CN111925010A

CN111925010A - Cleaning process for water treatment system in insulating paperboard production

Info

Publication number: CN111925010A
Application number: CN202010776676.5A
Authority: CN
Inventors: 朱军; 李逢祥; 许桂娟
Original assignee: WEIFANG HUISHENG INSULATION TECHNOLOGY CO LTD
Current assignee: WEIFANG HUISHENG INSULATION TECHNOLOGY CO LTD
Priority date: 2020-08-05
Filing date: 2020-08-05
Publication date: 2020-11-13

Abstract

The invention discloses a cleaning process of a water treatment system in insulating paperboard production, which mainly comprises the steps of carrying out intermittent sterilization on a raw water pool through a first bactericide, intermittently adding a second bactericide between the raw water pool and a multi-medium filter, periodically cleaning the multi-medium filter and an activated carbon filter, periodically replacing a cartridge filter element of a security filter and cleaning a reverse osmosis membrane of a reverse osmosis system by sections by using different medicaments. The invention overcomes the defects of the cleaning process of each part element in the water treatment process at present, can effectively reduce the pressure difference before and after each component, improve the water production flow, ensure the normal performance of the system, prolong the operation period and the service life of each component and ensure that the water quality of the produced water meets the production requirements.

Description

Cleaning process for water treatment system in insulating paperboard production

Technical Field

The invention belongs to the technical field of water treatment and purification, and particularly relates to a cleaning process of a water treatment system in insulating paperboard production.

Background

In the production process of the insulating paperboard, in order to meet the insulating performance of the insulating paperboard, conductive ions such as calcium, magnesium and the like in production water need to be removed. At present, most of insulating paperboard manufacturers adopt water after a reverse osmosis pure water treatment system for production water.

The reverse osmosis pure water treatment system applies a membrane separation technology to remove charged ions, inorganic matters, colloidal particles, bacteria, organic matters and the like in water, and has the characteristics of small occupied area, low energy consumption, stable effluent quality and the like. The reverse osmosis membrane element is used as a core component of the whole reverse osmosis system and is high in price, the value of the reverse osmosis membrane element of the whole reverse osmosis system is about 30-50 ten thousand, and the service life is 3-5 years. In prior art water treatment operations, however, reverse osmosis membrane elements are contaminated with suspended or poorly soluble substances that may be present in the feed water, the most common of which are calcium carbonate scale, calcium sulfate scale, metal oxide scale, silicon deposits, and organic or biological deposits. The nature of the contaminants and the rate of contamination are dependent on the feed water conditions, and the contamination is slow to develop and, if not taken early, will impair the performance of the membrane element in a relatively short period of time. The method is characterized in that the water yield and the desalination rate of a system are reduced, and the membrane differential pressure is increased, wherein microbial pollution is a common problem of the reverse osmosis membrane, and particularly, the reverse osmosis membrane is frequently polluted and blocked due to poor turbidity of inlet water and insufficient sterilization measures.

Therefore, it is necessary to improve the water treatment process in the prior art, and especially to overcome the defects of the cleaning process of each component in the current water treatment process, so as to ensure that the reverse osmosis system can exert the normal efficiency thereof, prolong the operation period and the service life of the membrane, and enable the water quality of the produced water to meet the design requirements.

The invention content is as follows:

the technical problem to be solved by the invention is as follows: the cleaning process of the water treatment system in the production of the insulating paperboard is provided, the defects of the cleaning process of each part element in the existing water treatment process are overcome, the reverse osmosis system is ensured to exert the normal efficiency, the operation cycle and the service life of the membrane are prolonged, and the quality of produced water meets the design requirements.

The prior art has the following water treatment process:

clear water from a water treatment plant enters a raw water tank (if the water temperature exceeds 40 ℃, the clear water firstly enters a cooling tower for cooling), enters a multi-medium filter and an activated carbon filter under the action of water level pressure difference and a suction pump, a scale inhibitor is added into a pipeline behind the activated carbon filter, then enters two-stage security filters, is pressurized by a high-pressure water pump and enters an RO (reverse osmosis) device, and produced water is stored in a water production tank for use in a production plant. The cleaning and sterilizing process comprises the following steps: (1) continuously adding a bactericide into a raw water pool, (2) backwashing the multi-medium and activated carbon filter when the pressure difference between an inlet and an outlet exceeds 0.3Mpa, and (3) performing online chemical cleaning by using an online chemical cleaning device when the reverse pressure difference of a reverse osmosis membrane exceeds 0.3 Mpa. The specific process flow is shown in the attached figure 1 of the specification.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a cleaning process of a water treatment system in insulating paperboard production comprises the following steps:

a. sterilizing a raw water pool: the method comprises the following steps that a stainless steel blind pipe is arranged at the top of a raw water pool, the blind pipe is inserted below the water surface, a plurality of through holes are formed in the blind pipe at the underwater part, and a first bactericide is added through the blind pipe, is a composite non-oxidation bactericide and is a sterilization algicide compounded by quaternary ammonium salt and isothiazoline copper; adding the first bactericide into the raw water pool once every 12-36 hours from the blind pipe;

b. sterilizing by a dosing pump: a dosing pump is arranged on the raw water pool and the multi-media filter, a second bactericide is intermittently added to the water entering the multi-media filter, the second bactericide comprises the components of bromine and bromine compounds (including organic bromine, 2-dibromo-2-cyanoacetamide, bronopol and the like), and the second bactericide is added once every 2-6 hours, wherein the adding time is 3-7 minutes, and the adding amount is 2-4 ppm;

c. cleaning a multi-medium filter and an activated carbon filter: under the condition that the pressure difference is not more than 0.3Mpa, the multi-medium filter and the activated carbon filter are cleaned once every 10-20 days, backwashing is carried out by using water, and then washing is carried out by using water;

d. periodic replacement of cartridge filter elements: under the condition that the pressure difference is not more than 0.3Mpa, replacing the cartridge filter element every 3 months (replacing in time when the pressure difference suddenly appears within 3 months and exceeds 0.03 Mpa);

the safety filter can effectively intercept particulate matters directly larger than 5um in water after being treated by the multi-media and activated carbon filters, ensures that water entering a reverse osmosis system is clean and limpid, and reduces blockage and scratch of the reverse osmosis membrane. The cartridge filter element is replaced when the differential pressure of the cartridge filter exceeds 0.03MPa, and the cartridge filter element is replaced every 3 months, so that the hidden danger of reverse osmosis membrane blockage caused by incomplete water treatment after the filter element is blocked is reduced.

e. Cleaning a reverse osmosis system: and (3) segmenting a reverse osmosis membrane of a reverse osmosis system, dividing the reverse osmosis membrane into a reverse osmosis first section and a reverse osmosis second section, respectively cleaning the reverse osmosis first section and the reverse osmosis second section, respectively cleaning the reverse osmosis first section by using a first cleaning agent (alkali liquor), a second cleaning agent or a third cleaning agent according to a detection result when the pressure difference between the front and the back of the reverse osmosis system is more than or equal to 0.2Mpa, and cleaning the reverse osmosis second section by using a fourth cleaning agent.

Preferably, in the step a, the blind pipe is communicated to a first cleaning agent storage tank arranged outside the raw water pool through a metering pump; the aperture ratio of the blind pipe is 40 percent, the amount of the first cleaning agent added each time is 2ppm, and the time for adding the first cleaning agent is controlled to be sterilized once in 24 hours.

The first cleaning agent and water can be fully mixed by adopting an underwater intermittent bactericide adding mode, and the using amount of the bactericide is reduced; the bactericide formula is specially prepared aiming at the bacteria, fungi and algae in the water for producing the insulating paperboard, and has the advantages of high efficiency, broad spectrum, low toxicity, quick and lasting drug effect, strong permeability, permeation and stripping effect on microorganisms, colloidal sediments or slime, and small influence by the pH value in water.

Preferably, the first bactericide in the step a is a bactericidal algicide consisting of 20-30% of isothiazoline copper, 20-30% of quaternary ammonium salt compound and 50% of deionized water in percentage by mass.

Preferably, the second bactericide in step b is added once every 4 hours for 5 minutes at an amount of 3 ppm.

Preferably, the second bactericide in the step b is a bronopol bactericide.

