatic activity of the microorganisms present. An additional object was to provide a process which allows the phosphate to be removed from the waters, soils, sediments and / or silts, so that the phosphate content decreases below the maximum ecologically required content and the phosphate is bound in such a way that it is not released again by water by dissolution or by leaching. A further object is to reduce the content of other contaminants present in such systems simultaneously with the removal of the phosphate. The present invention relates to a process for treating waters, such as standing water and streams and wastewater, soils, sediments and / or silts, characterized because the waters or sediments are treated with alkaline earth metal peroxides. Surprisingly, it has been found that by using alkaline earth metal peroxides to treat waters, soils, sediments, and / or silt, the content of organic matter is present as silt or suspended matter, can be greatly reduced and the degradation operation Microbial can also be promoted. It is assumed that when the alkaline earth metal peroxides are added to the waters, soils, sediments and / or silt, a mineralization of the organic matter takes place, that is, the conversion of organic matter to inorganic matter. At the same time other dangerous substances can be immobilized, for example if they are precipitated together with other solids. Experiments have found that odoriferous substances and flavorings are also degraded and nitrification is promoted. In the treatment of phosphate-containing waters, soils, sediments and / or sludge with alkaline earth metal peroxides, the phosphate can be removed in an excellent manner so that the phosphate concentration is below 30 μg of P / L after the treatment. The experimental results currently available have found a decrease in the orthophosphate concentration of 3.26 and 0.33 mg of P / L to 6 and 3 μg of P / L, respectively, within a very short period of time. Furthermore, it has been found that the pH of the system treated according to the invention is increased in the alkaline region and elemental oxygen is eliminated. This action can generally be evaluated as positive in aquatic systems, since it counteracts the oxygen deficiency due to the processes of degradation that consume oxygen. The advantage over the elimination of biological phosphate is the reliable elimination of phosphate. The advantage over other chemical processes of phosphate removal is the high efficiency, ie the greater reduction in phosphate concentration with a relatively low use of alkaline earth metal peroxide used according to the invention. The process of the invention can prevent the development of algae in bulk and thus avoid the problems associated with aqueous bodies. The alkaline earth metal peroxide, used in equimolar quantities, can remove the phosphate from the water. In addition, the product of precipitation is suitable as raw material fertilizer material and thus is capable of being recycled.

After the use of the process of the invention, it is not necessary to remove any material precipitated from the waters or soils, sediments and / or silts, this can remain in the water or in the sediment. The precipitated material consists essentially of mineralized substances to which the substances that damage the quality of the water are also bound by absorption or can also be incorporated into the solid. The process hereof is therefore used advantageously, in particular in what are known as passive water treatment systems. The alkaline earth metal peroxides have previously been used, inter alia, as additives in bread, toothpaste, in the cosmetics industry and as oxygen donors in compost. The alkaline earth metal peroxides are obtained from solutions of alkaline earth metal hydroxide and H2O2 in a specific process. It is known that the simple mixing of hydroxide and H2O2 solutions does not lead to alkaline earth metal peroxides, but only to the decomposition of the H2O2 used. When this process is used to clean wastewater, there is the additional advantage that, depending on the properties of the wastewater, it can be cleaned in a short time in a process of a single stage relatively simple. This implies a comparatively lower outlay on equipment and thus is less expensive. It has been found that the use of alkaline earth metal peroxides of the invention to treat aqueous body sediments, silts and soils remove the phosphates as poorly soluble compounds and permanently bind them, so that the remobilization and leaching of the phosphate on contact with water is effectively suppressed. The observations to date imply that, without verifying this, the phosphate is precipitated and immobilized in mineral form as hydroxylapatite, by the process. It has also been found that the treatment of waters or soils, sediments and / or slimes of the invention, due to the precipitation of the phosphates, also reduces the content of other contaminants, which damage the water quality, such as metal compounds heavy and organic compounds. It was assumed that a synergism occurs which results from the oxidative action of the peroxides used according to the invention, the increase in pH and the associated formation of poorly soluble alkali metal species.

For the purposes of the present invention, waters, means all waters, for example waters in ponds, lakes, rivers, saltwater and freshwater aquariums, centers for raising fish and other marine animals, water from treatment plants wastewater and other water treatment plants, etc., and any wastewater including industrial wastewater, wastewater may also include soils, sediments and / or silt and sedimented and floating matter. Soils for the purposes of this invention mean both [lacuna]. For the purposes of the present invention sediments means solids present in waters, for example in ponds, lakes and rivers. The silt can originate, for example, from wastewater treatment plants, sewage filters, etc. Suitable alkaline earth metal peroxides are, for example, the peroxides of magnesium, calcium, barium, strontium and their mixtures, with calcium and magnesium or their mixtures being preferably used. Particular preference is given to calcium peroxides, with calcium being capable of being replaced by magnesium peroxide, strontium peroxide or barium peroxide, in amounts of 0.02% by weight to 50% by weight, preferably up to 30% by weight. % by weight, based on Ca02. In Commercial products, the alkaline earth metal peroxide is present as a mixture with the corresponding carbonate and hydroxide. Particularly good results have been obtained when the alkaline earth metal peroxides are used in a mixture with carbonate-alkali metal peroxide hydrates. A microbicidal action of alkali metal carbonate-peroxide hydrates is known when used in water. Alkali metal carbonate-peroxide hydrates are adducts of alkali metal carbonates and H202, e2C03.xH202, for example 2Me2C0 .3H202. They are also called alkali metal percarbonate and are commercially available. From the point of view of economic and ecological aspects, carbonate-sodium peroxide hydrate has proved to be particularly suitable. The alkaline earth metal peroxides and the alkali metal carbonate-peroxide hydrates are preferably used in ratios of 1: 1 to 1: 0.03. The precipitation of the phosphate can be increased if apatite crystals or phosphate compounds moderately soluble in water are added to the system to be treated.

