A water treatment system for removing total organic carbon from coal chemical biochemical tail water

Abstract

The utility model relates to the technical field of water treatment, and specifically to a water treatment system for removing total organic carbon from coal chemical biochemical tail water, comprising an advanced oxidation system, a deep biochemical system, a deep oxidation system, a deep adsorption system, a deep separation system and a reverse osmosis system arranged in sequence; the application removes total organic carbon through the coordinated and complementary removal of the various components of the above-mentioned systems, thereby solving the problem that the coal chemical biochemical tail water cannot meet the water requirements of high-temperature and high-pressure boilers.

Description

Technical Field

[0001] The utility model relates to the technical field of water treatment, in particular to a water treatment system for removing total organic carbon from coal chemical biochemical tail water. Background Art

[0002] Coal chemical wastewater is generally divided into easily degradable coal chemical wastewater and difficult to degrade coal chemical wastewater. After physical, chemical and biochemical treatment, its biochemical tail water is divided into difficult to degrade coal chemical biochemical tail water and degradable coal chemical biochemical tail water. Coal chemical large-scale production not only produces a large amount of production wastewater, but also consumes a large amount of high-temperature and high-pressure steam. When high-temperature and high-pressure boiler water is gasified at high temperature, the organic matter in the boiler water will react with water to generate hydrogen. The accumulation of hydrogen causes the danger of boiler explosion. Therefore, the water entering the high-temperature and high-pressure boiler must meet the total organic carbon (TOC) of less than 0.5mg / L. Although the organic matter in the raw water is generally low, the total organic carbon (TOC) of the effluent water of the boiler can be reduced to less than 0.5mg / L by using the reverse osmosis treatment system supporting the boiler. However, due to the extreme water shortage in coal-rich areas such as the northwest, it is very necessary to treat the biochemical tail water into water with a total organic carbon (TOC) of less than 0.5mg / L.

[0003] The composition of coal chemical wastewater is complex, and its biochemical tail water composition is even more complex. The technologies for removing organic matter from coal chemical biochemical tail water generally include activated carbon adsorption and nanofiltration membrane removal, and reverse osmosis membrane is mainly used for desalination. Activated carbon adsorption has a strong adsorption capacity for organic matter with poor solubility, poor hydrophilicity, and weak polarity (such as benzene, phenols, petroleum and petroleum products), but has a weak adsorption capacity for organic matter with large solubility, strong hydrophilicity, and strong polarity, and the removal effect is poor. It mainly removes weak polar organic matter such as benzene, phenols, petroleum and petroleum products. Nanofiltration membrane uses the Donnan effect, and has a good removal effect on macromolecules and multivalent ion organic matter larger than the pore size of the nanofiltration membrane, and has a low removal rate for monovalent ion organic matter and non-ionic organic matter; nanofiltration membrane basically does not intercept monovalent ions, and has a certain interception of multivalent ions according to the pore size and performance of the nanofiltration membrane. Due to the defects of activated carbon adsorption and nanofiltration membrane, it is currently difficult to treat coal chemical biochemical tail water to a total organic carbon (TOC) of less than 0.5 mg / L, and it cannot meet the water requirements of high-temperature and high-pressure boilers (GB / T1576-2018 Industrial Boiler Water Quality). It can only be used at the low end, such as circulating water, greening, flushing toilets, and river water replenishment. The treatment of coal chemical biochemical tail water faces the problems of low resource utilization and waste of water resources. Utility Model Content

[0004] The utility model aims to provide a water treatment system for removing total organic carbon from biochemical tail water, so as to solve the problems of low resource utilization rate and water resource waste faced by the current treatment of biochemical tail water in coal chemical industry.