Preferably, the interval time between the cleaning of the multi-media filter and the cleaning of the activated carbon filter in the step c is 15 days, if sudden pressure difference occurs and exceeds 0.3Mpa, the multi-media filter and the activated carbon filter are immediately cleaned when the pressure difference exceeds 0.3Mpa, and backwashing and then forward washing are carried out. The pollution blocking degree of a pretreatment system is reduced, suspended impurities, colloids, organic matters and the like in the system can be effectively removed, and the pollution of the reverse osmosis membrane by the impurities is reduced; meanwhile, a forward washing operation step is added, and forward washing operation is carried out on the pretreatment according to the operation flow of the equipment, so that suspended impurities, colloid, organic matters and the like remained in the system after backwashing are discharged out of the system, and secondary pollution of a subsequent system is reduced.

Further, the washing step of backwashing in the step c is as follows: 1. and (3) backwashing loose layers: opening the lower inlet valve, then opening the upper discharge valve, simultaneously opening a backwashing pump, and controlling the water inflow to be 2-3 times of the normal water inflow generally by adjusting a backwashing pump outlet valve or a filter lower inlet valve, wherein the layer loosening time is 2-5 min; after the layer loosening is finished, all valves and pumps are closed; 2. draining water: opening an exhaust valve and a lower exhaust valve, discharging water to a position 20-30 cm above a filter layer in the mechanical filter, and then closing the lower exhaust valve; 3. air scrubbing: keeping the exhaust valve and the upper discharge valve open, opening the exhaust valve of the Roots blower, and starting the Roots blower; then opening an air inlet valve of the sand filter, closing an exhaust valve of the Roots blower, and enabling the sand filter to enter an air scrubbing state; the air inlet pressure is 0.03-0.1 MPa, the air inlet amount is 18-20L/S.m 2, and the scrubbing time is 3-5 min; opening an exhaust valve of the Roots blower, closing an air inlet valve of the filter, then stopping the Roots blower, and then closing the exhaust valve of the Roots blower, and finishing air scrubbing; 4. large-flow backwashing: starting a backwashing pump, starting a water outlet valve, then starting a lower inlet valve, an upper exhaust valve and an exhaust valve of the sand filter, and starting another backwashing pump after one backwashing pump runs for 2-3 minutes in a backwashing mode, wherein the sand filter enters a large-flow backwashing state, and the backwashing flow is controlled at 15-16L/m 2 & s; after the backwashing time is 30 minutes, when the backwashing water is clear, stopping one backwashing pump, stopping the other backwashing pump after 3-5 minutes, then closing all valves on the filter, the backwashing pump and the water outlet valve, and ending the backwashing;

the forward washing steps are as follows: closing the lower inlet valve and the exhaust valve, opening the upper inlet valve and the lower exhaust valve, simultaneously opening the raw water pump, and starting the forward washing of the filter; the forward washing flow is the working flow, the forward washing time is generally 10-30 min, and when the SDI15 of the effluent is less than or equal to 4, the forward washing is finished, and the filter can be put into normal operation.

Preferably, the first cleaning agent (alkali liquor) in the step e is 0.1-0.3% NaOH solution with the temperature of 30-35 ℃ and the pH value of 10-12; the second cleaning agent is a mixed solution of 0.2-0.3% of sodium dodecyl benzene sulfonate, 0.5-1.5% of sodium tripolyphosphate and 1-3% of sodium carbonate in percentage by mass, wherein the temperature of the second cleaning agent is 30-35 ℃, and the pH value of the second cleaning agent is 10-12; the third cleaning agent is a mixed solution of 0.1-0.3% of NaClO, 0.6-1.0% of EDTA tetrasodium and 1-3% of sodium tripolyphosphate solution at the temperature of 30-35 ℃ and the pH value of 10-12 in percentage by mass; the fourth cleaning agent (acid liquid) is 0.1-0.3% hydrochloric acid solution with pH value of 3.

Wherein, the fourth cleaning agent (acid liquor) is mainly used for removing pollutants such as carbonate, metal oxide and the like, and the alkaline cleaning agent is mainly used for removing pollutants such as colloid, microorganisms and the like; the second cleaning agent is mainly used for cleaning pollutants such as colloid, microorganisms and organic matters, and the third cleaning agent is mainly used for cleaning pollutants such as microorganisms, organic matter sediment, fungi and sulfate. Because the cleaning agent is specially prepared aiming at different pollutants, the cleaning effect is better.

