RU2285669C1 - Method of purification of the underground water from the iron, manganese and the hardness salts - Google Patents

Abstract

FIELD: purification of the underground water from iron, manganese and hardness salts.

SUBSTANCE: the invention is pertaining to the field of a purification of the underground waters from iron, manganese, hydrogen sulfide, carbon dioxide and the hardness salts of for the potable water purposes. The method provides for oxidation of the compounds of iron and manganese with simultaneous degasification of hydrogen sulfide and carbon dioxide on the non-flooded granular-fibrous polymeric loading with the bed depth of 1.0-1.5 m. The granules diameter is equal to 10-30 mm, the diameter of the fiber threads is equal to 1-2 mm at the specific consumption of the counter currently fed air of 4 -10 m³/h per 1 m³ of the initial water by a return flow of an incoming water and the specific hydraulic loading with respect to the treated water of 6-8 m/h³ per 1 m² of the layer surface, the additional oxidation of the iron and manganese compounds, deironing and demanganesing are conducted on the heterogeneous polymeric floating, granular loading with the granules diameter of 0.7-2.5 mm at the loading layer depth of 1.4-1.6 m and the speed of the filtration of 4.5-8 m/h at realization of the purification process in the self-flowing mode in one reactor-filter. The softening with application of the caustic soda in amount of 2.5-3.5 mg-equivalent/dm³ is conducted in the fluidized layer of the inert fine-grained contact mass with the diameter of the grains of 0.1-0.2 mm, the fluidized layer thickness of 1.5-1,7 m and the specific hydraulic loading with respect to the water - 50-60 m³/h per 1 m² with the subsequent deep postpurification by filtration through the granular filtering layer of 1.0-1.5 m thick. The grains diameter is equal to 1-2 mm and at the speed of the filtration of 8-12 m/h. The method ensures purification of the underground waters up to the quality of the drinking water at the simultaneous cost reduction of the method realization.

EFFECT: the invention ensures purification of the underground waters up to the quality of the drinking water at the simultaneous cost reduction of the method realization.

4 tbl, 3 ex

Description

The invention relates to the field of purification of groundwater from iron, manganese, hydrogen sulfide, carbon dioxide and hardness salts for drinking purposes.

A known method of purifying water from iron and manganese by oxidizing impurities, their destruction by oxidation with oxygen in the air during aeration of the purified water and its subsequent contact in a filter reactor equipped with a carrier with microorganisms attached to the latter. The filter reactor is flushed with a reverse water flow (see application DE No. 10044696, A1 MPK C 02 F 1/64 with priority 08.09.2000, publ. 21.03.2002).

The disadvantages of this method are the inability to soften water containing hardness salts - calcium and magnesium, the accumulation of residual contaminants and secondary water pollution during washing of the filter reactor support.

A known method of purification of groundwater from iron for drinking water supply by spraying water over the surface of the granular charge, contacting the purified water with a water-air mixture injected in countercurrent with respect to the purified water, air blowing the gases contained in the water while it is saturated with oxygen. The volume of the water-air mixture is two times the volume of water supplied for treatment (see patent RU No. 2181109, IPC C 02 F 1/64 with prior. 01.27.2000, publ. 10.04.2002).

The disadvantage of this method is the inability to soften water, in addition, the volume of the water-air mixture, twice the amount of water supplied for treatment, is insufficient for blowing off aggressive gases - hydrogen sulfide and carbon. The disadvantage of this method is the intensive increase in pressure losses in the load with an iron content of more than 5 mg / l and an increase in the number of required leaching.

There is a method of purifying groundwater from iron during the intake of freshwater sources, which consists in supplying purified water to an oxidizing agent, contacting it with air supplied by a water-air injector, followed by treating the water in cavitation mode and passing it through a pre-treatment unit and then through a fine-purification unit, equipped with microporous cartridges from a material of a spatially globular structure. Cartridge washing is provided (see patent RU No. 41722, IPC C 02 F 1/64, 9/02 with priority June 18, 2004, publ. November 10, 2004)

The disadvantage of this method is the lack of the possibility of water softening and the need to replace cartridges due to the inevitable decrease in their productivity over time and the inability to completely restore the throughput.

