Membrane integrated treatment process for food pickling high-salinity wastewater

Abstract

According to the technical scheme, the membrane integrated treatment process mainly comprises the following steps: firstly, the food pickling high-salinity wastewater enters a wastewater collection tank, and sequentially enters an inorganic silicon carbide ceramic membrane pretreatment system and a silicon carbide ceramic membrane through a delivery pump to filter and remove pollutants such as suspended solids; the silicon carbide ceramic membrane concentrated liquid is subjected to outsourcing treatment; the silicon carbide ceramic membrane penetrating fluid enters a nanofiltration membrane treatment system to obtain nanofiltration concentrated water and nanofiltration produced water, the nanofiltration concentrated water is subjected to catalytic oxidation through an ozone catalysis tower, and wastewater without COD, NH3-N, plant washing water and the like enters a biochemical treatment-MBR (AAO / MBR) membrane treatment system together to be discharged after reaching the nanotube standard; the nanofiltration produced water is divided into two streams, one stream is recycled for pickling, and the other stream passes through a bipolar membrane system to prepare hydrochloric acid and liquid caustic soda which are applied to acid-base regulation in a factory area. The method provided by the invention realizes recycling of food pickling wastewater, and has the advantages of high efficiency, stability, energy conservation, consumption reduction and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-salt and high-organic matter wastewater treatment, and particularly relates to a membrane integrated treatment process for high-salt wastewater from food pickling. Background Art

[0002] Food pickling involves a wide range of industries, such as pickled mustard tuber (e.g. Chongqing Fuling area), kimchi (Sichuan Chengdu area), canned fish (Zhejiang Ningbo area), etc., which produces a large amount of wastewater with high salt, high COD, and high ammonia nitrogen. For example, the high-salt wastewater from pickled mustard tuber (COD≤10000 mg / L, Cl⁻≤30000 mg / L, NH3-N≤1000 mg / L, TP≤300 mg / L), the treatment processes for this type of wastewater mainly include traditional biochemical methods, evaporation and crystallization, etc. CN202010913182 reported a high-salt food wastewater treatment system and treatment method, which integrated a UASB reactor, an oxidation ditch, a secondary sedimentation tank, a tertiary sedimentation tank and a filter to treat high-salt food wastewater. CN202311464294 reported a method for constructing a high-salt wastewater biologically induced chemical phosphorus removal system. By enriching the native halophilic / halophilic functional bacteria in high-salt food processing wastewater, the organic matter and nitrogen metabolism process of the native halophilic / halophilic functional bacteria, and the EPS produced by the native halophilic / halophilic functional bacteria were used to drive and induce the formation of phosphate precipitation, thereby realizing the construction of a high-salt food processing wastewater biologically induced chemical phosphorus removal system to solve the inhibition of phosphorus removal microorganisms due to salinity. Most processes have defects such as low biological activity, poor treatment effect, high energy consumption and high operating costs.

[0003] The present invention intends to realize resource utilization of pickled food wastewater through membrane integrated treatment technology, while reducing the wastewater treatment volume and achieving stable and standard-compliant wastewater treatment. Summary of the Invention

[0004] The purpose of the present invention is to provide a membrane integrated treatment process for high-salt wastewater from food pickling.

[0005] The technical solution of the present invention is: A membrane integrated treatment process for high-salt food pickling wastewater mainly comprises: the high-salt food pickling wastewater first enters a wastewater collection tank and then enters an inorganic silicon carbide ceramic membrane pretreatment system via a delivery pump. The silicon carbide ceramic membrane filters and removes suspended solids and other pollutants to obtain silicon carbide ceramic membrane permeate and silicon carbide ceramic membrane concentrate, wherein the silicon carbide ceramic membrane concentrate is outsourced for treatment; the silicon carbide ceramic membrane permeate enters a nanofiltration membrane treatment system to obtain nanofiltration concentrate and nanofiltration product water, and the nanofiltration concentrate is catalytically oxidized in an ozone catalytic tower to remove COD and NH3-N. The wastewater, including in-plant flushing water, enters a biochemical treatment-MBR (AAO / MBR) membrane treatment system to meet nanotube discharge standards, with COD ≤ 500 mg / L, NH3-N ≤ 15 mg / L, total P ≤ 1 mg / L, and Cl ≤ 5000 mg / L; the nanofiltration product water is split into two streams, one of which is reused for pickling, and the other is passed through a bipolar membrane system to produce hydrochloric acid and liquid alkali, which are used for acid-base regulation in the plant.