Further, in the step e, the cleaning time of the fourth cleaning agent (acid liquor) is 30-60 minutes, and the flow rate is 20-30 m³The flushing pressure is 0.2-0.3 Mpa; the time is 30 to 60 minutes, and the flow of the first cleaning agent (alkali liquor) is 20 to 30m³The flushing pressure is 0.2-0.3 Mpa; the cleaning time of the second cleaning agent is 30-50 minutes, and the cleaning flow is 25-30 m³The flushing pressure is 0.2-0.3 Mpa; the cleaning time of the third cleaning agent is 30-50 minutes, and the cleaning flow is 25-30 m³The flushing pressure is 0.2-0.3 MPa.

Further, the cleaning time of the fourth cleaning agent (acid liquor) in the step e is 45 minutes, and the flow rate is 25m³H, the flushing pressure is 0.25 Mpa; the cleaning time of the first cleaning agent (alkali liquor) is 45 minutes, and the flow rate is 25m³H, the flushing pressure is 0.25 Mpa; the cleaning time of the second cleaning agent is 40 minutes, and the cleaning flow is 28m³H, the flushing pressure is 0.25 Mpa; the cleaning time of the third cleaning agent is 40 minutes, and the cleaning flow is 28m³The flushing pressure is 0.25 MPa.

Due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. the invention adopts the mode of adding the bactericide intermittently underwater, can realize the full mixing of the bactericide and water, and reduces the using amount of the bactericide, and because the adopted bactericide is prepared by specially aiming at the water treatment in the production of the insulating paperboard, the invention has the effects of high efficiency, broad spectrum, low toxicity, quick and lasting pesticide effect, strong permeability, good treatment effect, low using amount, safety, environmental protection and cost reduction;

2. the invention adds the dosing pump between the original pool and the multi-medium filter for sterilization, and the intermittent addition of the dosing pump can be utilized to intermittently sterilize the multi-medium and active carbon filters, because the pesticide effect of the bactericide has certain timeliness and can still reach 92.74 percent within 48 hours, the bactericide is added in a timed, quantitative and intermittent manner during the operation; the sterilization and inhibition effects on bacteria and mould in the system are achieved, and the use cost is reduced while the sterilization effect is met;

3. the multi-medium filter and the activated carbon filter are cleaned regularly, so that the pollution blocking degree of a pretreatment system is reduced, suspended impurities, colloids, organic matters and the like in the system can be effectively removed, and the phenomenon that the reverse osmosis membrane is polluted by the part of impurities is reduced; meanwhile, a forward washing operation step is added, and forward washing operation is carried out on the pretreatment according to the operation flow of the equipment, so that suspended impurities, colloid, organic matters and the like remained in the system after backwashing are discharged out of the system, and secondary pollution of a subsequent system is reduced;

4. the invention changes the cleaning of the reverse osmosis system from the simultaneous cleaning in the prior art into the reverse osmosis first-stage and reverse osmosis second-stage segmented individual cleaning, and carries out on-line chemical cleaning when the differential pressure of the reverse osmosis system is changed from more than or equal to 0.3Mpa to more than or equal to 0.2Mpa in the prior art, thereby eliminating pollutants as early as possible and ensuring a smoother water treatment process; and the prior art is changed from pure acid washing and alkali washing into cleaning by selecting different cleaning agents according to different pollutant types; the secondary pollution of pollutants dissolved in cleaning liquid to a reverse osmosis system in the cleaning process can be reduced by the sectional flushing, because the pollutants in the first reverse osmosis section are mainly bacteria and organic matters, and the pollutants in the second reverse osmosis section are mainly inorganic salts, the pollutants are dissolved in the cleaning liquid in the cleaning process, the cleaning liquid circulates in the whole system, part of organic pollutants can pollute the reverse osmosis membrane in the second reverse osmosis section, and meanwhile, part of inorganic pollutants can also pollute the reverse osmosis membrane in the first reverse osmosis section; different cleaning agents clean different pollutants more thoroughly, and after the reverse osmosis first section and the reverse osmosis second section are cleaned separately, the reverse osmosis first section only needs to be washed by alkali or cleaned by corresponding cleaning agents, and the reverse osmosis second section only needs to be washed by acid or cleaned by corresponding cleaning agents.

In a word, the invention carries out corresponding cleaning in a targeted manner by different pollutant types, components and polluted parts, can effectively reduce the pressure difference between the front and the back of each component, improves the flow of produced water, ensures the normal performance of a system, prolongs the operation cycle and the service life of each component, and ensures that the quality of the produced water meets the production requirement.

Drawings

FIG. 1 is a prior art water treatment process of the present invention.