There is a method of purification of groundwater from iron, manganese and hardness salts, the closest in purpose and technical essence to the claimed one, which consists in aeration of the source water, during which oxidation of iron and manganese compounds with atmospheric oxygen, oxidation of iron compounds to hydroxide forms, iron removal and demanganization carried out in a pressure filter filled with an inert charge, filtering on a Na-cation exchange filter through an KU-2 ion exchange resin to remove hardness salts and electrodialysis salt-free. Silica sand, quartzite, albitofire, granodiorite, burned rocks, etc. are used as an inert charge at the oxidation stage by filtration. The filter is flushed with a reverse current of water (see patent RU No. 2182890, IPC C 02 F 1/469 sec. 08.12.2000 published on May 27, 2002).

The disadvantage of this method is the lack of effective pre-treatment of groundwater containing both iron, manganese, hydrogen sulfide, carbon dioxide before softening, and the inability to ensure that the standards for drinking water quality are met, the high cost of the method and its complexity, due to the implementation of separate processes: aeration in a pressureless aerator, during which oxidation of iron compounds occurs, filtration in pressure mode through inert loading, filters removal of organic compounds and filtering through KU-2 ion exchange resin in the Na ⁺ form, which do not allow the removal of aggressive gases from the water: hydrogen sulfide and carbon dioxide and it is quite effective to carry out the process of deferrization and demanganization on an inert charge with a low specific grain surface and ineffective for its washing (it requires powerful pump having a specific capacity of at least 15 l / s / m ^2, which entails a high energy consumption, and water consumption per wash), which makes the method ineffective and economical ki unprofitable.

A disadvantage of the known method is the complexity and duration of the regeneration of the Na-cation exchange filter, which requires the preparation of a regeneration solution, loosening the load with clean water for up to 30-40 minutes, saturating the load with a 7% regeneration solution of sodium chloride for 40 minutes, followed by a long washing clean water for 30-40 minutes; the regeneration of Na-cation exchange filters leads to the formation of a large number of brines, the disposal of which is very difficult and expensive.

The technical result of the invention is the ability to purify groundwater containing both iron, manganese, hydrogen sulfide, carbon dioxide and hardness salts to the standards required for the quality of drinking water while reducing the cost of the method.

The technical result is achieved by the fact that in the method of purification of groundwater from iron, manganese and hardness salts, including oxidation of iron and manganese compounds with atmospheric oxygen, additional oxidation of ferrous iron to its hydroxide forms, deferrization and demanganization by filtration on an inert charge, softening, oxidation of ferrous iron and manganese with simultaneous degassing of hydrogen sulfide and carbon dioxide is carried out on an unburied granular-fibrous polymer charge with a layer thickness of 1.0-1.5 m, a diameter of Str 10-30 mm, 1-2 mm diameter fiber strands at a specific flow rate of air supplied to countercurrent 4-10 m ³ / h per m ³ of initial water and the specific hydraulic load of the feed water of 6-8 m ³ / h per m ² of surface layer , the oxidation of iron and manganese compounds, iron removal and demanganization are carried out on an inhomogeneous polymer floating granular load with a granule diameter of 0.7-2.5 mm with a loading layer thickness of 1.4-1.6 m and a filtration rate of 4.5-8 m / h during the process of purification in gravity in one reactor filter, and softening using caustic soda in an amount of 2.5-3.5 mEq / dm ^{3 is} carried out in a suspended layer of an inert fine-grained contact mass with a grain diameter of 0.1-0.2 mm, a thickness of the suspended layer of 1.5-1.7 m and specific a hydraulic load of water of 50-70 m ³ / h per m ² followed by deep post-treatment by filtration through a granular filter layer with a diameter of granules of 1-2 mm, a layer thickness of 1-1.5 m with a filtering speed of 8-12 m / h.

The method of purification of groundwater from iron, manganese and hardness salts is as follows:

Source groundwater with a pH of 6.5-7.5 containing hydrogen sulfide - H ₂ S = 0.7-2.5 mg / dm ³ , carbon dioxide - CO ₂ = 60-120 mg / dm ³ , total iron - Fe _total = 1.5-15 mg / dm ³ , manganese - Mn ⁺² = 0.15-0.5 mg / dm ³ and hardness salts - Ca and Mg - W _total = 8-12 mEq / dm ³ , served in a dispersed stream over a granular-fiber loading of the filter reactor, while simultaneously supplying air with a specific flow rate of 4-10 m ³ / m ^{3 of} source water under loading through dispersants.

