CN116282775A - Method for removing calcium and sulfate in papermaking wastewater - Google Patents
Method for removing calcium and sulfate in papermaking wastewater Download PDFInfo
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- CN116282775A CN116282775A CN202310597897.XA CN202310597897A CN116282775A CN 116282775 A CN116282775 A CN 116282775A CN 202310597897 A CN202310597897 A CN 202310597897A CN 116282775 A CN116282775 A CN 116282775A
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- 239000002351 wastewater Substances 0.000 title claims abstract description 115
- 239000011575 calcium Substances 0.000 title claims abstract description 52
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 title claims abstract description 39
- 229910052791 calcium Inorganic materials 0.000 title claims abstract description 38
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000004062 sedimentation Methods 0.000 claims abstract description 55
- 238000006243 chemical reaction Methods 0.000 claims abstract description 38
- 230000020477 pH reduction Effects 0.000 claims abstract description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000011282 treatment Methods 0.000 claims abstract description 29
- 230000007062 hydrolysis Effects 0.000 claims abstract description 27
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 27
- 238000005273 aeration Methods 0.000 claims abstract description 18
- 230000001105 regulatory effect Effects 0.000 claims abstract description 17
- 230000015271 coagulation Effects 0.000 claims abstract description 16
- 238000005345 coagulation Methods 0.000 claims abstract description 16
- 238000005189 flocculation Methods 0.000 claims abstract description 9
- 230000016615 flocculation Effects 0.000 claims abstract description 9
- 230000001276 controlling effect Effects 0.000 claims abstract description 3
- 239000008394 flocculating agent Substances 0.000 claims abstract description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 40
- 239000007789 gas Substances 0.000 claims description 22
- 238000002485 combustion reaction Methods 0.000 claims description 15
- 238000007599 discharging Methods 0.000 claims description 12
- RQPZNWPYLFFXCP-UHFFFAOYSA-L barium dihydroxide Chemical group [OH-].[OH-].[Ba+2] RQPZNWPYLFFXCP-UHFFFAOYSA-L 0.000 claims description 8
- 229910001863 barium hydroxide Inorganic materials 0.000 claims description 8
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical group [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 8
- 238000004064 recycling Methods 0.000 claims description 8
- 238000010248 power generation Methods 0.000 claims description 5
- 238000005276 aerator Methods 0.000 claims description 4
- 230000014759 maintenance of location Effects 0.000 claims description 2
- 238000004065 wastewater treatment Methods 0.000 abstract description 5
- 239000010802 sludge Substances 0.000 description 28
- 230000002308 calcification Effects 0.000 description 10
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 8
- 230000000903 blocking effect Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- 239000003344 environmental pollutant Substances 0.000 description 8
- 231100000719 pollutant Toxicity 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 230000008569 process Effects 0.000 description 5
- WDIHJSXYQDMJHN-UHFFFAOYSA-L barium chloride Chemical compound [Cl-].[Cl-].[Ba+2] WDIHJSXYQDMJHN-UHFFFAOYSA-L 0.000 description 4
- 229910001626 barium chloride Inorganic materials 0.000 description 4
- 229910000019 calcium carbonate Inorganic materials 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- ZNCPFRVNHGOPAG-UHFFFAOYSA-L sodium oxalate Chemical compound [Na+].[Na+].[O-]C(=O)C([O-])=O ZNCPFRVNHGOPAG-UHFFFAOYSA-L 0.000 description 4
- 229940039790 sodium oxalate Drugs 0.000 description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 239000013589 supplement Substances 0.000 description 3
- 230000001988 toxicity Effects 0.000 description 3
- 231100000419 toxicity Toxicity 0.000 description 3
- 241000894006 Bacteria Species 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 2
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 239000013043 chemical agent Substances 0.000 description 2
- 238000009388 chemical precipitation Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000002455 scale inhibitor Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- 206010033799 Paralysis Diseases 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003851 biochemical process Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
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- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
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- 229910052760 oxygen Inorganic materials 0.000 description 1
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- 230000000149 penetrating effect Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004076 pulp bleaching Methods 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/101—Sulfur compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/26—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof
- C02F2103/28—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof from the paper or cellulose industry