[0006] Among them, the inorganic membrane pretreatment system is preferably a silicon carbide ceramic membrane with a pore size of 200nm-500nm, a pH tolerance of 1-14, and an operating pressure of 0.4-0.7 MPa. Its main purpose is to remove suspended solids. The silicon carbide ceramic membrane concentrate is outsourced for treatment, and the silicon carbide ceramic membrane permeate recovery rate is not less than 95%. Among them, the nanofiltration membrane treatment system has a pore size of 1.5-2nm, a NaCl retention rate ≤ 20%, a COD retention rate ≥ 70%, an NH3-N retention rate ≥ 30%, and a total P retention rate ≥ 90%; Among them, the ozone treatment system has an ozone dosage of 8-15 mg / L, a COD removal rate of ≥90%, and an NH3-N removal rate of ≥70%; Among them, for the AAO / MBR membrane treatment system, the MBR membrane selected is preferably PTFE hollow fiber membrane with a pore size of 100-200nm, a flux of 15-20LMH, a COD removal rate ≥90%, an NH3-N removal rate ≥90%, a total P removal rate ≥90%, and a turbidity of 0.6-1.0NTU; Among them, in the bipolar membrane system, the nanofiltration water enters the bipolar membrane system to produce hydrochloric acid and liquid alkali, with a mass concentration of 6%-8%, and is returned to the production workshop for pH adjustment.

[0007] Compared with the existing technology, the present invention has significant advantages: first, the high-salt wastewater from food pickling is pretreated in a graded manner through inorganic membranes, and combined with nanofiltration membranes, AAO / MBR membranes, and bipolar membrane systems, the resource reuse of food pickling wastewater is realized, and part of the nanofiltration water is made into hydrochloric acid and liquid alkali for deep resource utilization, which reduces the treatment volume of high-salt wastewater and saves the replenishment of fresh water; second, through the AAO / MBR membrane treatment system, high-salt wastewater is treated efficiently and at a low cost, with a COD degradation rate of more than 90%, an ammonia nitrogen removal rate of more than 90%, and a total P removal rate of more than 90%, thereby realizing the nanotube discharge of wastewater; finally, the membrane integrated treatment process has the advantages of high efficiency, stability, energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a schematic diagram of the membrane integrated treatment process for high-salt wastewater from food pickling provided by the present invention. DETAILED DESCRIPTION

[0009] Comparative Example 1: High-salt wastewater from pickled mustard tuber, water volume 50m 3 / d, COD is 12540 mg / L, NH3-N is 980 mg / L, total P is 120 mg / L, first pump into a 100m 3 Wastewater collection tank, mixed water such as washing in the factory 250m 3 It also enters the biochemical treatment-MBR (AAO / MBR) membrane treatment system, and the water production indicators are COD of 672mg / L, NH3-N of 25mg / L, and total P of 32mg / L, which cannot meet the pipe standard. Example

