KR20040101850A - Treatment apparatus for rainwater using metal membrane combined with ozonization and treatment method using thereof - Google Patents

Abstract

PURPOSE: To provide an apparatus and a method for treating rainwater by using membrane separation combined with ozone injection process, wherein high membrane permeation rate is always maintained by injecting an ozone gas with strong oxidizing power as a membrane cleaning means into a membrane module, thereby preventing internal fouling and formation of cake layer on the surface of membrane. CONSTITUTION: The apparatus comprises a screen(70a) for primarily removing suspended solid inside rainwater(A); a separation tank(70b) in which rainwater flown out is contained, and which separates contaminated water and sludge; a filtering and cleaning means installed inside the separation tank to filter and clean raw water flown in the separation tank; an ozone contained gas ejection means installed under the filtering and cleaning means to clean the ozone contained gas by ejecting and bubbling an ozone contained gas and supplying the bubbled ozone contained gas onto the outer surface of the filtering and cleaning means and into the filtering and cleaning means; a permeation water discharge means of which one end is connected to an upper part of the filtering and cleaning means to suck and discharge permeation water passing through the filtering and cleaning means; and an ozone generation means(120) installed at the outer side of the separation tank to selectively supply the ozone-contained gas to the ozone-contained gas ejection means and the permeation water discharge means.

Description

Treatment apparatus for rainwater using membrane separation combined with ozone injection method {Treatment apparatus for rainwater using metal membrane combined with ozonization and treatment method using

The present invention relates to a rainwater treatment device and a method using a filtration membrane device, in particular, in the treatment of sewage and wastewater using membrane separation, by introducing a membrane contamination suppression method such as intermittent ozone treatment to maximize the treatment efficiency It relates to a rainwater treatment apparatus and method using a membrane separation combined with the injection method.

In general, environmental pollutants such as particulates contained in exhaust gases emitted from automobiles, dust caused by tire wear, and dust generated by asphalt wear are contained on the road surface and the collecting surface of the building during rainfall. And suspended airborne substances such as dust and dust. The mixed contaminants may contain organic pollutants such as polynuclear aromatic hydrocarbons (PAHs) or heavy metals such as cadmium, and may contain eutrophic nutrients such as nitrogen or phosphorus, and endocrine disrupting action. Endocrine obstructions may also be present.

In this way, the pollutants deposited on the road or catchment surface are transported by rainfall, flowed into storm and sewage sinks, and then discharged into conduits. In this case, when the sewerage system is a classification, the pollutants are not treated and are introduced into the surrounding water, but the pollutants introduced into the surrounding water without being treated may cause eutrophication, and endocrine obstacles are introduced into the ecosystem. It may be adversely affected.

On the other hand, when the sewage system is a confluence type, the pollutant is introduced into the sewage manager and treated. However, if the pollutant contains heavy metals, a separate treatment means for removing the pollutant is required, so that the sewage treatment cost is increased, There was a problem that the process was complicated. Therefore, it is desirable to provide a water treatment method capable of efficiently treating the spilled rainwater.

Among the various water treatment methods, the membrane separation method can secure stable water quality without depending on the sedimentation property of sludge generated in the treatment process and the final sedimentation is unnecessary. have. However, despite the many advantages of membrane separation, in actual application of membrane separation, deterioration of the membrane may occur over time, and the membrane permeation flow rate decreases due to internal fouling. May result. Therefore, there is a problem of maintaining a stable membrane permeation flow rate and extending the membrane life. In addition, low-pressure membrane separation methods such as microfiltration and ultrafiltration cannot effectively control trace contaminants or endocrine disruptors in contaminated rainwater, so reverse osmosis or nanofiltration should be used for their removal. There is a problem that requires a high pressure processing environment and a high processing cost.

Accordingly, the present invention has been made in order to solve the above problems, using membrane separation, by injecting a strong oxidizing ozone gas into the membrane module as a cleaning means of the membrane to the internal fouling phenomenon and the surface of the membrane It is an object of the present invention to provide an excellent treatment apparatus and method using membrane separation combined with an ozone injection method that prevents cake layer formation and always maintains a high membrane permeation flow rate.

In addition, through the injection of ozone, there is another object to provide an excellent treatment apparatus and method using a membrane separation combined with the ozone injection method that can decompose or detoxify the trace contaminants present in the influent.