Detailed Description

The technical solution of the present invention is further described below with reference to examples:

the first embodiment is as follows:

a. sterilizing a raw water pool: the method comprises the following steps that a stainless steel blind pipe is arranged at the top of a raw water pool, the blind pipe is inserted below the water surface, a plurality of through holes are formed in the blind pipe at the underwater part, and a first bactericide is added through the blind pipe, wherein the first bactericide is 25% of quaternary ammonium salt compound, 25% of isothiazoline copper and 50% of deionized water in percentage by mass; adding the first bactericide into the raw water pool from the blind pipe once every 24 hours;

b. sterilizing by a dosing pump: a dosing pump is arranged on the raw water pool and the multi-media filter, a second bactericide is intermittently added to the water entering the multi-media filter, the component of the second bactericide is organic bromine, the second bactericide is added every 4 hours, the adding time is 5 minutes, and the adding amount is 3 ppm;

c. cleaning a multi-medium filter and an activated carbon filter: under the condition that the differential pressure is not more than 0.3Mpa, the multi-medium filter and the activated carbon filter are cleaned once every 15 days, firstly, backwashing is carried out by water, and then, washing is carried out by water (the specific cleaning process refers to the technical scheme part in the invention);

d. periodic replacement of cartridge filter elements: under the condition that the pressure difference is not more than 0.3Mpa, replacing the cartridge filter element every 3 months;

e. cleaning a reverse osmosis membrane: the method comprises the steps of detecting a reverse osmosis membrane element when the pressure difference between the front and the back of a reverse osmosis membrane is larger than or equal to 0.2Mpa, finding out that slime (mainly including bacteria, nematodes and excretion products thereof) and partial microbial pollution exist at an end cover of the reverse osmosis membrane and inorganic salt (carbonate, sulfate and the like) pollution exists at a reverse osmosis second-stage membrane, and carrying out chemical cleaning on a reverse osmosis system. The specific cleaning is as follows: the alkaline washing is to circularly wash the fabric for 1 hour by using NaOH solution with the pH value of 11, keep the pH value at 10-12 and the temperature at 30 ℃, circularly wash the fabric for 1 hour by adopting an intermittent circulation method, and repeatedly wash the fabric by soaking for 2 hours. The cleaning end point of the first cleaning agent is that the color of the cleaning solution is not changed and the PH value is not changed any more. After the first cleaning agent is cleaned, the cleaning liquid in the system is washed by deionized water, the washing time is 25-30 minutes, and the pH value of produced water is detected to be about 7; the pickling is to use hydrochloric acid with the pH value of 2-3 and the temperature of 30 ℃ to perform cyclic cleaning for 1 hour by adopting an intermittent cyclic method and to perform reciprocating cyclic cleaning for 1 hour by soaking. And the fourth cleaning end point is that the color of the cleaning liquid is not changed and the pH value is not changed. And after the fourth cleaning agent is cleaned, the cleaning agent in the system is washed by the deionized water, the washing time is 25-30 minutes, the washing effect is subject to the qualification of the pH value of the conductivity and the concentrated water side, and the concentrated water is detected according to the following conditions before the washing is stopped: the difference between the pH value of the concentrated water and the pH value of the inlet water is within 1; the difference between the conductivity of the concentrated water and the conductivity of the inlet water is less than 100%; the concentrated water has no foam. If the three conditions are all met, the cleaning is finished, and the system can be started normally.

The indexes cleaned by the method can be compared with the corresponding processing indexes in the prior art from the following table:

TABLE 1 reverse osmosis membrane influent SDI value and influent turbidity

Item	Reverse osmosis system inlet water SDI value	Inlet water turbidity of reverse osmosis system
			Prior Art	3.8/3.6	1.0/1.1
Step c No front washing	1.8/1.5	0.5/0.5
			Step c performing a main wash	0.8/1.0	0.2/0.18

TABLE 2 colony count assay

As can be seen from the colony count measurement in the prior art, when the colony count of the water in the raw water pool reaches the reverse osmosis membrane, the number of microorganisms is increased because of impurities contained in the water, so that the treatment load of the reverse osmosis membrane is increased; however, the process adds the bactericide for sterilization, and the corresponding microbial quantity is linearly reduced in the whole treatment process.

