RU2110484C1 - Method of treating waste waters - Google Patents

Abstract

FIELD: waste water treatment. SUBSTANCE: invention relates to removing surfactants, petroleum derivatives, dyestuffs, fats, and heavy metals from industrial waste waters and to treating domestic and livestock-farm sewage. Method consists in consecutively performed filtration of waste water at acidic pH through carbonate mineral bed, first coagulation, filtration in acidic conditions through dust coal combustion product, second coagulation, filtration in acidic conditions through compacted iron material charge, third coagulation, filtration in alkaline conditions through aluminum chip charge, fourth coagulation, filtration in acidic conditions through aluminum chip bed, fifth coagulation, and filtration through crushed silicate lump bed. Method is distinguished by using sludge from corresponding coagulation and first coagulant for the first, second, and third coagulation procedures; fourth coagulation sludge and second coagulant for the fourth coagulation procedure; and, for the fifth coagulation procedure, fifth coagulation sludge and 1:1 mixture of sodium hydroxide in amount 0.1 to 0.5 g per 1 l of waste water and lime water in amount of 1 to 5 g of calcium oxide per 1 l of waste water. The first coagulant employs aluminum chip charge dissolved in alkaline filtrate medium, and the second one employs the same dissolved in acidic filtrate medium. Coagulation procedures are conducted under opposite acidic-alkaline characteristics of filtrate and coagulant. EFFECT: enhanced process efficiency. 1 dwg, 3 tbl

Description

 The invention relates to the treatment of wastewater from surfactants, petroleum products, dyes, fats, as well as to the treatment of domestic wastewater and wastewater from livestock farms.

 Known treatment schemes for industrial and urban wastewater with a view to applying them for industrial water supply needs, including biological treatment, the use of coagulants, flocculants, ozone and other oxidizing agents, biosorption, ultrafiltration, adsorption of activated carbon (Koganovsky A.M., Tkachuk T.M. Analysis of existing technological schemes for the purification of biologically treated urban and industrial wastewater for use in industrial water supply. Chemistry and water treatment technology. 1991, v. 14, No. 6).

 A disadvantage of the known schemes is the combination of a large number of specific physical and chemical cleaning methods that are difficult to implement, which leads to the bulkiness of the technological scheme and the complexity of its hardware design.

 The closest to the invention in terms of features is a method of treating wastewater from heavy metal ions, including sequential filtering through a layer of iron powder at pH 4 - 5, a layer of crushed silicate block and a layer of aluminum shavings at pH 9 - 10, after which the water is treated with either lime water in an amount of 0.5-1.5 g of calcium oxide per 1 liter of wastewater at pH 9-14, or at pH 6-7, chlorine lime, calcium chloride, aluminum sulfate and alumina are introduced in series, g / l, 1 - 2, 3 - 6, 1 - 2 and 5 - 10, respectively (US Pat. ent of the USSR N 1838249, class C 02 F 1/62).

 The disadvantage of this method is its specificity and the inability to treat wastewater containing a complex of pollutants.

 The objective of the invention is solved by a method in which wastewater is filtered in an acidic medium through a layer of carbonate rocks, the first coagulation is carried out, filtered in an acidic medium through the combustion product of pulverized coal, a second coagulation is carried out, filtered in an acidic medium through a charge of compact iron material, a third coagulation, filtered in an alkaline medium through a load of aluminum shavings, conduct the fourth coagulation, then filtered water in an acidic environment through a layer of aluminum shavings, after which the fifth coag ligation and filtered through a layer of crushed silicate block, while for the first, second, third coagulation use the slurry of the corresponding coagulation and the first coagulant, for the fourth coagulation - the slurry of the fourth coagulation and the second coagulant, for the fifth coagulation use the slurry of the fifth coagulation and the mixture in the ratio 1: 1 caustic soda in an amount of 0.1-0.5 g per 1 liter of wastewater and lime water in an amount of 1 - 5 g of calcium oxide per 1 liter of wastewater; as a first coagulant, a load of aluminum chips dissolved in an alkaline medium of a filtrate is used; as a second coagulant, a load of aluminum chips dissolved in an acidic medium of a filtrate is used, while the coagulation processes are carried out with opposite acid-base indicators of the filtrate and coagulant.

