Based on the papermaking deep process waste water recycling method of chemical decalcification
Technical field
The present invention relates to a kind for the treatment of process of papermaking deep process waste water, particularly relate to a kind of reuse method of the papermaking deep process waste water based on chemical decalcification technic, electrochemical techniques and membrane technique.
Background technology
Paper-making effluent refers to the cooking waste liquor (also known as black liquor, red liquid) that chemical pulping produces, the plain boiled water produced in the middle section water produced in pulp washing bleaching process and copy paper operation.General 1t sulfate pulp of often producing just has 1t organism and 400kg bases, sulphide dissolves in black liquor; Producing 1t sulfite pulp about has 900kg organism and 200kg oxide compound (calcium, magnesium etc.) to be dissolved in red liquid with sulfide.Waste liquid to enter in rivers not only severe contamination water source, and causes a large amount of wastings of resources.Paper-making industry traditional uses water rich and influential family, is also one of important source of pollution causing water pollutions.At present, the first place of China's paper-making industrial waste water quantity discharged and COD quantity discharged Jun Ju China all types of industries quantity discharged, paper industry is the most serious to the pollution of water surrounding, it not still China's industrial pollution caused by paper manufacturing control matter of utmost importance, be also the matter of utmost importance that national trade effluent carries out process up to standard and water saving.According to statistics, the above papermaking in county of China and county and paper products industry wastewater discharge account for 18.6% of national industrial total release, wherein process emission compliance amount and account for 49.3% of paper-making industrial waste water total release, in waste discharge, COD accounts for 44.0% of national industrial COD total release.Therefore, how eliminating that paper waste pollutes and make the precious resources in waste liquid obtain utilizing is a job with great social effect and economic worth, should attach great importance to.Along with expanding economy, China faces the problem of shortage of fresh water, scarcity of raw material day by day, and on the other hand, water pollutions is also more and more serious.In recent years, through unremitting effort in many ways, paper industry water prevention and cure of pollution have achieved certain achievement, although paper and paperboard production increase year by year, the COD in waste discharge but reduces year by year.But the waste water that current paper industry accounts for total emission volumn 50% not yet carries out process up to standard, after pulping wastewater treatment, recycling is few especially, therefore, and paper waste prevention and cure of pollution and to recycle task also quite heavy.
Paper waste complicated component, biodegradability is poor, belongs to more unmanageable trade effluent, and its source and feature are:
1, cooking section waste liquid
The i.e. black liquor of alkaline process generation and the red liquid of acid polishing generation.Overwhelming majority paper mill adopts alkaline process and produces black liquor.In black liquor, contained pollutent has accounted for more than 90% of industrial pollution caused by paper manufacturing total emission volumn, and has the characteristic of high density and difficult degradation, and its improvement is a great problem always.Main component in black liquor has 3 kinds, i.e. xylogen, poly-pentose and total alkali.Xylogen is the nontoxic natural high molecular substance of a class, and have been widely used as industrial chemicals tool, poly-pentose can be used as animal feed.
2, middle section water
Effluent refers to the waste water that the boiling slurry after black liquid extraction is discharged in the processes such as screening, washing, bleaching, and color is deep yellow, accounts for 8% ~ 9% of industrial pollution caused by paper manufacturing total emission volumn, ton slurry COD load about 310kg.Middle section water concentration is higher than sanitary sewage, and the ratio of BOD and COD is between 0.20 to 0.35, and biodegradability is poor, and organism is difficult to biological degradation and intractability is large.Organism in middle section water is xylogen, Mierocrystalline cellulose, organic acid etc. mainly, based on solubility COD.Wherein, the chlorine-contained wastewater that environmental pollution the most seriously produces in bleaching process, such as Chlorinated Bleaching waste water, hypo(chlorite)bleaching waste water etc.Hypo(chlorite)bleaching waste water, mainly containing trichloromethane, also containing other organic chlorides of kind more than 40, be wherein maximum with various chlorinated phenol, as dichloro-phenol, three chlorinated phenols etc.In addition, containing toxic extremely strong carcinogenic substance Dioxins in bleaching waste liquor, serious threat is caused to ecotope and HUMAN HEALTH.