In this case, the process of degassing the treated water occurs - removal of hydrogen sulfide and carbon dioxide with the simultaneous oxidation of divalent iron and manganese with atmospheric oxygen on the surface and in the pores of the granular fiber loading with a diameter of synthetic filamentary fibers d _in = 1-2 mm, length l _in = 0, 5-0.8 mm, the diameter of the granules of expanded polystyrene foam (foam) d _p = 10-30 mm and the thickness of the loading layer N _p = 1.0-1.5 m. In this case, the specific air flow is q _air = 4-10 m ³ / h per m ^{3 of} water, and the specific hydraulic load of the source water q _water = 6-8 m ³ / h per m ^{2 the} surface of the layer.

The effective course of the degassing process is facilitated by the uniform distribution of the "blow-off" air supplied under the combined granular-fiber loading and passing through it. The inventive loading parameters with a developed surface also contribute to the efficient course of the oxidation of ferrous iron and manganese by atmospheric oxygen.

With a specific air flow rate of less than 4 m ³ / h per m ^{3 of} water, insufficient oxidation of divalent iron and manganese by atmospheric oxygen occurs, which ultimately does not allow to achieve a technical result.

With a specific air consumption of more than 10 m ³ / h per m ^{3 of} water, air is consumed irrationally, which leads to unreasonably high energy costs without a noticeable improvement in the quality of cleaning.

When the specific hydraulic load on the source water is less than 6 m ³ / h per m ^{2 of} the layer surface, the cost of the cleaning process unreasonably increases.

When the specific hydraulic load on the source water is more than 8 m ³ / h per m ^{2 of} the layer surface, the effect of iron removal and demanganization is reduced, which also does not allow to achieve a technical result.

Water after degassing and oxidation contains: H ₂ S = 0.03-0.06 mg / dm ³ , CO ₂ = 10-30 mg / dm ³ , Fe _total = 4.8-5.6 mg / dm ³ , Mn = 0.05-0.2 mg / dm ³ , W _total = 10-12 mEq / dm ³ .

Data indicating the feasibility of the claimed parameters of the process of degassing hydrogen sulfide and carbon dioxide and the oxidation of ferrous iron and manganese are presented in table No. 1.

With a further downward movement of water, the latter is filtered at a speed of 4.5-8 m / h through the underlying layer of an inhomogeneous polymer floating load with a granule diameter of 0.7 to 2.5 mm and a layer thickness of 1.4-1.8 m, held from surfacing with a grating, where the oxidation of iron and manganese compounds contained in water, deferrization and demanganization of the treated water occurs.

The use of a heterogeneous polymer floating load with a developed specific surface provides an increase in the dirt capacity of the filter layer by 3-4 times in comparison with the known load.

The inventive speed and a decrease in the thickness of the layer help to prevent the breakthrough in the filtrate of compounds of iron and manganese and prevent the growth of pressure losses.

An increase in the recommended rate and a decrease in the thickness of the loading layer lead to a breakthrough in the filtrate of iron and manganese compounds and cause an intensive increase in pressure losses.

A decrease in the recommended speed and an increase in the thickness of the loading layer lead to an unjustified rise in the cost of the process.

Data indicating the feasibility of the claimed parameters of oxidation, deferrization and demanganization are presented in table No. 2.

It is planned to flush the floating load with a downward flow of source water, which eliminates the use of flushing pumps.

The water at the outlet of the filter reactor contains: H ₂ S = 0.01-0.03 mg / dm ³ , CO ₂ = 5-10 mg / dm ³ , Fe _total = 0.3-0.2 mg / dm ³ , Mn = 0.03-0.05 mg / dm ³ , W _total = 8-12 mEq / dm ³ .

Thus, the process of degassing, deferrization and demanganization proceeds in a gravity mode in one filter reactor.

Next, the water purified to the minimum concentrations of hydrogen sulfide, carbon dioxide, iron and manganese is supplied to the softener, carried out in a suspended layer of an inert fine-grained contact mass with a particle diameter of 0.1-0.2 mm, a thickness of the suspended layer of 1.5-1.7 m and the specific hydraulic load on water is 50-60 m ³ / h per m ² , with preliminary water treatment with a 4% NaOH solution with a dose of 2.5-3.5 mEq / dm ³ .