 The proposed method differs from the prototype in the following features: preliminary filtration of water in an acidic medium through a layer of carbonate rocks; the first coagulation; filtering in an acidic medium through the product of the combustion of pulverized coal with the second coagulation; carrying out the third coagulation after filtration in an acidic medium through loading from an iron compact material; the fourth coagulation after filtration in an alkaline medium through a layer of aluminum chips; the fifth coagulation after filtration in an acidic medium through a layer of aluminum chips; use for the first, second, third coagulation of sludge appropriate coagulation and the first coagulant; using for the fourth coagulation sludge of the fourth coagulation and the second coagulant; using the fifth coagulation sludge for the fifth coagulation and the mixture in a 1: 1 ratio of caustic soda in an amount of 0.1-0.5 g per 1 liter of wastewater and lime water in an amount of 1-5 g calcium oxide per 1 liter of wastewater; using, as a first coagulant, a filtrate of loading from aluminum chips dissolved in an alkaline medium as a second coagulant - of a filtrate of loading of aluminum chips dissolved in acidic medium.

 The combination of all the essential features characterizing the proposed method allows to achieve a technical result, which consists in reducing the content of surfactants, oil products, dyes, fats, organic and mineral components of domestic wastewater, wastewater of livestock farms to values below the maximum permissible concentrations.

 The drawing shows a diagram of the installation for wastewater treatment.

 The installation includes series-connected reactor 1, coagulator 2, reactor 3, coagulator 4, reactor 5, coagulator 6, reactor 7, coagulator 8, reactor 9, coagulator 10, filter 11 loaded with a silicate block (granule size 15 - 20 mm) and installed with the possibility of periodic shaking.

 The reactor 1 is loaded with carbonate rocks, for example, chalk crumb with granule sizes of 5 - 20 mm.

 The reactor 3 is loaded with the product of the combustion of pulverized coal (for example, ashes of a thermal power station), the reactor 5 with an iron compact material (for example, iron powder placed in metal baskets), the reactors 7 and 9 are loaded with aluminum shavings.

 Reactors 1, 3, 5, 7 and 9 are connected to a metering tank 12 for dosing sulfuric acid and a metering tank 13 for dosing a caustic solution. Solutions of sulfuric acid and caustic are used to achieve the required pH values in the wastewater treatment process.

 In addition, the coagulator 10 is connected to the metering tank 13 and to the metering tank 14 with a solution of lime water.

The unit is equipped with pumps, for example, type VKS-1/16, with a capacity of 3.6 m ³ / h.

 Reactors 1, 3, 5, 7, and 9 are constantly sparging fresh air.

 Example 1. Wastewater containing a surfactant is pumped at a rate of 0.5 l / s for filtration into a reactor 1, in which pH 4-5 is maintained with sulfuric acid from a metering tank 12; After passing through a layer of chalk crumb, the filtrate enters coagulator 2 for the first coagulation. For the first coagulation, the slurry of the first coagulation and the first coagulator are used. Sludge in an amount of 10 - 20% of the sediment volume is taken from the lower part of the coagulator 2 and sent by a pump to the upper part of the coagulator 2. At the same time, the first coagulant enters the coagulator 2, which is loaded with a filtrate dissolved in an alkaline medium (pH 8-14) aluminum shavings; the first coagulant is selected from the middle of reactor 7. The solution used as the first coagulant contains sodium aluminate (a product of dissolution of aluminum chips in an alkaline environment) and a small amount of water polluting components, since reactor 7 is located at the end of the process.

 The first coagulant enters coagulator 2 until it reaches a pH value of 6 - 8.

 Next, the filtrate enters the reactor 3 with the product of the combustion of pulverized coal (ash TPP); in the reactor 4, a pH value of 0-5 is maintained (with a solution of sulfuric acid from the metering tank 12); then the filtrate enters the coagulator 4 for the second coagulation. For this, the second coagulation sludge and the first coagulant are used. Sludge in an amount of 10 - 20% of the sediment volume is taken from the lower part of the coagulator 4 and sent to its upper part. At the same time, the first coagulant is fed into coagulator 4 until pH 6 - 8 is reached in coagulator 4.