3, plain boiled water
Plain boiled water and copy paper workshop section waste water, it derives from paper machine room paper making process.Plain boiled water is mainly containing fiber fines, filler, coating and lysed wood component, and the sizing material, Wet Strength Resin, sanitas etc. that add, and based on insoluble COD, biodegradability is lower, and its sanitas added has certain toxicity.The plain boiled water water yield is comparatively large, but the organic pollution load contained by it is well below black digestion liquid and middle-stage wastewater.Now nearly all paper mill paper machine room all have employed part or totally-enclosed system to reduce papermaking water loss, saves power consumption, improves white water recycling rate, reduce unnecessary plain boiled water and discharge.
At present, the method for pulping wastewater treatment mainly contains: physical filtering method, coagulant sedimentation, absorption method, advanced oxidation processes, By Bubble-floating Method, acid adding absorption process, catalytic oxidation, biochemical process etc., often kind of method all has respective relative merits.Because single treatment process is difficult to be effective, in practice, normally according to the practical situation that will process waste water, several method is combined, typical production technique is by paper waste through physical treatment such as filtrations grade, then qualified discharge after biochemical treatment again after flocculation sediment.
Chinese patent CN101708927A discloses a kind of advanced treatment method for papermaking waste water of investing little, that technique is simple, pollutants removal rate is high, working cost is cheap oxidative degradation+flocculation sediment+sand filtration.COD < 70mg/L, BOD5 < 20mg/L, SS < 30mg/L after the method process.
Chinese patent CN1420091 discloses a kind of Ecological Disposal and resource recycling Application way of paper waste, and it utilizes ecological engineering technology, and paper mill wastewater carries out BOD in settling tank
5: COD
crratio adjustment, then enter series connection anaerobic pond and facultative lagoon digestion, draining carries out COD in equalizing tank
cr: after N: P ratio adjustment, many groups rainwash wetland in parallel is distributed into by water distribution system, water outlet is better than the primary standard of paper industry Sewage Water Emissions, can stay, supplement clear water needed for equalizing tank, be back to rainwash wetland and carry out degree of depth reprocessing through aerobic ponds storage.The method overcome the shortcoming that paper waste trophic structure is uneven, biodegradability is poor, Absorbable organic halogens realizes Ecological Disposal and the resource recycling utilization of paper waste effectively.
Chinese patent CN101337752 discloses a kind of advanced treatment process for paper-making waste water, this technique comprises the following steps: the paper waste after secondary biochemical treatment is introduced micro-aeration Fe3+ reduction bed, in micro-aeration Fe3+ reduction bed, load iron filings, paper waste carries out reduction reaction in micro-aeration Fe3+ reduction bed; Water outlet after step 1. being processed is introduced in coagulation basin, adds coagulating agent and coagulant aids, impel the particle aggregation in water in coagulation basin; Water outlet after step 2. being processed is introduced in settling tank and is carried out mud-water separation; The water outlet of settling tank introduced in filtering basin and filter, the water outlet after filtration, after sterilization and disinfection, introduces reuse water pipe network; Mud in settling tank and the sewage backwash water in filtering basin are introduced sludge thickener, and after dehydration, outward transport is disposed; Meanwhile, the overflowing liquid in dehydration filtrate and sludge thickener is introduced in coagulation basin and is carried out reprocessing.Present invention process is simple, good decolorizing effect and with low cost.
Above method all obtains reasonable effect to the process of paper waste, but it is inadequate all to there is treating depth, the middle water produced also containing more pollutent, can only be applicable to some to by the less demanding production technique of quality, its purposes consumption is all restricted.Paper waste is regenerated, and what meet various processes uses water requirement, particularly the requirement of high quality water, must carry out deep purifying process to it, as purified again through membrane filtration process through further by the waste water of biochemical gained, obtains pure water.Chinese patent 201010567041.0,201020635352.1 describes papermaking deep process waste water and adopts membrane filtration to carry out the method for recycling utilization, but in implementation process, find that in paper waste, calcium ion content is up to 150 ~ 400 mg/L, produce a large amount of fouling, serious difficulty is caused to the regeneration of waste water.
Summary of the invention
The object of the invention is to higher for cost existing in existing pulping wastewater treatment method, usefulness is lower, waste water after process mostly is discharge, does not have the problems such as advanced treatment recycle, waste water resource, there is provided a kind of to combine with membrane technique based on chemical decalcification technic, electrochemical techniques, cost is lower, usefulness is higher, makes it the reuse method of the papermaking deep process waste water reaching recycle.
