CN101323469A - Electrocoagulation sea water pretreatment - Google Patents
Electrocoagulation sea water pretreatment Download PDFInfo
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- CN101323469A CN101323469A CNA2007100576105A CN200710057610A CN101323469A CN 101323469 A CN101323469 A CN 101323469A CN A2007100576105 A CNA2007100576105 A CN A2007100576105A CN 200710057610 A CN200710057610 A CN 200710057610A CN 101323469 A CN101323469 A CN 101323469A
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- seawater
- sea water
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- turbidity
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Abstract
The invention relates to a novel reverse-osmosis seawater desalinization pre-processing method, namely an electro-coagulation method. When DC is switched on, high-pure aluminum plates or iron plates are adopted as electrodes to directly electrolyze sea water, and aluminum hydroxide or iron hydroxide floc units generated in electrolysis agglomerates the suspended matters, microorganisms and organic matters, etc. in seawater so as to reach the purpose of reducing seawater turbidity, SDI, COD and microorganisms, etc. Simultaneously, hydrogen can be obtained. The high-effective coagulant aid is added to enhance the settling speed of hydroxide floc units. The invention provides a novel method and a simple process, and the reaction condition of the invention is mild and can be controlled easily. The method of the invention can profoundly promote the comprehensive exploitation to seawater, and the meaning of the theory and practice is significant and the invention can bring revolutionary changes to the seawater desalinization technology.
Description
Technical field
The invention belongs to sea water desaltination preconditioning technique field, designed a kind of method pre-treating seawater that adopts electrocoagulation especially.
Background technology
The mankind face serious fresh water problem in short supply in 21 century, and water resources lacks has become the significant problem that is related to poverty, Sustainable development and even international peace and security.Therefore sea water desaltination more and more comes into one's own, and utilizes desalination technology potable water from seawater, has become a kind of important means that people obtain fresh water.The present main method for desalting seawater that adopts in the world, comprise in multistage flash evaporation (MSF), multiple-effect evaporation (MED), the reverse osmosis (RO), the RO technology because of its have less investment, easy to operate, the construction period is short, floor space is little etc., and advantage obtains using comparatively widely, find that in existing statistics the ratio that the RO method is occupied has the trend that increases year by year in desalination technology, seawater reverse osmosis saturating (SWRO) will be main method for desalting seawater in the sea water desaltination market of 21 century.Yet, guarantee that reverse osmosis unit can move steadily in the long term, be vital to water pretreatment.
Cohesion in the sea water preprocessing is meant that coagulating agent or flocculation agent are mixed with water and makes the process of elimination of colloid stability, flocculation, what purpose was to change colloid, suspended substance, solute, bacterium and other microorganism etc. in the former seawater exists character and state, promptly precipitate, filter the particle of removing, to reach the purpose of brine disposal in conjunction with generating big can passing through.Coagulating agent commonly used has Tai-Ace S 150 (Al
2(SO
4)
314H
2O), polymerize aluminum chloride ([Al
2(OH)
n(Cl)
6-n]), iron trichloride (FeCl
36H
2O) and ferrous sulfate (FeSO
47H
2O) etc.
Electrochemical techniques have been widely used in the middle of the processing of trade effluent and sanitary wastewater as a kind of treatment process of strong to various wastewater treatment adaptability, efficient, non-secondary pollution.As far back as 1887, electrochemical process just was used for feedwater and wastewater treatment.By 1963, the American handled municipal wastewater with electrocoagulation.1974, the someone adopted electrocoagulation to handle food wastewater, 1984, the electrocoagulation that moving is grown up has studied tap water is handled, be that electrolytic ion causes coagulation (electrocoagulation), produce tap water subsequently after filtration, become the water treatment method that is different from traditional coagulation process.They studied current density and aluminium consumption relation, handle the concentration of residual Al in the water of back and, point out that electrocoagulation is applicable to small-sized water treatment plant the removal effect of soil ulmin.Up to now, electrocoagulation has developed into the new water technology that merits attention and trust through semicentennial research.
Summary of the invention
Electrocoagulation claims the electricity flocculation again, is exactly under the external voltage effect, utilizes soluble anodes such as iron or aluminium to produce a large amount of positively charged ions, and former seawater is carried out coagulative precipitation.Metal electrode (as iron) is placed processed seawater, pass to direct current then, iron ion hydrolysis in water, polymerization that metal anode generation this moment oxidizing reaction produces generate a series of multinuclear hydrolysates and a cohesion, and its process and mechanism and chemical coagulation process are basic identical.
Anodic oxidation: Fe → Fe
2++ 2e
Fe→Fe
3++3e
Cathodic reduction: 2H
2O+2e → H
2+ 2OH
-
Total reaction is: Fe+2H
2O → Fe (OH)
2+ H
2
4Fe+10H
2O+O
2→4Fe(OH)
3+4H
2
Simultaneously, the hydrogen of the nascent state that in the electrocoagulation device, produces on the negative electrode, its reducing power is very strong, can play reduction reaction with the pollutent in the seawater, or generates hydrogen.Also have oxygen and emit on anode, hydrogen and oxygen occur with the form of microbubble, and in water treatment procedure, contact and can obtain good adhesion property with suspended particle, thus raising sea water preprocessing efficient.