In addition, by using a filtration membrane made of an ozone-resistant material as the material of the membrane, it combines an ozone injection method that enables the application of ozone that is impossible with a conventional resin membrane (organic material membrane) and can extend the membrane life almost semi-permanently. It is another object to provide a rainwater treatment apparatus and method using the membrane separation.

1 is a conceptual diagram showing a rainwater treatment method using a membrane separation combined with the ozone injection method according to the present invention.

Figure 2 is a block diagram schematically showing a stormwater treatment apparatus using membrane separation combined with the ozone injection method according to the present invention.

Figure 3 is a schematic diagram of the filtration membrane module of the stormwater treatment apparatus using the membrane separation combined with the ozone injection method according to the present invention.

Figure 4 is a graph showing the time change of the membrane permeation flow rate when the cleaning according to the operating factors shown in Table 1.

* Description of the main parts of the drawings

10: building 20: road

30: storm pipe 40: membrane separation / ozone device

70a: screen 70b: separator

80: metal film module 90: diffuser

100: suction pipe 110: suction pump

130a: ozone width pipe 130b: filtered water ozone injection pipe

130c: ozone injection pipe for backwashing A: excellent

B: Permeate C: Excess Excellent

In order to achieve the above object, the present invention, the first screen to remove the suspended matter in rainwater; The discharged rainwater is received and received, the separation tank for separating the contaminated water and sludge; Filtration and washing means installed in the separation tank to filter and clean the raw water flowing into the separation tank; An ozone-containing gas ejection means installed under the filtration and washing means and blowing and blowing ozone-containing gas to supply and clean the ozone-containing gas to the outside and inside of the filtration and washing means; Permeate water discharge means, one end of which is connected to an upper portion of the filtration and washing means and sucks and discharges permeate water that has permeated therethrough; And an ozone injection method including an ozone injection means installed at an outer side of the separation tank and ozone generating means for selectively supplying ozone-containing gas to the ozone-containing singer ejection means and the permeate discharge means. .

The separation tank may further include a space compartment member installed upright at a predetermined distance away from the bottom to allow the raw water supplied from the outside to have a smooth flow and a downflow.

The filtration and cleaning means may include a filtration membrane module including a filter body having open both sides and a metal membrane provided on both sides of the filter body; A suction port provided in communication with an upper portion of the filter body, one end of which is connected to the permeate discharge means; And it may be provided in communication with the lower portion of the filter medium may include an injection port for injecting the ozone-containing gas of the ozone generating means into the filter body.

In one embodiment, the metal membrane may have an effective filtration area of 0.12 m 2 on both sides and a membrane pore diameter of 0.2 μm.

The metal film may be formed by applying a powder of stainless steel to a gold mesh of stainless steel and sintering.

The ozone-containing gas ejection means includes an air diffuser connected to the ozone generating means and the first injection pipe to clean the outside of the filter body; And it may include a second injection pipe for injecting the ozone-containing gas supplied to the ozone generating means into the filtration membrane module.

The ozone generating means may include a plasma apparatus for converting oxygen in the tool into ozone therein.

The permeate discharge means is a suction pipe connected to the suction port of the filtration membrane module; And a suction pump installed on the suction pipe to suck and discharge the permeated water on the upper part of the filtration membrane module, and to maintain the inside of the filtration membrane module at a negative pressure.

In addition, the present invention, in the rainwater treatment method using the rainwater treatment device using the membrane separation combined with the above-described ozone injection method, in the state in which the filtration membrane module made of a metal membrane is installed in the raw water in the separation tank, by the suction pump A first step in which raw water is drawn into the filtration membrane module to perform solid-liquid separation; A second step of performing membrane cleaning by intermittently injecting ozone gas generated by an ozone generator into raw water sucked into the filtration membrane module; And a third step of ejecting the ozone gas generated by the ozone generator through the diffuser and cleaning the outer surface of the filtration membrane module by the bubbling thereof.

The first step may include a fourth step in which sludge is precipitated while rainwater flowing into the separation tank collides with a partition plate installed upright in the separation tank to form a downflow, and contaminated water rises toward the filtration membrane module side.

The first step may include a fifth step of separating solid solution by lowering an internal pressure of the filtration membrane module whose position is maintained by a negative pressure provided from the suction pump to an external pressure.