Papermaking deep process waste water recycling method based on chemical decalcification of the present invention comprises the following steps:
(1) chemical decalcification
Secondary clarifier effluent (i.e. papermaking deep process waste water) after papermaking biochemical treatment flows into one-level decalcification reaction tank through pipeline, appropriate lime saturated solution adjust pH to 8.5 ~ 9.5 are under agitation first added by chemicals dosing plant, after removing false hardness (supercarbonate), flow into secondary decalcification reaction tank, add the Na of 100 ~ 600mg/L
2cO
3, carbonate and calcium ions and magnesium ions are reacted and generate carbonate deposition, then add the FeSO of 2 ~ 10mg/L
4, then add Na
2cO
3anti-adjust pH to 8 ~ 9, finally add the polyphenyl alkene acid amides (PAM) of 1 ~ 3mg/L, enter settling tank after reacting completely, carry out precipitate and separate, thus remove calcium magnesium in papermaking deep process waste water, useless water hardness is reduced to 30 ~ 80mg/L, prevent follow-up equipment, facility because Ca
2+, Mg
2+excessive concentration and fouling; Throw out (i.e. mud) is sent in sludge sump through pump and pipeline, finally in sludge dehydration device, carries out filtering separation, and reclaims calcium carbonate, and waste water then enters next step and filters;
(2) filter
Waste water after chemical decalcification is pumped into filtering system and carries out filtering separation, further except the SS in anhydrating and colloid;
(3) electrolysis
Waste water after filtering is pumped into electrolysis machine electrolysis, with organic macromolecule of degrading, removes colourity, improve the biodegradability of waste water, the adjacent two interelectrode voltages of electrolysis machine are 2 ~ 12V, and current density is 10 ~ 320mA/cm
2;
(4) membrane sepn
Waste water after electrolysis enters film separating system, the particle in waste water, macromolecular colloid compound and microorganism is removed by membrane sepn effect, obtain water-dialyzing and condensed water, water-dialyzing enters desalting treatment system, and condensed water flow to recycle in the electrolysis machine of step (3) through back of pipeline;
(5) desalination
Membrane sepn gained water-dialyzing pump pumps into desalination system, and obtain water-dialyzing and condensed water through desalination system filtering separation, water-dialyzing enters basin and obtains reuse water; A condensed water part is back to electrolytic system, and redundance discharges.
Filtering system described in step (2) filtration is the one in multi-medium filtering, fabric filter element, sand filtration, active sand filtration, filtering cloth filtering pool.
Described in step (3) electrolysis, electrolysis machine is provided with power supply and electrolyzer, and the electrode materials in described electrolyzer is the one in graphite, titanium, iron, aluminium, zinc, copper, lead, nickel, molybdenum, chromium, alloy and nano-catalytic inert material; The top layer of described nano-catalytic noble electrode is coated with the metal oxide inertia catalyst coatings that crystal grain is 10 ~ 35nm, and the substrate of described nano-catalytic noble electrode is titanium plate or plastic plate.
Step (4) described film separating system is the one in ultrafiltration or MBR.Described ultrafiltration molecular weight cut-off is 1000 ~ 50000MWCO, working conditions is: normal temperature ~ 45 DEG C, the operating pressure of immersion ultrafiltration is-1 ~-50kPa, ultrafiltration is the one of immersion ultrafiltration, pillar ultrafiltration, tubular type ultrafiltration, spiral wound or plate-type hyperfiltration, and the operating pressure of pillar ultrafiltration, tubular type ultrafiltration, spiral wound and plate-type hyperfiltration is 3 ~ 300kPa.The membrane module of described MBR system is selected from the one in Pvdf Microporous Hollow Fiber Membrane, polypropylene hollow fiber membrane, ps hollow fiber uf membrane, polyether sulphone hollow fibre film, polyacrylonitrile hollow fiber membrane and PVC hollow fiber membrane; The membrane pore size of the MBR membrane module of described MBR system is 0.10 ~ 0.2 μm, and operating pressure is-1 ~-50kPa, and working temperature is 5 ~ 45 DEG C.