[0010] High-salt wastewater from pickled mustard tuber, water volume 50m 3 / d, COD is 12540 mg / L, NH3-N is 980 mg / L, total P is 120 mg / L, first pump into a 100m 3 The wastewater is collected in the wastewater collection box and then enters the inorganic silicon carbide ceramic membrane pretreatment system through the delivery pump. The pore size of the silicon carbide ceramic membrane is 200nm and the operating pressure is 0.5bar. After filtration, pollutants such as suspended solids are removed to obtain 49m 3 Silicon carbide ceramic membrane permeate and 1m 3 Silicon carbide ceramic membrane concentrate, of which the silicon carbide ceramic membrane concentrate is outsourced for processing; the silicon carbide ceramic membrane permeate enters the nanofiltration membrane treatment system, the nanofiltration membrane pore size is 1.5nm, the operating pressure is 0.4bar, and 8.2m 3 Nanofiltration concentrated water, COD is 49650 mg / L, NH3-N is 1108 mg / L, total P is 153 mg / L and 40.8m 3Nanofiltration produced water, COD 8160mg / L, NH3-N 735mg / L, total P 14.7mg / L, nanofiltration concentrated water was catalytically oxidized in an ozone catalytic tower, with an ozone dosage of 10mg / L to remove COD and NH3-N, and 60m3 of flushing water in the plant 3 They all enter the biochemical treatment-MBR (AAO / MBR) membrane treatment system. The MBR membrane uses PTFE hollow fiber membrane with a pore size of 100nm. The water production indicators are COD of 482mg / L, NH3-N of 15mg / L, total P of 0.8mg / L, and turbidity of 0.7NTU, meeting the nanofiltration discharge standard; the nanofiltration water is divided into two streams, one is recycled for pickles, and the other passes through the bipolar membrane system to produce hydrochloric acid and liquid alkali with a mass concentration of 8%, which is used for acid-base regulation in the plant area. Example

[0011] Kimchi pickling high-salt wastewater, water volume 50m 3 / d, COD is 10260 mg / L, NH3-N is 1073 mg / L, total P is 95 mg / L, first pump into a 100m 3 The wastewater is collected in the wastewater collection box and then enters the inorganic silicon carbide ceramic membrane pretreatment system through the delivery pump. The pore size of the silicon carbide ceramic membrane is 500nm and the operating pressure is 0.4bar. After filtration, pollutants such as suspended solids are removed to obtain 48.5m 3 Silicon carbide ceramic membrane permeate and 1.5m 3 Silicon carbide ceramic membrane concentrate, of which the silicon carbide ceramic membrane concentrate is outsourced for processing; the silicon carbide ceramic membrane permeate enters the nanofiltration membrane treatment system, the nanofiltration membrane pore size is 2nm, the operating pressure is 0.7bar, and 7.6m 3 Nanofiltration concentrated water, COD is 42360 mg / L, NH3-N is 1229 mg / L, total P is 128 mg / L and 42.4m 3 Nanofiltration produced water with COD of 5893mg / L, NH3-N of 683mg / L, and total P of 9.4mg / L. Nanofiltration concentrated water was catalytically oxidized in an ozone catalytic tower with an ozone dosage of 8mg / L to remove COD and NH3-N. 50m3 of flushing water in the plant 3 They all enter the biochemical treatment-MBR (AAO / MBR) membrane treatment system. The MBR membrane uses PTFE hollow fiber membrane with a pore size of 200nm. The water production indicators are COD of 369mg / L, NH3-N of 12mg / L, total P of 0.7mg / L, and turbidity of 0.9NTU, meeting the nanofiltration discharge standard; the nanofiltration water is divided into two streams, one is recycled for pickles, and the other passes through the bipolar membrane system to produce hydrochloric acid and liquid alkali with a mass concentration of 6%, which are used for acid-base regulation in the plant area. Example

[0012] Kimchi pickling high-salt wastewater, water volume 50m3 / d, COD is 11475 mg / L, NH3-N is 1003 mg / L, total P is 115 mg / L, first pump into a 100m 3 The wastewater is collected in the wastewater collection box and then enters the inorganic silicon carbide ceramic membrane pretreatment system through the delivery pump. The pore size of the silicon carbide ceramic membrane is 300nm and the operating pressure is 0.5bar. After filtration, pollutants such as suspended solids are removed to obtain 48.8m 3 Silicon carbide ceramic membrane permeate and 1.2m 3 Silicon carbide ceramic membrane concentrate, of which the silicon carbide ceramic membrane concentrate is outsourced for processing; the silicon carbide ceramic membrane permeate enters the nanofiltration membrane treatment system, the nanofiltration membrane pore size is 1.5nm, the operating pressure is 0.8bar, and 8.4m 3 Nanofiltration concentrated water, COD is 45690 mg / L, NH3-N is 1082 mg / L, total P is 143 mg / L and 41.6m 3 Nanofiltration produced water with COD of 6732mg / L, NH3-N of 706mg / L, and total P of 2.6mg / L. Nanofiltration concentrated water was catalytically oxidized in an ozone catalytic tower with an ozone dosage of 10mg / L to remove COD and NH3-N. The flushing water in the plant was 55m 3 They all enter the biochemical treatment-MBR (AAO / MBR) membrane treatment system. The MBR membrane uses PTFE hollow fiber membrane with a pore size of 100nm. The water production indicators are COD of 428mg / L, NH3-N of 13mg / L, total P of 0.9mg / L, and turbidity of 0.6NTU, meeting the nanofiltration discharge standard; the nanofiltration water is divided into two streams, one is recycled for pickles, and the other passes through the bipolar membrane system to produce hydrochloric acid and liquid alkali with a mass concentration of 7%, which is used for acid-base regulation in the plant area.

