CN111777220A - Novel softening treatment method for high-salinity and high-permanent-hardness wastewater - Google Patents
Novel softening treatment method for high-salinity and high-permanent-hardness wastewater Download PDFInfo
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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
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- 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
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- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
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- 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
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- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- C—CHEMISTRY; METALLURGY
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- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- 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
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- 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
- C02F5/06—Softening water by precipitation of the hardness using calcium compounds
Abstract
The invention belongs to the technical field of wastewater treatment, in particular to a novel high-salinity and high-permanent-hardness wastewater softening treatment method, which comprises the steps of feeding salt-containing and high-permanent-hardness wastewater from a reclaimed water reverse osmosis device into an efficient sedimentation tank, adding a chemical agent, and carrying out sedimentation and flocculation treatment; and then adding a pH regulator into the effluent water of the high-efficiency sedimentation tank to regulate the pH, and then sequentially carrying out multi-medium filtration and nanofiltration treatment. The method adopts calcium hydroxide as a chemical agent, combines flocculation and multiple filtration treatment, can effectively remove carbonate hardness (temporary hardness) and non-carbonate hardness (permanent hardness) in the wastewater, does not need to add sodium carbonate compared with the prior art agent softening method, and reduces the operation cost by more than 30-50%; organic matters in the wastewater can be removed simultaneously, and the subsequent reverse osmosis process operation pollution and blockage can be avoided; the permanent hardness is mainly removed through subsequent nanofiltration salt separation, the generated chemical precipitation sludge is less, and the subsequent sludge treatment difficulty and cost are reduced.
Description
Technical Field
The invention belongs to the technical field of wastewater treatment, and particularly relates to a novel high-salinity and high-permanent-hardness wastewater softening treatment method.
Background
The reclaimed water, also called reclaimed water or reuse water, refers to non-drinking water which can be reused in a certain range and meets certain use requirements after wastewater or rainwater is properly treated. Compared with seawater desalination and cross-basin water transfer, the reclaimed water has obvious advantages. From the economic perspective, the cost of the reclaimed water is lowest, and from the environmental protection perspective, the sewage recycling is beneficial to improving the ecological environment and realizing the virtuous cycle of water ecology. From the aspect of the situation development of the modern world, the promotion of the continuous prospect of the reclaimed water industry is of great significance to the whole country and even the world, mainly because: (1) the population is continuously increased, so that the waster water in the world is continuously spread; (2) global drought frequently occurs, and water resources are gradually reduced; (3) environmental policies are becoming more stringent; (3) can reduce the cost of industrial production water.
At present, in domestic plant reclaimed water recycling projects, a reverse osmosis membrane system is generally utilized to ensure that the quality index of recycled water meets the requirement of plant production water, salt content, hardness, COD (chemical oxygen demand) and the like in rear-end water are increased by several times due to the use of reverse osmosis, and if the high-salt-content water is recycled, the hardness in the water must be reduced by adopting a softening technology. The adopted softening technology mainly comprises the following steps: the removal of the hardness in water mainly adopts a medicament softening method, an ion exchange method, an electrodeionization method and a membrane separation method.
The chemical softening method is a process of removing a hard-soluble compound formed by hardness and the like contained in water under the action of a proper chemical by using the principle of a chemical precipitation method and according to the principle of a concentration product; the common medicaments mainly comprise lime, sodium carbonate, caustic soda, trisodium phosphate and the like; the main principle is as follows: CaO + H2O→Ca(OH)2、Ca(OH)2+Ca(HCO3)2→2CaCO3↓+2H2O、Ca(OH)2Mg(HCO3)2→CaCO3↓+MgCO3+2H2O、Ca(OH)2+MgCO3→CaCO3↓+Mg(OH)2↓. According to the reaction formula, lime mainly removes carbonate hardness (temporary hardness) in water, and if non-carbonate hardness (permanent hardness) in water needs to be removed, sodium carbonate needs to be added, and the main principle is as follows: CaSO4+Na2CO3→CaCO3↓+Na2SO4、CaCl2+Na2CO3→CaCO3↓ +2 NaCl; if the permanent hardness of the water is 500mg/L, the adding amount of the sodium carbonate is 600mg/L, and 1.5 yuan is increased because the sodium carbonate is added into each ton of water for treatment. By lime or lime purityIn the alkali softening method, the residual hardness in water is generally 100-200mg/L (calculated by calcium carbonate), 50mg/L can be achieved only when the excess of soda is large, and the hardness value of the outlet water is easy to fluctuate and is influenced by factors such as the quality of the inlet water, the addition of medicaments, personnel operation and the like. In addition, in order to ensure the stable hardness of the effluent and improve the recovery rate of a subsequent reverse osmosis membrane system, an ion exchange method mainly comprising a sodium bed or a weak acid cation bed is generally added after the process of a medicament softening method, the process can generally ensure the hardness of the effluent to be below 20mg/L, but the regeneration period of the ion exchange method is short, a large amount of acid and alkali regeneration wastewater can be generated, and meanwhile, the resin is easily polluted and blocked by organic matters in the inlet water.
