CN1296857A - Groundwater filter for producing drinking water - Google Patents

Abstract

An underground water filter for preparing drinking water has an enclosed container containing filter matrix which is the polymer particles with 1.4-2.7 of specific weight. A regenerating film is generated on the surface of said particle. Said film is preferably iron hydroxide. Controlling the number of Fe ions and pH value of the raw water coming into said container can reduce the contents of iron and manganese in water.

Description

Groundwater filter for producing drinking water

The present invention relates to water filtration systems and apparatus, and more particularly to water filtration systems and apparatus for removing iron and manganese from groundwater.

There are several technical processes for removing iron and manganese from water sources, and most of the processes can be divided into 3 major categories: first oxidation and then solid/liquid separation; ion exchange method; complexation (sequestration and/or stabilization). Please see "some thinking about iron removal" by sung.w. and Forbes, E.J (journal of environmental engineering, 12/month 6 1984, vol. 110). Sung and Forbes mention that a common control technique may be chlorination followed by filtration, which falls within the first category mentioned above. However, they also note that recent advances have been made to combine the formation of higher trihalomethanes with prior chlorination, which may require modifications to the process to favor aeration or oxidation.

The oxidation method previously used to remove iron from aqueous systems was to first remove ferrous iron (Fe)²⁺) Oxidation to ferric iron (Fe)³⁺) (i.e. water-soluble Fe)²⁺Conversion to water insoluble Fe³⁺) Then precipitating the water-insoluble iron in a large-scale filter tank to remove Fe³⁺. In these conventional processes, the raw water is typically aerated (or an oxidant is added) and then fed into a large oxidation pond, where the water undergoes a slow oxidation reaction (natural oxidation), but the iron removal process is rather slow because it mainly physically precipitates water-insoluble iron.

Attempts have been made to improve this process by adding air to water containing ferrous iron, organic matter and H2S. See japanese patent document 51-102343. The mixture of water and air is passed through a filter layer (e.g. limestone, carbon) and iron oxyhydroxide (FeOOH) is used as a catalyst. In this system, the influent raw water is filled with oxygen and the filter layer is always inflated. French patent 77-35994 (foossel) discloses a gravity filtration system which removes iron, manganese and calcium from water. The first filter bed is a sand layer with different particle sizes, which can remove most of iron and part of manganese and can also remove organic matters. A porous element contactor is arranged between the sand filter layer and the carbon filter layer. Manganese filtered through the sand filter is accumulated at the outlet of the porous element contactor. After passing through the sand filter, water free of iron, manganese and calcium is obtained. And simultaneously injecting air into the first sand filtering layer reversely. In this system, solids formed on the upper surface of the sand screen, which may contain iron hydroxide (FeO (OH), may be removed through a pipe to prevent clogging of the sand screen.

There have also been attempts to explain the reported Fe²⁺Oxidation kinetics rate constant of (2). The article entitled "kinetics of ferrous oxidation and products thereof in Water systems" by Sung and Morgan (published in the journal of the American chemical society, fifth 5.5.1980, volume 14) investigated the effect of ion, alkalinity and temperature on the movement of oxygenated molecules and attempted to determine the products of oxidation. They have studied the kinetics of homogeneous-heterogeneous oxidation. As a result, it was found that the rate constant of homogeneous oxidation decreases with increasing ionic strength and increases with increasing temperature when the pH of water and the oxygen concentration are constant. Chloride and sulfide ions reduce the rate of oxidation. Heterogeneous oxidation studies have concluded that autocatalytic action is only apparent at pH values of about 7 or greater, primarily due to the increased rate of particle surface formation and greater preference for Fe at these pH values²⁺Absorption of (2). The above-mentioned Sung and Forbes also indicate that a key problem in removing iron from water is how to remove FeOOH particles by flocculation or filtration. They also mention that iron removal by filtration is not completely understood and that silica both promotes and prevents iron removal and affects iron deposits. Sung, in "characteristics and properties of iron precipitates" ("journal of environmental engineering", Vol.2/109 1983), noted that typical iron hydroxide particles have a surface area of about 200m²Pergm, the aging process of these particles reduces the surface area and allows for the absorption of Fe²⁺The total number of active sites in (a) is reduced to about 1/10. Japanese patent publication 58-186493 discloses a system that combines chlorination with oxidation, followed by filtration, to remove iron from groundwater. The granulated oyster shells are immersed in NaClO and then water in which oxygen is dissolved is allowed to flow therethrough. The treatment agent is said to be regenerated by a rinsing process. In addition, it relates toThere is also WO89-11454(Partanen) which discloses that convection of air and water helps to remove dirt from the surface of the filter bed, using chemical or biological materials followed by a screen in the first stage of iron removal.