[0005] In order to achieve the above-mentioned purpose, the utility model provides a water treatment system for removing total organic carbon from biochemical tail water of coal chemical industry. The utility model classifies the biochemical tail water of coal chemical industry according to the biodegradability B / C ratio (5-day biochemical oxygen demand / chemical oxygen demand) from the source. The degradable biochemical tail water with a B / C ratio greater than 0.3 directly enters the deep biochemical system, and the difficult-to-degrade biochemical tail water with a B / C ratio less than 0.3 is subjected to advanced oxidation treatment to improve the biodegradability. The B / C ratio is increased to more than 0.3 before entering the deep biochemical system. After being treated by the deep biochemical system, the content of total organic carbon (TOC) in the effluent is stably controlled, and the effluent total organic carbon (TOC) is less than 25 mg / L; the effluent of the deep biochemical system is then subjected to deep oxidation to remove the oxidizable molecular groups of organic matter (such as hydroxyl groups, aldehydes, etc.). The deep oxidation system can remove organic matter such as alkyl, ketone, phenolic hydroxyl, methylene, etc., into carboxyl groups, so that organic matter can form alkyl polycarboxylic acid (R(COOH)n) as much as possible, and the deep oxidation removal rate of total organic carbon (TOC) is between 50-70%; the effluent after deep oxidation enters the deep adsorption system, firstly removes small molecular organic matter such as difficult-to-oxidize organic matter, benzene, petroleum and petroleum products, monocarboxylic acid, etc., and then enters the negatively charged nanofiltration membrane system, and removes multivalent ionic organic matter in the water through the charged Donnan effect on the membrane surface of the negatively charged nanofiltration membrane, and removes some large molecules through the nanometer-scale pore diameter of the nanofiltration membrane; the deep oxidation system, deep adsorption system and deep separation system complement each other, and finally remove salt and a small amount of total organic carbon through the reverse osmosis system, which can achieve a total organic carbon (TOC) of less than 0.5mg / L in the effluent.

[0006] Based on the above ideas, the utility model provides a water treatment system for removing total organic carbon from coal chemical biochemical tail water, which sequentially sets up an advanced oxidation system, a deep biochemical system, a deep oxidation system, a deep adsorption system, a deep separation system and a reverse osmosis system. The treatment steps of the system are as follows:

[0007] (1) The tail water of the coal chemical wastewater after biochemical treatment is divided into hard-to-degrade coal chemical biochemical tail water and degradable coal chemical biochemical tail water, and the hard-to-degrade coal chemical biochemical tail water is further treated by an advanced oxidation system;

[0008] (2) The effluent from the difficult-to-degrade coal chemical biochemical tail water treated by the advanced oxidation system and the degradable coal chemical biochemical tail water are mixed and sent into the deep biochemical system for treatment, and the total organic carbon (TOC) of the effluent is less than 25 mg / L, preferably 15-20 mg / L;

[0009] (3) the effluent from step (2) is sent to a deep oxidation system for treatment;

[0010] (4) the effluent from step (3) enters a deep adsorption system;

[0011] (5) the effluent from step (4) is treated in a deep separation system, and the total organic carbon (TOC) of the effluent is less than 1 mg / L, preferably 0.6-0.8 mg / L;

[0012] (6) returning the concentrated phase water from step (5) to step (2) and entering the deep biochemical system for treatment;

[0013] (7) The effluent from step (5) is treated in a reverse osmosis system, wherein the total organic carbon (TOC) of the effluent is less than 0.5 mg / L, preferably 0.3-0.5 mg / L; the concentrated phase water of the reverse osmosis system is treated in a desalination system.

[0014] The advanced oxidation system is an ozone catalytic oxidation system or a hydrogen peroxide ozone combined catalytic oxidation system; the ozone catalytic oxidation system includes an inlet buffer tank, an inlet pump, a vacuum adsorption oxygen generator, an ozone generator, an ozone and oxygen separation and oxygen recovery system, a catalytic oxidation tower system and a circulation pump; the hydrogen peroxide ozone combined catalytic oxidation system includes an inlet buffer tank, an inlet pump, a vacuum adsorption oxygen generator, an ozone generator, an ozone and oxygen separation and oxygen recovery system, a hydrogen peroxide storage tank, a hydrogen peroxide feed pump, a catalytic oxidation tower system and a circulation pump; after the difficult-to-degrade coal chemical biochemical tail water is treated by the advanced oxidation system, the effluent B / C (5-day biochemical oxygen demand / chemical oxygen demand) ratio is greater than 0.3.

