Tanning main immersion water resourceful treatment device

Abstract

The utility model relates to a resourceful treatment device for leather-making main immersion water, which aims at the characteristics of large water volume, high pollutant concentration, complex components, high suspended solids and high salt content of the leather-making main immersion water, and comprises the following steps: firstly, reducing the hardness, sulfate radicals and COD (Chemical Oxygen Demand) of the main immersion water by utilizing a primary reaction tank and a primary sedimentation tank; waste oil is recovered, COD and divalent salt are separated and concentrated through electrolytic flotation, a second-stage reaction tank, a second-stage sedimentation tank, an oil removal membrane, a material separation membrane and a two-stage NF membrane in sequence, and the waste oil and the divalent salt are returned to the front end for treatment; producing reuse water with TDS of less than or equal to 700 mg / L by using an ultrahigh pressure RO membrane, and concentrating sodium chloride to be more than or equal to 100000 mg / L; and finally, dilute acid and dilute alkali are produced by using a bipolar membrane, so that the aim of resourceful treatment of the tannery wastewater is fulfilled.

Description

Technical Field

[0001] This utility model relates to a resource-based treatment device for tanning main soaking water, belonging to the technical field of industrial wastewater treatment. Background Technology

[0002] The leather production process mainly includes three steps: (1) Preparation step: First, the hide is restored to a fresh state by soaking in water, and impurities on the hide are washed away. Subcutaneous tissue and fat on the hide are removed by removing flesh. Then, hair on the hide is removed by dehairing and liming to loosen the hide fibers appropriately. Finally, lime in the hide is removed by deliming and softening to lower the pH value of the hide and further loosen the hide fibers. (2) Tanning step: First, the pH value of the hide is adjusted by soaking in acid. Then, the collagen in the hide is combined with the tanning agent by tanning to improve the stability and water resistance of the hide. Finally, the quality and performance of the leather are further improved by retanning, that is, the fullness, softness and dyeing performance of the leather are increased. (3) Finishing step: The pH value of the leather is adjusted to 5-6 by neutralizing agent. The leather is given the required color and softness by dyeing and fatliquoring to improve the quality and performance of the leather. The moisture in the leather is removed by drying to achieve a certain degree of dryness. The leather surface is protected by coating to improve the gloss, wear resistance and water resistance of the leather.

[0003] The soaking process in the preparation stage of leather tanning generally involves two steps. First, pre-soaking removes salts from the raw hides used for preservation and washes away impurities such as salt grains, blood, feces, and dirt from the surface. Second, main soaking involves adding bactericides, degreasers, sodium hydroxide, and other soaking aids to restore the hides to an appropriate moisture content and swelling level, maintaining their freshness. This pre-soaking process generates a large amount of main soaking water, characterized by its large volume, high concentration of contaminants, complex composition, high suspended solids, and high salt content. Typical main soaking water for leather tanning has a pH of 8–10, a COD (chemical oxygen demand) of 10,000–20,000 mg / L, an NH3-N (ammonia nitrogen) concentration of 200–500 mg / L, and a TDS (total dissolved solids) concentration of 20,000–30,000 mg / L.

[0004] For high-concentration, high-salt tanning wastewater, there are currently some patents, such as (1) Patent application number 201410544075.6 Tanning wastewater treatment method, which treats tanning wastewater by passing it through a screen for sanding, (adding PAC and polyaluminum flocculant) reaction sedimentation, biological decomposition oxidation, secondary sedimentation, filtration, and disinfection before discharge to meet standards. The effluent water quality is good, but it does not solve the problem of high salt content in tanning wastewater; (2) Patent application number 201110044405.1 Tanning wastewater recycling device based on electrochemistry and ultrafiltration, in which tanning wastewater passes through pre-filtration, flocculation reaction, nano-catalytic electrolysis, sedimentation, air flotation, biochemical treatment, secondary nano-catalytic electrolysis, filtration and ultrafiltration in sequence, and the effluent is recycled. However, it is also limited by the salt content of tanning wastewater. (3) Patent application No. 201810826347.X is a tannery wastewater purification and desalination device. The tannery wastewater is purified and desalinated by passing through a sedimentation tank, a wastewater storage tank, a chromium removal tank, a hardness removal tank, a gas removal unit, and a reverse osmosis unit in sequence, so as to realize the recycling of the effluent. The process is simple. The disadvantage is that the pretreatment is not effective in treating oil and COD, and the reverse osmosis concentrate is not treated. (4) Patent application No. 200920109967.8 is a tannery wastewater desalination treatment device. For tannery wastewater that has undergone biological treatment, high-temperature oxidation, secondary evaporation, and water vapor reuse are carried out by adding alkali and oxygen. The saturated solution is cooled and crystallized to separate solid salt. The disadvantage is that direct evaporation crystallization consumes a lot of energy, and the solid salt is a mixed salt that cannot be used. Utility Model Content