The ozone gas generated by the ozone generator is supplied to the permeate side of the filtration membrane module to sterilize pathogenic microorganisms and protozoa and to oxidize trace organics and endocrine disruptors.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a conceptual diagram showing a rainwater treatment method using a membrane separation combined with the ozone injection method according to the present invention. Figure 2 is a block diagram schematically showing a rainwater treatment device using a membrane separation combined with the ozone injection method according to the present invention, Figure 3 is a rainwater treatment apparatus using a membrane separation combined with the ozone injection method according to the present invention. It is a schematic diagram of a filtration membrane module.

Rainwater A leaked from the building 10 or the road surface 20 is collected through the rainwater conduit 30 and sent to the membrane treatment device 40. The treated rainwater B is then sent to a river or appeal 50. Outflow water (A) is first passed through the screen (70a) for removing the solids of 1mm or more flows into the separation tank (70b). In the separation tank 70b, a filtration membrane module is installed, and a lower part of the separation tank 70b is provided with an diffuser 90 for cleaning the side surface of the filtration membrane module 80 by bubbling generated by blowing ozone-containing gas. . In addition, one end is in communication with the upper portion of the filtration membrane module 80, the suction pipe 100 for sucking the permeated water (C) that has passed through the filtration membrane module 80 to be introduced into the suction pump side to be described later.

In addition, the other end of the suction pipe 100 to discharge the permeated water (C) and at the same time by removing the air inside the filtration membrane module 80 to lower the internal pressure than the external pressure, the filtration membrane module 80 A suction pump 110 for maintaining the inside at a negative pressure is installed, and ozone generation for selectively injecting ozone-containing gas into the permeate side of the filtration membrane module 80 and the diffuser pipe 90 outside the separation tank 70b. Device 120 is installed.

In addition, the first injection pipe 130a is connected to the diffuser 90 and the ozone generator 120 to supply the ozone-containing gas generated by the ozone generator 120 to the diffuser 90. In order to inject the ozone-containing gas into the permeate (C) side, one end is connected to the ozone generator 120, the other end is provided with a second injection pipe (130b) to face the filtration membrane module (80) . In addition, a third injection pipe 130c is connected to the ozone injection device 120 and the suction pipe 100 so as to supply the ozone-containing gas to the permeated water A discharged to the suction pipe 100 to be sterilized.

In the center portion of the separation tank (70b), a partition plate in which the supplied rainwater (A) has a smooth flowability is arranged upright. At this time, the circumferential plate 140 is located a predetermined distance away from the bottom in the separation tank (70b), the raw water supplied from the outside hit the partition plate 140 to form a downflow sludge is precipitated and contaminated water is It is raised to the filtration membrane module 80 side.

The filtration membrane module 80 includes a filter body 81 that is open to both sides, a metal membrane 82 provided on both sides of the filter body 81 that are open, and a suction pipe (2) on top of the filter body 81. The suction port 83 is connected to the 100, and the lower portion of the filter plate 81, the second inlet pipe 130b is connected to introduce the ozone-containing gas supplied from the inside of the filter body 81 It is made of an injection hole (84).

In addition, in the present embodiment, the effective filtration area of the metal film 82 is 0.12 m 2 in total on both sides, the membrane pore diameter is 0.2 μm, and the metal film 82 is sintered by applying a powder of stainless steel to a gold mesh of stainless steel. will be.

The ozone generator 120 includes a plasma device to convert oxygen in the air into ozone by plasma.

In the rainwater treatment device using the membrane separation combined with the ozone injection method according to the present invention configured as described above, when the raw water is introduced in the state in which the filtration membrane module 80 is immersed in the inflow (A) in the separation tank (70b) The raw water impinges on the partition plate 140 to form a downflow, and flows back into the filtration membrane module 80 against the lower part of the partition plate 140 again.

At this time, the internal pressure of the filtration membrane module 80 in a state in which the filtration membrane module 80 floats in the water by the negative pressure provided from the suction pump 110 to suction less than the external pressure of the raw water (A) Solid-liquid separation is performed, and excess sludge separated from the raw water is then removed through the lower portion of the separation tank 70b.

In addition, ozone gas generated by the ozone generator 120 is intermittently injected into the filtration membrane module 80 having the permeated water C sucked through the second injection pipe 130b and the injection port 84. Perform film cleaning.

