FI116566B - Metal complex organic coagulant for wastewater purification - Google Patents

Description

116566

Metal complexed organic coagulant for wastewater treatment -Metallkompexerad organicisk coagulant för rening av avloppsvatten

The present invention relates to metal complexed organic coagulants for the treatment of municipal wastewater and to a process for the treatment of municipal wastewater.

GB 1,512,022 describes a flocculating agent for water treatment comprising a concentrated aqueous solution of an inorganic flocculating agent and an organic cationic polymer. The inorganic flocculant is ferric sulfate, ferrosulfate, aluminum chlorohydrate, aluminum sulfate or ferric sulfate, and the organic cationic polymer is, for example, polyvinylpyridine, polyamide, polyamine or polyalkyleneimine. The flocculant is introduced into a stream of an aqueous suspension of solid material to form and precipitate the hydroxide corresponding to an inorganic flocculant. In a concentrated aqueous solution, the amount of inorganic flocculant 15 is equal to or greater than the amount of cationic polymer. Large amounts of inorganic flocculant cause large amounts of slurry (iron or aluminum hydroxide) to be formed, which is undesirable for further processing of the slurry.

··· GB 2 322 128 A describes coagulant for clarifying drinking water: V: 20 t. This coagulant is formed by introducing an inorganic coagulant. i. react with a cationic polymer at elevated temperature, typically,,; at a temperature in the range of 45-65 ° C. The inorganic coagulant is aluminum * «. nisulphate, ferric chloride, aluminum polyhydroxychlorosulphate or ferric sulphate, and i · '..; the cationic polymer is obtained by polymerizing vinyl monomers such as diallyl * · '···' dimethylammonium chloride. The amount of polymer relative to the inorganic coagulant is very small, and the amount of polymer in the final product is also very small, typically 0.5% or 1% of the total weight of the final product. This coagulant is intended solely for the purification of raw water (containing less organic matter such as humic acids and cations and anions) in drinking water treatment plants. 1 2 · '; KR 2000059008 A describes combination removers for colorants and chemical .... oxygen depletion (COD) in coloring wastewater using decolorization and agglomeration. These combination removers consist of a cationic decolorization polymer, a stabilizer, and a coagulant, 2 2 1 1 6 5 6 6 such as Fe (III) and alum. The polymer is made from dicyandiamide, ammonium chloride and formalin. According to this document, the cationic polymer and the inorganic compounds do not react with each other.

GB 2 296 238 A discloses a composition for decolorization of waste water from the textile industry, comprising a ferro salt, a polyamine or a diallyl dialkyl ammonium polymer (polydadmac) and dicyandiamide-formaldehyde ammonium chloride. These three components are added either as a mixture or separately. This composition is said to provide a synergistic effect and remove the final brown color from the waste water.

WO 03/029151 A1 describes a composition for use as a coagulant and flocculating agent in waste water treatment. The described composition consists of an aqueous solution of polyaluminium chloride as the major component, a magnesium or calcium compound, and an organic polymeric flocculant. The organic flocculant is polyamine, poly-diallyl dimethylammonium chloride, polyethyleneimine stearate or polyethyleneimine. The amount of organic flocculant is preferably 20 to 25 parts by weight per 100 parts by weight of aluminum.

US 4,891,422 describes polymer additive compositions of a mixture of inorganic and organic materials for the purification of drinking water, paper mill wastewater or industrial wastewater. The adductic acid * * · 20 nuclide is formed by an inorganic polymer in the reaction of guanidine poly-. '. · With a polymer or an organic mixture of a polymer and a polyamine, a polyquatemated polymer, a polyamide or a polyamine / polyamide polymer. In the compositions shown in Examples': 1: the ratio of polymer (s) to metal (s) is typically very high, i.e. the amount of metal is small compared to the amount of polymer. A preferred; '*'. The 25 metal component appears to be aluminum.

t · »