[0005] This utility model proposes a resource-based treatment device for the main soaking water in leather tanning. Its purpose is to address the characteristics of leather tanning main soaking water: large volume, high pollutant concentration, complex composition, high suspended solids, and high salt content. Existing physicochemical, biochemical, and filtration treatment technologies result in high effluent salt content, and reverse osmosis desalination fails to effectively treat the reverse osmosis concentrate, or evaporates and crystallizes impurities, failing to effectively recover salt resources. This device specifically addresses the following issues: pH value 8–10, COD 10000–20000 mg / L, NH3-N 200–500 mg / L, TDS 20... The main soaking water for leather tanning, with a concentration of 000–30000 mg / L, firstly utilizes a primary reaction tank and a primary sedimentation tank. Lime, soda ash, PFS (polyferric sulfate), PAM (polyacrylamide), and powdered carbon are added to precipitate calcium carbonate and saturated calcium sulfate in the main soaking water, resulting in a hardness ≤0.5 mmol / L, sulfate ≤1800 mg / L, and COD 1500–3000 mg / L. Then, hydrochloric acid is added to adjust the pH to 6–8. The second step utilizes electrolytic flotation, a secondary reaction tank, and a secondary sedimentation tank, and adds CO2... The D-stage collector reduces COD to 500–1000 mg / L; the third step uses an oil removal membrane to reduce oil content to ≤100 mg / L, collecting waste oil for further use; the fourth step uses a material separation membrane to separate and recover COD, returning it to the front-end treatment, reducing effluent COD to 150–300 mg / L, while simultaneously protecting the material separation membrane by adding a reducing agent; the fifth step uses a two-stage NF (nanofiltration) membrane to effectively concentrate COD and divalent salts (sodium sulfate), returning them to the front-end treatment, resulting in effluent COD ≤30 mg / L and divalent salts ≤20 mg / L. In step L, scale inhibitors and non-oxidizing bactericides are added to protect the two-stage NF membranes. In step VI, an ultra-high pressure RO (reverse osmosis) membrane is used to produce recycled water with TDS ≤ 700 mg / L, and the monovalent salt (sodium chloride) in the concentrated water is concentrated to TDS ≥ 100000 mg / L. Finally, a BPED (bipolar membrane) device is used to produce dilute acid (HCl) and dilute alkali (NaOH) with a concentration of 2 mol / L. Ultimately, the water and salt resources in the main soaking water of leather tanning are effectively recovered, achieving the purpose of resource-based treatment of leather tanning wastewater and production of recycled water and dilute acid and alkali.

[0006] To solve the above-mentioned technical problems, this utility model adopts the following technical solution: This utility model provides a resource-based treatment device for tanning main soaking water, including: a raw water tank, a raw water pump, a primary reaction tank, a primary sedimentation tank, an electrolytic flotation system, a secondary reaction tank, a secondary sedimentation tank, a No. 1 clear water tank, a No. 1 clear water pump, an oil removal membrane device, a No. 2 clear water tank, a No. 2 clear water pump, a material separation membrane device, a No. 3 clear water tank, a No. 3 clear water pump, a two-stage nanofiltration system, a nanofiltration product water tank, a reverse osmosis booster pump, an ultra-high pressure reverse osmosis device, a reverse osmosis concentrate tank, a bipolar membrane booster pump, a bipolar membrane device, a dilute acid tank, a dilute acid pump, a dilute alkali tank, a dilute alkali pump, a sludge tank, a sludge pump, a plate and frame filter press, a concentrated oil tank, a concentrated oil pump, a No. 1 dosing device, a No. 2 dosing device, and a No. 3 dosing device. The system consists of: a #4 dosing unit, a #5 dosing unit, a wastewater recovery tank, a wastewater recovery pump, a reverse osmosis permeate tank, and a reverse osmosis permeate pump. The main immersion water is connected to the #1 inlet of the raw water tank. The outlet of the raw water tank is connected to the inlet of the primary reaction tank via the raw water pump. The outlet of the #1 dosing unit is connected to the inlet of the primary reaction tank. The outlet of the primary reaction tank is connected to the inlet of the primary sedimentation tank. The outlet of the primary sedimentation tank is connected to the inlet of the electrolytic flotation unit. The outlet of the #2 dosing unit is also connected to the inlet of the electrolytic flotation unit. The outlet of the electrolytic flotation unit is connected to the inlet of the secondary sedimentation tank via the secondary reaction tank. The outlet of the #3 dosing unit is connected to the inlet of the secondary reaction tank. The outlet of the secondary sedimentation tank is connected to the inlet of the #1 clear water tank. The outlet of the #1 clear water tank... The oil removal membrane unit's inlet is connected to pump #1, and its outlet is connected to the inlet of water tank #2. The outlet of water tank #2 is connected to the inlet of the material separation membrane unit via pump #2. The outlet of dosing device #4 is also connected to the inlet of the material separation membrane unit. The product water outlet of the material separation membrane unit is connected to the inlet of water tank #3. The outlet of water tank #3 is connected to the inlet of the two-stage nanofiltration system via pump #3. The outlet of dosing device #5 is also connected to the inlet of the two-stage nanofiltration system. The product water outlet of the two-stage nanofiltration system is connected to the inlet #1 of the nanofiltration product water tank. The outlet of the nanofiltration product water tank is connected to the inlet of the ultra-high pressure reverse osmosis unit via a reverse osmosis booster pump. The concentrate outlet of the ultra-high pressure reverse osmosis unit is connected to the reverse osmosis concentrate outlet. The inlet of the water tank and the outlet of the reverse osmosis concentrate tank are connected to the inlet of the bipolar membrane device via a bipolar membrane booster pump. The outlet of the bipolar membrane device is connected to the No. 2 inlet of the nanofiltration permeate tank. The acid outlet of the bipolar membrane device is connected to the acid inlet of the dilute acid tank. The acid outlet of the dilute acid tank delivers dilute hydrochloric acid via a dilute acid pump. The alkali outlet of the bipolar membrane device is connected to the alkali inlet of the dilute alkali tank. The alkali outlet of the dilute alkali tank delivers dilute sodium hydroxide via a dilute alkali pump. The sludge outlet of the primary sedimentation tank is connected to the No. 1 sludge inlet of the sludge tank. The sludge outlet of the electrolytic flotation and the sludge outlet of the secondary sedimentation tank are connected to the No. 2 sludge inlet of the sludge tank. The sludge outlet of the sludge tank is connected to the sludge inlet of the plate and frame filter press via a sludge pump. The outlet of the plate and frame filter press is also connected to the inlet of the electrolytic flotation. The sludge cake is delivered from the sludge outlet of the plate and frame filter press.The oil outlet of the oil removal film unit is connected to the oil inlet of the concentrate tank. The oil outlet of the concentrate tank is pumped out for waste oil recycling. The concentrate outlet of the material separation membrane unit is connected to the No. 1 inlet of the wastewater recovery tank. The concentrate outlet of the two-stage nanofiltration system is connected to the No. 2 inlet of the wastewater recovery tank. The outlet of the wastewater recovery tank is connected to the No. 2 inlet of the raw water tank via a wastewater recovery pump. The permeate outlet of the ultra-high pressure reverse osmosis unit is connected to the inlet of the reverse osmosis permeate tank. The outlet of the reverse osmosis permeate tank is pumped out for reuse.