Step (5) described desalination system is nanofiltration, reverse osmosis, just permeate, electrodialysis, capacitive adsorption, ion-exchange or fill electrodialysis (EDI) one.The membrane module of described nanofiltration system is the one of tubular membrane component, rolled membrane module or plate film assembly, and operating pressure is 6 ~ 45bar, and working temperature is 20 ~ 45 DEG C, and optimum temps is 35 ~ 40 DEG C.Described reverse osmosis membrane system adopts molecular weight cut-off to can be the reverse osmosis membrane of 50 ~ 200MWCO, and membrane module is tubular membrane component or rolled membrane module, and entrance pressure can be 6.0 ~ 35.0bar, goes out pressure and can be 4.5 ~ 33.5 bar.The described membrane module just permeated is the one in plate and frame module, rolled membrane module, tubular membrane component and packet mode membrane module.Described electrodialytic working conditions is operating voltage pressure 0.5 ~ 3.0 ㎏/cm
2, operating voltage 50 ~ 250V, strength of current 1 ~ 3A.The working conditions of described capacitive adsorption is volts DS is 110V/m ~ 2 × 10
6v/m.The ion-exchanger that described ion-exchange uses is divided into inorganic ion exchanger and the large class of organic ion exchanger two, inorganic ion exchanger has natural zeolite and synthetic zeolite etc., and organic exchanger resins is the one in strong-acid cation-exchange resin, weakly acidic cationic exchanger resin, strong anion-exchange resin, weak basic anion exchange resin, resin and organic adsorption resin etc.Described filling electrodialysis (EDI) is a kind of separating desalination technique electrodialysis and ion-exchange organically combined, and filling electrodialysis unit inflow requirement is resistivity is 0.025 ~ 0.5M Ω cm.
The present invention had both overcome the defect of alone membrane filtration separating treatment or adsorption treatment high cost, the treatment effect overcoming again conventional paper waste method is undesirable, the defects such as the contaminated wastewater environment of discharge, by existing papermaking deep process purification of waste water and recycle and reuse.Compared with the prior art, there is following outstanding advantages:
(1) papermaking deep process waste water is through process, and 70% ~ 85% can recycling utilization, both reduces discharge of wastewater, avoid waste water environmental pollution, reduce water resource waste again, the recirculated water cost of regeneration can also be made lower than tap water price, economical rationality, produces good economic benefit.
(2) after removing false hardness (supercarbonate) by the one-level decalcification of chemical decalcification system reaction, then through secondary decalcification reaction tank, carbonate and calcium ions and magnesium ions are reacted to generate carbonate deposition, then with FeSO
4flocculate mutually with coagulant aidss such as polyphenyl alkene acid amides (PAM), be gathered into thick alumina blossom particles, settle down in settling tank, high-concentration Ca, magnesium ion in final effective elimination papermaking deep process waste water, reduce water hardness, prevent equipment scaling, ensure that subsequent technique is smooth, steady running.
(3) reduce COD further by nano-catalytic electrolysis, one is to make the reclamation rate of waste water improve, and both reduces discharge of wastewater, and avoids waste water environmental pollution, reduce water resource waste again; Two is the microorganisms such as the bacterium can killed in waste water, eradicates the biological pollution of subsequent nano-filtration film and reverse osmosis membrane, significantly reduces the wash number of nanofiltration membrane and reverse osmosis membrane, reduce film and clean regeneration cost, improve the service efficiency of film, extend the work-ing life of film, reduce film replacement cost.
(4) after film separating system process, particle in waste water and macromolecular colloid compound are removed further, for follow-up technique creates good condition of water quality, pollutant in water will be decomposed further by the oxygenolysis of microorganism in MBR system simultaneously, utilize the efficient rejection effect of film, the indexs such as SS, colourity, pollutent are effectively removed.
(5) significantly reduce water consumption index and the discharge of wastewater index of ton paper, improve business economic technical indicator.
Papermaking deep process waste water alleged by the present invention refers to paper waste secondary clarifier effluent after traditional filtration, flocculation and biochemical treatment, namely reaches the waste water of more than three grades emission standards.
Accompanying drawing explanation
Fig. 1 is process flow sheet of the present invention.