GB-1 424 702 discloses a coagulant which may consist of a complex of a '': condensation polymer and a polyvalent metal ion. For example, the metal ion may be Fe, Al or Cu, with Cu being particularly preferred. Weight ratio po- '. between the polymer and the metal ion is very broadly defined to be 1:, · ·. 0.0005-0.5, preferably 1: 0.02-0.3. Examples 16 and 21-28 of this publication, which describe a condensation copolymer of diethylenetriamine and formaldehyde or a condensation polymer of aniline and acetaldehyde, employ complexes containing a considerable amount of polymer, wherein the metal ion ratio is greater than about 10: 1. The invention disclosed in this GB publication is specifically developed for the purification of dyed waste solutions 116566 3, i.e., for the removal of dye therefrom, and is characterized in that these cleanable waste solutions contain a non-cationic dye. Such waste solutions are mainly generated in the textile industry.

Most of the documents discussed above relate to the treatment of drinking water and special industrial wastewater such as colored wastewater and paper industry wastewater. In contrast, the present invention focuses on the treatment of urban waste water. Most of the organic load from municipal waste water is organic matter with a specific particle size distribution. The soluble organic material typically has a particle size of less than 0.1 μιη, while the colloidal particles and suspended solids typically have a particle size greater than 0.1 μηη. Urban waste waters also contain significant amounts of dissolved nutrients, especially phosphorus.

It is an object of the present invention to provide a coagulant for municipal waste water treatment, which provides good purification efficiency, is easy to prepare and produces a small amount of metal hydroxide slurry.

A first aspect of the invention relates to a complex coagulant having an inorganic divalent or trivalent metal moiety and an organic polymer moiety, wherein the weight ratio of the organic polymer moiety to the inorganic moiety is in the range of about 7: 1-3: 1, said organic polymer moiety being di ... ". 20 cyanodiamide-formaldehyde ammonium salt polymer.

. . The metal complexed polymeric coagulant of the invention is water soluble, cationic and cationic.

Preferably, said organic polymer moiety to inorganic moiety has a weight ratio of from about 6: 1-4: 1, for example about 5: 1.

• (25) The said organic polymer is a polymer obtained by reaction of dicyandiamide with formaldehyde and an ammonium salt.

A preferred organic polymer is a polymer prepared from formaldehyde, dicyandiamide and ammonium chloride.

; Said divalent or trivalent metal may be divalent or: trivalent iron, trivalent aluminum or divalent copper. The metal is preferably trivalent iron.

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A preferred metal-complexed polymeric coagulant according to the invention is a Fe3 + -complexed dicyandiamide-formaldehyde-ammonium chloride polymer.

The metal complexed polymeric coagulant is preferably in the form of an aqueous solution.

The metal complexed polymeric coagulant of the invention can be prepared by reacting an organic polymer capable of complexing with a divalent or trivalent metal, with a source of a divalent or trivalent metal in an aqueous solution at 0-45 ° C, preferably 10-30 ° C, and more preferably at 15-25 ° C.

The source of the divalent or trivalent metal may be sulphate or chloride of said metal, for example ferric chloride, ferric sulphate, ferrous sulphate, aluminum sulphate (alum), aluminum chloride, hydroxyaluminium chloride, hydroxyaluminium sulphate, cupric sulphate.

The above metal salts may be in solid form or in aqueous solution form. The aqueous solution may be a concentrated solution of the metal salt.

The invention also relates to the use of a metal complexed polymeric coagulant as defined above for the purification of municipal waste water.

Another aspect of the invention relates to a process for purifying municipal wastewater, comprising the step of adding a coagulant which is complex to the municipal wastewater, having an inorganic divalent or trivalent metal moiety and an organic polymer moiety and wherein the organic polymer moiety and inorganic moiety: is in the range of 7: 1-3: 1.

.; Said organic polymer may be selected from the group consisting of: condensation products of alkylamines, polyalkylamines, ammonia or a mixture thereof and polyfunctional aliphatic dihalides or halohydrines, *; 25 - urea-formaldehyde condensation products, melamine-formaldehyde condensation products,] '- Mannich (co) polymers, and polymers based on dicyandiamide, or polymers obtained by reaction of v: dicyandiamide with formaldehyde and possibly ammonium; -; Salt and / or an alkylene polyamine and / or urea.