In addition, the ozone gas generated by the ozone generator 120 is supplied to the diffuser 90 through the first injection pipe 130a, by bubbling the ozone-containing gas provided from the diffuser 90 The side of the filtration membrane module 80 is cleaned.

In addition, in the present embodiment, since the lid 150 is in a state of shielding the upper opening of the separation tank 70b, the separation tank 70b is filled with inflow water so that the outflow water no longer enters. If it is, the excess water flows through the upper surface of the lid without being blocked by the lid 150 and entering the separation tank 70b. Therefore, the contaminated water in the separation tank 70b is agitated, and the sediment deposited on the lower portion thereof is swept together and does not rise upward.

In addition, the ozone-containing gas generated in the ozone generator 120 is supplied to the suction pipe 100 through the third injection pipe 130c to oxidize and sterilize the permeated water C discharged to the suction pipe 100. Then, the treated permeate C is discharged to the suction pump 110 side.

Here, the metal membrane filtration pressure is operated in the range of 60 to 90 (kPa), the injection ozone concentration is 20 (mgO ₃ / Lcm ³ / cycle) or more, and the amount of ozone injected at the same time is 0.27 per cm ³ of the inner volume of the metal membrane. and the ^{_{(mgO 3 / Lcm 3 / cycle}} ) or more.

In addition, the ozone-containing gas is ejected from the permeate side of the membrane to the inflow source side, whereby the recovery of the membrane permeation flow rate is remarkable, especially when the injection ozone amount is 0.53 (mgO ₃ / Lcm ³ / cycle) or more.

This operation is performed by injecting strong oxidizing ozone gas into the inside and outside of the metal film module 80 to prevent internal fouling, and to prevent the formation of a cake layer by forming on the surface of the film. The flow rate is maintained, and application of ozone is not possible with a normal resin film (organic material film), but by using a metal film which is an ozone-resistant material.

Hereinafter, the result of the filtration experiment and the washing experiment in the separation tank using the metal membrane module described above will be described.

Table 1 shows the experimental conditions when the filtration experiment was carried out to compare the recovery of membrane permeation flow rate by washing.

Run 1 to Run 3 ejects air or ozone-containing gas from the diffuser 90 under the metal film module 80, and Run 4 to Run 11 discharges air or ozone-containing gas from the ozone generator 120. It injected into the permeated water C side (inner side) of the metal membrane module 80, and jetted to the raw water A side (outer side) of the metal membrane module 80. In this case, the ozone-containing gas is not discharged from the suction pipe 100.

In Table 1, ozone concentration (mg / L) represents ozone amount per 1L of ozone-containing gas, and injection flow rate (L / min) means supply flow rate of ozone-containing gas.

Classification operation factor Run1 Run2 Run3 Run4 Run5 Run6 Run7 Run8 Run9 Run10 Run11 Bubbling from Outside the Membrane Bubbling from inside the membrane Ozone generator Ozone Concentration (mgO ₃ / L) 0 50 50 0 40 40 40 20 10 40 40 Injection flow rate (L / min) 5 5 10 4 4 2 One 4 4 4 4 Injection cycle 5min / 20min (3cycles / 1hr) 20min / 30min (2 cycles / 1hr) Total injection ozone (mgO ₃ / cycle) 0 1250 2500 0 320 160 80 160 80 320 320 Ozone injection rate per unit volume inside the metal film (mgO ₃ / cm ³ / cycle) - - - 0 0.53 0.27 0.13 0.27 0.13 0.53 0.53 Membrane module Filtration pressure (kPa) 75 75 75 75 75 75 75 75 75 50 100 Filtration cycle 10min On, 2min Off 24min On, 6min Off Separator Average Inflow SS Concentration (mg / L) 83-95

In addition, the injection cycle of Run1 to Run3 is a case of injecting 20 minutes in one cycle unit for 5 minutes (15 minutes of filtration and washing for 5 minutes), and the injection cycle of Run4 to Run11 is injecting 30 minutes in one cycle unit for 2 minutes ( 28 minutes of filtration and 2 minutes of washing), which is a cycle of ozone washing for 3 hours and 2 cycles in 1 hour each. That is, in the present invention, one cycle means combining the filtration operation and the washing operation once.