To carry out the process of the invention, the substances used, ie the alkaline earth metal peroxides and, if appropriate, the carbonate-alkali metal peroxide hydrates and other optional constituents are added in an amount of 30 to 300 g / l. m2 of water. In the treatment of sediment, silt or soil, due to the usually greater amount of oxidizable material, the addition of the substances used according to the invention can be several times the amount to be added to the waters. In addition, using the novel process, it is possible to decrease the alkali metal content and the content of interfering anions, for example POa3", N? 2 ~, S? 32 ~, S2 ~. When used to treat industrial wastewater, in some cases the official limit values currently applicable (ordinary or indirect introduction), which makes possible the direct introduction of the waste water into the receiving aqueous bodies The used peroxides of the invention and other possibly used components can be added to the systems to be treated either as individual substances or in a mixture with other substances such as solids, solutions or aqueous suspensions. used are especially silicates, such as layered silicates or structured silicates, preferably selected from the group consisting of zeolites and bentonites. For practical reasons, it is particularly convenient to compact the materials present in solid form and use them for example as granules, pearls or tablets. In the elimination of water phosphate, it has proven advantageous to pass the water through an apparatus comprising the components of the invention, possibly applied to support materials. Passing the water on a fixed bed comprising the components of the invention used is also possible, in which case a contact time must be ensured so that the reaction between the phosphate and the peroxide can take place. Depending on the quality of the water and the quality of the sediment, such as carbonate content, pH etc., it may be appropriate to add other compounds that increase water quality or sediment quality. Examples of such compounds that may be mentioned are Ca (OH) 2, CaO, CaCO3, CaCl2, Ca (N03) 2, CaSO ", CaSi04, CaF2, Cal2, CaBr2, Ca3 (P0) 2, Ca4H (P04) 2 , Ca2P20 ,, CaHP0, Ca (P03) 3, Ca (H2P04) 2 and the calcium apatites and mixtures of the above. Depending on the --------you---?----?------------------ properties of the untreated water, it may be necessary to treat the water to increase the pH using alkali metal salts or alkaline earth metal salts, in particular oxides, hydroxides, carbonates or acid carbonates. In a preferred embodiment, the compounds of the invention used will be present in combination with a mixture of CaC03, CaCl- and / or Ca (N0) 2 and possibly magnesium salts, together with NaHCO 3 and possibly KHCO 3 with CaCO 3 and CaCl 2 and / or Ca (N03) 2 and possibly magnesium salts being present in a quantitative ratio of 0.01: 1 to 2: 1 and CaCl2 and / or Ca (N03) 2, and possibly magnesium salts, and NaHCO3 and possibly KHC03 being present in a quantitative ratio from 1: 3 to 2: 1. Tale mixture and its suitability for treating water and sediments is described in European patent application 737 169. The presence of salts, for example of iron and aluminum, and of oxides, hydroxides, acid carbonates, carbonates, sulfates, nitrates, chlorine and Fluorine can promote the effectiveness of the process: especially dosing metal ions and aluminum and fluorine, for example, in the form of NaF, KF or MgF2, or other ions having a small ionic radius, these compounds are used in such an amount that the Water quality is not damaged.

The process of the invention can be used to treat solids, aqueous sediments, silt and water / wastewater in systems containing open and closed water, bodies of water such as salt water, fresh water, for example in dams, artificial or natural lakes , waters for bath or waters of fishery, ponds and ornamental aquariums. In addition, in wastewater, for example, waste treatment plants, wastewater treatment plants, recycling plants, cooling water plants and heat exchange plants, wastewater from wastewater treatment plants chemical products, or in the treatment of water resulting from decomposition and condensation processes (for example, water leached from landfills or condensate from thermal water use plants) or by leaching processes (for example, water seeping through of contaminated soils, sediments or silt from aqueous bodies). The process of the invention can be carried out by direct dosing of the solid components by devices or manual aids or techniques such as dosing systems. The material can be dosed directly in the water to be treated or by the water to be treated by passing it through containers comprising the material in solid form, for example filter cartridges, fixed bed or fluidized bed reactors. Thus, experiments with highly contaminated wastewater from plastics recycling operations have found that, after the separation of the products from precipitation, the quality of the process water has improved to a great extent, so that in some cases the introduction of the treated water in the water receiving body was possible according to the criteria of direct or indirect ordering introduction. In additional applications, the components of the invention used are incorporated into soils, sludges or sediments of aqueous bodies by positive mixers, rotating hoses or other mechanical mixers. The precipitated phosphates can be precipitated, provided that their contaminating content allows this, be used as raw materials, for example fertilizers, aids for the formation of compost or in farming and agriculture. The use of the invention of alkaline earth metal peroxides, in addition to increasing the enzymatic activity of the present organisms, increases their microbiological activity in general, which leads to an accelerated and increased mineralization process, which can be observed via a decrease in the loss or ignition of the mineralized substrate.