Said organic polymer may also comprise reaction or condensation products of two or more of the aforementioned polymers or condensation products.

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The organic polymer is preferably a dicyandiamide-formaldehyde-ammonium salt polymer, more preferably a dicyandiamide-formaldehyde-ammonium chloride polymer.

In the metal complexed polymer coagulant, the weight ratio of organic polymer moiety to non-organic moiety is preferably in the range of about 6: 1 to 4: 1, for example about 5: 1. The metal complexed polymer coagulant is as defined above.

The metal complexed polymeric coagulant may be added as an aqueous solution. Preferably, the coagulant is added to the treated municipal wastewater in an amount of 0.2-1.1 mg / NTU (nephelometric turbidity unit) based on the dry matter of the coagulant. More preferred is 0.6-1.0 mg / NTU.

The pH of ordinary municipal waste water is 5-8. The metal complexed polymeric coagulant of the invention is capable of operating at pHs 2 to 9.

The purification process of the invention may also include biological treatment. Thus, in this embodiment, the treatment with a coagulant is a biological treatment of compound-15. The coagulant treatment may be a pretreatment followed by a biological treatment or a post-treatment preceded by a biological treatment. Biological treatment methods are well known in the art.

, Said biological treatment may be an aerobic or anaerobic process. In a preferred aerobic biological treatment, the effluent is treated in a moving bed-1 biofilm reactor (MBBR).

The process of the present invention and the metal complexed polymeric coagulant of the present invention are highly effective in removing the colony. organic matter (predominantly suspended solids and colloids) in phosphorus.

In the production of the metal complexed polymeric coagulant of the invention, the preparation process is very simple and no heating is required. In addition, there is a need; ·. Usual chemicals are inexpensive.

'' Since the hydrolysis of the metal complexed polymeric coagulant of the invention has been found to take place at a pH above 7, metal hydroxides such as iron; -: 30 The formation of hydroxides (ie the amount of sludge) during municipal waste water treatment is expected to be low.

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An advantage of the metal-complexed polymeric coagulant according to the invention and of the process is that, due to the polymer-metal-complexed polymeric coagulant, the amount of metal hydroxide slurry is very small and the precipitated slurry has a good dewatering effect, facilitating further sludge treatment. After incineration of the sludge, the ash content is low. The slurry is also suitable for composting or as a land filler. The flo-kits are also tightly packed in the slurry, whereby the volume of the slurry is small.

The invention will now be described, by way of example and with reference to the accompanying drawing, in which Figure 1 shows the results of the deposition experiments obtained using the Fe3 + complexed DCD polymer coagulant and the reference DCD polymer coagulant of the invention.

Example 1 An aqueous solution of DCD polymer (prepared from formaldehyde, dicyandiamide and ammonium chloride) was used as starting material.

The Fe3 + complexed DCD polymer coagulant is prepared by gradually adding powdered FeCl3-6H2O (1 g) to the DCD polymer solution (2 g) and stirring the solution for 30 minutes while the iron dissolves at room temperature. Part of the resulting coagulant! (0.2 g) dissolved in 30 ml of distilled water was titrated with concentrated NaHCO 3; 20 solution and the pH was monitored. The precipitate formed at pH -6.8-7.0. Iron hydroxide precipitates from pure Fe (III) solution at pH <4. Trivalent Iron and DCD! ? The formation of the complex between the polymers prevents precipitation of iron hydroxides at a pH lower than -7. Compared to DCD polymer, the Fe3 + complexed DCD polymer of the invention has a higher cationic charge density in the molecule.

. 'Example 2; Settlement tests were carried out on urban waste water. Four different samples of the same ice. Teva water was treated with different doses of the Fe3 + complexed DCD polymer (DCD + Fe) prepared in Example 1. Turbidity, total phosphorus (tot P) and chemical oxygen: 30 consumption (COD) were measured. The results of the descent experiments are shown in Table 1 below.