Many of the methods and devices described above are expensive and complicated to control. The ability to remove iron and manganese from water depends on several factors, such as PH, alkalinity, sulfate ion, soluble silicon, and the like. Moreover, even those processes which apparently use iron hydroxide as a catalyst exhibit an aging process in which the total number of active sites on the catalyst surface for iron absorption will decrease over time. Also, most of the above systems require extensive rinsing to remove water insoluble materials.

It would therefore be advantageous to develop a system for removing iron and/or manganese that greatly reduces manufacturing and operating costs, and that also provides a filtration media that does not significantly age or wear, does not require replacement, remains environmentally clean, and has a short (less than about 10 minutes) flush time.

Thousands of experiments over decades have now been found that Fe can be produced under certain chemical conditions as long as one contacts Fe in water²⁺A filter medium which can be immediately reacted, thereby enabling contact oxidation to Fe²⁺Rapid oxidation to form Fe³⁺And thus is disposed of. The oxidation speed achieved by using the filter medium is about 60 times of that of natural oxidation, so that the iron removal time is greatly shortened, and the process is greatly simplified. Moreover, a large oxidation pond is not required.

The water filtration system of the present invention comprises a closed container containing a filtration matrix comprised of a plurality of particles having a regeneration membrane formed directly on the surface of the particles. Through a number of experiments, it has been found that the Fe in the raw water entering the closed container can be controlled³⁺In amounts and at a pH suitable to reduce iron and manganese in the water entering the vessel, even when the chemical nature of the groundwater changes.

In one example, the filter substrate is comprised of a plurality of particles (e.g., anthracite, quartz sand, or non-toxic plastic particles) selected from particles having a specific gravity of 1.4 to 2.7, a non-uniformity coefficient of no greater than about 2, and an average diameter of about 1.0mm to 1.6 mm. A film is preferably formed on the upper surface of the particles, which is oxygen and Fe²⁺And Mn⁴⁺The impurities selected from manganese react and the film is preferably iron hydroxide (FeO (OH)).

The water filtration system and apparatus of the present invention have many advantages. When groundwater enters the vessel, it is washed for about 6 to 10 minutes for filtration. There is no need to pause (shut down the machine) in the process to drain the groundwater into the apparatus. The groundwater flowing out of the double vessel filter is suitable for human use. The water after removal of iron and manganese has reached international standards for daily use and for human consumption, i.e. the filtered water should contain iron in a concentration of less than about 0.3 mg/l.

The film formed on the surface of the particles in the vessel is a contact oxide film as long as the effluent water has a pH and Fe³⁺The concentration is properly controlled, and the oxidation speed is improved by about 25 times compared with the prior filter medium. Such films never age, wear or require replacement.

The operation of the filter does not require any expensive automatic control means. The device can be operated in several ways by means of an electrically operated control panel: iron and manganese were removed and filtered off, flushed, and shut down. The water filtration system consumes less power and less water for flushing than prior art systems. Since water drawn from a deep well can be used without washing with high-pressure water, a special water tower or high-pressure water pump does not need to be installed, which not only reduces the initial installation cost but also simplifies the operation procedure of the filtration system. The water filtering system comprises a closed container or a container, anair compressor (or an ejector), a tubular stirrer and related pipelines, so that the installation and maintenance are convenient, the occupied space and the operation cost of the filtering system are lower than those of a common iron removal system, and the filtering system can be used for respectively treating water for daily use and industrial water, thereby reducing the quantity of water needing to be filtered and the treatment cost.

The water filtration system is not only suitable for home use, but also suitable for use in large cities. The water filtration system provides excellent quality water. In addition, only simple process technology is required to manufacture such a water filtration system. When groundwater containing iron and manganese flows through a filtration system with exceptional oxidizing power, the effluent water is ready for use. This water is practically free of iron and manganese.