[0007] Furthermore, the No. 1 dosing device includes a dosing tank for lime, soda ash, polyferric sulfate, polyacrylamide, and powdered carbon, and a No. 1 metering pump;

[0008] The aforementioned dosing device #2 includes a hydrochloric acid dosing tank and a #2 metering pump;

[0009] The aforementioned dosing device #3 includes a COD collector dosing tank and a #3 metering pump;

[0010] The aforementioned dosing device #4 includes a reducing agent dosing tank and a #4 metering pump;

[0011] The aforementioned dosing device #5 includes a dosing tank for scale inhibitor and non-oxidizing bactericide, and a #5 metering pump.

[0012] The advantages of this utility model: This utility model relates to a resource-based treatment device for tanning wastewater. It addresses the characteristics of tanning wastewater, including large volume, high pollutant concentration, complex composition, high suspended solids, and high salt content. First, a primary reaction tank and a primary sedimentation tank are used to reduce the hardness, sulfate, and COD of the wastewater. Then, electrolytic flotation, a secondary reaction tank and a secondary sedimentation tank, an oil removal membrane, a material separation membrane, and two-stage NF membranes are used sequentially to recover waste oil and separate and concentrate COD and divalent salts, returning them to the front-end treatment. Next, an ultra-high pressure RO membrane is used to produce reclaimed water with TDS ≤ 700 mg / L and to concentrate sodium chloride to ≥ 100,000 mg / L. Finally, a bipolar membrane is used to produce dilute acid and dilute alkali, achieving the goal of resource-based treatment of tanning wastewater. Attached Figure Description

[0013] Appendix Figure 1 A schematic diagram of the overall structure of the leather processing main soaking water resource utilization device.