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/30—Aerobic and anaerobic processes
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/34—Biological treatment of water, waste water, or sewage characterised by the microorganisms used
- C02F3/345—Biological treatment of water, waste water, or sewage characterised by the microorganisms used for biological oxidation or reduction of sulfur compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
- C02F5/04—Softening water by precipitation of the hardness using phosphates
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F7/00—Aeration of stretches of water
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
Abstract
The invention discloses a method for removing calcium and sulfate in papermaking wastewater, and relates to the technical field of wastewater treatment. The invention filters papermaking wastewater through a grid and an inclined screen filter screen, flows into an aeration tank, then carries out aeration treatment after adding a calcium remover, and the effluent enters a coagulation tank; then adding a sulfate remover into the coagulation tank, then adding a flocculating agent for flocculation reaction, and allowing the flocculated papermaking wastewater to enter a radial primary sedimentation tank for sedimentation; then the effluent of the radial-flow primary sedimentation tank flows into a pre-hydrolysis acidification tank, the water temperature and the pH value of papermaking wastewater in the pre-hydrolysis acidification tank are regulated, and the effluent enters an IC anaerobic reaction tower; and controlling the temperature of the papermaking wastewater in the IC anaerobic reaction tower to be 35-38 ℃, enabling the effluent to enter an A/O system for treatment, and finally enabling the effluent to enter a secondary sedimentation tank for sedimentation treatment, wherein the effluent of the secondary sedimentation tank is recycled or discharged. The invention can effectively reduce calcium and sulfate in papermaking wastewater, and has low treatment cost and small operation difficulty.
Description
Technical Field
The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for removing calcium and sulfate in papermaking wastewater.
Background
The processes of papermaking, pulping, pulp bleaching, paper making and the like use a large amount of sulfuric acid or sulfate, so that papermaking wastewater contains more sulfate, and the sulfate is reduced into hydrogen sulfide (H) in the anaerobic biochemical process 2 S), the hydrogen sulfide has a strong inhibition effect on methane bacteria, so that the effect of anaerobic treatment is reduced, and the methane yield and the subsequent power generation are affected.
The papermaking industry commonly uses calcium carbonate as a filler and coating for papermaking, resulting in the accumulation of a large amount of calcium ions in the papermaking wastewater. The existence of a large amount of calcium ions in papermaking wastewater can cause the problems of pipeline scaling, anaerobic granular sludge calcification, aerobic sludge calcification and the like of a wastewater treatment system, and the method comprises the following steps of:
in the anaerobic reactor, ca 2+ Easy CO 3 2- 、SO 4 2- 、PO 4 3- And calcium precipitation is formed, and the calcium precipitation is adsorbed to the anaerobic granular sludge to cause calcification of the granular sludge, so that the activity of the granular sludge is reduced, and the sedimentation performance is reduced. In addition, calcified granular sludge not only can influence the internal circulation of the anaerobic reactor, but also can cause the scaling and blocking of the reactor, and seriously influence the operation effect of an anaerobic system.
Aiming at the problem of scale formation of the pipeline internals of the anaerobic reactor, most enterprises in industry throw a large amount of scale inhibitor, regularly open a tank to overhaul the inside of the anaerobic reactor, dredge the scale formation pipeline, regularly discharge calcified sludge at the bottom of the anaerobic reactor, and supplement outsourced anaerobic granular sludge to maintain the normal operation of the anaerobic reactor. However, this has the following problems:
(1) anaerobic system blockage and anaerobic sludge calcification lead to low anaerobic system treatment efficiency, even system paralysis in severe cases, enterprises need to open tanks periodically to overhaul, so that operation cost is increased, even the enterprises need to stop production completely, and production is seriously influenced.
(2) Enterprises need to spend millions of yuan every year to purchase anaerobic granular sludge to supplement into an anaerobic reactor, so that the problems can not be fundamentally solved, the internal operating environment can not be improved, the problem of sludge calcification still exists, and the continuous mud supplementing is needed.
(3) In the discharge process of calcified sludge, the slurry in the reactor has higher fluidity due to the running state, and most of non-calcified sludge is discharged together with the slurry, so that the loss is larger.