[0013] Application effect comparison Table 1 Comparison of the effects of the embodiments of the present invention and conventional processes The present invention uses a membrane integrated treatment process for high-salt wastewater from food pickling, integrating inorganic silicon carbide ceramic membranes and organic nanofiltration membranes to achieve nanofiltration water reuse and resource preparation of acids and alkalis from food pickling wastewater, while greatly reducing the discharge of high-salt wastewater; the nanofiltration concentrate is processed through the AAO / MBR membrane process to achieve standard nanotube discharge.

Claims

1. A membrane integrated treatment process for high-salt wastewater from food pickling, characterized by: Food pickling high-salt wastewater first enters the wastewater collection box and then enters the inorganic silicon carbide ceramic membrane pretreatment system through the delivery pump. The inorganic silicon carbide ceramic membrane has a pore size of 200-500nm, a tolerance of pH 1-14, and an operating pressure of 0.4-0.7 MPa, silicon carbide ceramic membrane filtration removes suspended matter and other pollutants to obtain silicon carbide ceramic membrane permeate and silicon carbide ceramic membrane concentrate, of which the silicon carbide ceramic membrane concentrate is outsourced for treatment; the silicon carbide ceramic membrane permeate enters the nanofiltration membrane treatment system with a pore size of 1.5-2nm to obtain nanofiltration concentrate and nanofiltration product water. The nanofiltration concentrate is catalytically oxidized in the ozone catalytic tower with an ozone concentration controlled at 8-15mg / L to remove COD and NH3-N. The factory flushing water and other wastewater enter the biochemical treatment-MBR (AAO / MBR) membrane treatment system to meet nanotube discharge standards. The nanofiltration product water is divided into two streams, one is reused for pickling, and the other passes through the bipolar membrane system to produce hydrochloric acid and liquid alkali, which are used for acid-base regulation in the factory.

2. The membrane integrated treatment process for high-salt wastewater from food pickling according to claim 1 is characterized by: The recovery rate of silicon carbide ceramic membrane permeate generated by the silicon carbide ceramic membrane pretreatment system is not less than 95%.

3. The membrane integrated treatment process for high-salt wastewater from food pickling according to claim 1 is characterized by: The nanofiltration membrane treatment system has a NaCl retention rate of ≤20%, a COD retention rate of ≥70%, an NH3-N retention rate of ≥30%, and a total P retention rate of ≥90%.

4. The membrane integrated treatment process for high-salt wastewater from food pickling according to claim 1 is characterized by: The ozone treatment system has a COD removal rate of ≥90% and an NH3-N removal rate of ≥70%.

5. The membrane integrated treatment process for high-salt wastewater from food pickling according to claim 1 is characterized by: In the AAO / MBR membrane treatment system, the MBR membrane is preferably a PTFE hollow fiber membrane with a pore size of 100-200 nm, a flux of 15-20 LMH, a COD removal rate ≥ 90%, an NH3-N removal rate ≥ 90%, a total P removal rate ≥ 90%, and a turbidity of 0.6-1.0 NTU.

6. The membrane integrated treatment process for high-salt wastewater from food pickling according to claim 1 is characterized by: The mass concentration of hydrochloric acid and liquid alkali produced by the bipolar membrane system is controlled at 6%-8%.

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