[0014] In the attached diagram, MIW represents the main immersion tank, RWT represents the raw water tank, RWP represents the raw water pump, RWT / RWP represents the raw water tank and raw water pump, RT1 represents the primary reaction tank, ST1 represents the primary sedimentation tank, RT1 / ST1 represents the primary reaction tank and primary sedimentation tank, EF represents electrolytic flotation, RT2 represents the secondary reaction tank, ST2 represents the secondary sedimentation tank, EF / RT2 / ST2 represents electrolytic flotation, secondary reaction tank, and secondary sedimentation tank, CWT1 represents No. 1 clear water tank, CWP1 represents No. 1 clear water pump, CWT1 / CWP1 represents No. 1 clear water tank and No. 1 clear water pump, and DOMS represents the oil film removal device. CWT2 indicates No. 2 clean water tank; CWP2 indicates No. 2 clean water pump; CWT2 / CWP2 indicates No. 2 clean water tank and No. 2 clean water pump; MSMS indicates material separation membrane unit; CWT3 indicates No. 3 clean water tank; CWP3 indicates No. 3 clean water pump; CWT3 / CWP3 indicates No. 3 clean water tank and No. 3 clean water pump; 2NFS indicates two-stage nanofiltration unit; NFPWT indicates nanofiltration permeate tank; ROP indicates reverse osmosis booster pump; NFPWT / ROP indicates nanofiltration permeate tank and reverse osmosis booster pump; UHPROS indicates ultra-high pressure reverse osmosis unit; ROCWT indicates reverse osmosis concentrate tank; BPEDP indicates bipolar... Membrane booster pump; ROCWT / BPEDP indicates reverse osmosis concentrate tank and bipolar membrane booster pump; BPEDS indicates bipolar membrane unit; DAT indicates dilute acid tank; DAP indicates dilute acid pump; DAT / DAP indicates dilute acid tank and pump; DHCl indicates dilute hydrochloric acid; DALT indicates dilute alkali tank; DALP indicates dilute alkali pump; DALT / DALP indicates dilute alkali tank and pump; DNaOH indicates dilute sodium hydroxide; SRT indicates sludge tank; SRP indicates sludge pump; BF indicates plate and frame filter press; SRT / SRP / BF indicates sludge tank, sludge pump, and plate and frame filter press; SC indicates cake; COT indicates concentrate. Oil tank; COP indicates concentrate pump; COT / COP indicates concentrate tank and concentrate pump; WO indicates waste oil; DS1 indicates dosing device #1; DS2 indicates dosing device #2; DS3 indicates dosing device #3; DS4 indicates dosing device #4; DS5 indicates dosing device #5; WWRT indicates wastewater recovery tank; WWRP indicates wastewater recovery pump; WWRT / WWRP indicates wastewater recovery tank and wastewater recovery pump; ROPWT indicates reverse osmosis permeate tank; ROPWP indicates reverse osmosis permeate pump; ROPWT / ROPWP indicates reverse osmosis permeate tank and reverse osmosis permeate pump; RCW indicates recycled water. Detailed Implementation

[0015] Example 1

[0016] As attached Figure 1As shown, a resource-based treatment device for tanning main soaking water includes a raw water tank RWT, a raw water pump RWP, a primary reaction tank RT1, a primary sedimentation tank ST1, an electrolytic flotation unit EF, a secondary reaction tank RT2, a secondary sedimentation tank ST2, a #1 clear water tank CWT1, a #1 clear water pump CWP1, an oil removal membrane device DOMS, a #2 clear water tank CWT2, a #2 clear water pump CWP2, a material separation membrane device MSMS, a #3 clear water tank CWT3, a #3 clear water pump CWP3, a two-stage nanofiltration system 2NFS, a nanofiltration permeate tank NFPWT, a reverse osmosis booster pump ROP, and an ultra-high pressure reverse osmosis device U. HPROS, Reverse Osmosis Concentrate Tank ROCWT, Bipolar Membrane Booster Pump BPEDP, Bipolar Membrane Unit BPEDS, Dilute Acid Tank DAT, Dilute Acid Pump DAP, Dilute Alkali Tank DALT / , Dilute Alkali Pump DALP, Sludge Tank SRT, Sludge Pump SRP, Plate and Frame Filter Press BF, Concentrate Oil Tank COT, Concentrate Oil Pump COP, 1# Dosing Device DS1, 2# Dosing Device DS2, 3# Dosing Device DS3, 4# Dosing Device DS4, 5# Dosing Device DS5, Wastewater Recovery Tank WWRT, Wastewater Recovery Pump WWRP, Reverse Osmosis Permeate Tank ROPWT and Reverse Osmosis Permeate Pump ROPWP;The main immersion water (MIW) is connected to the No. 1 inlet of the raw water tank (RWT). The outlet of the raw water tank (RWT) is connected to the inlet of the primary reaction tank (RT1) via the raw water pump (RWP). The outlet of the No. 1 dosing device (DS1) is connected to the inlet of the primary reaction tank (RT1). The outlet of the primary reaction tank (RT1) is connected to the inlet of the primary sedimentation tank (ST1). The outlet of the primary sedimentation tank (ST1) is connected to the inlet of the electrolytic flotation (EF). The outlet of the No. 2 dosing device (DS2) is also connected to the inlet of the electrolytic flotation (EF). The outlet of the electrolytic flotation (EF) is connected to the inlet of the secondary sedimentation tank (ST2) via the secondary reaction tank (RT2). The outlet of the No. 3 dosing device (DS3) is connected to the inlet of the secondary reaction tank (RT2). The outlet of the secondary sedimentation tank (ST2) is connected to... The system connects to the inlet of water tank #1 (CWT1). The outlet of water tank #1 (CWT1) is connected to the inlet of the oil removal film device (DOMS) via water pump #1 (CWP1). The outlet of DOMS is connected to the inlet of water tank #2 (CWT2). The outlet of water tank #2 (CWT2) is connected to the inlet of the material separation membrane device (MSMS) via water pump #2 (CWP2). The outlet of dosing device #4 (DS4) is also connected to the inlet of MSMS. The product water outlet of MSMS is connected to the inlet of water tank #3 (CWT3). The outlet of water tank #3 (CWT3) is connected to the inlet of the two-stage nanofiltration system (2NFS) via water pump #3 (CWP3). The system also connects to dosing device #5 (DS5). The outlet of the chemical filter is also connected to the inlet of the two-stage nanofiltration system 2NFS. The product water outlet of the two-stage nanofiltration system 2NFS is connected to the No. 1 inlet of the nanofiltration product water tank NFPWT. The outlet of the nanofiltration product water tank NFPWT is connected to the inlet of the ultra-high pressure reverse osmosis unit UHPROS via the reverse osmosis booster pump ROP. The concentrate outlet of the ultra-high pressure reverse osmosis unit UHPROS is connected to the inlet of the reverse osmosis concentrate tank ROCWT. The outlet of the reverse osmosis concentrate tank ROCWT is connected to the inlet of the bipolar membrane unit BPEDS via the bipolar membrane booster pump BPEDP. The outlet of the bipolar membrane unit BPEDS is connected to the No. 2 inlet of the nanofiltration product water tank NFPWT. The acid outlet of the bipolar membrane unit BPEDS is connected to the dilute acid tank DAT. The acid inlet and the acid outlet of the dilute acid tank DAT are connected to the dilute acid pump DAP to deliver dilute hydrochloric acid DHCl. The alkali outlet of the bipolar membrane device BPEDS is connected to the alkali inlet of the dilute alkali tank DALT. The alkali outlet of the dilute alkali tank DALT is connected to the dilute alkali pump DALP to deliver dilute sodium hydroxide DNaOH. The sludge outlet of the primary sedimentation tank ST1 is connected to the sludge inlet #1 of the sludge tank SRT. The sludge outlet of the electrolytic flotation EF and the sludge outlet of the secondary sedimentation tank ST2 are connected to the sludge inlet #2 of the sludge tank SRT. The sludge outlet of the sludge tank SRT is connected to the sludge inlet of the plate and frame filter press BF through the sludge pump SRP. The water outlet of the plate and frame filter press BF is also connected to the water inlet of the electrolytic flotation EF. The sludge cake SC is delivered from the sludge outlet of the plate and frame filter press BF (for off-site treatment).The oil outlet of the DOMS oil removal unit is connected to the inlet of the COT (Concentrated Oil Tank). The COT outlet discharges waste oil (WO) (for recycling) via the COP (Concentrated Oil Pump). The concentrate outlet of the MSMS (Material Separation Membrane Unit) is connected to the #1 inlet of the WWRT (Wastewater Recovery Tank). The concentrate outlet of the 2NFS (Two-Stage Nanofiltration System) is connected to the #2 inlet of the WWRT. The WWRT outlet is connected to the #2 inlet of the RWT (Raw Water Tank) via the WWRP (Wastewater Recovery Pump). The permeate outlet of the UHPROS (Ultra-High Pressure Reverse Osmosis Unit) is connected to the inlet of the ROPWT (Reverse Osmosis Permeate Tank). The ROPWT outlet discharges recycled water (RCW) via the ROPWP (Reverse Osmosis Permeate Pump).