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table 1

Test Koagu- Composition Poly- Metal T pH Turbidity Tot P COD

no lantti sea

Poly-Metal μ | / 1 mg / I mg / 1 ° C (NTU) mg / 1 mg / L

sea weight-by-weight% __% ________ Output "ΠΓ 7.37 137 6.05 342

4 DCD + Fe 33 ^ 6 6 ^ 8 W 13.4 2J 7J3 0.746 89T

2 DCD + Fe 33 ~ 6 6 ^ 8 6Ö ~ 20.2 4J 16 ~ 7.09 3/72 0.452 83X

Ϊ DCD + Fe 33 ^ 6 6/8 8Ö 26 ^ 9 5 ^ 4 15 6 ^ 96 3 ^ 61 0.192 78+ "3 DCD + Fe 33 ^ 6 M 120" 40.3 SÖ · W 6.97 +85 0.084 81

The above results show that the highest turbidity was obtained with the highest dose (120 μΐ) of coagulant, but also lower doses produced excellent results, for example, at turbidity and total phosphorus (tot P).

Example 3

Settlement tests were carried out on urban waste water. In the first experiment, wastewater -,;. the sample was treated with pure DCD polymer and in another experiment the effluent sample was treated with the Fe3 + complexed DCD polymer prepared in Example 1. '; By complexation it is possible to achieve a much higher charge density in the molecule * '* ·. The results of the sedimentation tests (turbidity vs. dose) are shown in Figure 1.

* '· *; Experimental results show that turbidity is significantly reduced when wastewater is treated with kek- '; Fe3 + complexed DCD polymer of the invention. This is due to the higher cationic density in the molecule. Comparative DCD polymer was much less volatile.

Example 4, '' Municipal waste water was taken from the water entering the pilot plant. The Fe3 + complexed DCD polymer (DCD + Fe) prepared in Example 1 was tested at different doses; for.

The experiments were performed using a laboratory scale flotation tester.

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From the clarified water, suspended solids (SS) were analyzed using a GF / C filter, turbidity, chemical oxygen demand (COD) and filtered COD (FCOD) (filtered with a GF / C filter with a nominal pore size of 1.2 μm). The slurry samples were analyzed for dry solids (DC) and volatile solids (VS).

5 The results of the analysis of the experiments are shown in Table 2 below.

Table 2 Waste water _DCD + Fe_ _io m 30 m so m SS (mg / L) 113 40 3 3

Turbidity (NTU) 62.5 23.1 1.16 0.29 COD (mg / L) 308 197 136 130 FCOD (mg / L) 157 140 132 129

Slurry DS (mg) 83 143 156

Slurry VS (mg) 64 110 119 pH_7 ^ 07_

The above test results show that the removal efficiencies were good in all cases.

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Claims (14)