TABLE 3 comparison of cleaning results

Example two:

a. sterilizing a raw water pool: the method comprises the following steps that a stainless steel blind pipe is arranged at the top of a raw water pool, the blind pipe is inserted below the water surface, a plurality of through holes are formed in the blind pipe at the underwater part, and a first bactericide is added through the blind pipe, wherein the first bactericide is a quaternary ammonium salt compound accounting for 20% of the mass percentage, isothiazoline copper accounting for 30% of the mass percentage and deionized water accounting for 50% of the mass percentage; adding the first bactericide into the raw water pool from the blind pipe once every 24 hours;

b. sterilizing by a dosing pump: a dosing pump is arranged on the raw water pool and the multi-media filter, a second bactericide is intermittently added to the water entering the multi-media filter, the component of the second bactericide is 2, 2-dibromo-2-cyanoacetamide, the second bactericide is added once every 4 hours, the adding time is 5 minutes, and the adding amount is 3 ppm;

e. cleaning a reverse osmosis membrane: and (3) respectively cleaning the reverse osmosis first section and the reverse osmosis second section, respectively detecting the reverse osmosis first section and the reverse osmosis second section when the pressure difference between the front and the back of the reverse osmosis membrane is more than or equal to 0.2Mpa, wherein the detection result shows that microorganisms and organic matters on the reverse osmosis first section are precipitated and have higher colloid content, and the reverse osmosis second section has higher inorganic salt content, so that the reverse osmosis first section is cleaned by adopting a second cleaning agent, and the reverse osmosis second section is cleaned by adopting a fourth cleaning agent. The specific cleaning is as follows: when the second cleaning agent is used for cleaning, 2.5 kg of solid sodium dodecyl benzene sulfonate solid, 10 kg of solid sodium tripolyphosphate and 20 kg of solid sodium carbonate are slowly added into a cleaning tank according to each ton of water, the solid sodium dodecyl benzene sulfonate solid, the solid sodium tripolyphosphate and the solid sodium carbonate are thoroughly stirred and dissolved, NaOH is added to adjust the pH value of the cleaning liquid to be 11, the cleaning liquid is heated to 30-35 ℃, an intermittent circulation method is adopted for circulation for 1 hour, and the cleaning liquid is soaked for 2 hours for reciprocating circulation cleaning. The cleaning end point of the second cleaning agent is that the color of the cleaning solution is not changed and the pH value is not changed. After the second cleaning agent is cleaned, the cleaning liquid in the system is washed by deionized water, the washing time is 25-30 minutes, and the pH value of produced water is detected to be about 7;

and the fourth cleaning agent is used for cleaning by using hydrochloric acid with the pH value of 2-3 and the temperature of 30 ℃ and adopting an intermittent circulation method to circulate for 1 hour, and soaking for 1 hour to perform reciprocating circulation cleaning. The cleaning end point of the fourth cleaning agent is that the color of the cleaning solution is not changed and the pH value is not changed. And after the fourth cleaning agent is cleaned, the cleaning agent in the system is washed by the deionized water, the washing time is 25-30 minutes, the washing effect is subject to the qualification of the pH value of the conductivity and the concentrated water side, and the concentrated water is detected according to the following conditions before the washing is stopped: the difference between the pH value of the concentrated water and the pH value of the inlet water is within 1; the difference between the conductivity of the concentrated water and the conductivity of the inlet water is less than 100%; the concentrated water has no foam. If the three conditions are all met, the cleaning is finished, and the system can be started normally.

The indexes cleaned by the method can be obtained from the following table:

TABLE 4 reverse osmosis membrane influent SDI value and influent turbidity of the process

Item	Reverse osmosis system inlet water SDI value	Inlet water turbidity of reverse osmosis system
			Step c No front washing	1.8/1.5	0.5/0.5
Step c performing a main wash	0.8/1.0	0.2/0.18