Embodiment
The present invention be complete after the composition to existing papermaking deep process waste water, character and existing processing scheme go deep into the comparative study of system to the purification of papermaking deep processed waste water and the design of cyclic utilization method, it is by the united application of the methods such as chemical decalcification, electrolysis, membrane filtration, thus forms one and be particularly suitable for papermaking deep process and give up water purification and reuse method.
Referring to Fig. 1, the specific embodiment of the present invention is described.
Embodiment 1
The reuse method of 800 ton per day papermaking deep process waste water.
Described papermaking deep process waste water quality index is as shown in table 1 after measured.
The water-quality guideline of table 1 papermaking deep process waste water
Sequence number | Project | Unit | Measured value | Sequence number | Project | Unit | Measured value |
1 | COD
Cr | mg/L | 150 | 4 | Colourity | ? | 100 |
2 | SS | mg/L | 120 | 5 | Ca | mg/L | 400 |
3 | Specific conductivity | μS/cm | 1600 | 6 | Hardness | mmol/L | 9.9 |
(1) chemical decalcification
After papermaking biochemical treatment, secondary clarifier effluent (i.e. papermaking deep process waste water) flows into one-level decalcification reaction tank through pipeline, appropriate lime saturated solution adjust pH to 8.5 is under agitation first added by chemicals dosing plant, after removing false hardness (supercarbonate), flow into secondary decalcification reaction tank, add the Na of 600mg/L
2cO
3, carbonate and calcium ions and magnesium ions are reacted and generate carbonate deposition, then add the FeSO of 5mg/L
4, then add Na
2cO
3anti-adjust pH to 8.5, finally adds the polyphenyl alkene acid amides (PAM) of 1mg/L, enters settling tank, carry out precipitate and separate after reacting completely, thus removes calcium magnesium, the reduction water hardness in papermaking deep process waste water, prevents follow-up equipment, facility because Ca
2+excessive concentration and fouling; Throw out (i.e. mud) is sent in sludge sump through pump and pipeline, finally in sludge dehydration device, carries out filtering separation, and reclaims calcium carbonate, and waste water then enters next step and filters;
(2) filter
Waste water after chemical decalcification is pumped into filtering system and carries out filtering separation, further except the SS in anhydrating and colloid;
Above-mentionedly be filtered into multi-medium filtering.Filtration can be the one in multi-medium filtering, fabric filter element, sand filtration, active sand filtration, filtering cloth filtering pool.
(3) electrolysis
Waste water after filtering is pumped into electrolysis machine electrolysis, with organic macromolecule of degrading, removes colourity, improve the biodegradability of waste water, the adjacent two interelectrode voltages of electrolysis machine are 2V, and current density is 200mA/cm
2;
(4) membrane sepn
Waste water after electrolysis enters film separating system, the particle in waste water, macromolecular colloid compound and microorganism is removed by membrane sepn effect, obtain water-dialyzing and condensed water, water-dialyzing enters desalting treatment system, and condensed water flow to recycle in the electrolysis machine of step (3) through back of pipeline;
Described film separating system is MBR system.The membrane module of MBR system is selected from the one in Pvdf Microporous Hollow Fiber Membrane, polypropylene hollow fiber membrane, ps hollow fiber uf membrane, polyether sulphone hollow fibre film, polyacrylonitrile hollow fiber membrane and PVC hollow fiber membrane; The membrane pore size of MBR membrane module is 0.10 ~ 0.2 μm, and operating pressure is-1 ~-50kPa, and working temperature is 5 ~ 45 DEG C.
(5) desalination
Membrane sepn gained water-dialyzing pump pumps into desalination system, and obtain water-dialyzing and condensed water through desalination system filtering separation, water-dialyzing enters basin and obtains reuse water; A condensed water part is back to electrolytic system, and redundance discharges.
Described desalination system is reverse osmosis system.Reverse osmosis membrane system adopts molecular weight cut-off to can be the reverse osmosis membrane of 50 ~ 200MWCO, and membrane module is tubular membrane component or rolled membrane module, and entrance pressure can be 6.0 ~ 35.0bar, goes out pressure and can be 4.5 ~ 33.5 bar.
Reuse water water-quality guideline is as shown in table 2 after measured.