The water filtration system requires only one procedure, while other filtration systems require 3 or more procedures. The investment cost can be saved by about 42% by building a factory by using the new technology. Both procedures additionally required for other filtration systems require complicated structural engineering and require expensive equipment and large buildings. Moreover, such a water filtration system can save about 50% of the available land.

The water filtration system of the invention is easy and convenient to maintain. All that is required is to install a filter or filter tank having a strong oxidizing power, which is inexpensive and space-saving. Iron and manganese are removed when groundwater containing them is passed through the filter, which saves electricity by about 60% compared to filtration systems made with previous processes.

Another aspect of the present invention is the installation of a coarse filter head at the bottom of the closed vessel of the filtration system, which unique coarse filter head reduces the required particle height and size of the closed vessel, thereby further reducing the cost of the filtration system, and which coarse filter head allows for more efficient flushing and increases the overall filtration rate.

Further details and advantages of the present invention can be appreciated in view of the following figures and discussion.

FIG. 1 is a schematic process flow diagram of a method of treating groundwater according to the present invention.

Fig. 2 is a detailed flow diagram of the potable water filter and process of the present invention.

Fig. 3 is a cross-sectional side view of a closed container of a potable water filtration system.

Fig. 4 is a cross-sectional side view of the coarse filter head of the present invention.

Fig. 5(a-c) are front, plan and side views of a potable water filtration apparatus;

fig. 6(a-h) are the results of the adjustment of various parameters and their effect on the filtration characteristics of the water filter of the present invention.

FIG. 1 is a schematic diagram of a method of treating groundwater for removal of iron and manganese. The raw water is charged with a gas containing oxygen (generally air), the mixture of which is made [ Fe]²⁺]0/[Fe²⁺]The ratio and PH are controlled (see explanation below) and fed into one or more vessels containing filter matrix particles (anthracite, quartz sand, non-toxic plastic particles, etc.). The FeO (OH) film adheres to the upper surface of the particle layer.

FIG. 2 is a detailed view of an exemplary water filtration system and apparatus of the present invention. The filtration system shown in FIG. 1 generally comprises first and second closed vessels 10, 12 which contain water delivered by a water pump 14 from an underground well or other source of raw water. Process water may be taken directly through a connection such as 16. To obtain potable water, air is injected into the water by an air compressor or eductor 18, the air flows through a filter 20 and then into a tubular agitator 22, where the air and water are mixed. The closed containers 10 and 12 each have a pressure relief valve 24a and 24b, which are closed under normal water pressure conditions.

The apparatus shown in figure 2 has three modes of operation, filtration, flushing and shut-down or quiescent. In the filtration mode, iron and other soluble ions become insoluble compounds, valves 30, 32, 26a and 26b are closed, and valves 28a, 28b and 34 are opened, allowing the outflow of water to flow into the closed containers 10 and 12 in sequence. The water exiting the system through valve 34 or faucets 36, 38 is essentially de-ironed clean water and can be stored directly in the water tower. It can be seen that if both closed vessels 10 and 12 are used for filtration, the valve 36 will be closed. Whereas if only the closed vessel 10 is used, the valve 38 is closed and the valve 36 is opened.According to the condition of raw water source, the required filtering steps or the closed container can be conveniently determined. The dotted line in fig. 2 shows the general path of the water in the filtration mode, D₁、D₂,、D₃And D₄The diameter of the pipe used in the apparatus is shown (see table 3).

In the flush mode, valves 28a, 28b and 34 are closed, valves 30, 32, 26a and 26b are opened, and raw water drawn from the deep well or other source flows in a return flow into the containment vessel 10 and 12, and "dirty water" is drained from conduit 35. In the shutdown or rest mode, valves 26a, 26b, 28a, 28b, 32, 30, and 34 are all closed.

When the apparatus is used in filtration mode, the air feed to the tubular agitator 22 should be approximately 0.1 to 0.3 times the volume of raw water fed in, so that it is easy to select the air compressor or the ejector 18, the nominal capacity of the filtration system is calculated from 12 working hours per day, and so on, and if it is operated for 24 hours, the supply of drinking water will be doubled.