[0017] The DS1 dosing unit includes dosing tanks for lime, soda ash, PFS, PAM, and powdered carbon, as well as a metering pump.

[0018] The DS2 dosing unit (2#) includes a hydrochloric acid dosing tank and a metering pump (1#).

[0019] The DS3 dosing unit (3#) includes a COD collector dosing tank and a metering pump (2#).

[0020] The DS4 dosing unit (4#) includes a reducing agent dosing tank and a metering pump (3#).

[0021] The DS5 dosing unit (No. 5) includes a dosing tank for scale inhibitor and non-oxidizing bactericide, and a metering pump (No. 4).

[0022] The treatment method of the leather tanning main soaking water resource utilization device includes the following steps:

[0023] 1) The tanning water is passed through a primary reaction tank and a primary sedimentation tank in sequence. The hardness, sulfate and COD in the water are reduced by adding chemicals, and then acid is added to adjust the pH value back to 6-8.

[0024] 2) The COD is reduced by adding a COD collector after passing through the electrolytic flotation EF, the secondary reaction tank RT2 and the secondary sedimentation tank ST2 in sequence.

[0025] 3) Waste oil is recovered through the DOMS (Oil Film Removal System);

[0026] 4) COD is separated and reduced by using the MSMS material separation membrane device;

[0027] 5) The COD is further separated and reduced by a two-stage nanofiltration device (2NFS), and divalent salts are removed.

[0028] 6) Reclaimed water is produced through the ultra-high pressure reverse osmosis unit UFPROS, and the monovalent salt is concentrated to TDS≥100000mg / L;

[0029] 7) A dilute acid and a dilute base with a concentration of 2 mol / L were separated by a bipolar membrane device BPEDS.

[0030] Step 1) The water is passed sequentially through the primary reaction tank RT1 and the primary sedimentation tank ST1. Specifically, for the main soaking water for leather tanning with a pH of 8-10, COD of 10000-20000 mg / L, NH3-N of 200-500 mg / L, and TDS of 20000-30000 mg / L, the water quality and quantity are first adjusted and increased using the raw water tank RWT and the raw water pump RWP. By adding lime, soda ash, PFS (polyferric sulfate), PAM (polyacrylamide), and powdered carbon, the calcium carbonate and saturated calcium sulfate in the main soaking water react and precipitate, so that the effluent hardness is ≤0.5 mmol / L, sulfate ≤1800 mg / L, and COD is 1500-3000 mg / L. Then, hydrochloric acid is added to adjust the pH value back to 6-8.