Fig. 4 shows the time change of the membrane permeation flow rate when the cleaning is performed according to the operation factors shown in Table 1. For example, Run1 in FIG. 4 performs filtration / cleaning over three hours under the operating conditions shown in Table 1, and measures the change of the transmembrane flow rate in the meantime. As can be seen from the results shown in Fig. 4, the cleaning effect according to the operating conditions of Run1 to Run4 shown in Table 1 was less than 50% of the membrane permeation flow rate at the initial stage of the filtration for 3 hours. As such, its applicability is unlikely.

However, in the case of Run5 ~ Run11, the average membrane permeation flow rate was maintained relatively close to the membrane permeation flow rate in the initial stage of filtration.In the case of Run5, the average membrane permeation flow rate was 2.0 (m ³ / (m ² · day ), The highest transmembrane flow rate was obtained.

As the treatment characteristics according to the operating factors, as the amount of ozone injection increased, the ratio (Ja / Ji) of the average membrane permeation flux and the initial membrane permeate flow rate tended to be high, and (Ja / Ji) was 90% or more. When the concentration is 40 (mg / L), the ozone-containing gas flow rate is 2 (L / min) or more, and when the ozone concentration is 20 (mg / L), the ozone-containing gas flow rate is 4 (L / min) or more. Appeared.

The experimental results are summarized based on the unit volume inside the metal film, and the average amount of ozone permeated when the amount of injected ozone is 0.27 (mgO ₃ / cm ³ / cycle) or more and the injected ozone concentration meets the requirements of 20 (mg / L) The ratio of the flow rate and the initial membrane permeation rate (Ja / Ji) is determined to satisfy the practical limit of 90% or more.

In the relationship between the filtration pressure, the ratio of the average membrane permeation flux and the initial membrane permeate flux (Ja / Ji), the higher the filtration pressure, the smaller the ratio Ja / Ja of the average membrane permeate flux and the initial membrane permeate flow rate. The efficiency was shown to decrease.

Therefore, it is judged that it is advantageous in terms of energy efficiency to operate the filtration pressure as low as possible within the range where practical membrane permeation flow rate is obtained. From the experimental results, the filtration pressure was found to be in the range of 65 to 85 (kPa).

Table 2 below is a table showing the results of experiments on the average water quality and removal rate of the influent sewage and membrane permeate using the rainwater treatment system using membrane separation combined with the ozone injection method according to the present invention.

Manipulation Factor Influent sewage Transmembrane % Removal PH 6.5 6.9 _ SS (mg / L) 83 0 100 Degree of turbidity 42 1.7 96 Chroma 182 58 68 TOC (mgC / L) 61 27 56 T-N (mgN / L) 33 14 58 NH ₄ ⁺ -N (mgN / L) 15 14 7 T-P (mgN / L) 7.5 4.2 44 General bacteria count (pcs / mL) 3 × 10 ⁸ Not detected 100

Table 2 shows the average water quality and removal rate of influent sewage and membrane permeate during the experimental period. It can be seen that the suspended solids in the influent sewage are completely removed from the water of the membrane permeate, and even general bacteria including protozoa such as griptosporium were not detected at 0.2 μm, the pore diameter of the metal membrane used in this example. .

Turbidity was almost 100%, but the removal rate of chromaticity was 68%, which was lower than that of turbidity. Total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC) concentrations showed removal rates around 50% with the removal of solids by the metal film, but the removal rate of soluble substances such as ammonia nitrogen was low. there was.

As a result of observing the appearance of the metal film at the end of the experiment, it was found that the oxidative breakage phenomenon of the film material, which is generally observed in the organic film, was not observed. Thus, the metal film has sufficient resistance to ozone. .

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and alterations are possible within the scope without departing from the technical spirit of the present invention. It will be apparent to those who have knowledge.

As described above, according to the present invention, in the application of the membrane separation device, by introducing a new membrane cleaning method called intermittent ozone backwashing, it is possible to maximize the efficiency of the device operation by solving the complexity of the membrane cleaning that the existing methods have. In addition, there is an effect that can treat the rainwater using a relatively inexpensive metal film.

In addition, since the metal membrane is easy to maintain and allows intermittent filtration, it is suitable as a rainwater treatment device that requires operation only when it is raining, and grasps the cleaning effect according to the change of operating factors in the membrane cleaning method using intermittent ozone backwashing Therefore, there is another effect of maximizing the utilization of the operation equipment by calculating the optimum value of the operation factor for each situation in practical application.

In addition, the post-treatment by ozone has another effect of removing trace organic contaminants or harmful microorganisms present in the treated water.