The ion exchange method and the electrodeionization method are suitable for incoming water with low salt content and low organic matter content, and have high requirements on the quality of the incoming water, complex process and high operating cost. The membrane separation method has high requirements on the quality of inlet water, the pretreatment process is complex, the total hardness of the inlet water is required, a certain concentration product cannot be exceeded, and otherwise, scaling is easy to occur, and the system cannot normally operate.
Therefore, the new softened water process is the focus of attention and research in the reclaimed water industry.
The patent with publication number CN105198144A discloses a zero discharge method of high-salinity high-hardness wastewater, firstly, a microfiltration hardness removal technology is adopted to remove hardness in the high-salinity high-hardness wastewater, then, a high-efficiency reverse osmosis technology is adopted to further concentrate the wastewater after the hardness removal to obtain high-efficiency reverse osmosis produced water and high-efficiency reverse osmosis concentrated water, the high-efficiency reverse osmosis concentrated water is subjected to membrane distillation deep concentration to obtain membrane distillation produced water and membrane distillation concentrated water, the membrane distillation concentrated water is subjected to evaporative crystallization, salt solids in the concentrated water are crystallized out and are subjected to centralized drying treatment, and the high-efficiency reverse osmosis produced water, the membrane distillation produced water and the evaporative crystallization produced water produced in the treatment process can be recycled for the production process. The patent adopts a method of micro-filtration hardness removal, high-efficiency reverse osmosis, membrane distillation and evaporative crystallization to remove high-salt and high-hardness wastewater, and has the advantages of complex process, high operating cost and unsuitability for industrial application.
The patent with publication number CN105621772A discloses a zero discharge method for high-salt and high-hardness wastewater, which comprises removing hardness in high-salt and high-hardness wastewater by microfiltration, further concentrating the wastewater after removing hardness by disc-tube reverse osmosis to obtain reverse osmosis produced water and reverse osmosis concentrated water, and performing evaporative crystallization on the reverse osmosis concentrated water to obtain salt crystals and evaporative crystallized produced water. The patent adopts 'micro-filtration hardness removal, disc tube type reverse osmosis and evaporative crystallization' to treat high-salt high-hardness wastewater, and has the advantages of complex process, high operating cost and unsuitability for industrial application.
Patent publication No. CN109607830A discloses a chemical-membrane coupling softening method for high-hardness wastewater, which comprises the following steps: firstly, the wastewater enters a mixing reaction zone of a chemical treatment unit, a softening agent is added, and the wastewater enters a precipitation zone after being mixed and staying for a period of time; secondly, adding coagulation in a settling area, forming floc alum floc by the sediment, entering a sludge tank through an inclined pipe, a sludge collecting hopper and a sludge discharge pipe, and discharging supernatant to a membrane treatment unit through a water collecting pipe; and the membrane processing unit effectively intercepts the small particles of calcium carbonate and magnesium hydroxide generated by the chemical processing unit by utilizing the membrane element. The patent adopts a chemical agent method combined with a membrane separation method to treat high-hardness wastewater. The hardness of the wastewater treated by the method is still higher, and the hardness of produced water is less than or equal to 80 mg/L; and the sodium hydroxide and the sodium carbonate are adopted as chemical agents, so that the cost is higher.