(2) CO produced by anaerobic systems 2 Dissolving in the waste water to generate HCO 3 - The wastewater enters an aerobic system, and CO in the wastewater is removed by aeration of an aerobic tank 2 Cause Ca to 2+ Easy CO 3 2- 、PO 4 3- Etc. to form calciumThe sediment is adsorbed on the aerobic sludge to cause calcification of the aerobic sludge, so that the activity of the sludge is weakened, and the pollutant removal efficiency is affected.
Ca in papermaking wastewater 2+ And SO 4 2- Seriously affects the normal operation of a biochemical system, and can efficiently remove Ca in wastewater with low cost 2+ And SO 4 2- Still a research hotspot in the paper industry.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for removing calcium and sulfate in papermaking wastewater. The invention is realized by adopting the following technical scheme:
the method for removing calcium and sulfate in papermaking wastewater specifically comprises the following steps:
step 1, filtering papermaking wastewater through a grid and an inclined screen filter screen, flowing into an aeration tank, adding a calcium remover, performing aeration treatment, and enabling effluent to enter a coagulation tank;
step 2, adding a sulfate remover into the coagulation tank, then adding a flocculating agent for flocculation reaction, and allowing the flocculated papermaking wastewater to enter a radial primary sedimentation tank for sedimentation;
step 3, flowing the effluent of the radial-flow primary sedimentation tank into a pre-hydrolysis acidification tank, adjusting the water temperature and the pH value of papermaking wastewater in the pre-hydrolysis acidification tank, and feeding the effluent into an IC anaerobic reaction tower;
and step 4, controlling the temperature of the papermaking wastewater in the IC anaerobic reaction tower to be 35-38 ℃, enabling the effluent to enter an A/O system for treatment, and finally enabling the effluent to enter a secondary sedimentation tank for sedimentation treatment, and recycling or discharging the effluent of the secondary sedimentation tank.
Preferably, ca in the papermaking wastewater 2+ 1543mg/L SO 4 2- 1040mg/L HCO 3 - 3278mg/L, pH 6.2.
Preferably, the aeration tank is aerated by a cyclone aerator, and the hydraulic retention time is 2.5h; the calcium remover is disodium hydrogen phosphate, and the adding amount of the calcium remover is 500-800 ppm.
Preferably, the sulfate remover is barium hydroxide, and the adding amount of the sulfate remover is 600 ppm-700 ppm; the flocculant is nonionic PAM, and the adding amount of the flocculant is 1ppm.
Preferably, the water temperature of the papermaking wastewater in the 3 rd step pre-hydrolysis acidification tank is 30 ℃, and the pH of the papermaking wastewater is 6.8-7.2.
Preferably, the 3 rd step is that a pretreatment device is arranged at the front end of the prehydrolysis acidification tank, tail gas generated by methane combustion is introduced, the waste water inlet temperature is adjusted to 30 ℃ by utilizing the tail gas residual temperature, and CO in the tail gas is utilized 2 The pH value of the wastewater is regulated to 6.8-7.2.
Preferably, in the step 4, a heat exchanger is arranged at the front end of the IC anaerobic reaction tower, and the tail gas generated by methane combustion is utilized to adjust the water inlet temperature of the wastewater to be 35-38 ℃.
Preferably, in the step 4, the pH value of the papermaking wastewater in the IC anaerobic reaction tower is controlled between 6.8 and 7.2.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention utilizes high-concentration HCO contained in papermaking wastewater 3 - To remove Ca in wastewater 2+ The wastewater is pretreated by adopting aeration and a calcium remover, and the advantages of aeration (low cost) and alkaline calcium remover (adjusting the pH of the wastewater) are combined to promote HCO 3 - Conversion to CO 3 2- The adding amount of the calcium remover is reduced, the cost is saved, and the removal rate of calcium is improved.