 Then the filtrate enters the reactor 5 with iron powder; in reactor 5, a pH of 0-4 is maintained; Further, the filtrate enters the coagulator 6 for the third coagulation with the sludge of the third coagulation and the first coagulant. Sludge in an amount of 10 - 20% of the sediment volume is taken from the lower part of the coagulator 6 and sent to its upper part. At the same time, the first coagulant is fed into coagulator 6 until the pH value of 6 - 8 is reached in coagulator 6.

 In the next stage, water is filtered in a reactor 7 at pH 8-14 through a layer of aluminum shavings, then part of the filtrate is used as the first coagulant and sent to coagulators 2, 4 and 6, and the rest of the filtrate enters coagulator 8, where at pH 5 - 8 carry out the fourth coagulation with the sludge of the fourth coagulation and the second coagulant. The sludge of the fourth coagulation in the amount of 10 - 20% of the sediment volume is taken from the lower part of the coagulator 8 and sent to its upper part. At the same time, a second coagulant is supplied to coagulator 8.

 As a second coagulator, a loading of aluminum chips dissolved in an acidic medium (pH 0-4) of a filtrate is used; the second coagulant is selected from the middle part of reactor 9. The solution used as the second coagulant contains aluminum sulfate (a product of dissolution of aluminum chips in an acidic environment) and a small amount of water polluting components.

 Then the water is sent to the reactor 9 for filtration at pH 0-4 through a layer of aluminum chips, after which part of the filtrate is used as a second coagulant and sent to coagulator 8, and the rest of the filtrate enters coagulator 10, where at a pH value of 5-5, 5 carry out the fifth coagulation. The fifth coagulation is carried out by the sludge of the fifth coagulation (sludge in an amount of 10 - 20% of the sediment volume is taken from the bottom of the coagulator 10) and a mixture in a ratio of 1: 1 caustic soda in an amount of, for example, 0.4 g per 1 liter of wastewater (fed from a metering tank 13) and lime water in an amount of 3 g of calcium oxide per 1 liter of wastewater (lime water is supplied from the metering tank 14).

 In the last stage, the purified water is passed through a reactor 11 filled with crushed silicate block.

 When cleaning the first portions of water, coagulation is carried out only by the first and second coagulants.

 Upon receipt of new portions of purified water, it is only necessary to maintain the pH value in reactors 1, 3, 5, 7, and 9 and coagulators 2, 4, 6, 8, and 10 at predetermined intervals.

 In the table. 1 shows the results of analyzes of wastewater treatment with different initial concentrations of surfactants in accordance with the modes of example 1 for a four-week cycle.

 Example 2. Purification of water containing petroleum products, fats, heavy metal ions (artificial mixture) was carried out in a laboratory setting under the conditions of example 1.

 The results of the four-week cleaning cycle are summarized in table. 2.

 Example 3. Under the conditions of example 1, the fecal wastewater is cleaned, in order to precipitate a solid fraction, the wastewater is pre-treated with lime water, the precipitate is filtered off, the filtrate is sent for purification according to example 1.

 The results of the three-week cycle are summarized in table. 3.

Claims (1)

 A method of wastewater treatment, including filtering in an acidic medium through loading from an iron compact material, filtering in an alkaline medium through loading from aluminum chips, conducting a coagulation process and filtering through a layer of crushed silicate block, while the coagulation process is carried out at opposite acid-base indicators of the filtrate and coagulant, characterized in that the water is pre-filtered in an acidic medium through a layer of carbonate rocks, the first coagulation is carried out, filtered in an acidic medium through the product of combustion of pulverized coal, a second coagulation is carried out, after filtration in an acidic medium through loading from an iron compact material, a third coagulation is carried out, after filtration in an alkaline medium through a layer of aluminum shavings, a fourth coagulation is carried out, then water is filtered in an acidic medium through a layer of aluminum shavings, after what is the fifth coagulation carried out, while for the first, second, third coagulations use the slurry of the corresponding coagulation and the first coagulant, for the fourth coagulation - the slurry of the fourth oagulation and a second coagulant, for the fifth coagulation use the fifth coagulation sludge and a mixture in a ratio of 1: 1 caustic soda in an amount of 0.1 - 0.5 g per 1 liter of wastewater and lime water in an amount of 1 - 5 g calcium oxide per 1 liter waste water, while the first coagulant is used, loading from aluminum chips dissolved in the alkaline medium of the filtrate, and the load of aluminum chips dissolved in the acidic medium of the filtrate is used.

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