The water pressure of the discharged water after filtering depends on the pressure of the raw water flowing in. Generally, when the water inlet pressure is about 2 to 4kg/cm²(preferably not more than about 5 kg/cm)²) When the pressure of the effluent is about 2.0kg/cm²To 2.5kg/cm²This pressure is generally sufficient to drive water to 40 to 50 feet, approximately four to five storied buildings.

In the flushing mode, the actual time taken for flushing is very small, depending on the actual size of the capsules 10 and 12 and the amount of dirt or impurities in the raw water supplied to the system, and a suitable flushing time is about 6 to 10 minutes, depending on the size of the capsule used.

Reference is now made to fig. 3, which is a side partial sectional view of a containment vessel. This view shows a closed container 10 having a raw water inlet tube 36 from which raw water can flow into the closed container 10 in any manner. In fig. 3, raw water flows in a vertical direction and flows out from the nozzle 38. In the lower portion of the closed vessel 10, the matrix particles 40 occupy approximately 2/3 of the closed vessel. The substrate may be selected fromSelected from materials having a specific gravity of about 1.4 to 2.7 (coefficient of non-uniformity K (d)₈₀/d₁₀) Less than about 2) and an average particle size of about 1.0 to 1.6 mm. Such materials are, for example, anthracite coal particles, quartz sand of various particle sizes, and non-toxic plastic particles made of materials such as polyethylene. The upper surface of the substrate layer has a layer of FeO (OH), sometimes referred to as FeOOH, which is Fe³⁺The product formed by the reaction with oxygen has a pH controlled above about 6 and contains Fe which enters the vessel³⁺Controlled in the range of about 1mg/liter to about 5 mg/liter. The granular substrate 40 is placed on the upper part of the coarse filter head 42 shown in FIG. 2, and the coarse filter head is installed on the bottom of the closed vessel 10. The coarse filter head 42 is secured to the closed vessel 10 by a flanged joint 44 and an outlet conduit 46.

Fig. 4 is a side partial cross-sectional view of the coarse filter head of the present invention, with the upper portion of the coarse filter head 42 having a bell-shaped housing 48 with a plurality of elongated passages 50. The elongate passage 50 widens from the top end portion of the coarse filter head down to the bottom of the bell housing. Other shapes of strainer heads may have the same function and the claims are not limited to this particular shape.

Fig. 3 and 4 (see also fig. 5b and 5c) show reference letters showing the actual length dimensions of a particular form of the containment vessel and coarse filter head of the present invention. This data is shown in tabular form. See tables 1, 2 and 3.

TABLE 1

T-shape coarse filter head specification (gap width: 0.9mm)
											The dimension is in mm
Model number	D1	d2	d3	h1	h2	h3	k1	k2	n	1
											T1 T2 T3 T4 T5	112 112 216 216 216	100 100 200 200 200	25 32 32 40 50	52 52 107 107 107	48 48 93 93 93	70 70 70 100 100	6 6 8 8 8	5 5 6 6 6	18 20 16 22 30	34 34 70.5 70.5 70.5

TABLE 2

T-coarse filter head and air inlet specification required for different types of filters
			Filter type	T-coarse strainer head type number	Air inlet (liter/minute)
Y1 Y2 Y3 Y3 Y4	T1 T2 T3 T4 T5	1.4 2.4 3.0 4.1 6.0

TABLE 3

Model number	Throughput of treatment (liter/second)	Supply of Number of people Number of	Size of
																		A	B	c	D	E	F	G	H	I	J	K	D1	D2	D3	D4
			Y1 Y2 Y3 Y4 Y5	0.116 0.2 0.24 0.34 0.46	5-8 8-10 10-15 15-20 20-30	900 900 950 1000 1100	200 200 250 300 400	700 700 700 700 700	250 300 350 400 500	500 500 500 500 500	550 600 650 800 900	250 250 250 250 250	150 150 200 200 240	400 400 400 400 400	200 200 200 200 210	150 150 150 200 250	20 25 25 32 40																15 15 15 20 20	25 32 40 50 50	15 15 15 15 15

The material of the Y-shaped filter is as follows: stainless steel, 2. working pressure: 5kg/cm ²3. When the water inlet pressure is 3kg/cm²When the pressure of the effluent is 2.2kg/cm²This pressure is sufficient to press the water to 4 stories high.