The patent with publication number CN105540974A discloses a method for treating high-hardness wastewater generated after ion exchange regeneration in a high-concentration brine treatment system, wherein the high-hardness wastewater generated after cation resin exchange saturation regeneration enters a water collecting tank for storage, is lifted to a reaction sedimentation tank after the water level of the water collecting tank is stable, caustic soda and soda are added into the reaction tank, the hardness forms precipitates through chemical reaction, solid-liquid separation is carried out in the sedimentation tank, and the supernatant is sent to an adjusting tank; and (3) sending the precipitated sludge in the reaction sedimentation tank and the precipitated sludge in the clarification tank to a sludge dewatering room, sending the dehydrated press filtrate to a water collecting tank, mixing the press filtrate with high-hardness wastewater generated by the regeneration of the cationic resin, treating the mixture in the reaction sedimentation tank to ensure that no wastewater in the system is discharged outside, and sending the dehydrated sludge cakes to a landfill for landfill. The patent adopts 'chemical agent + ion exchange + evaporation crystallization' to treat high-concentration salt wastewater; the ion exchange resin is easy to be polluted and blocked by organic matters in the inlet water, the regeneration period is short, and the operation cost is high.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a novel high-salinity and high-permanent-hardness wastewater softening treatment method, which is low in operation cost and high in effluent quality and is realized by the following technical scheme:
a novel softening treatment method for high-salinity and high-permanent-hardness wastewater is characterized in that after the salinity and high-permanent-hardness wastewater from a reclaimed water reverse osmosis device is tempered, the wastewater is sent into an efficient sedimentation tank and added with chemical agents for sedimentation and flocculation treatment; and then adding a pH regulator into the effluent water of the high-efficiency sedimentation tank to regulate the pH, and then sequentially carrying out multi-medium filtration and nanofiltration treatment.
Preferably, the novel high-salinity and high-permanent-hardness wastewater softening treatment method specifically comprises the following steps:
(1) quenching and tempering: the waste water with salt content and high permanent hardness from the reclaimed water reverse osmosis device is firstly put into a regulating water tank for storage and regulation;
(2) and (3) precipitation treatment: the modified wastewater is lifted by a lift pump to enter a high-efficiency sedimentation tank, lime is added to adjust the pH value to 10.5-11.5, and Ca (HCO) in the water3)2、Mg(HCO3)2And Ca (OH)2A chemical reaction takes place to form CaCO3、Mg(OH)2And (4) precipitating.
(3) Flocculation treatment: and adding a flocculating agent and a PAM medicament into the high-efficiency sedimentation tank to form large-particle sediments so as to achieve the purpose of removing the temporary hardness in water.
(4) The multiple filtration treatment comprises the following steps: adding concentrated sulfuric acid into the effluent of the high-efficiency sedimentation tank to adjust the pH value to about 6-8, then flowing into an intermediate water tank, and then pressurizing by a nanofiltration water feed pump to enter a multi-medium filter to remove residual suspended matters in water; the filtrate of the multi-medium filter enters a nanofiltration device after being pressurized by a high pressure pump, and the permanent hardness (CaSO) in water is separated by nanofiltration4、CaCl2) The concentrated water side is separated and discharged at the concentrated water side, and most organic matters are also intercepted at the concentrated water side; backwashing drainage of the multi-medium filter for recycling to adjustA water-saving pool.
As lime is added into the high-efficiency sedimentation tank, the PH value of the water reaches 10.5-11.5, the PH value of the water is reduced to 6.5-8.0 by adding concentrated sulfuric acid, the requirement of the normal operation PH value of the nanofiltration membrane is met, the salt separation effect of nanofiltration is ensured, and the damage of the high PH value to the nanofiltration membrane is reduced.
Preferably, in the step (1), the thermal refining is: the submersible stirrer is arranged in the adjusting water tank to stir, mix and adjust the incoming water with different water qualities.
Preferably, in the step (3), the flocculating agent is PAC, the addition amount of the flocculating agent is 10-30mg/L, and the addition amount of the PAM agent is 0.5-2 mg/L.
Preferably, the packing of the multimedia filter mainly comprises: quartz sand with the grain diameter of 0.4-0.6mm and 16-mesh anthracite.
Preferably, the nanofiltration device: the integrated device comprises a nanofiltration membrane, a matched membrane shell, a valve, an instrument, a pipeline, a rack and the like, wherein the nanofiltration membrane is made of a polyamide composite membrane, and 8-inch standard membrane elements.