[0031] Step 2) The water is passed sequentially through electrolytic flotation EF, secondary reaction tank RT2, and secondary sedimentation tank ST2. Specifically, for the effluent from the primary sedimentation tank ST1, COD is reduced by adding a COD collector. The COD of the effluent is reduced from 1500-3000 mg / L to 500-1000 mg / L and NH3-N is reduced from 200-500 mg / L to 20-50 mg / L by using electrolytic flotation EF, secondary reaction tank RT2, and secondary sedimentation tank ST2.

[0032] Step 3) The oil removal film device DOMS is used to remove the oil from the secondary sedimentation tank ST2. First, the water is stored and pumped using the No. 1 clean water tank CWT1 and the No. 1 clean water pump CWP1. Then, the oil content of the effluent is reduced to ≤100mg / L by the oil removal film device DOMS. The waste oil is collected and transported for further treatment and reuse.

[0033] Step 4) The material separation membrane device MSMS, specifically for the effluent from the oil removal membrane device DOMS, first uses the No. 2 clean water tank CWT2 and the No. 2 clean water pump CWP2 to store and lift the effluent, and then uses the material separation membrane device MSMS to separate and recover COD, which is then returned to the front end for treatment, reducing the COD of the effluent to 150-300 mg / L. At the same time, a reducing agent is added to protect the material separation membrane.

[0034] Step 5) The water is treated by two-stage nanofiltration membranes. Specifically, for the effluent from the material separation membrane, the water is first stored and pressurized using a No. 2 clean water tank and a No. 2 clean water pump. Then, the two-stage nanofiltration system is used to further separate and reduce COD, remove divalent salts, and effectively concentrate COD and divalent salts (sodium sulfate). The water is then returned to the front-end treatment, so that the effluent COD is ≤30mg / L and divalent salts are ≤20mg / L. At the same time, scale inhibitors and non-oxidizing bactericides are added to protect the two-stage NF membranes.

[0035] Step 6) Using the ultra-high pressure reverse osmosis (UFPROS) device, specifically for nanofiltration membrane effluent, the nanofiltration product water tank and RO booster pump are used for storage and pressurization. Then, the UFPROS device is used to concentrate the monovalent salt (sodium chloride) of the concentrate to TDS≥100000mg / L, and produce recycled water with TDS≤700mg / L, effectively recovering the water resources in the main soaking water of leather making.

[0036] Step 7) Using the bipolar membrane device BPEDS, specifically for ultra-high pressure reverse osmosis effluent, the RO concentrate is first stored and pressurized by circulating it with the bipolar membrane booster pump BPED. Then, the bipolar membrane device BPEDS is used to separate dilute acid and dilute alkali, producing HCl (hydrochloric acid) and NaOH (sodium hydroxide) with a concentration of 2 mol / L, respectively. This effectively recovers the salt resources in the main soaking water of leather tanning, achieving the purpose of resource-based treatment of leather tanning wastewater and producing recycled water and dilute acid and alkali.

[0037] Example 2

[0038] This embodiment is the second embodiment of the present invention. Unlike the first embodiment, this embodiment provides a verification test of the leather tanning water immersion resource utilization device to verify and explain the technical effects adopted in this method.

[0039] A new materials company is located in the local leather industry development zone, covering an area of ​​200 mu (approximately 33 acres), with a total investment of 200 million yuan, forming an annual production capacity of 1.5 million pieces of cowhide automotive leather. The preparation, tanning, and dyeing and finishing processes in the leather production process generate a large amount of production wastewater. This embodiment mainly targets the high salt and heavy pollution characteristics of the main soaking water in the preparation process, and uses the resource-based treatment technology of the main soaking water in leather production to conduct pilot-scale verification, effectively recovering water and salt resources from the wastewater.

[0040] 1. Design influent water quality, quantity, and products.

[0041] The water quality for the main soaking water in the leather tanning process is designed as follows: Unit: g / L (except pH).

[0042] Element TDS COD <![CDATA[NH3-N]]> Oil pH content 22300 19680 385 190 8.5

[0043] The designed water volume for the main immersion of leather is 24T / D (1T / H).

[0044] The amount of recycled water produced is 16.6 T / D (0.69 T / H), and the TDS is ≤700 mg / L.

[0045] The product yields 2.23 T / D (0.093 T / H) of hydrochloric acid at a concentration of 2 mol / L (80 g / L) and 1.87 T / D (0.078 T / H) of sodium hydroxide at a concentration of 2 mol / L (73 g / L).

[0046] 2. Pilot-scale equipment

[0047] The pilot-scale equipment for the resource utilization treatment of tanning main soaking water is shown in the table below:

[0048]

[0049]

[0050]

[0051] 3. Pilot-scale results

[0052] Firstly, considering that the pilot-scale system for the resource-based treatment of tannery soaking water is relatively small, the dosage of chemicals is difficult to control, and the dilution degree of some chemicals is greater than that of the project scale.