For example, model T1 has a diameter D₁112mm、D₂100mm、D₃25mm, etc. TABLE 2Is an air inlet corresponding to various coarse filter heads. E.g. T₁The coarse filter head can hold 1.4 liters of air intake per minute, and T₂The coarse filter head has an air requirement of 2.4 litres per minute. As shown in Table 3, Y₁The treatment capacity of the filter is 0.116 liter per second, and stable drinking water can be provided for 5 to 8 people. Y is₁The total height "A" of the type filter is equal to 900 mm.

Reference is now made to fig. 5a-c, wherein fig. 5a is a front view of a water filtration system of the present invention having two closed vessels 10 and 12. Fig. 5a also shows a control panel 56 having 3 buttons for the filtration mode, backwash mode and rest mode, respectively. Button a is used for the filter mode, button B is used for the rinse mode, and button C is used for the still mode. In this embodiment of the invention, valves 26a, 26b, 28a, 28b, 30, 32 and 34 are all automatic valves; in other words, the signals from the control panel 56 can control the valve actions. The automatic valve may also be an electrically operated valve. Fig. 5b is a plan view of the device of fig. 5a, showing more specifically the positions of the various electrically operated valves of the device. Fig. 5c is a side view of the hermetic container 10 in fig. 5a and 5 b. In particular, a drain 58 is shown for letting the flushing water out of the system into a drainage system 60, fig. 5a also showing the drain 58.

The filtration system of FIGS. 2-5(a-c) may be used to filter groundwater having an iron content of less than 30 mg/l (preferably less than 25 mg/l) and a pH of not less than 6. For raw water with iron content above 25 mg/l, or containing manganese, the iron and manganese in the water can be removed by adding one or more vessels such as a closed vessel 12. The groundwater from the double vessel filter is suitable for human consumption because after removal of iron and manganese, the effluent water meets international standards for daily use and drinking of less than 0.3mg iron per liter.

The closed vessels 10, 11, the corresponding pipes, valves, coarse filter heads and tubular stirrers are made of known materials, such as cast iron, stainless steel or plain carbon steel. Or may be made of plastic. Although this is not the most preferred form, the preferred material for the containment vessel, valves, corresponding piping, etc. is one of many different grades of stainless steel, such as stainless steel 316, 304, etc. Depending on the impurity content of the raw water to be treated. If the water contains more corrosive impurities, it may be necessary to use other materials of manufacture, such as brass or nickel plated metal.

The regenerated film formed on the particles in the closed vessels 10 and 12 may be formed under certain chemical conditions and will react with the Fe entering the closed vessel²⁺The reaction takes placeimmediately upon contact (that is, contact oxidation is carried out), thereby making ferrous iron (Fe)²⁺) Is oxidized into ferric iron (Fe)³⁺) And the rate of oxidation using this regenerated membrane is about 50 to 70 times that of natural oxidation (i.e., using a large scale oxidation pond) when removed from water. Therefore, the iron removing time is greatly shortened, and the process is greatly simplified. The reaction sequence used to make the regenerated membrane and regenerate this membrane is as follows:

(1)

FeOOH is a rust film that adheres to the surface of the filter substrate particles. This material has various crystal shapes and is known to have a strong iron removal capacity by contact oxidation.

After the formation of the FeOOH regenerated membrane, the regenerated membrane exhibits cation exchange adsorption characteristics if the pH of the iron-containing raw water is generally maintained at a value above the FeO (OH) isoelectric point (about 6.0). Firstly Fe in water²⁺Ion exchange adsorption is carried out, and then H is added⁺Conversion to water was done according to the equimolar value. The reaction formula is as follows:

(2)

it can be seen that Fe²⁺Is oxidized into Fe³⁺Is an autocatalytic reaction, ensures the new process of removing iron by contact oxidation, and can prevent the aging of the regeneration membrane. The last reaction step of the reaction sequence is:

(3)

can be controlled by controlling the pH and Fe of the raw water entering the closed containers 10 and 12³⁺The concentration is controlled to form FeOOH film on the surface of the substrate particles even if the concentration of other chemical properties, such as silica, sulfide, alkalinity, carbonate and other chemical components, is changing, and the water temperature, the type of filter medium and the filtration rate are also changing.