The invention has the beneficial effects that:
the method adopts calcium carbonate as a chemical agent, combines flocculation and multiple filtration treatment, can effectively remove carbonate hardness (temporary hardness) and non-carbonate hardness (permanent hardness) in the wastewater, does not need to add sodium carbonate compared with the prior art agent softening method, and reduces the operation cost by more than 30-50%; organic matters in the wastewater can be removed simultaneously, and the subsequent reverse osmosis process operation pollution and blockage can be avoided; the permanent hardness is mainly removed through subsequent multiple filtration treatment, compared with the permanent hardness of sodium carbonate precipitation in the prior art, the generated chemical precipitation sludge is less, and the subsequent sludge treatment difficulty and cost are reduced.
According to the wastewater treatment method provided by the invention, the effluent quality is good and stable, the effluent hardness can be reduced to below 20mg/L, the salt content and the organic matter content are low, and the stable and normal operation of a subsequent reverse osmosis membrane system can be ensured; and the process is simple and the operation cost is low.
Drawings
FIG. 1 is a flow chart of the treatment process of the present invention.
Detailed Description
The technical solution of the present invention is further defined below with reference to the specific embodiments, but the scope of the claims is not limited to the description.
Example 1
The high-salinity and high-permanent-hardness wastewater from the reclaimed water reverse osmosis device is detected to have the following components: the hardness of the carbonate is 500mg/L, the hardness of the non-carbonate is 500mg/L, and the content of the organic matter is 100-300 mg/L.
Softening treatment:
(1) quenching and tempering: the waste water with salt content and high permanent hardness from the reclaimed water reverse osmosis device is firstly put into a regulating water tank for storage and regulation;
(2) and (3) precipitation treatment: the modified wastewater is lifted by a lift pump to enter a high-efficiency sedimentation tank, lime is added to adjust the pH value to 10.5-11.5, and Ca (HCO) in the water3)2、Mg(HCO3)2And Ca (OH)2A chemical reaction takes place to form CaCO3、Mg(OH)2And (4) precipitating.
(3) Flocculation treatment: and adding a flocculating agent and a PAM medicament into the high-efficiency sedimentation tank to form large-particle sediments so as to achieve the purpose of removing the temporary hardness in water.
(4) The multiple filtration treatment comprises the following steps: adding concentrated sulfuric acid into the effluent of the high-efficiency sedimentation tank to adjust the pH value to about 6-8, then flowing into an intermediate water tank, and then pressurizing by a nanofiltration water feed pump to enter a multi-medium filter to remove residual suspended matters in water; the filtrate of the multi-medium filter enters a nanofiltration device after being pressurized by a high pressure pump, and the permanent hardness (CaSO) in water is separated by nanofiltration4、CaCl2) The concentrated water side is separated and discharged at the concentrated water side, and most organic matters are also intercepted at the concentrated water side; and backwashing drainage water of the multi-medium filter is recycled to the regulating water tank.
In the step (1), the thermal refining comprises the following steps: the submersible stirrer is arranged in the adjusting water tank to stir, mix and adjust the incoming water with different water qualities.
In the step (3), the flocculating agent is PAC, the addition amount of the flocculating agent is 10-30ppm, and the addition amount of the PAM agent is 0.5-2 ppm.
The packing of the multi-media filter mainly comprises: 0.4-0.6mm quartz sand and 16-mesh anthracite.
The nanofiltration device comprises: the integrated device comprises a nanofiltration membrane, a matched membrane shell, a valve, an instrument, a pipeline, a rack and the like, wherein the nanofiltration membrane is made of a polyamide composite membrane, and 8-inch standard membrane elements.
In the above example 1, 100m3The wastewater with high salt content and high permanent hardness can be recovered by 80-90m after softening treatment3The water and water recovery rate is 80-90%, the chemical sludge production is about 350kg (water content is 70%), and the medicament and electricity operation cost is 1.0 yuan/m3. And (3) effluent quality: the hardness of the effluent is less than 20mg/L, and the content of organic matters is less than 20 mg/L.
Example 2
The high-salinity and high-permanent-hardness wastewater from the reclaimed water reverse osmosis device is detected to have the following components: the hardness of the carbonate is 500mg/L, the hardness of the non-carbonate is 1000mg/L, and the content of the organic matter is 100-300 mg/L.
Softening treatment:
(1) quenching and tempering: the waste water with salt content and high permanent hardness from the reclaimed water reverse osmosis device is firstly put into a regulating water tank for storage and regulation;
(2) and (3) precipitation treatment: the modified wastewater is lifted by a lift pump to enter a high-efficiency sedimentation tank, lime is added to adjust the pH value to 10.5-11.5, and Ca (HCO) in the water3)2、Mg(HCO3)2And Ca (OH)2A chemical reaction takes place to form CaCO3、Mg(OH)2And (4) precipitating.