[0053] First, the tanning soaking water has a Q of 24 T / D (1 T / H), TDS of 22300 mg / L, and COD of 19680 mg / L. It enters the raw water tank for water quality and quantity adjustment. It is then combined with the material separation membrane concentrate and the second-stage NF concentrate recovered later, which has a Q of 3.8 T / D (0.158 T / H). The total Q is 27.8 T / D (1.158 T / H). It is then pumped into the first-stage reaction tank by the raw water pump.

[0054] By adding Ca(OH)2 at a concentration of 3% and a concentration of 50 L / H, Na2CO3 at a concentration of 10% and a concentration of 19 L / H, PFS at a concentration of 5% and a concentration of 11.7 L / H, PAM at a concentration of 0.1% and a concentration of 5.8 L / H, and powdered carbon at a concentration of 3% and a concentration of 7.8 L / H respectively, the mixture was reacted in a primary reactor and then settled in a primary precipitator. The resulting effluent COD concentration was reduced to 2952 mg / L, and SO42- was significantly lower. 2- The concentration was reduced to 1451 mg / L; the pH of the effluent was adjusted back to 70.5 by adding HCl with a concentration of 5% and a concentration of Q of 1.7 L / H, and then the effluent flowed into the electrolytic flotation unit.

[0055] After electrolytic flotation treatment, the effluent enters the secondary reaction tank, where a COD collector with a concentration of 3% and a flow rate of Q of 3.9 L / H is added. After passing through the secondary reaction tank and the secondary sedimentation tank, the effluent has a flow rate of Q of 25.86 T / D (1.08 T / H), with COD reduced to 984 mg / L and NH3-N reduced to 38 mg / L, and then enters the clear water tank 1. Here, the sludge discharged from the primary and secondary sedimentation tanks is pumped into the sludge tank by two sludge pumps. After being filtered by plate and frame filter press, a sludge cake with a flow rate of Q of 2.21 T / D (0.092 T / H) and a moisture content of 70% is discharged.

[0056] The secondary sedimentation effluent is pressurized by the No. 1 clean water pump and enters the oil removal membrane device. The waste oil with a value of Q = 1.29T / D (0.054T / H) is separated and recovered by the ceramic membrane and sent to the oil concentration tank. The effluent Q = 24.57T / D (1.02T / H), TDS = 22300mg / L, COD = 984mg / L, and oil content ≤100mg / L, and then enters the No. 2 clean water tank.

[0057] The effluent from the oil removal membrane unit is pressurized by pump #2 and enters the material separation membrane unit. The material separation membrane is protected by adding a reducing agent with a concentration of 1% and a concentration of Q of 0.5 L / H. Organic matter is separated and recovered by the material separation membrane, with a recovery rate of 95%. The concentrate from the material separation membrane, Q, is 1.23 T / D (0.051 T / H) and is returned to the front-end treatment. The permeate from the material separation membrane, Q, is 23.34 T / D (0.973 T / H), with a TDS of 22300 mg / L and a COD of 295 mg / L, and enters the clean water tank 3.

[0058] The material is pressurized by a water pump 3 and fed into a two-stage nanofiltration (NF) unit. The two NF membranes are protected by adding a scale inhibitor (Q = 0.5 L / H, 1% concentration) and a non-oxidizing bactericide (Q = 0.4 L / H, 0.5% concentration). Organic matter and divalent salts are separated and recovered using the NF membranes. The recovery rate of the two-stage NF membrane unit is 89%. The concentrate from the two-stage NF membranes, Q = 2.57 T / D (0.107 T / H), is returned to the front-end treatment. The permeate from the two-stage NF membranes, Q = 20.77 T / D (0.865 T / H), has a TDS of 21300 mg / L, a COD of 29 mg / L, and an SO42-level concentration of [missing information]. 2- ≤20mg / L, enter the nanofiltration product water tank.

[0059] The NF permeate is pressurized by an ultra-high pressure reverse osmosis booster pump and enters the ultra-high pressure reverse osmosis unit. The ultra-high pressure reverse osmosis unit has a desalination rate of 97% and a recovery rate of 80%, producing recycled water with a Q of 16.62 T / D (0.693 T / H) and a TDS of 639 mg / L, which enters the ultra-high pressure reverse osmosis permeate tank. At the same time, the concentrate (mainly NaCl) with a Q of 4.15 T / D (0.173 T / H) and a TDS of 103944 mg / L is concentrated and enters the ultra-high pressure reverse osmosis concentrate tank.

[0060] Finally, the RO concentrate is pressurized by a bipolar membrane booster pump and fed into the bipolar membrane device, which produces hydrochloric acid with a concentration of 2 mol / L (80 g / L) and a concentration of 1.87 T / D (0.078 T / H) with a concentration of 2 mol / L (73 g / L).