It has been found that the generation and regeneration of the filter membrane is governed by the following functional relationship:

∑[ζ]^ρ×K=[φ](4)

[Fe²⁺]₀/[Fe²⁺]×[PH]×K=[φ](5)

∑[ζ]_ρ=[Fe²⁺]0/1Fe²⁺×[PH]×K (6)

wherein:

[ ζ]ρ represents various chemical factors;

[ phi]represents the influence of various chemical factors on the reaction formulas (2) and (3);

[Fe²⁺]= ferrous iron concentration in raw water;

[Fe²⁺ ₀]the ferrous concentration of the water entering the closed vessel (after addition of air); and is

K = constant;

ρ = index number.

Referring again to fig. 1, fig. 1 is a schematic diagram of a water treatment process for removing iron and manganese by the above-described chemical reaction.

The raw water is charged with a gas containing oxygen (generally air) to cause Fe in the mixture²⁺]0/[Fe²⁺]The ratio and PH are controlled (see explanation below) and the mixture is fed into one or more vessels containing filter matrix particles (anthracite, rock sand, non-toxic plastic particles, etc.). The FeO (OH) film adheres to the upper surface of the particle layer. Equations (4), (5) and (6) show that while other factors may also affect chemical reactions (2) and (3), only control of [ Fe]²⁺]₀/[Fe²⁺]And the pH value can obtain the optimum reaction process phi]_c. Except that Fe in the water to be introduced into the closed vessel³⁺The concentration is controlled in the range of about 1mg/l to 5mg/l, and iron removal can be effectively controlled by controlling the pH, although the alkalinity, the sulfide ion concentration, the carbonate ion concentration, the soluble silica concentration, the water temperature, etc. of the raw water are also changed.

In typical chemical reactions (1), (2), (3) that occur, such as the flow rate of water, the rate of oxygen (air) addition, the temperature and pressure of the incoming water, and the degree of agitation and mixing, can be any value as long as there is no control of the pressure or temperature in the vessel, or iron leaks into the outgoing water, or the vessel is clogged, but the chemical reaction is allowed to proceed within a commercially reasonable and useful time.

For these three reactions, the temperature within the vessel may range from about 0 ℃ to 90 ℃. Lower temperatures may cause icing and clogging of the vessel, while higher temperatures may cause water evaporation, both of which are not conducive to efficient operation of the apparatus. The temperature is preferably in the range of about 0 ℃ to 30 ℃.

The operating pressure of the vessel may vary, as desiredThe degree depends on the supply pressure of the raw water, but is also influenced by the pumping pressure and the charging air. The pressure is preferably about 2 to 5kg/cm²In the meantime. Higher pressures that are not within the optimum range do not significantly affect the performance of the system using the above reaction. Lower operatingpressures reduce capital investment for the equipment because the pipes and vessels do not require as thick walls, but the pumping heights and distances may not exceed the required values using lower pressures.

As noted above, the pH is generally maintained above about 6.0 because this is close to the isoelectric point of FeOOH films. Above this pH, the FeO (OH) membrane acts as a cation exchanger, Fe²⁺Exchange H⁺And is adsorbed. Below this PH, the chemical reaction does not occur significantly.

Determination of Fe Using a branded Instrument in the field³⁺The concentration can be indirectly measured to obtain [ Fe]²⁺]₀/[Fe²⁺]Of Fe into the reaction vessel³⁺The concentration is approximately 1mg/l to 5 mg/l. Higher concentrations indicate insufficient oxygen or insufficient air and water mixing into the container.

The main advantage of this regenerated membrane is that its formation and regeneration process is simple, easy to master and suitable for production, since it is not only used to control the pH and Fe entering the filter³⁺Besides the concentration, other chemical factors and the relationship between the chemical factors and each other do not need to be noticed. The film is inexpensive to produce and is resistant to aging. The film adheres to many substrate particles without falling off, and is not washed off even at the time of washing. Therefore, the washing does not affect the iron removal. The specifications (parameters) of the filtering device can be selected according to the required treatment capacity of the domestic water.

The following examples given in connection with fig. 6a-h show the effect of different parameters on a filtration plant containing regenerated membranes.

Examples of the invention

The results of the parameter changes affecting the operation of the filtration system using the apparatus and method described above are shown in fig. 6 (a-h). FIG. 6a shows the remaining iron (mg/l) as a function of the pH of the water, curve "a" representing 8 hours of operation and curve "b" representing 8 days of operation. The remaining iron concentration of both curves passes through a minimum of about PH = 6.