The pH value of the papermaking wastewater body is 6.2, and the carbonic acid mainly adopts HCO 3 - The form exists in the following equilibrium:
adding disodium hydrogen phosphate into the wastewater, aerating, and blowing CO in dehydration 2 The gas breaks the carbonic acid balance system in the water body, so that the balance moves rightwards, and the balance moves along with CO 2 Stripping of gas to promote Ca in wastewater 2 + With CO 3 2- And HPO 3 2- The calcium carbonate and calcium hydrophosphate crystal grains are formed by combination, and the specific reaction is as follows:
。
(2) The invention adopts the cyclone aerator to aerate and promote CO 2 The removal rate can prevent the produced calcium salt from blocking the aeration device.
Because of the high-speed mixing, compression and gradual expansion and micro-bubble cutting functions of the cyclone aerator, the gas-liquid mixing is more complete, the dissolved oxygen rate is high, the penetrating power of the gas, water and sludge mixture rotating at high speed is strong, and CO 2 High removal rate and no blockage of the aeration head.
(3) The invention adopts barium hydroxide to remove Ca in wastewater 2+ And SO 4 2- The nonionic PAM is adopted to enable suspended matters in calcium carbonate, calcium hydrophosphate, barium sulfate and water to form larger colloidal flocs, so that the clarity of the effluent is improved.
(4) The tail gas after methane combustion and power generation mainly contains CO 2 And water, wherein the water is used for replacing steam to heat and regulate the temperature of the waste water in the pre-acidification tank to 30 ℃, and the CO contained in the water is used 2 The pH value is regulated to 6.8-7.2, the hydrolysis and acidification treatment efficiency is improved, and the energy conservation and the emission reduction are realized.
(5) The tail gas after methane combustion and power generation is utilized to replace steam to heat and adjust the water temperature of an IC anaerobic reaction tower to 35-38 ℃, and sulfate reducing bacteria are utilized to convert sulfate into S 2- 、HS - Or S simple substance is removed. The toxicity of sulfides to methanogens is mainly derived from free H 2 S, the pH value of the water from the hydrolysis acidification tank is 6.8-7.2, and sulfur mainly adopts HS - State exists, H is reduced 2 S toxicity to methanogens; carbonic acid mainly comprising CO 2 And HCO 3 - Morphology exists, and a small amount of Ca remained in the water body 2+ With soluble Ca (HCO) 3 ） 2 The form exists, the service life of the anaerobic granular sludge is prolonged, and a plurality of difficult problems of anaerobic sludge calcification, scaling and blocking of an internal pipeline of an IC (integrated circuit) reactor, scaling and blocking of a three-phase separator, scaling and blocking of a water distribution system, reduction of methane production capacity and the like are effectively solved.
(6) The invention removes Ca in the wastewater at the front end of wastewater treatment 2+ The calcification of the sludge in the pipeline and the subsequent biochemical system is reduced; removing part of SO in the wastewater at the front end of wastewater treatment 4 2- Control IC anaerobic reaction tower inflow COD: SO (SO) 4 2- Is 5:1, H is reduced 2 S toxicity, and improves the pollutant removal efficiency of the biochemical system.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The invention will be further illustrated with reference to specific examples. Ca in the papermaking wastewater adopted by the invention 2+ 1543mg/L SO 4 2- 1040mg/L HCO 3 - 3278mg/L, total hardness of 4685mg/L (calculated as calcium carbonate) and pH 6.2.
Example 1: step 1, filtering the wastewater by a grid and an inclined screen filter screen, allowing the wastewater to flow into an aeration tank, adding 500ppm of disodium hydrogen phosphate, aerating for 2.5 hours, and allowing the effluent to enter a coagulation tank.
Step 2, adding 600ppm of barium hydroxide into the coagulation tank, further removing calcium and sulfate, adding 1ppm of nonionic PAM for flocculation reaction, and then entering a radial primary sedimentation tank for sedimentation.
Step 3, the effluent of the radial-flow primary sedimentation tank enters a pre-hydrolysis acidification tank, the tail gas generated by methane combustion is introduced into a pretreatment device at the front end of the pre-hydrolysis acidification tank, the temperature of the waste water of the pre-acidification tank is regulated to be 30 ℃, and the CO contained in the waste water is utilized 2 The pH value of the wastewater is regulated to 7.0, the hydrolysis and acidification treatment efficiency is improved, and the effluent enters an IC anaerobic reaction tower.