(3) Flocculation treatment: and adding a flocculating agent and a PAM medicament into the high-efficiency sedimentation tank to form large-particle sediments so as to achieve the purpose of removing the temporary hardness in water.
(4) The multiple filtration treatment comprises the following steps: adding concentrated sulfuric acid into the effluent of the high-efficiency sedimentation tank to adjust the pH value to about 6-8, then flowing into an intermediate water tank, and then pressurizing by a nanofiltration water feed pump to enter a multi-medium filter to remove residual suspended matters in water; the filtrate of the multi-medium filter enters a nanofiltration device after being pressurized by a high pressure pump, and the permanent hardness (CaSO) in water is separated by nanofiltration4、CaCl2) Side of concentrated waterThe separated organic matter is discharged from the concentrated water side, and most of the organic matter is also intercepted from the concentrated water side; and backwashing drainage water of the multi-medium filter is recycled to the regulating water tank.
In the step (1), the thermal refining comprises the following steps: the submersible stirrer is arranged in the adjusting water tank to stir, mix and adjust the incoming water with different water qualities. .
In the step (3), the flocculating agent is PAC, the addition amount of the flocculating agent is 10-30ppm, and the addition amount of the PAM agent is 0.5-2 ppm.
The packing of the multi-media filter mainly comprises: quartz sand with the grain diameter of 0.4-0.6mm and 16-mesh anthracite.
The nanofiltration device comprises: the integrated device comprises a nanofiltration membrane, a matched membrane shell, a valve, an instrument, a pipeline, a rack and the like, wherein the nanofiltration membrane is made of a polyamide composite membrane, and 8-inch standard membrane elements.
In the above example 2, 100m3The wastewater with high salt content and high permanent hardness can be recovered by 80-90m after softening treatment3The yield of water and chemical sludge is 350kg (water content is 70%), and the operation cost of the medicament and the electricity is 1.1 yuan/m3. And (3) effluent quality: the hardness of the effluent is less than 20mg/L, and the content of organic matters is less than 20 mg/L.
Example 3
The high-salinity and high-permanent-hardness wastewater from the reclaimed water reverse osmosis device is detected to have the following components: the hardness of the carbonate is 500mg/L, the hardness of the non-carbonate is 1500mg/L, and the content of the organic matter is 100-300 mg/L.
Softening treatment:
(1) quenching and tempering: the waste water with salt content and high permanent hardness from the reclaimed water reverse osmosis device is firstly put into a regulating water tank for storage and regulation;
(2) and (3) precipitation treatment: the modified wastewater is lifted by a lift pump to enter a high-efficiency sedimentation tank, lime is added to adjust the pH value to 10.5-11.5, and Ca (HCO) in the water3)2、Mg(HCO3)2And Ca (OH)2A chemical reaction takes place to form CaCO3、Mg(OH)2And (4) precipitating.
(3) Flocculation treatment: and adding a flocculating agent and a PAM medicament into the high-efficiency sedimentation tank to form large-particle sediments so as to achieve the purpose of removing the temporary hardness in water.
(4) The multiple filtration treatment comprises the following steps: adding concentrated sulfuric acid into the effluent of the high-efficiency sedimentation tank to adjust the pH value to about 6-8, then flowing into an intermediate water tank, and then pressurizing by a nanofiltration water feed pump to enter a multi-medium filter to remove residual suspended matters in water; the filtrate of the multi-medium filter enters a nanofiltration device after being pressurized by a high pressure pump, and the permanent hardness (CaSO) in water is separated by nanofiltration4、CaCl2) The concentrated water side is separated and discharged at the concentrated water side, and most organic matters are also intercepted at the concentrated water side; and backwashing drainage water of the multi-medium filter is recycled to the regulating water tank.
In the step (1), the thermal refining comprises the following steps: the submersible stirrer is arranged in the adjusting water tank to stir, mix and adjust the incoming water with different water qualities.
In the step (3), the flocculating agent is PAC, the addition amount of the flocculating agent is 10-30ppm, and the addition amount of the PAM agent is 0.5-2 ppm.
The packing of the multi-media filter mainly comprises: quartz sand 16-mesh anthracite with the grain diameter of 0.4-0.6 mm.