The water-quality guideline of table 2 reuse water
Sequence number | Project | Unit | Measured value | Sequence number | Project | Unit | Measured value |
1 | COD
Cr | mg/L | 8 | 4 | Colourity | ? | 8 |
2 | SS | mg/L | ≤1 | 5 | Ca | mg/L | 45 |
3 | Specific conductivity | μS/cm | 80 | 6 | Hardness | mmol/L | 1.1 |
Embodiment 2
The reuse method of 5000 ton per day papermaking deep process waste water.
Described papermaking deep process waste water quality index is as shown in table 3 after measured.
The water-quality guideline of table 3 papermaking deep process waste water
Sequence number | Project | Unit | Measured value | Sequence number | Project | Unit | Measured value |
1 | COD
Cr | mg/L | 100 | 4 | Colourity | ? | 150 |
2 | SS | mg/L | 120 | 5 | Ca | mg/L | 150 |
3 | Specific conductivity | μS/cm | 1800 | 6 | Hardness | mmol/L | 4 |
(1) chemical decalcification
After papermaking biochemical treatment, secondary clarifier effluent (i.e. papermaking deep process waste water) flows into one-level decalcification reaction tank through pipeline, appropriate lime saturated solution adjust pH to 9 is under agitation first added by chemicals dosing plant, after removing false hardness (supercarbonate), flow into secondary decalcification reaction tank, add the Na of 100mg/L
2cO
3, carbonate and calcium ions and magnesium ions are reacted and generate carbonate deposition, then add the FeSO of 2mg/L
4, then add Na
2cO
3anti-adjust pH to 8, finally adds the polyphenyl alkene acid amides (PAM) of 3mg/L, enters settling tank, carry out precipitate and separate after reacting completely, thus removes calcium magnesium, the reduction water hardness in papermaking deep process waste water, prevents follow-up equipment, facility because Ca
2+excessive concentration and fouling; Throw out (i.e. mud) is sent in sludge sump through pump and pipeline, finally in sludge dehydration device, carries out filtering separation, and reclaims calcium carbonate, and waste water then enters next step and filters;
(2) filter
Waste water after chemical decalcification is pumped into filtering system and carries out filtering separation, further except the SS in anhydrating and colloid;
Above-mentionedly be filtered into multi-medium filtering.Filtration can be the one in multi-medium filtering, fabric filter element, sand filtration, active sand filtration, filtering cloth filtering pool.
(3) electrolysis
Waste water after filtering is pumped into electrolysis machine electrolysis, with organic macromolecule of degrading, removes colourity, improve the biodegradability of waste water, the adjacent two interelectrode voltages of electrolysis machine are 12V, and current density is 10mA/cm
2;
(4) membrane sepn
Waste water after electrolysis enters film separating system, the particle in waste water, macromolecular colloid compound and microorganism is removed by membrane sepn effect, obtain water-dialyzing and condensed water, water-dialyzing enters desalting treatment system, and condensed water flow to recycle in the electrolysis machine of step (3) through back of pipeline;
Described film separating system is ultrafiltration system, and ultrafiltration is immersion ultrafiltration, and working conditions is: normal temperature ~ 45 DEG C, and operating pressure is-1 ~-50kPa; Ultrafiltration can be the one of immersion ultrafiltration, pillar ultrafiltration, tubular type ultrafiltration, spiral wound or plate-type hyperfiltration.
(5) desalination
Membrane sepn gained water-dialyzing pump pumps into desalination system, and obtain water-dialyzing and condensed water through desalination system filtering separation, water-dialyzing enters basin and obtains reuse water; A condensed water part is back to electrolytic system, and redundance discharges.
Described desalination system is reverse osmosis system.Reverse osmosis membrane system adopts molecular weight cut-off to can be the reverse osmosis membrane of 50 ~ 200MWCO, and membrane module is tubular membrane component or rolled membrane module, and entrance pressure can be 6.0 ~ 35.0bar, goes out pressure and can be 4.5 ~ 33.5 bar.
Reuse water water-quality guideline is as shown in table 4 after measured.
The water-quality guideline of table 4 reuse water
Sequence number | Project | Unit | Measured value | Sequence number | Project | Unit | Measured value |
1 | COD
Cr | mg/L | 10 | 4 | Colourity | ? | 5 |
2 | SS | mg/L | ≤1 | 5 | Ca | mg/L | 30 |
3 | Specific conductivity | μS/cm | 100 | 6 | Hardness | mmol/L | 0.75 |
Embodiment 3
The reuse method of 20000 ton per day papermaking deep process waste water.