[0015] The deep biochemical system is an anoxic-aerobic-aerated biological filter (AO-BAF) system or an anoxic-aerobic-microfiltration membrane (AO-MBR) system; the anoxic-aerobic-aerated biological filter (the AO-BAF system includes a sewage lifting pump, a buffer tank, an anoxic tank, an aerobic tank, an aerated biological filter, a filter backwashing system, a mixed liquor circulation pump, an aeration system and a sludge concentration system, and the hydraulic retention time of the AO-BAF system is 12-48 hours, preferably 24 hours; the AO-MBR system includes a sewage lifting pump, a buffer tank, an anoxic tank, an aerobic tank, an aerated biological reaction tank, a membrane cleaning and regeneration system, a mixed liquor circulation pump, an aeration system and a sludge concentration system; the hydraulic retention time of the AO-MBR) system is 12-48 hours, preferably 24 hours.

[0016] The deep oxidation system is an ozone catalytic oxidation system, which includes an inlet buffer tank, an inlet pump, a vacuum adsorption oxygen generator, an ozone generator, an ozone and oxygen separation and oxygen recovery system, a catalytic oxidation tower system and a circulation pump, wherein the vacuum adsorption oxygen generator, the ozone generator and the advanced oxidation system are shared; after treatment by the deep oxidation system, the total organic carbon (TOC) removal rate of the effluent is 50-70%, preferably 60%.

[0017] The deep adsorption system is a macroporous adsorption resin system or an activated carbon adsorption system, preferably an activated carbon adsorption system.

[0018] The deep separation system is a negatively charged nanofiltration membrane system, the material of which is polyamide (PA), sulfonated polysulfone (SPS), polyvinyl alcohol (PVA), sulfonated polyethersulfone (SPES), cellulose acetate (CA), polysulfone (PS), polyetheretherketone (PEEK) or a composite membrane formed by the above materials, preferably polyamide (PA); the filtration accuracy is between 150-600 Daltons, preferably 300-400 Daltons.

[0019] The reverse osmosis system is a desalination reverse osmosis membrane filtration system, and the selected reverse osmosis membrane material is cellulose acetate, aromatic polyamide, chitosan membrane, polyphenylene reverse osmosis membrane or a composite membrane made of the above materials.

[0020] The deep separation system and reverse osmosis system include a lifting water pump, a water storage tank, a pressure pump, a multi-media fine filtration system, a dosing device, a booster pump, a nanofiltration device, a nanofiltration membrane chemical cleaning device, a backwash pump, a water tank, an RO water pump, a dosing device, a security filter, an RO high-pressure pump, a reverse osmosis device and a water storage tank.

[0021] The activated carbon is coal-based granular carbon, wood activated carbon, fruit shell activated carbon, synthetic resin activated carbon, rubber / plastic activated carbon, regenerated granular activated carbon or bamboo charcoal, preferably fruit shell activated carbon or regenerated granular activated carbon; the macroporous adsorption resin is non-polar, weakly polar, medium polar or polar resin, preferably polar resin; the activated carbon is medium-porous activated carbon or macroporous activated carbon.

[0022] The utility model realizes the innovation of the technology by firstly performing advanced oxidation on the difficult-to-degrade coal chemical biochemical tail water, then performing deep biochemical treatment together with the degradable coal chemical biochemical tail water, and then performing a series of steps including deep oxidation, deep adsorption, deep separation and reverse osmosis.

[0023] Beneficial effects of the utility model: The utility model sequentially sets up an advanced oxidation system, a deep biochemical system, a deep oxidation system, a deep adsorption system, a deep separation system and a reverse osmosis system to complement each other and strongly remove total organic carbon. Finally, the reverse osmosis system is used to remove salt and total organic carbon, and the effluent is stably treated to a total organic carbon (TOC) of less than 0.5 mg / L. The utility model solves the problem that the biochemical tail water of the coal chemical industry cannot be treated to a total organic carbon (TOC) of less than 0.5 mg / L and cannot meet the water requirements of high-temperature and high-pressure boilers (GB / T1576-2018 industrial boiler water quality), and solves the problem of low water resource utilization and water waste in coal chemical enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic flow diagram of an embodiment of a water treatment system for removing total organic carbon from biochemical tail water of a coal chemical industry according to the utility model;