The traditional process of softening in a similar suspended layer of an inert fine-grained contact mass without preliminary degassing, iron removal and demanganization is 30-40% more expensive due to the greater consumption of alkali.

Then softened water is subjected to deep purification by filtration through a layer of granular load with a diameter of 1-2 mm, a layer thickness of 1.0-1.5 m and a filtration rate of 8-12 m / h.

The claimed filtering parameters and filtration rates can eliminate the turbidity in case of its occurrence.

The softening carried out in a suspended layer of an inert fine-grained contact mass with the claimed parameters during pretreatment of water with a 4% NaOH solution with a dose of 2.5-3.5 mEq / dm ³ and the claimed parameters of the granular loading and filtering speed allows to obtain drinking water quality that meets the requirements of SanPiN 2.1.4.1074-01 while reducing the cost of cleaning.

Data indicating the feasibility of the claimed parameters of the process of softening and post-treatment are presented in table No. 3.

The purified and softened water has the following composition: H ₂ S = 0.001-0.035 mg / dm ³ , CO ₂ = 0.03-0.045 mg / dm ³ , Fe _total = 0.08-0.09 mg / dm ³ , Mn = 0.01-0.008 mg / dm ³ , W _total = 5.0-6.5 mEq / dm ³ , which meets the requirements for the quality of drinking water.

Example No. 1.

Source underground water with a pH of 7, containing hydrogen sulfide H ₂ S = 1.6 mg / dm ³ , carbon dioxide CO ₂ = 90 mg / dm ³ , total iron Fe _total = 10 mg / dm ³ , manganese Mn = 0.35 mg / dm ³ and hardness salts - calcium and magnesium F _total. = 11 mEq / dm ^{3 in a} dispersed stream with a specific hydraulic load of feed water of 6.0 m ³ / h per m ^{2 of the} surface of the layer is fed to a granular-fiber loading of the filter reactor, while at the same time feeding air with specific gravity under the load through dispersants flow rate of 4 m ³ / h per m ^{3 of} source water.

On a non-flooded granular-fiber loading and in its pores with a loading layer thickness of 1 m, a diameter of granules of expanded polystyrene foam 10 mm, a diameter of threads 1 mm, hydrogen sulfide and carbon dioxide are removed from the water with simultaneous partial oxidation of divalent iron and manganese with atmospheric oxygen.

Water with a filtration rate of 4.5 m / h is filtered from top to bottom through an underlying heterogeneous floating load of expanded polystyrene granules with a granule diameter of 0.7 mm and a layer thickness of 1.4 m; in this case, additional oxidation, deferrization, and demanganization of water occur.

Purified water from hydrogen sulfide, carbon dioxide, iron and manganese is subjected to treatment with a 4% NaOH solution in an amount of 2.5 mEq / dm ³ and softening in a vortex reactor in a suspended layer of a fine-grained contact mass with a particle diameter of 0.1 mm and a thickness a suspended layer of 1.5 m with a specific hydraulic load of 50 m ³ / h per m ² .

Next, the softened water is subjected to further purification by filtration through a layer of granular loading with a grain diameter of 1.0 mm, a layer thickness of 1.0 m with a filtering speed of 8 m / h.

The purified and softened water has the following composition: H ₂ S = 0.001 mg / dm ³ , CO ₂ = 0.045 mg / dm ³ , Fe _total = 0.08 mg / dm ³ , Mn = 0.01 mg / dm ³ , W _total = 6.5 mEq / dm ³ .

Example No. 2.

The method is carried out analogously to example No. 1 with the following average values of all parameters.

The source water stream is supplied with a specific hydraulic load of the source water of 7.0 m ³ / h per m ^{2 of the} surface of the layer, air with a specific flow rate of 7 m ³ / h per m ^{3 of the} source water is fed under load with a loading layer thickness of 1.25 m , the diameter of the granules of expanded polystyrene foam is 20 mm, the diameter of the filament fibers is 1.5 mm. Water with a filtration rate of 6.5 m / h is filtered from top to bottom through an underlying heterogeneous floating load of expanded polystyrene granules with a granule diameter of 1.6 mm and a layer thickness of 1.5 m; purified from hydrogen sulfide, carbon dioxide, iron and manganese water is subjected to treatment with a 4% NaOH solution in an amount of 3.0 mEq / dm ³ and softening is carried out in a vortex reactor in a suspended layer of fine-grained contact mass with a particle diameter of 0.15 mm and the thickness of the suspended layer of 1.6 m with a specific hydraulic load of 55 m ³ / h per m ² ; tertiary treatment by filtration is carried out through a granular loading layer with a grain diameter of 1.5 mm, a layer thickness of 1.25 m at a speed of 10 m / h.