Claims

1. A resource-based treatment device for tanning main soaking water, characterized in that: The system includes a raw water tank, raw water pump, primary reaction tank, primary sedimentation tank, electrolytic flotation, secondary reaction tank, secondary sedimentation tank, #1 clear water tank, #1 clear water pump, oil removal membrane device, #2 clear water tank, #2 clear water pump, material separation membrane device, #3 clear water tank, #3 clear water pump, two-stage nanofiltration system, nanofiltration permeate tank, reverse osmosis booster pump, ultra-high pressure reverse osmosis device, reverse osmosis concentrate tank, bipolar membrane booster pump, bipolar membrane device, dilute acid tank, dilute acid pump, dilute alkali tank, dilute alkali pump, sludge tank, sludge pump, plate and frame filter press, concentrate oil tank, concentrate oil pump, #1 dosing device, #2 dosing device, #3 dosing device, #4 dosing device, #5 dosing device, wastewater recovery tank, wastewater recovery pump, reverse osmosis permeate tank, and reverse osmosis permeate pump; among which, the main immersion water... The system connects to the No. 1 inlet of the raw water tank. The outlet of the raw water tank is connected to the inlet of the primary reaction tank via the raw water pump. The outlet of the No. 1 dosing device is connected to the inlet of the primary reaction tank. The outlet of the primary reaction tank is connected to the inlet of the primary sedimentation tank. The outlet of the primary sedimentation tank is connected to the inlet of the electrolytic flotation system. The outlet of the No. 2 dosing device is also connected to the inlet of the electrolytic flotation system. The outlet of the electrolytic flotation system is connected to the inlet of the secondary sedimentation tank via the secondary reaction tank. The outlet of the No. 3 dosing device is connected to the inlet of the secondary reaction tank. The outlet of the secondary sedimentation tank is connected to the inlet of the No. 1 clear water tank. The outlet of the No. 1 clear water tank is connected to the inlet of the oil film removal device via the No. 1 clear water pump. The outlet of the oil film removal device is connected to the inlet of the No. 2 clear water tank. The outlet of the first water unit is connected to the inlet of the material separation membrane unit via the No. 2 clean water pump. The outlet of the No. 4 dosing unit is also connected to the inlet of the material separation membrane unit. The product water outlet of the material separation membrane unit is connected to the inlet of the No. 3 clean water tank. The outlet of the No. 3 clean water tank is connected to the inlet of the two-stage nanofiltration system via the No. 3 clean water pump. The outlet of the No. 5 dosing unit is also connected to the inlet of the two-stage nanofiltration system. The product water outlet of the two-stage nanofiltration system is connected to the No. 1 inlet of the nanofiltration product water tank. The outlet of the nanofiltration product water tank is connected to the inlet of the ultra-high pressure reverse osmosis unit via the reverse osmosis booster pump. The concentrate outlet of the ultra-high pressure reverse osmosis unit is connected to the inlet of the reverse osmosis concentrate tank. The outlet of the reverse osmosis concentrate tank is connected to the inlet of the bipolar membrane unit via the bipolar membrane booster pump. The water outlet is connected to the No. 2 inlet of the nanofiltration permeate tank. The acid outlet of the bipolar membrane device is connected to the acid inlet of the dilute acid tank. The acid outlet of the dilute acid tank delivers dilute hydrochloric acid via a dilute acid pump. The alkali outlet of the bipolar membrane device is connected to the alkali inlet of the dilute alkali tank. The alkali outlet of the dilute alkali tank delivers dilute sodium hydroxide via a dilute alkali pump. The sludge outlet of the primary sedimentation tank is connected to the No. 1 sludge inlet of the sludge tank. The sludge outlets of the electrolytic flotation and the secondary sedimentation tank are connected to the No. 2 sludge inlet of the sludge tank. The sludge outlet of the sludge tank is connected to the sludge inlet of the plate and frame filter press via a sludge pump. The water outlet of the plate and frame filter press is also connected to the water inlet of the electrolytic flotation. The sludge outlet of the plate and frame filter press delivers sludge cake. The oil outlet of the oil removal film device is connected to the oil inlet of the concentrated oil tank. The oil outlet of the concentrated oil tank delivers waste oil for recycling via a concentrated oil pump.The concentrate outlet of the material separation membrane unit is connected to the No. 1 inlet of the wastewater recovery tank; the concentrate outlet of the two-stage nanofiltration system is connected to the No. 2 inlet of the wastewater recovery tank; the outlet of the wastewater recovery tank is connected to the No. 2 inlet of the raw water tank via a wastewater recovery pump; the permeate outlet of the ultra-high pressure reverse osmosis unit is connected to the inlet of the reverse osmosis permeate tank; the outlet of the reverse osmosis permeate tank is pumped out as recycled water.

2. The leather tanning main soaking water resource utilization device according to claim 1, characterized in that, The No. 1 dosing device includes a dosing tank for lime, soda ash, polyferric sulfate, polyacrylamide, and powdered carbon, and a No. 1 metering pump; The aforementioned dosing device #2 includes a hydrochloric acid dosing tank and a #2 metering pump; The aforementioned dosing device #3 includes a COD collector dosing tank and a #3 metering pump; The aforementioned dosing device #4 includes a reducing agent dosing tank and a #4 metering pump; The aforementioned dosing device #5 includes a dosing tank for scale inhibitor and non-oxidizing bactericide, and a #5 metering pump.

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