And step 4, arranging a heat exchanger at the front end of the IC anaerobic reaction tower, regulating the water inlet temperature of the wastewater to 35 ℃ by utilizing tail gas generated by methane combustion, enabling the pH value of the wastewater to be 7.0, enabling the effluent to enter an A/O system, removing other pollutants, and then enabling the effluent to enter a secondary sedimentation tank for sedimentation, and recycling or discharging the effluent of the secondary sedimentation tank.
Example 2: step 1, filtering the wastewater by a grid and an inclined screen filter screen, allowing the wastewater to flow into an aeration tank, adding 600ppm of disodium hydrogen phosphate, aerating for 2.5 hours, and allowing the effluent to enter a coagulation tank.
And step 2, adding 700ppm of barium hydroxide into the coagulation tank, further removing calcium and sulfate, adding 1ppm of nonionic PAM for flocculation reaction, and then, entering a radial primary sedimentation tank for sedimentation.
Step 3, the effluent of the radial-flow primary sedimentation tank enters a pre-hydrolysis acidification tank, the tail gas generated by methane combustion is introduced into a pretreatment device at the front end of the pre-hydrolysis acidification tank, the temperature of the waste water of the pre-acidification tank is regulated to be 30 ℃, and the CO contained in the waste water is utilized 2 The pH value of the wastewater is regulated to 7.2, the hydrolysis and acidification treatment efficiency is improved, and the effluent enters an IC anaerobic reaction tower.
And step 4, arranging a heat exchanger at the front end of the IC anaerobic reaction tower, regulating the water inlet temperature of the wastewater to 35 ℃ by utilizing tail gas generated by methane combustion, enabling the pH value of the wastewater to be 7.2, enabling the effluent to enter an A/O system, removing other pollutants, and then enabling the effluent to enter a secondary sedimentation tank for sedimentation, and recycling or discharging the effluent of the secondary sedimentation tank.
Example 3: step 1, filtering the wastewater by a grid and an inclined screen filter screen, allowing the wastewater to flow into an aeration tank, adding 700ppm of disodium hydrogen phosphate, aerating for 2.5 hours, and allowing the effluent to enter a coagulation tank.
Step 2, adding 600ppm of barium hydroxide into the coagulation tank, further removing calcium and sulfate, adding 1ppm of nonionic PAM for flocculation reaction, and then entering a radial primary sedimentation tank for sedimentation.
Step 3, the effluent of the radial-flow primary sedimentation tank enters a pre-hydrolysis acidification tank, the tail gas generated by methane combustion is introduced into a pretreatment device at the front end of the pre-hydrolysis acidification tank, the temperature of the waste water of the pre-acidification tank is regulated to be 30 ℃, and the CO contained in the waste water is utilized 2 The pH value of the wastewater is regulated to 6.8, the hydrolysis and acidification treatment efficiency is improved, and the effluent enters an IC anaerobic reaction tower.
And step 4, arranging a heat exchanger at the front end of the IC anaerobic reaction tower, regulating the water inlet temperature of the wastewater to 38 ℃ by utilizing tail gas generated by methane combustion, enabling the pH value of the wastewater to be 6.8, enabling the effluent to enter an A/O system, removing other pollutants, and then enabling the effluent to enter a secondary sedimentation tank for sedimentation, and recycling or discharging the effluent of the secondary sedimentation tank.
Example 4: step 1, filtering the wastewater by a grid and an inclined screen filter screen, allowing the wastewater to flow into an aeration tank, adding 800ppm of disodium hydrogen phosphate, aerating for 2.5 hours, and allowing the effluent to enter a coagulation tank.
And step 2, adding 700ppm of barium hydroxide into the coagulation tank, further removing calcium and sulfate, adding 1ppm of nonionic PAM for flocculation reaction, and then, entering a radial primary sedimentation tank for sedimentation.
Step 3, radial flow typeThe effluent of the primary sedimentation tank enters a pre-hydrolysis acidification tank, tail gas generated by methane combustion is introduced into a pretreatment device at the front end of the pre-hydrolysis acidification tank, the temperature of waste water of the pre-acidification tank is regulated to be 30 ℃, and CO contained in the waste water is utilized 2 The pH value of the wastewater is regulated to 7.2, the hydrolysis and acidification treatment efficiency is improved, and the effluent enters an IC anaerobic reaction tower.