In addition, under the effect of electric current, the partial organic substances in the waste water may be decomposed into low molecule organic matter, also might directly be oxidized to CO
2And H
2O and do not produce mud.Not by the organism of exhaustive oxidation partly also can with suspended solids by Al (OH)
3Adsorption-condensation also drives float downward at hydrogen and oxygen and separates.In a word, the former seawater of electrocoagulation pre-treatment is the synergy of various procedures, and pollutent easily is removed under these effects.
This law is carried out pre-treatment to seawater and mainly be may further comprise the steps:
(1) medicine adds: directly add polyacrylamide (PAM) 1～2mg/L in seawater;
(2) electrolytic reaction: the parallel placement of aluminium flake or iron plate takes acyclic type to connect as electrode, and energising is stirred simultaneously;
(3) standing sedimentation: left standstill 0.5 hour, supernatant liquid is through pretreated seawater, lower floor is ironic hydroxide or aluminium hydroxide flocs unit, this flocs unit has condensed the suspended substance in the seawater, microorganism, organic matter etc., thereby reaches the purposes such as turbidity, sludge density index (SDI) (SDI), chemical oxygen demand (COD) and content of microorganisms that reduce seawater.
In the method for above-mentioned electrocoagulation sea water preprocessing, the seawater after the processing can be used for sea water desaltination, direct seawater utilization and relevant salt manufacturing industry.
Description of drawings
Fig. 1 is an electrocoagulation sea water pre-treatment electrolysis reaction device of the present invention.
1, crystal current stabilizer 2, magnetic stirring apparatus 3, iron stand
4, electrode 5, beaker 6, magneton 7, lead
Specific embodiments
This enforcement is convenient to that applied seawater is a simulated seawater in the work, water body turbidity 40.0NTU～60.0NTU, so when adopting reverse osmosis membrane to desalinate processing, need be reductions such as turbidity, prevent to stop up reverse osmosis membrane, make film forming frequent replacing and influence the normal operation of sea water desaltination.Particularly important based on this because of, the pretreatment process of sea water desaltination provided by the present invention and device thereof.
The present embodiment system thinking electrolysis time, electric current, pH value, distance between plates from etc. factor to the influence of electrocoagulation, found optimum reaction conditions.Therefrom drawn the advantage of electrocoagulation technology, promptly relative other technologies of electrocoagulation technology have advantages such as adaptability is strong, treatment effect good, equipment is simple, easy to operate, and need not add any chemical agent, and it is little to consume energy.
Example one
Get 4 parts of former seawater water water samples (turbidity is 45.2NTU), every part is 500mL, be electrolysis 20min under the condition of 0.25A, 0.50A, 0.75A, 1.00A at electric current respectively, (pH is 8.29) got supernatant liquor and surveyed its turbidity, SDI value and calculating turbidity removal rate after reaction finishes.Test-results is as shown in table 1.
Table 1 strength of current is to the influence of reverse osmosis sea water preprocessing effect
| The test sequence number | 1 | 2 | 3 | 4 |
| Strength of current/A | 0.25 | 0.50 | 0.75 | 1.00 |
| Residual turbidity/NTU | 0.86 | 0.45 | 0.16 | 0.11 |
| Turbidity removal rate/% | 98.09 | 99.00 | 99.65 | 99.76 |
Can find out that from table 1 turbidity removal effect to seawater when strength of current is 1.00A is better.
Example two
Get 6 parts of former seawater samples (turbidity is 46.7NTU), the water yield is the same, transfers its pH to be respectively 4,6,7,8,10,12, is that 0.5A, rotating speed are to react 20min under the condition of middling speed at electric current, reaction is got supernatant liquor after finishing, and surveys its turbidity, SDI value and calculates its turbidity removal rate.Test-results is as shown in table 2.
Table 2pH value is to the influence of reverse osmosis sea water preprocessing effect
| The test sequence number | 1 | 2 | 3 | 4 | 5 | 6 |
| The |
4 | 6 | 7 | 8 | 10 | 12 |
| Residual turbidity/NTU | 0.69 | 0.4 | 0.24 | 0.55 | 0.9 | 1.05 |
| Turbidity removal rate/% | 98.52 | 99.14 | 99.49 | 98.82 | 98.07 | 97.75 |
Can find out that from table 2 turbidity removal effect to seawater when the pH value is 7 left and right sides is better.
Example three
Attempt to shorten electrolysis time, thereby reduce power consumption by adding coagulant aids.Selecting polyacrylamide PAM, cationic PAM respectively for use is coagulant aids, and test-results is as shown in table 3.Former turbidity of sea water 46.7NTU.
Table 3 coagulant aids is to the influence of reverse osmosis sea water preprocessing effect
| The test sequence number | 1 | 2 | 3 |
| The coagulant aids situation | Do not add PAM | Add PAM | Add cationic PAM |
| Residual turbidity/NTU | 0.47 | 0.05 | 0.27 |
| Turbidity removal rate/% | 98.99 | 99.89 | 99.42 |
Can find out that from table 3 it is better to the turbidity removal effect of seawater to add PAM.