FIG. 6b shows Fe at system temperatures of 30 ℃ and 5 ℃²⁺The relationship between the ratio (%) of the total Fe content and the pH of water (curves "a" and "b", respectively). It can be seen that the higher the temperature, the more Fe is removed from the system²⁺The higher the amount.

FIGS. 6c and 6d show the remaining iron concentration (mg/l) versus filtration time using different matrix materials (FIG. 6c) and filtration rates (FIG. 6 d). In fig. 6c for 3 matrix materials: quartz sand, anthracite, and Guangxi manganese sand were compared. Fig. 6d then shows the results for 4 filtration rates: 20, 115,10 and 5 meters³Comparison was made in hours. It can be seen that the higher the filtration rate, the less iron is removed per litre of raw water, but the difference in iron removal efficiency becomes less pronounced with increasing filtration time. (this can be more clearly understood with reference to fig. 6 g).

FIGS. 6e and 6f show the residual iron concentration versus NaHCO added to influent raw water₃(FIG. 6e) and NaHSO₄(FIG. 6f) relationship between the impact on the system. Added NaHCO₃Increasing from 20mg/l to 80mg/l did not cause the remaining iron to show a linear rise as expected. Thus, the film appears to be very resilient to this variation in purities. Adding Na₂SO₄(FIG. 6f) clearly affects the association of the effluent with the remaining iron. However, the membrane showed that it was able to resume normal operation very quickly and well.

Figure 6g shows the results of various experiments at different filtration rates and matrix media. In each case it will be noted that for the same raw water, both the matrix and the membrane go through 3 stages: fe²⁺Adsorption; curing; and (5) stable operation. This is in contrast to previous filtration systems using FeO (OH)In contrast, the latter had a decrease in iron removal efficiency over time (aging), and FIG. 6g shows Fe as it entered the filtration system³⁺And the pH value, are properly controlled, the FeO (OH) film is practically stable and therefore does not have to be replaced, as determined by its regenerative properties. Table 4 shows the differencesThe difference between the thickness of the filter layer Li and the increase in the rate of iron removal.

The above description is intended primarily to illustrate the invention. It is apparent that modifications and variations can be made in the materials used, the shapes thereof, and the arrangement of various members by those skilled in the art without departing from the scope of the present invention defined in the appended claims.

TABLE 4

Iron concentration and iron removal capacity in the filtrate
				Depth (cm)	Coi(mg/L)	Ci(mg/L)	Ki(after 27 hours). times.100%
10	20	5.0	13.86
35	20	0.7	7.86
70	20	0.15	4.4

Wherein:

C_oi= iron concentration in influent water

C_i= iron concentration in effluent

L_i= filter layer thickness

K_i= average iron removal rate of different filter layers $K_i=\frac{\mathrm{In}\frac{C_{\mathrm{oi}}}{C_i}}{L_i}$

Claims (6)

1. The water filtration system includes:

a closed container;

a filter matrix contained within the container, the filter matrix being comprised of a plurality of particles; and is

A regenerated film formed on the upper surface of the particles and adhered to the particles, the regenerated film being formed of oxygen and Fe²⁺Or Mn⁴⁺The composition of the reaction product of (1).

2. The water filtration system of claim 1, said particles having a specific gravity of about 1.4 to 2.7 and a non-uniformity coefficient of particle, K (d)₈₀/d₁₀) Less than about 2 and the average diameter of the particles is about 1.0mm to 1.6 mm.

3. The water filtration system of claim 2, said particles being selected from the group consisting of anthracite coal, quartz sand, or non-toxic plastic particles.

4. A water filtration system as claimed in claim 1 wherein said membrane is FeOOH by controlling the Fe feed into the system²⁺With Fe in the water source²⁺And controlling the pH above about 6.0.

5. The water filtration system of claim 1, further comprising a coarse filter head disposed at the bottom of the vessel, the coarse filter head having a housing with a plurality of elongated passages formed therein at an upper portion thereof. The elongate channel widens from the top to the bottom of the housing.

6. The water filtration system of claim 1 further comprising a plurality of capsules substantially identical to the first capsule, the capsules being arranged in series.

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