[0025] Figure 2 This is a block diagram of the ozone catalytic oxidation system;

[0026] Figure 3 This is a block diagram of the hydrogen peroxide ozone combined catalytic system;

[0027] Figure 4 This is a block diagram of the anoxic-aerobic-aerated biological filter system;

[0028] Figure 5 Block diagram of anoxic-aerobic-microfiltration membrane system;

[0029] Figure 6 This is a block diagram of the deep separation system and reverse osmosis system. DETAILED DESCRIPTION

[0030] The following is further described in detail through specific implementation methods:

[0031] Example

[0032] like Figure 1-6 As shown, a water treatment system for removing total organic carbon from coal chemical biochemical tail water includes an advanced oxidation system, a deep biochemical system, a deep oxidation system, a deep adsorption system, a deep separation system and a reverse osmosis system arranged in sequence; wherein,

[0033] Advanced oxidation system, used to further oxidize and treat the difficult-to-degrade coal chemical biochemical tail water;

[0034] Deep biochemical system, used to mix the effluent treated by the advanced oxidation system with the biodegradable coal chemical biochemical tail water for biochemical treatment;

[0035] Deep oxidation system, used to oxidize the effluent from the deep biochemical system;

[0036] Deep adsorption system, used to adsorb the effluent from the deep oxidation system;

[0037] The deep separation system is used to separate and treat the effluent from the deep adsorption system and send the obtained concentrated phase water to the deep biochemical system;

[0038] The reverse osmosis system is used to treat the effluent from the deep separation system by reverse osmosis, and the concentrated phase water obtained by the reverse osmosis system enters the desalination system.

[0039] Among them, the advanced oxidation system is a hydrogen peroxide-ozone combined catalytic oxidation system, a second catalytic oxidation tower and a second tail water inlet pipeline, a hydrogen peroxide inlet pipeline and a second ozone inlet pipeline connected thereto, wherein the second tail water inlet pipeline includes an inlet pump and a buffer tank, the second ozone inlet pipeline includes a vacuum adsorption oxygen generator, an ozone generator and an ozone and oxygen separation and recovery device, and the hydrogen peroxide inlet pipeline includes a hydrogen peroxide storage tank and a hydrogen peroxide feed pump; after the difficult-to-degrade coal chemical biochemical tail water is treated by the advanced oxidation system, the effluent B / C (5-day biochemical oxygen demand / chemical oxygen demand) ratio is 0.35.

[0040] The deep biochemical system is an anoxic-aerobic-microfiltration membrane (AO-MBR) system, which includes a sewage lifting pump, a buffer tank, an anoxic tank, an aerobic tank and a microfiltration membrane system arranged in sequence, the aerobic tank is connected to an aeration device, a mixed liquor circulation pump and a sludge concentration device are arranged between the aerobic tank and the anoxic tank, and the microfiltration membrane system is connected to a membrane cleaning and regeneration device; the hydraulic retention time of the AO-MBR system is 24 hours.

[0041] The deep oxidation system is an ozone catalytic oxidation system, including a first catalytic oxidation tower and a first tail water inlet pipeline and a first ozone inlet pipeline connected thereto, wherein the first tail water inlet pipeline includes an inlet pump and a buffer tank, and the first ozone inlet pipeline includes a vacuum adsorption oxygen generator, an ozone generator and an ozone and oxygen separation and recovery device, wherein the vacuum adsorption oxygen generator, the ozone generator and the advanced oxidation system are shared; after treatment by the deep oxidation system, the total organic carbon (TOC) removal rate of the effluent is 60%.

[0042] The deep adsorption system is an activated carbon adsorption system.

[0043] The deep separation system is a negatively charged nanofiltration membrane system, which is made of polyamide (PA); the filtration accuracy is 300-400 Daltons.

[0044] The reverse osmosis system is a desalination reverse osmosis membrane filtration system, and the selected reverse osmosis membrane material is aromatic polyamide.