And step 4, arranging a heat exchanger at the front end of the IC anaerobic reaction tower, regulating the water inlet temperature of the wastewater to 35 ℃ by utilizing tail gas generated by methane combustion, enabling the pH value of the wastewater to be 7.2, enabling the effluent to enter an A/O system, removing other pollutants, and then enabling the effluent to enter a secondary sedimentation tank for sedimentation, and recycling or discharging the effluent of the secondary sedimentation tank.
Comparative example 1
And treating the wastewater by adopting a conventional treatment process flow chart of a paper-making enterprise.
Step 1, filtering the wastewater by a grid and an inclined screen filter screen, enabling the wastewater to enter a water collecting tank from the flow, lifting the wastewater to a coagulation tank by a pump, adding 400ppm PAC and 2ppm PAM, performing flocculation reaction, and then entering a radial-flow primary sedimentation tank for sedimentation.
And 2, discharging water from the radial-flow primary sedimentation tank into a pre-hydrolysis acidification tank, heating and adjusting the temperature of the waste water in the pre-acidification tank to 30 ℃ by utilizing steam, adding acid or alkali to adjust the pH value of the waste water to 7.0, improving the hydrolysis acidification treatment efficiency, and discharging water into an IC anaerobic reaction tower.
And 3, setting steam heating at the front end of the IC anaerobic reaction tower, adjusting the water inlet temperature of the wastewater to 35 ℃, adjusting the pH of the wastewater to 7.0, enabling the effluent to enter an A/O system, removing other pollutants, and then enabling the effluent to enter a secondary sedimentation tank for sedimentation, wherein the secondary sedimentation tank is used for recycling or discharging the effluent.
Comparative example 2
The wastewater is treated by adopting a chemical precipitation method, and sodium oxalate is taken as an example for removing calcium and barium chloride and removing sulfate.
Step 1, filtering the wastewater by a grid and an inclined screen filter screen, enabling the wastewater to enter a water collecting tank from the flow, lifting the wastewater to a coagulation tank by a pump, adding 5000ppm of sodium oxalate, 600ppm of barium chloride and 2ppm of PAM, performing flocculation reaction, and then entering a radial primary sedimentation tank for sedimentation.
And 2, discharging water from the radial-flow primary sedimentation tank into a pre-hydrolysis acidification tank, heating and adjusting the temperature of the waste water in the pre-acidification tank to 30 ℃ by utilizing steam, adding acid or alkali to adjust the pH value of the waste water to 7.0, improving the hydrolysis acidification treatment efficiency, and discharging water into an IC anaerobic reaction tower.
And 3, setting steam heating at the front end of the IC anaerobic reaction tower, adjusting the temperature of wastewater inlet to 35 ℃, adjusting the pH of wastewater to 7.0, enabling effluent to enter an A/O system, removing other pollutants, and then feeding the wastewater into a secondary sedimentation tank for sedimentation, and recycling or discharging the effluent of the secondary sedimentation tank.
The results of each step of treating papermaking wastewater in the above examples and comparative examples are shown in Table 1.
Table 1 results of each step (unit: mg/L) of treatment of papermaking wastewater in examples and comparative examples
(2) As a result of comparative example 2, ca in wastewater was obtained by adding sodium oxalate 2+ Reducing the concentration to below 300mg/L, and using barium chloride and anaerobic energy to convert SO 4 2- The treatment cost is reduced to below 400mg/L, but the treatment cost is high, and the treatment cost of each ton of wastewater reaches 52.1 yuan only by chemical agents (10000 yuan per ton of sodium oxalate market price and 3500 yuan per ton of barium chloride market price).