In addition, since the upper open portion of the separation tank can be opened and closed by the lid, even if the rainfall exceeds the capacity of the membrane, there is another effect that the excess water can be discharged to the discharge portion through the upper surface of the lid with the lid closed. .

Claims (12)

A screen that primarily removes suspended matter in the rainwater; The discharged rainwater is received and received, the separation tank for separating the contaminated water and sludge; Filtration and washing means installed in the separation tank to filter and clean the raw water flowing into the separation tank; An ozone-containing gas ejection means installed under the filtration and washing means and blowing and blowing ozone-containing gas to supply and clean the ozone-containing gas to the outside and inside of the filtration and washing means; Permeate water discharge means, one end of which is connected to an upper portion of the filtration and washing means and sucks and discharges permeate water that has permeated therethrough; And Ozone generating means installed on the outside of the separation tank for selectively supplying the ozone-containing gas to the ozone-containing water ejecting means and the permeate discharge means Rainwater treatment system using a membrane separation combined with an ozone injection method comprising a. The method of claim 1, The separation tank is installed upright in a position away from the bottom predetermined distance therein, the space compartment member for the raw water supplied from the outside to have a smooth flow and the downflow is formed Rainwater treatment system using a membrane separation that combines the ozone injection method further comprising. The method of claim 1, The filtration and cleaning means may include a filtration membrane module including a filter body having open both sides and a metal membrane provided on both sides of the filter body; A suction port provided in communication with an upper portion of the filter body, one end of which is connected to the permeate discharge means; And It is provided to be in communication with the lower portion of the filter medium to inject the ozone-containing gas of the ozone generating means into the filter medium Rainwater treatment system using membrane separation incorporating an ozone injection method comprising. The method of claim 3, The metal membrane has an effective filtration area of 0.12 m 2 on both sides and a membrane pore diameter of 0.2 μm. Rainwater treatment system using membrane separation combined with ozone injection method. The method of claim 3, The metal film is sintered by applying a powder of stainless steel to a gold mesh of stainless steel Rainwater treatment system using membrane separation combined with ozone injection method. The method of claim 1, The ozone-containing gas ejection means An diffuser connected to the ozone generating means and the first injection pipe to clean the outside of the filter medium; And Second injection pipe for injecting the ozone-containing gas supplied to the ozone generating means into the filtration membrane module Rainwater treatment system using a membrane separation combined with an ozone injection method comprising a. The method of claim 1, The ozone generating means is a rainwater treatment apparatus using a membrane separation combined with an ozone injection method comprising a plasma apparatus for converting the oxygen in the tool into ozone therein. The method according to claim 1 or 3, The permeate discharge means A suction pipe connected to a suction port of the filtration membrane module; And A suction pump installed on the suction pipe and sucking and discharging the permeated water on the upper part of the filtration membrane module, and maintaining the inside of the filtration membrane module at a negative pressure. Rainwater treatment system using a membrane separation incorporating ozone injection method comprising a. In the stormwater treatment method, A first step in which raw water is sucked into the filtration membrane module by a suction pump to perform solid-liquid separation in a state in which a filtration membrane module made of a metal membrane is installed in raw water in the separation tank; A second step of performing membrane cleaning by intermittently injecting ozone gas generated by an ozone generator into raw water sucked into the filtration membrane module; And A third step of ejecting the ozone gas generated by the ozone generator through the diffuser and cleaning the outer surface of the filtration membrane module by the bubbling; Excellent treatment method using a membrane separation combined with an ozone injection method comprising a. The method of claim 9, The first step is The rainwater flowing into the separation tank is impregnated with the slate plate installed upright in the separation tank to form a downflow sludge is settled, the contaminated water comprises a fourth step of rising to the filter membrane module side Rainwater treatment method using membrane separation combined with ozone injection method. The method of claim 9, The first step is And a fifth step of separating solids by lowering an internal pressure of the filtration membrane module whose position is maintained by a negative pressure provided from the suction pump to an external pressure. Rainwater treatment method using membrane separation combined with ozone injection method. The method of claim 9, The ozone gas generated by the ozone generator is supplied to the permeate side of the filtration membrane module to sterilize pathogenic microorganisms and protozoa, and to oxidize trace organics and endocrine disruptors. Rainwater treatment method using membrane separation combined with ozone injection method.