DESCRIPTION OF THE PREFERRED MODALITIES OF THE INVENTION Examples Comparison of the stability of CaQ2 and a mixture of Ca (OH) 2 and H2Q2 1. 500 ml of distilled water was placed in 1 glass beaker of 11 and 5 g of IXPER 75C (Ca02, commercial product of Solvay Interox , Hanover). Immediately after mixing, the first sample was filtered via a black belt filter and dried in a drying cabinet overnight at 70 ° C. In the dry residue, using KMn04 (0.02 mol / ml) the content of Ca02 and active oxygen (value of 0) (determination in duplicate). The results are shown in the following table: ----------------- 2. 5 g of a 50 wt% sample of Ca (OH) 2 and 50 wt% of H02 in 500 ml of water were placed. Even after 1 day H202 could not be detected by analysis.

Effect of CaQ2 on waters and sediments The prey sediment including the supernatant water was first released from oxygen by treatment with argon gas and then IXPER 75c (Experiment 1) and IXPER 60C (Experiment 2) were added [quality grades of Ca02 commercial, obtainable from Solvay Interox, Hanover] in an amount of 177 g / m3. l Microbial activity and loss with ignition were determined as an index of organic content. The experimental results and the results of the control experiments were reproduced in the diagram of Figure 1. It is clear that the samples of the treated invention have a significantly higher esterase activity. The loss after ignition, which is an index of the content of organic matter in the sample was also significantly lower.

Phosphate removal Water having a phosphate content of 320 μg / ml was treated with different amounts of CaÜ2 (IXPER 75C). In each case the phosphate concentration was determined after the treatment. In Figure 2 the experimental results are reproduced. They show the significant decrease in phosphate content.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. ------------------- t-É-É-i

Claims (14)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A process for treating waters, such as stagnant water and streams and wastewater, soils, sediments and / or silt, characterized in that the waters or sediments are treated with alkaline earth metal peroxides.

2. The process according to claim 1, characterized in that the alkaline earth metal peroxides used are the calcium, magnesium peroxides or their mixtures.

3. The process according to claim 1 or 2, characterized in that the peroxides are used in combination with alkaline earth metal carbonates.

4. The process according to any of claims 1 to 3, characterized in that carbonate hydrates of an alkali metal peroxide, in particular Na2C03, are additionally used. xH202, preferably 2Na2C03.3H202, or a mixture of Na2C03 and

5. The process according to any of claims 1 to 4, characterized in that the alkali metal peroxides are used in combination with a mixture of CaC03, CaCl2 and / or Ca (N03) 2 and possibly magnesium salts, together with NaHCO3 and possibly KHC0, with CaC03 and CaCl2 and / or Ca (N03 > 2 and possibly magnesium salts being present in a quantitative ratio of 0.01: 1 to 2: 1 and CaCl2 and / or Ca (N03) 2 and possibly magnesium salts and NaHC03 and possibly KHC03, being present in a quantitative ratio of 1: 3 to 2: 1.

6. The process according to any of claims 1 to 5, characterized in that silicates, such as layered silicates or structured silicates, are also used. preferably selected from the group consisting of zeolites and bentonites

7. The process according to any of claims 1 to 6, characterized in that iron ions or aluminum ions, fluorine ions or other ions are additionally added. other ions that have a small ionic radius.

8. The process according to any of claims 1 to 7, characterized in that the components are added to the water to be treated -__ ¡--É-_1 --__ directly, in solid form or as a suspension or aqueous solution, by hand or via suitable dosing systems.

9. The process according to any of claims 1 to 8, characterized in that the components are present in solid form and the water to be treated flows therethrough.

10. The process according to any of claims 1 to 9, characterized in that the active components are incorporated in soils, silts or saltwater sediments by positive mixers, rotating hoses or other mechanical mixers.

11. The process according to any of claims 1 to 10, characterized in that it serves to remove phosphate ions and heavy metals from water and sediments, in which they are precipitated as poorly soluble components.

12. The process according to claim 11, characterized in that the precipitated phosphates are used as fertilizers, aids for compost or in tillage and agriculture.

13. The process according to any of claims 1 to 10, characterized in that it serves for the oxidation of the oxidizing constituents present in soils, sediments and / or slimes.

14. The process according to any of claims 1 to 10, characterized in that it serves for the oxidation of the oxidizable constituents present dissolved and / or suspended in the waters.