TABLE 5 determination of the number of colonies in the Process

TABLE 6 cleaning Effect of the Process

Example three:

a. sterilizing a raw water pool: the method comprises the following steps that a stainless steel blind pipe is arranged at the top of a raw water pool, the blind pipe is inserted below the water surface, a plurality of through holes are formed in the blind pipe at the underwater part, and a first bactericide is added through the blind pipe, wherein the first bactericide is a quaternary ammonium salt compound accounting for 30% of the mass ratio, isothiazoline copper accounting for 20% of the mass ratio and deionized water accounting for 50% of the mass ratio; adding the first bactericide into the raw water pool from the blind pipe once every 24 hours;

b. sterilizing by a dosing pump: a dosing pump is arranged on the raw water pool and the multi-medium filter, a second bactericide is intermittently added to the water entering the multi-medium filter, the component of the second bactericide is bronopol, the second bactericide is added every 4 hours, the adding time is 5 minutes, and the adding amount is 3 ppm;

e. cleaning a reverse osmosis membrane: and (3) respectively cleaning the reverse osmosis first section and the reverse osmosis second section, respectively detecting the reverse osmosis first section and the reverse osmosis second section when the pressure difference between the front and the back of the reverse osmosis membrane is more than or equal to 0.2Mpa, wherein the detection result shows that microorganisms and organic matters are precipitated and the colloid content on the reverse osmosis first section membrane is higher, and the inorganic salt content on the reverse osmosis second section membrane is higher, so that the reverse osmosis first section is cleaned by adopting a third cleaning agent, and the reverse osmosis second section is cleaned by adopting a fourth cleaning agent. The specific cleaning is as follows: when the third cleaning agent is used for cleaning, 2 kg of solid sodium hypochlorite, 8 kg of solid EDTA tetrasodium and 20 kg of sodium tripolyphosphate are slowly added into the cleaning tank according to each ton of water, the solid sodium hypochlorite and the solid EDTA tetrasodium are thoroughly stirred and dissolved, NaOH is added to adjust the pH value of the cleaning liquid to 11, the cleaning liquid is heated to 30-35 ℃, an intermittent circulation method is adopted for circulation for 1 hour, and the cleaning liquid is soaked for 2 hours for reciprocating circulation cleaning. The alkali wash end point is that the color of the cleaning liquid does not change and the pH value does not change. Washing the cleaning liquid in the system with deionized water after the alkali washing is finished, wherein the washing time is 25-30 minutes, and the pH value of the produced water is detected to be about 7; the fourth cleaning agent is used for cleaning, hydrochloric acid with the pH value of 2-3 and the temperature of 30 ℃ is used, an intermittent circulation method is adopted for circulation for 1 hour, and the fourth cleaning agent is used for soaking for 1 hour for reciprocating circulation cleaning. The cleaning end point of the fourth cleaning agent is that the color of the cleaning solution is not changed and the pH value is not changed. And after the fourth cleaning agent is cleaned, the cleaning agent in the system is washed by the deionized water, the washing time is 25-30 minutes, the washing effect is subject to the qualification of the pH value of the conductivity and the concentrated water side, and the concentrated water is detected according to the following conditions before the washing is stopped: the difference between the pH value of the concentrated water and the pH value of the inlet water is within 1; the difference between the conductivity of the concentrated water and the conductivity of the inlet water is less than 100%; the concentrated water has no foam. If the three conditions are all met, the cleaning is finished, and the system can be started normally.

The indexes cleaned by the method can be obtained from the following table:

TABLE 7 reverse osmosis membrane influent SDI value and influent turbidity of the process

TABLE 8 determination of the number of colonies in this procedure

TABLE 9 cleaning Effect of the Process

Reverse osmosis system	Before cleaning	After cleaning, cleaning	Phase difference
				System water inlet pressure (Mpa)	1.37	1.17	0.20
System concentrated water pressure (Mpa)	1.11	1.07	0.04
				Pressure difference of system water inlet and concentrated water (Mpa)	0.26	0.10	0.16
Salt rejection (%)	95.3	98.6	3.3
				Water flow (m3/h)	35	51	16

It can be seen from the above embodiments that after the process is implemented, the pressure of the raw water pump is stabilized at 0.30Mpa, the pressure drop phenomenon caused by the pollution and blockage of the pretreatment system does not occur, the pressure difference between the cartridge filter and the reverse osmosis membrane at one section is less than 0.25Mpa, the reverse osmosis water production flow is stably increased, bacterial colonies at each section of the system are inhibited, and the bacterial colonies in the raw water pool and the water production pool are obviously reduced.