Example four
Get 7 parts of former seawater water water samples (turbidity is 48.7NTU), the water yield is the same to be tested under electrolysis time is the condition of 1min, 5min, 10min, 20min, 30min, 40min respectively, (pH is 8.29) got supernatant liquor and surveyed its turbidity, SDI value and calculate turbidity removal rate after reaction finishes.It is as shown in the table for test-results.
Table 4 electrolysis time is to the influence of reverse osmosis sea water preprocessing effect
| The test sequence number | 1 | 2 | 3 | 4 | 5 | 6 |
| Electrolysis time/min | 1 | 5 | 10 | 20 | 30 | 40 |
| Residual turbidity/NTU | 6.25 | 2.41 | 1.18 | 0.86 | 0.43 | 0.16 |
| Turbidity removal rate/% | 87.17 | 95.05 | 97.58 | 98.23 | 99.12 | 99.67 |
Can find out that from table 4 turbidity removal effect to seawater when electrolysis time is 40 minutes is better.
Example five
Get 4 parts of former seawater water water samples (turbidity 50.5NTU), the water yield is the same, tests under pole span is the condition of 0.5cm, 1cm, 2cm, 3cm respectively, and (pH is 8.29) got supernatant liquor and surveyed its turbidity, SDI value and calculating turbidity removal rate after reaction finishes.It is as shown in the table for test-results.
Table 5 pole span is to the influence of reverse osmosis sea water preprocessing effect
| The test sequence number | 1 | 2 | 3 | 4 |
| Pole span/cm | 0.5 | 1 | 2 | 3 |
| Residual turbidity/NTU | 0.43 | 0.71 | 0.89 | 1.02 |
| Turbidity removal rate/% | 99.15 | 98.59 | 98.24 | 97.98 |
Can find out that from table 5 turbidity removal effect to seawater when pole span is 0.5cm is better.
Claims (5)
1, electrocoagulation is the pretreated novel method of a kind of sea water desaltination, and its feature may further comprise the steps:
(1) medicine adds: directly add polyacrylamide (PAM) 1～2mg/L in seawater;
(2) electrolytic reaction: the parallel placement of aluminium flake or iron plate takes acyclic type to connect as electrode, and energising is stirred simultaneously;
(3) standing sedimentation: left standstill 0.5 hour, supernatant liquid is through pretreated seawater.
2, as the method for right 1 described electrocoagulation to sea water preprocessing, it is characterized in that: used coagulant aids is polyacrylamide (PAM), and add-on is 1～2mg/L;
3, as the method for right 1 described electrocoagulation to sea water preprocessing, it is characterized in that: electrode used therein is highly purified aluminium or iron plate, takes acyclic type to connect;
4, as the method for right 1 described electrocoagulation to sea water preprocessing, it is characterized in that: used stirring is a magnetic agitation, and stirring velocity is 20～200r/min;
5, as described in the right 1,2,3,4, pretreated seawater can be used for sea water desaltination, direct seawater utilization and relevant salt manufacturing industry.
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|---|---|---|---|
| CNA2007100576105A CN101323469A (en) | 2007-06-13 | 2007-06-13 | Electrocoagulation sea water pretreatment |
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|---|---|---|---|
| CNA2007100576105A CN101323469A (en) | 2007-06-13 | 2007-06-13 | Electrocoagulation sea water pretreatment |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102476881A (en) * | 2010-11-30 | 2012-05-30 | 通用电气公司 | Treatment method and device of oil-containing wastewater |
| CN106115856A (en) * | 2016-07-27 | 2016-11-16 | 温州泓呈祥科技有限公司 | A kind of weak electric pulse activation chilling reunion desalination reactor processing industrial wastewater |
| CN108996622A (en) * | 2018-07-19 | 2018-12-14 | 江苏京源环保股份有限公司 | A kind of electric flocculation processing method under the conditions of low turbidity water quality |
| CN113233548A (en) * | 2021-03-25 | 2021-08-10 | 上海应用技术大学 | Electrochemical-supported chloride ion capturing method and device |
-
2007
- 2007-06-13 CN CNA2007100576105A patent/CN101323469A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102476881A (en) * | 2010-11-30 | 2012-05-30 | 通用电气公司 | Treatment method and device of oil-containing wastewater |
| CN106115856A (en) * | 2016-07-27 | 2016-11-16 | 温州泓呈祥科技有限公司 | A kind of weak electric pulse activation chilling reunion desalination reactor processing industrial wastewater |
| CN106115856B (en) * | 2016-07-27 | 2018-12-07 | 杭州绿一环保技术有限公司 | It is a kind of handle industrial wastewater weak electric pulse activation-chilling reunite remove salt reactor |
| CN108996622A (en) * | 2018-07-19 | 2018-12-14 | 江苏京源环保股份有限公司 | A kind of electric flocculation processing method under the conditions of low turbidity water quality |
| CN113233548A (en) * | 2021-03-25 | 2021-08-10 | 上海应用技术大学 | Electrochemical-supported chloride ion capturing method and device |
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Open date: 20081217 |