116566 1. A coagulant in the form of a complex omfattande en ororganic divalent eller triva-15 tape of metals and organic polymers, in the case of organic compounds of organic origin, in the colors 7: 1-3: 1, in the colors of the organic polymer. dicyandiamid-formaldehyde-ammonium salt of the-polymer. A complex coagulant having an inorganic divalent or trivalent metal moiety and an organic polymer moiety having an organic polymer moiety to an inorganic moiety of from 7: 1 to 3: 1, said organic polymer moiety being dicyandiamide-formaldehyde ammonium salt. polymer. 2. Coagulant enligt patent crav 1, dicyandia-dicyandia-: midformaldehyde ammonium chloride polymer. . 3. Coagulant enligt patent crav 1 eller 2, divalenta eller trivalenta metal; * I have a divalent eller trivalent coarse, trivalent Aluminum eller divalent hood. » The coagulant of claim 1, wherein the organic polymer is a dicyandiamide-formaldehyde-ammonium chloride polymer. The coagulant of claim 1 or 2, wherein the divalent or trivalent metal is divalent or trivalent iron, trivalent aluminum, or divalent copper. 4. Coagulant enligt face av patent kraven 1-3, divalenta eller trivalenta metal, företredesvis trivalent. *: 5. The coagulant enligt face av patent craven 1-4, the color of the organic polymeric delenium account of the organic organol 6: 1-4: 1. The coagulant according to any one of claims 1 to 3, wherein the divalent or trivalent metal is iron, preferably trivalent iron. Coagulant according to any one of claims 1 to 4, wherein the weight ratio of the organic polymer component to the inorganic component is in the range of 6: 1 to 4: 1. 6. Coagulant enligt face av patent craven 1-5, color coagulanten business form av en; · 'Wadding. * t · ',': 7. Coagulant enligt face av patent kraven 1-6, color coagulanten erhällits genom »tomsättning av en organicisk polymer, som kapappat image in complex med en 116566 divalent eller trivalent metal, med en cäl för en divalent eller trivalent metal at a temperature of 0-45 ° C, företrädesvis 10-30 ° C. The coagulant of any one of claims 1 to 5, wherein the coagulant is in the form of an aqueous solution. A coagulant according to any one of claims 1 to 6, wherein the coagulant is obtained by reacting an organic polymer capable of forming a complex with a divalent or trivalent metal with a divalent or. with a trivalent metal source in aqueous solution at 0-45 ° C, '.,; preferably at 10-30 ° C. i · i · 8. Användning av en coagulant enligt nägot av patentkraven 1-7 för rening av kommunala avloppsvatten. 5 9. Förfarande för rening av Communal avloppsvatten, flashing förfarande innefattar pro dint me d an d communal avloppsvattnet tillet en coagulant i form av e complex omfattande en organic trivalent eller trivalent metals and organic polymer dyes, organic colors inom omrädet 7: 1-3: 1. 10. Förfarande enligt patent krav 9, varied in coagulant den organiska polymerde lens viktförhällande to den oorganiska delen omomomod om 6: 1-4: 1. Use of a coagulant according to any one of claims 1 to 7 for the purification of municipal waste water. •>; 9. A process for the treatment of municipal waste water comprising the step of: adding a coagulant in the municipal waste water in the form of a complex comprising: '*': an inorganic divalent or trivalent metal moiety and an organic poly. Λ the polymer moiety and wherein the weight ratio of the organic polymer moiety to the inorganic moiety is in the range of 7: 1-3: 1. The process of claim 9, wherein the weight ratio of the organic polymer moiety to the inorganic moiety in the coagulant is in the range of 6: 1 to 4: 1. 1 1 6566 ίο 11. Förfarande enligt patent application 9 eller 10, di-cyandiamide-formaldehyde-ammonium salt polymer, di-cyandiamide-formaldehyde-ammonium chloride polymer. 12 12. Förfarande enligt patent application 10 eller 11, shade coagulanten tillsätts som en vat tenlösning i det kommula avloppsvattnet som scall behandlas i en per liter av 0.2-1.1 mg / NTU, 0.6-1.0 mg / NTU raksnad main bas av av torrsub-stanshalten i coagulanten. The process according to claim 9 or 10, wherein the organic polymer is a dicyandiamide-formaldehyde-ammonium salt polymer, preferably a dicyandiamide-formaldehyde-ammonium chloride polymer. The method according to claim 10 or 11, wherein the coagulant is added to the treated municipal waste water as an aqueous solution per liter in an amount of 0.2 to 1.1 mg / NTU, preferably 0.6 to 1.0 mg / NTU, based on the dry matter content of the coagulant. 13. Förfarande enligt face av patent kraven 10-12, shade behandligen med koagu-20 lanten combin med en biological behandling. The method of any one of claims 10 to 12, wherein the coagulant treatment is combined with a biological treatment. The method of claim 13, wherein the coagulant treatment is a pretreatment followed by a biological treatment, or a post-treatment preceded by a biological treatment. 14. Förfarande enligt patent krav 13, the shade behandlingen med coagulanten en för-behandlig efterföldd av en biologisk behandling eller en efterbehandling som före-gäs av en biologisk behandling.