It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Claims

1. A cleaning process for a water treatment system in insulating paperboard production is characterized by comprising the following steps:

a. sterilizing a raw water pool: the method comprises the following steps that a stainless steel blind pipe is arranged at the top of a raw water pool, the blind pipe is inserted below the water surface, a plurality of through holes are formed in the blind pipe at the underwater part, and a first bactericide is added through the blind pipe, is a composite non-oxidation bactericide and is a sterilization algicide compounded by quaternary ammonium salt and isothiazoline copper; adding the first bactericide into the raw water pool once from the blind pipe every 12-36 hours;

b. sterilizing by a dosing pump: a dosing pump is arranged on the raw water pool and the multi-media filter, a second bactericide is intermittently added to water entering the multi-media filter, the ingredients of the second bactericide are bromine and bromine compounds, the bromine and bromine compounds comprise organic bromine, 2-dibromo-2-cyanoacetamide or bronopol, and the second bactericide is added once every 2-6 hours, the adding time is 3-7 minutes, and the adding amount is 2-4 ppm;

c. cleaning a multi-medium filter and an activated carbon filter: under the condition that the pressure difference is not more than 0.3Mpa, respectively cleaning the multi-medium filter and the activated carbon filter once every 10-20 days, firstly backwashing by using water, and then washing by using water;

e. cleaning a reverse osmosis system: and (3) segmenting a reverse osmosis membrane of the reverse osmosis system into a reverse osmosis first segment and a reverse osmosis second segment, respectively washing the reverse osmosis first segment with a first cleaning agent, a second cleaning agent or a third cleaning agent according to a detection result when the front-back differential pressure of the reverse osmosis system is more than or equal to 0.2Mpa, and washing the reverse osmosis second segment with a fourth cleaning agent.

2. The cleaning process for a water treatment system in the production of insulating paper boards according to claim 1, characterized in that: in the step a, the blind pipe is communicated with a first cleaning agent storage tank arranged outside the raw water pool through a metering pump; the aperture ratio of the blind pipe is 40 percent, the amount of the first cleaning agent added each time is 2ppm, and the time for adding the first cleaning agent is controlled to be sterilized once in 24 hours.

3. The cleaning process for a water treatment system in the production of insulating paper boards according to claim 1, characterized in that: the first bactericide in the step a is a bactericidal algicide consisting of 20-30% of isothiazoline copper, 20-30% of quaternary ammonium salt compound and 50% of deionized water in percentage by mass.

4. The cleaning process for a water treatment system in the production of insulating paper boards according to claim 1, characterized in that: and the second bactericide in the step b is a bronopol bactericide.

5. The cleaning process for a water treatment system in the production of insulating paper boards according to claim 1, characterized in that: and c, cleaning the multi-medium filter and the activated carbon filter at an interval of 15 days, and if sudden pressure difference exceeds 0.3Mpa, immediately cleaning the multi-medium filter and the activated carbon filter when the pressure difference exceeds 0.3Mpa, and performing backwashing and then forward cleaning.

6. The cleaning process for a water treatment system in the production of insulating paper boards according to claim 1, characterized in that: the first cleaning agent (alkali liquor) in the step e is 0.1-0.3% NaOH solution with the temperature of 30-35 ℃ and the pH value of 10-12; the second cleaning agent is a mixed solution of 0.2-0.3% of sodium dodecyl benzene sulfonate, 0.5-1.5% of sodium tripolyphosphate and 1-3% of sodium carbonate in percentage by mass, wherein the temperature of the second cleaning agent is 30-35 ℃, and the pH value of the second cleaning agent is 10-12; the third cleaning agent is a mixed solution of 0.1-0.3% of NaClO, 0.6-1.0% of EDTA tetrasodium and 1-3% of sodium tripolyphosphate solution at the temperature of 30-35 ℃ and the pH value of 10-12 in percentage by mass; the fourth cleaning agent (acid liquid) is 0.1-0.3% hydrochloric acid solution with pH value of 3.

7. Cleaning of water treatment system in insulating board production according to claim 6The process is characterized in that: in the step e, the cleaning time of the fourth cleaning agent is 30-60 minutes, and the flow is 20-30 m³The flushing pressure is 0.2-0.3 Mpa; the time is 30-60 minutes, and the flow of the first cleaning agent is 20-30 m³The flushing pressure is 0.2-0.3 Mpa; the cleaning time of the second cleaning agent is 30-50 minutes, and the cleaning flow is 25-30 m³The flushing pressure is 0.2-0.3 Mpa; the cleaning time of the third cleaning agent is 30-50 minutes, and the cleaning flow is 25-30 m³The flushing pressure is 0.2-0.3 MPa.