The nanofiltration device comprises: the integrated device comprises a nanofiltration membrane, a matched membrane shell, a valve, an instrument, a pipeline, a rack and the like, wherein the nanofiltration membrane is made of a polyamide composite membrane, and 8-inch standard membrane elements.
In the above example 3, 100m3The wastewater with high salt content and high permanent hardness can be recovered to 80-85m after softening treatment3The recovery rate of water and water is 80-85%, the chemical sludge yield is 350kg (the water content is 70%), and the operation cost of the medicament and the electricity is 1.2 yuan/m3. And (3) effluent quality: the hardness of the effluent is less than 20mg/L, and the content of organic matters is less than 20 mg/L.
Comparative example 1
The water quality of the wastewater with high salt content and high permanent hardness is the same as that of the wastewater in the example 1.
Softening treatment:
a method for treating high-hardness waste water generated after ion exchange regeneration in a high-concentration brine treatment system disclosed in the patent publication No. CN105540974A is adopted.
(1) The high-salinity and high-permanent-hardness wastewater from the reclaimed water device firstly enters an adjusting tank, meanwhile, supernatant of a reaction sedimentation tank enters the adjusting tank, the wastewater is subjected to water quality and water quantity adjustment in the adjusting tank, and adjusted strong brine enters a clarification tank;
(2) adding soda ash and caustic soda into a clarification tank, enabling most of hardness in water to generate precipitates through chemical reaction, enabling the hardness of outlet water of the clarification tank to be 50-80 mg/L calculated by calcium carbonate, enabling supernatant to enter a multi-media filter through lifting, and removing most of suspended matters and particulate matters through the filter;
(3) the effluent of the filter enters an ion exchanger, and the residual hardness is as follows: the calcium carbonate is calculated to be 50-80 mg/L, the residual hardness is subjected to ion exchange through cation exchange resin, strong brine after the ion exchange enters a brine concentration device, the strong brine is concentrated in the brine concentration device, most of water is recycled after concentration, a small amount of high brine is evaporated and crystallized, and zero discharge of water is realized.
In comparative example 1 above, 100m3The high-salinity and high-permanent-hardness wastewater can be recovered to 92-95m after being softened3The water and water recovery rate is 92-95%, the chemical sludge production is 500kg, and the medicament and electricity operating cost is 2.25 yuan/m3. And (3) effluent quality: the hardness of the effluent is 1ppm, and the content of organic matters is 90-270 mg/L.
Comparative example 2
The water quality of the wastewater with high salt content and high permanent hardness is the same as that of the wastewater in the example 1.
Softening treatment:
the patent of CN109607830A discloses a chemical-membrane coupling softening method for high-hardness wastewater. The method specifically comprises the following steps:
step 1, high-salt-content and high-permanent-hardness wastewater enters a mixed reaction zone of a chemical treatment unit, and softening agents (NaOH with the concentration of 10% and Na with the concentration of 20%) are added2CO3) Adding the calcium ions and the magnesium ions into the mixed reaction zone according to the amount which is 2 times of the content of the calcium ions and the magnesium ions, mixing the calcium ions and the magnesium ions in the mixed reaction zone for 30min by adopting a mechanical stirring mode, and then entering a precipitation zone for precipitation;
step 2, taking 2m of sediment surface load in a sediment zone3/(m2H) using polyvinyl chloride honeycomb inclined tubes with a diameter of 80mmA 60-degree inclined pipe assembly is arranged above the sludge suspension layer, so that suspended matters and cured matters in the raw water form floc alum floc after being added and coagulated, the surface area of the bottom side of the inclined pipe is gathered into a thin sludge layer, the sludge layer slides back to the sludge suspension layer under the action of gravity, and then the sludge layer is sunk into a sludge collecting hopper and is discharged into a sludge tank for further treatment through a sludge discharge pipe; the supernatant gradually rises to the water collecting pipe and is discharged to the membrane processing unit.
Step 3, the wastewater enters a membrane treatment unit after the chemical adding softening reaction, and a tubular membrane with the aperture of 0.1um is adopted to keep the aperture at 410L/m2H, the backwashing period is 30min, and the backwashing time is 2 min; during the continuous operation for 20 days, the operation pressure of the tubular microfiltration increases from the initial 0.04MPa to the later 0.15 MPa.