Purified water has the following composition:

H ₂ S = 0.015 mg / dm ³ , CO ₂ = 0.03 mg / dm ³ , Fe _total = 0.09 mg / dm ³ , Mn = 0.008 mg / dm ³ , W _total = 6.0 mEq / dm ³ .

Example No. 3.

The method is carried out analogously to example No. 1 and at the maximum values of all parameters.

The source water stream is supplied with a specific hydraulic load of the source water of 8.0 m ³ / h per m ^{2 of} the layer surface, air with a specific flow rate of 10 m ³ / h per m ^{3 of the} source water is supplied under loading with a loading layer thickness of 1.5 m, the diameter of the granules of expanded polystyrene foam is 30 mm; the diameter of the filaments of fiber is 2.0 mm. Water with a filtration rate of 8.0 m / h is filtered from top to bottom through an underlying heterogeneous floating load of expanded polystyrene granules with a granule diameter of 2.5 mm and a layer thickness of 1.6 m; purified from hydrogen sulfide, carbon dioxide, iron and manganese water is subjected to treatment with a 4% NaOH solution in an amount of 3.5 mEq / dm ³ and softening is carried out in a vortex reactor in a suspended layer of fine-grained contact mass with a particle diameter of 0.2 mm and the thickness of the suspended layer of 1.7 m with a specific hydraulic load of 60 m ³ / h per m ² ; tertiary treatment by filtration is carried out through a granular loading layer with a grain diameter of 2 mm, a layer thickness of 1.5 m at a speed of 12 m / h.

Purified water has the following composition:

H ₂ S = 0.035 mg / dm ³ , CO ₂ = 0.04 mg / dm ³ , Fe _total = 0.085 mg / dm ³ , Mn = 0.009 mg / dm ³ , W _total = 5.0 mEq / dm ³ .

Data indicating the feasibility of the claimed parameters of the process of softening and post-treatment are presented in table No. 3.

Table 1 Justification of the claimed parameters of the processes of degassing and oxidation of iron and manganese compounds. №№p / p Options Layer thickness, m d granules
mm d fiber mm Specific air consumption, m ³ / h / m ³ water The specific hydraulic load, m ³ / h per m ^{3 the} surface of the layer The content in purified water, mg / DM ³ Fe _commonly Mn CO ₂ H ₂ s F _total one Declare min one 10 1,0 four 6.0 4.8 0.05 10 0,03 10 2 average 1.25 twenty 1,5 7 7.0 5.2 0.1 17 0.04 eleven 3 max 1,5 thirty 2.0 10 8.0 5.60 0.2 thirty 0.06 12 four Beyond <min 0.9 9 0.9 3 5 Unreasonably high operating costs 5 > max 1,6 35 2,5 12 8.0 Required water quality not provided table 2 Justification of the claimed parameters of the processes of oxidation and deferrization and demanganization №№p / p Options Layer thickness, m D granules, mm Filtration rate, m / h The content in purified water, mg / DM ³ Fe _commonly Mn CO ₂ H ₂ s F _total one Declare min 1.4 0.7 4,5 0.3 0.05 5-10 0.01 8 2 average 1,5 1,6 6.5 0.3 0.05 5-10 0.01 10 3 max 1,6 2,5 8 0.3 0.05 5-10 0.01 12 four Beyond <min 1.3 0.6 4.0 Unreasonably high cost 8 5 > max 1.7 2.6 9 0.4 0,07 12 0.02 12