[0045] The deep separation system and reverse osmosis system include a lifting water pump, a water storage tank, a pressure pump, a multi-media filtration system, a dosing device, a booster pump, a nanofiltration device, a backwash pump, a water tank, a RO water pump, a dosing device, a safety filter, a RO high-pressure pump, a reverse osmosis device and a water storage tank which are arranged in sequence.

[0046] The activated carbon is fruit shell activated carbon, which is macroporous activated carbon.

[0047] Some components of the above system can be replaced according to actual conditions, such as:

[0048] The deep biochemical system is changed into an anoxic-aerobic-aerated biological filter (AO-BAF) system, which includes a sewage lifting pump, a buffer tank, an anoxic tank, an aerobic tank, and an aerated biological filter arranged in sequence. The aerobic tank and the aerated biological filter are provided with an aeration device, and a mixed liquid circulation pump and a sludge concentration device are provided between the aerobic tank and the anoxic tank.

[0049] The deep adsorption system is a macroporous adsorption resin system; the negatively charged nanofiltration membrane system is made of polyamide (PA), sulfonated polysulfone (SPS), polyvinyl alcohol (PVA), sulfonated polyethersulfone (SPES), cellulose acetate (CA), polysulfone (PS), polyetheretherketone (PEEK) or a composite membrane formed of the above materials; the reverse osmosis system is selected as a desalination reverse osmosis membrane filtration system, and the selected reverse osmosis membrane material is cellulose acetate, aromatic polyamide, chitosan membrane, polyphenylene reverse osmosis membrane or a composite membrane made of the above materials.

[0050] The usage of the above system is as follows:

[0051] (1) The tail water of coal chemical wastewater after physical, chemical and biochemical treatment is divided into hard-to-degrade coal chemical biochemical tail water and degradable coal chemical biochemical tail water. The hard-to-degrade coal chemical biochemical tail water is further treated by an advanced oxidation system. The B / C (5-day biochemical oxygen demand / chemical oxygen demand) ratio of the degradable coal chemical biochemical tail water is 0.4, and the total organic carbon (TOC) is 30 mg / L. The B / C (5-day biochemical oxygen demand / chemical oxygen demand) ratio of the degradable coal chemical biochemical tail water is less than 0.1, and the total organic carbon (TOC) is 120 mg / L. The ratio of degradable coal chemical biochemical tail water to hard-to-degrade coal chemical biochemical tail water is 1:1;

[0052] (2) The effluent from the difficult-to-degrade coal chemical biochemical tail water treated by the advanced oxidation system and the degradable coal chemical biochemical tail water are mixed and connected to the deep biochemical system for treatment, and the total organic carbon (TOC) of the effluent is 20 mg / L;

[0053] (3) the effluent from step (2) is sent to a deep oxidation system for treatment;

[0054] (4) the effluent from step (3) enters a deep adsorption system;

[0055] (5) The effluent from step (4) is sent to a deep separation system for treatment, and the total organic carbon (TOC) of the effluent is controlled at 0.7 mg / L;

[0056] (6) returning the concentrated phase water from step (5) to step (2) and entering the deep biochemical system for treatment;

[0057] (7) The effluent from step (5) enters the reverse osmosis system for treatment, the total organic carbon (TOC) of the effluent is controlled at 0.4 mg / L, and the effluent enters the boiler water system.

[0058] (8) The concentrated phase water from the reverse osmosis system enters the desalination system for treatment.

[0059] Those skilled in the art can adjust the operating process parameters according to actual conditions when using the above system, which will not be described in detail.