(3) As shown by the test results of the example 1, the example 2, the example 3 and the example 4, the mode of combining the aeration, the chemical precipitation method and the anaerobic calcium and sulfur control can be adopted to control Ca in wastewater 2+ Reducing the SO concentration to below 300mg/L 4 2- The cost of the chemical agent used for treating each ton of wastewater is 5.0-6.4 yuan (disodium hydrogen phosphate market price 3500 yuan/ton, barium hydroxide market price 5500 yuan/ton), which is far lower than that of comparative example 2. The method for removing calcium and sulfate in papermaking wastewater provided by the invention overcomes the problem of blockage of a water treatment system, prolongs the service life of anaerobic granular sludge, increases the methane yield and the generated energy, adjusts the water inlet temperature of a prehydrolysis acidification tank and an IC anaerobic reaction tower by using methane combustion power generation tail gas, reduces the steam consumption, does not need to add a scale inhibitor and supplement anaerobic granular sludge, and generates economic benefits far exceeding the cost of the added calcium remover and sulfate remover.
It should be noted that the above-mentioned embodiments are only a few specific embodiments of the present invention, and it is obvious that the present invention is not limited to the above embodiments, but other modifications are possible. All modifications directly or indirectly derived from the disclosure of the present invention will be considered to be within the scope of the present invention.
Claims (8)
1. A method for removing calcium and sulfate from papermaking wastewater, comprising the steps of:
step 1, filtering papermaking wastewater through a grid and an inclined screen filter screen, flowing into an aeration tank, adding a calcium remover, performing aeration treatment, and enabling effluent to enter a coagulation tank;
step 2, adding a sulfate remover into the coagulation tank, then adding a flocculating agent for flocculation reaction, and allowing the flocculated papermaking wastewater to enter a radial primary sedimentation tank for sedimentation;
step 3, flowing the effluent of the radial-flow primary sedimentation tank into a pre-hydrolysis acidification tank, adjusting the water temperature and the pH value of papermaking wastewater in the pre-hydrolysis acidification tank, and feeding the effluent into an IC anaerobic reaction tower;
and step 4, controlling the temperature of the papermaking wastewater in the IC anaerobic reaction tower to be 35-38 ℃, enabling the effluent to enter an A/O system for treatment, and finally enabling the effluent to enter a secondary sedimentation tank for sedimentation treatment, and recycling or discharging the effluent of the secondary sedimentation tank.
2. The method for removing calcium and sulfate from papermaking wastewater according to claim 1, wherein the papermaking wastewater contains Ca 2+ 1543mg/L SO 4 2- 1040mg/L HCO 3 - 3278mg/L, pH 6.2.
3. The method for removing calcium and sulfate from papermaking wastewater according to claim 1, wherein the aeration tank is aerated by a cyclone aerator, and the hydraulic retention time is 2.5h; the calcium remover is disodium hydrogen phosphate, and the adding amount of the calcium remover is 500-800 ppm.
4. The method for removing calcium and sulfate from papermaking wastewater according to claim 1, wherein the sulfate remover is barium hydroxide, and the adding amount of the sulfate remover is 600 ppm-700 ppm; the flocculant is nonionic PAM, and the adding amount of the flocculant is 1ppm.
5. The method for removing calcium and sulfate from papermaking wastewater according to claim 1, wherein the water temperature of the papermaking wastewater in the 3 rd step pre-hydrolysis acidification tank is 30 ℃, and the pH of the papermaking wastewater is 6.8-7.2.
6. The method for removing calcium and sulfate from papermaking wastewater according to claim 5, wherein in step 3, a pretreatment device is arranged at the front end of the pre-hydrolysis acidification tank, tail gas generated by methane combustion is introduced, the waste water inlet temperature is regulated to 30 ℃ by utilizing the residual temperature of the tail gas, and CO in the tail gas is utilized 2 The pH value of the wastewater is regulated to 6.8-7.2.
7. The method for removing calcium and sulfate from papermaking wastewater according to claim 1, wherein in step 4, a heat exchanger is arranged at the front end of the IC anaerobic reaction tower, and the tail gas after methane combustion power generation is used for adjusting the water inlet temperature of the wastewater to be 35-38 ℃.
8. The method for removing calcium and sulfate from papermaking wastewater according to claim 1, wherein the pH of the papermaking wastewater in the IC anaerobic reaction tower in the step 4 is controlled between 6.8 and 7.2.
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