Described papermaking deep process waste water quality index is as shown in table 5 after measured.
The water-quality guideline of table 5 papermaking deep process waste water
Sequence number | Project | Unit | Measured value | Sequence number | Project | Unit | Measured value |
1 | COD
Cr | mg/L | 150 | 4 | Colourity | ? | 120 |
2 | SS | mg/L | 80 | 5 | Ca | mg/L | 200 |
3 | Specific conductivity | μS/cm | 1200 | 6 | Hardness | mmol/L | 5 |
(1) chemical decalcification
After papermaking biochemical treatment, secondary clarifier effluent (i.e. papermaking deep process waste water) flows into one-level decalcification reaction tank through pipeline, appropriate lime saturated solution adjust pH to 9.5 is under agitation first added by chemicals dosing plant, after removing false hardness (supercarbonate), flow into secondary decalcification reaction tank, add the Na of 350mg/L
2cO
3, carbonate and calcium ions and magnesium ions are reacted and generate carbonate deposition, then add the FeSO of 10mg/L
4, then add Na
2cO
3anti-adjust pH to 9, finally adds the polyphenyl alkene acid amides (PAM) of 2mg/L, enters settling tank, carry out precipitate and separate after reacting completely, thus removes calcium magnesium, the reduction water hardness in papermaking deep process waste water, prevents follow-up equipment, facility because Ca
2+excessive concentration and fouling; Throw out (i.e. mud) is sent in sludge sump through pump and pipeline, finally in sludge dehydration device, carries out filtering separation, and reclaims calcium carbonate, and waste water then enters next step and filters;
(2) filter
Waste water after chemical decalcification is pumped into filtering system and carries out filtering separation, further except the SS in anhydrating and colloid;
Above-mentionedly be filtered into active sand filtration.Filtration can be the one in multi-medium filtering, fabric filter element, sand filtration, active sand filtration, filtering cloth filtering pool.
(3) electrolysis
Waste water after filtering is pumped into electrolysis machine electrolysis, with organic macromolecule of degrading, removes colourity, improve the biodegradability of waste water, the adjacent two interelectrode voltages of electrolysis machine are 2V, and current density is 320mA/cm
2;
(4) membrane sepn
Waste water after electrolysis enters film separating system, the particle in waste water, macromolecular colloid compound and microorganism is removed by membrane sepn effect, obtain water-dialyzing and condensed water, water-dialyzing enters desalting treatment system, and condensed water flow to recycle in the electrolysis machine of step (3) through back of pipeline;
Described film separating system is MBR system.The membrane module of MBR system is selected from the one in Pvdf Microporous Hollow Fiber Membrane, polypropylene hollow fiber membrane, ps hollow fiber uf membrane, polyether sulphone hollow fibre film, polyacrylonitrile hollow fiber membrane and PVC hollow fiber membrane; The membrane pore size of MBR membrane module is 0.10 ~ 0.2 μm, and operating pressure is-1 ~-50kPa, and working temperature is 5 ~ 45 DEG C.
(5) desalination
Membrane sepn gained water-dialyzing pump pumps into desalination system, and obtain water-dialyzing and condensed water through desalination system filtering separation, water-dialyzing enters basin and obtains reuse water; A condensed water part is back to electrolytic system, and redundance discharges.
Described desalination system is nanofiltration system.The membrane module of described nanofiltration system is the one of tubular membrane component, rolled membrane module or plate film assembly, and operating pressure is 6 ~ 45bar, and working temperature is 20 ~ 45 DEG C, and optimum temps is 35 ~ 40 DEG C.
Reuse water water-quality guideline is as shown in table 6 after measured.
The water-quality guideline of table 6 reuse water
Sequence number | Project | Unit | Measured value | Sequence number | Project | Unit | Measured value |
1 | COD
Cr | mg/L | 8 | 4 | Colourity | ? | 6 |
2 | SS | mg/L | ≤1 | 5 | Ca | mg/L | 60 |
3 | Specific conductivity | μS/cm | 60 | 6 | Hardness | mmol/L | 1.5 |