Table 3. Justification of the claimed parameters of softening and post-treatment processes. No. Options Softening Grain filter aftertreatment The content in purified water, mg / DM ³ Thick howl m D grains, mm Dose of NaOH, mEq / dm ³ Beats hydraulic heat by water, m ³ / hour per m ² Layer thickness, m D mm Speed filter. water, m / h Fe _commonly Mn CO ₂ H ₂ s F _total one Declare min 1,5 0.1 2,5 fifty 1,0 one 8 0.08 0.01 0,045 0.001 6.5 2 average 1,6 0.15 3.0 55 1.25 1,5 10 0.09 0.008 0,03 0.015 6.0 3 max 1.7 0.2 3,5 60 1,5 2 12 0,085 0.009 0.04 0,035 5,0 four Beyond <min 1.4 0.08 2.2 45 0.8 0.85 7 Unnecessarily increase operating and construction costs 5 > max 1.8 0.23 3.9 65 1.7 2,5 13

Data indicating the advantage of the proposed method in comparison with the known, are shown in table No. 4.

Table 4 №№p / p Ways Content in purified water Fe _total mg / dm ³ Mn, mg / dm ³ H ₂ S, mg / dm ³ СО ₂ , mg / dm ³ W _total , mEq / dm ³ one Proposed 0.08-0.09 0.009-0.01 0.001-0.035 0.04-0.045 5.0-6.5 2 Famous 0.25 0.08 0.1-0.5 0.7 7

Only a combination of such signs as:

- the implementation of degassing, oxidation, oxidation and deferrization by gravity in one filter reactor with simultaneous intensive processes of removal of hydrogen sulfide and carbon dioxide and oxidation of iron and manganese through the use of a filter charge with a developed surface (with the claimed parameters), at a certain air flow rate and specific hydraulic load, oxidation and deferrization on a heterogeneous polymer floating granular load with high dirt capacity, allowing to minimize the amount of pollution;

- further softening of the pre-treated water in a suspended layer of inert fine-grained contact mass using caustic soda in an amount of 2.5-3.5 mEq / dm ³ and the claimed process parameters, followed by deep post-treatment by filtration through a granular filter layer with the claimed parameters makes it possible to solve the problem - to purify groundwater containing both hydrogen sulfide, carbon dioxide, iron, manganese and hardness salts and reduce the cost of the method of purification of these waters by eliminating costly its Na-cation process.

An additional advantage is the simplification of the method, due to the simultaneous degassing, oxidation of ferrous iron and manganese, the oxidation of compounds of iron and manganese in a gravity mode in one apparatus - a filter reactor, followed by softening of pre-treated water in a suspended layer of fine-grained contact mass and deep purification, allowing exclude, in comparison with the known method, such operations as: preparation of regeneration solutions, the actual regeneration - loosening of the load Ki clean water, saturation of the load with a solution of sodium chloride, washing the load with clean water and processing regeneration solutions.

The proposed method of purification of groundwater from iron, manganese and hardness salts for drinking purposes in comparison with the known provides a cheaper method by 15-20%.

Claims (1)

The method of purification of groundwater from iron, manganese and hardness, including the oxidation of iron and manganese compounds with atmospheric oxygen, the oxidation of ferrous iron to its hydroxide forms, iron removal and demanganization by inert loading filtration and softening, characterized in that the oxidation of ferrous and manganese with simultaneous the degassing of hydrogen sulfide and carbon dioxide is carried out on an unfilled granular-fiber polymer charge with a layer thickness of 1.0-1.5 m, a diameter of granules of 10-30 mm, and a diameter of nit fiber 1-2 mm at a specific flow rate of countercurrent air 4-10 m ³ / h per m ^{3 of} source water and a specific hydraulic load of source water of 6-8 m ³ / h per m ^{2 of} the layer surface, additional oxidation of iron and manganese compounds, deferrization and demanganization are carried out on a non-uniform polymer floating granular charge with a granule diameter of 0.7-2.5 mm with a loading layer thickness of 1.4-1.6 m and a filtration rate of 4.5-8 m / h during the implementation of the gravitational cleaning process mode in a single reactor filter, and softening with the use of caustic soda in quantity ve 2.5-3.5 meq / dm ³ is performed in a suspension of fine-grained layer of inert contact mass with a grain diameter of 0.1-0.2 mm and a weighted layer thickness of 1.5-1.7 m and a specific hydraulic load on water 50-60 m ³ / h per m ² , followed by deep post-treatment by filtration through a granular filter layer with a diameter of granules of 1-2 mm, a layer thickness of 1-1.5 m, with a filtering speed of 8-12 m / h.