[0060] The above is only an embodiment of the utility model, and the common knowledge such as the known specific technical schemes and / or characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the technical scheme of the utility model. In the utility model, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the utility model can be understood according to the specific circumstances. The scope of protection claimed in this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A water treatment system for removing total organic carbon from coal chemical biochemical tail water, characterized in that: It includes an advanced oxidation system, a deep biochemical system, a deep oxidation system, a deep adsorption system, a deep separation system and a reverse osmosis system which are arranged in sequence; among which, Advanced oxidation system, used to further oxidize and treat the difficult-to-degrade coal chemical biochemical tail water; Deep biochemical system, used to mix the effluent treated by the advanced oxidation system with the biodegradable coal chemical biochemical tail water for biochemical treatment; Deep oxidation system, used to oxidize the effluent from the deep biochemical system; Deep adsorption system, used to adsorb the effluent from the deep oxidation system; The deep separation system is used to separate and treat the effluent from the deep adsorption system and send the obtained concentrated phase water to the deep biochemical system; The reverse osmosis system is used to treat the effluent from the deep separation system by reverse osmosis to obtain water with a total organic carbon content of less than 0.5 mg / L. The concentrated phase water obtained by the reverse osmosis system enters the desalination system.

2. A water treatment system for removing total organic carbon from coal chemical biochemical tail water according to claim 1, characterized in that: The advanced oxidation system is an ozone catalytic oxidation system or a hydrogen peroxide ozone combined catalytic oxidation system.

3. A water treatment system for removing total organic carbon from coal chemical biochemical tail water according to claim 2, characterized in that: The ozone catalytic oxidation system comprises a first catalytic oxidation tower and a first tail water inlet pipeline and a first ozone air inlet pipeline connected thereto, wherein the first tail water inlet pipeline comprises an inlet pump and a buffer tank, and the first ozone air inlet pipeline comprises a vacuum adsorption oxygen generator, an ozone generator and an ozone and oxygen separation and recovery device; the hydrogen peroxide ozone combined catalytic oxidation system comprises a second catalytic oxidation tower and a second tail water inlet pipeline, a hydrogen peroxide inlet pipeline and a second ozone air inlet pipeline connected thereto, wherein the second tail water inlet pipeline comprises an inlet pump and a buffer tank, the second ozone air inlet pipeline comprises a vacuum adsorption oxygen generator, an ozone generator and an ozone and oxygen separation and recovery device, and the hydrogen peroxide inlet pipeline comprises a hydrogen peroxide storage tank and a hydrogen peroxide feed pump.

4. A water treatment system for removing total organic carbon from coal chemical biochemical tail water according to claim 1, characterized in that: The deep biochemical system is an anoxic-aerobic-aerated biological filter system or an anoxic-aerobic-microfiltration membrane system.

5. A water treatment system for removing total organic carbon from coal chemical biochemical tail water according to claim 4, characterized in that: The anoxic-aerobic-aerated biological filter tank comprises a sewage lifting pump, a buffer tank, an anoxic tank, an aerobic tank, and an aerated biological filter tank which are arranged in sequence, the aerobic tank and the aerated biological filter tank are provided with an aeration device, and a mixed liquid circulation pump and a sludge concentrating device are arranged between the aerobic tank and the anoxic tank; the anoxic-aerobic-microfiltration membrane system comprises a sewage lifting pump, a buffer tank, an anoxic tank, an aerobic tank, and a microfiltration membrane system which are arranged in sequence, the aerobic tank is connected to the aeration device, a mixed liquid circulation pump and a sludge concentrating device are arranged between the aerobic tank and the anoxic tank, and the microfiltration membrane system is connected to a membrane cleaning and regeneration device.

6. A water treatment system for removing total organic carbon from coal chemical biochemical tail water according to claim 1 or 3, characterized in that: The deep oxidation system adopts an ozone catalytic oxidation system, in which a vacuum adsorption oxygen generator, an ozone generator and an advanced oxidation system are shared.

7. A water treatment system for removing total organic carbon from coal chemical biochemical tail water according to claim 1, characterized in that: The deep adsorption system is a macroporous adsorption resin system or an activated carbon adsorption system.

8. A water treatment system for removing total organic carbon from coal chemical biochemical tail water according to claim 1, characterized in that: The deep separation system and reverse osmosis system include a lifting water pump, a water storage tank, a pressure pump, a multi-media filtration system, a dosing device, a booster pump, a nanofiltration device, a backwash pump, a water tank, a RO water pump, a dosing device, a safety filter, a RO high-pressure pump, a reverse osmosis device and a water storage tank which are arranged in sequence.

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