In comparative example 2 above, 100m3The high-salinity and high-permanent-hardness wastewater can be recovered to 95-99m after being softened3The water recovery rate is 95-99%, the chemical sludge production is 500kg, and the medicament and electricity operating cost is 2.4 yuan/m3. And (3) effluent quality: the hardness of the effluent is 50-100ppm, and the content of organic matters is 80-250 mg/L.
It should be noted that the above examples and test examples are only for further illustration and understanding of the technical solutions of the present invention, and are not to be construed as further limitations of the technical solutions of the present invention, and the invention which does not highlight essential features and significant advances made by those skilled in the art still belongs to the protection scope of the present invention.
Claims (8)
1. A novel high-salinity and high-permanent-hardness wastewater softening treatment method is characterized in that after the salinity and high-permanent-hardness wastewater from a reclaimed water reverse osmosis device is tempered, the wastewater is sent into an efficient sedimentation tank and added with chemical agents for sedimentation and flocculation treatment; and then adding a pH regulator into the effluent water of the high-efficiency sedimentation tank to regulate the pH, and then sequentially carrying out multi-medium filtration and nanofiltration treatment.
2. The novel high-salinity and high-permanent-hardness wastewater softening treatment method of claim 1, which is characterized by comprising the following steps:
(1) quenching and tempering: the waste water with salt content and high permanent hardness from the reclaimed water reverse osmosis device is firstly put into a regulating water tank for storage and regulation;
(2) and (3) precipitation treatment: the modified wastewater is lifted by a lift pump to enter a high-efficiency sedimentation tank, and lime and Ca (HCO) in water are added3)2、Mg(HCO3)2And Ca (OH)2A chemical reaction takes place to form CaCO3、Mg(OH)2Precipitating;
(3) flocculation treatment: adding a flocculating agent and a PAM medicament into the high-efficiency sedimentation tank to form large-particle sediments so as to achieve the aim of removing temporary hardness in water;
(4) multiple filtration treatment: adding a pH regulator into the effluent of the high-efficiency sedimentation tank to regulate the pH value, then flowing into an intermediate water tank, and then pressurizing by a nanofiltration water feed pump to enter a multi-medium filter to remove the residual suspended matters in the water; the filtrate of the multi-medium filter enters a nanofiltration device after being pressurized by a high-pressure pump, and is separated at the permanent hardness concentrated water side in water and discharged at the concentrated water side through the nanofiltration salt separation effect, and most organic matters are also intercepted at the concentrated water side; and backwashing drainage water of the multi-medium filter is recycled to the regulating water tank.
3. The novel softening treatment method of wastewater with high salinity and high permanent hardness as claimed in claim 2, wherein in the step (1), the thermal refining treatment comprises the following steps: the submersible stirrer is arranged in the adjusting water tank to stir, mix and adjust the incoming water with different water qualities.
4. The novel high salinity and high permanent hardness wastewater softening treatment method according to claim 2, wherein in the step (2), lime is added to adjust the pH of the wastewater to 10.5-11.5.
5. The novel softening treatment method of wastewater with high salinity and high permanent hardness as claimed in claim 2, wherein in the step (3), the flocculating agent is PAC, the addition amount of the flocculating agent is 10-30ppm, and the addition amount of the PAM agent is 0.5-2 ppm.
6. The novel softening treatment method for wastewater with high salinity and high permanent hardness as claimed in claim 2, wherein in the step (4), the pH regulator is concentrated sulfuric acid, and the pH of the effluent of the high-efficiency sedimentation tank is adjusted to 6-8.
7. The novel high salinity, high permanent hardness wastewater softening treatment process of claim 2, wherein the packing of the multi-media filter mainly comprises: quartz sand with the grain diameter of 0.4-0.6mm and 16-mesh anthracite.
8. The novel high salinity, high permanent hardness wastewater softening treatment method of claim 2, the nanofiltration device: the integrated device comprises a nanofiltration membrane, a matched membrane shell, a valve, an instrument, a pipeline, a rack and the like, wherein the nanofiltration membrane is made of a polyamide composite membrane, and 8-inch standard membrane elements.
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| CN114394711A (en) * | 2022-01-25 | 2022-04-26 | 国网河北省电力有限公司电力科学研究院 | High-hardness industrial wastewater flue gas bicarbonate and lime coagulation treatment system |
| CN114716053A (en) * | 2022-03-02 | 2022-07-08 | 华电水务工程有限公司 | Softening pretreatment method for high-COD high-salinity wastewater |
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