Treatment system and treatment method for oily wastewater in aluminum product production

Abstract

The application discloses a treatment system and method for oily wastewater in aluminum product production. The treatment system for oily wastewater in aluminum product production comprises an oil separation tank, a gas float unit and a micro electrolysis unit. The oil separation tank is used for removing oil impurities and COD in the wastewater and outputs a first liquid. The gas float unit is used for gas float treatment of the first liquid to remove suspended solids, oil impurities and COD and outputs scum and a second liquid. The micro electrolysis unit is used for removing COD and BOD in the second liquid and outputs a third liquid. A hydrogen production unit is used for electrolytic hydrogen production by using the third liquid and removing organic matters and outputs hydrogen and a fourth liquid. The treatment system for oily wastewater in aluminum product production has simple structure, low investment and operation cost, can not only realize deep removal of organic matters, but also can recover hydrogen resources, effectively solves the technical problem of high wastewater treatment cost in the prior art and has strong practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum product production wastewater treatment, in particular to an oil-containing wastewater treatment system and method in aluminum product production. BACKGROUND

[0002] There are many quality problems in aluminum product production, and oil stain problem is a common quality loss. After the aluminum plate is rolled, too much oil is brought on the surface of the aluminum tip, and there are also excess oil components other than the rolling oil film. When the finished product is inspected and cut in the later stage, these visible oil components will be found on the surface. Many oil components are mainly distributed on the upper and lower parts of the rolling mill outlet or the roll neck, and after splashing, they are dripped on the box surface, causing abnormal conditions in the rolling mill roll cleaner due to oil dripping from the rolling mill thickness measuring head. Moreover, these oils are complex in composition and particularly dirty.

[0003] The oil stains on the surface of the aluminum material will affect the smoothness, flatness and color of the surface of the aluminum material, causing defects such as flaws, unevenness, stains, etc. on the surface of the aluminum material, reducing the grade and value of the product. If no oil removal treatment is performed, the oil stains on the surface of the aluminum material will block the mold, affecting the normal operation of the mold, and also reducing the efficiency of the subsequent process. These oil stains will also block equipment such as grinding tools and drill bits, causing the equipment to wear out faster and increasing the repair and replacement costs of the equipment. Therefore, the production process of aluminum products all includes an oil removal process section. Three traditional oil removal process sections are as follows: (1) alkali etching process: oil removal - water washing - alkali etching - water washing - water washing - lightening - water washing - water washing; (2) acid etching process: oil removal - water washing - acid etching - water washing - water washing - alkali etching - water washing - water washing - lightening - water washing - water washing - oxidation; (3) polishing process: oil removal - water washing - polishing - water washing - water washing - oxidation.

[0004] The above three oil removal process sections generate a lot of oil-containing wastewater. The organic matter (mainly COD and BOD) content in these oil-containing wastewater is very high, usually more than 10 times the discharge standard, and needs to be removed before discharge. The traditional treatment method for oil-containing wastewater is to use a Fenton reaction system to further remove organic matter after removing suspended solids and oils.

[0005] The Fenton reaction system uses a mixed solution of hydrogen peroxide (H2O2) and divalent iron ion Fe 2+ to oxidize many known organic compounds such as carboxylic acids, alcohols, and esters into inorganic states. The Fenton reaction system has a high ability to remove refractory organic pollutants, but the dosage of reagents is large, the reaction conditions are harsh, and the introduced reagents need to be removed by a softening precipitation process afterwards, significantly increasing the wastewater treatment cost, and the removal effect is not satisfactory. SUMMARY

[0006] The main purpose of the present application is to provide an oil-containing wastewater treatment system and method in aluminum product production to solve the technical problems of high cost and poor treatment effect in the prior art.

[0007] To achieve the above-mentioned purpose, the present application first provides an oil-containing wastewater treatment system in aluminum product production, and the technical solution is as follows:

[0008] The oil-containing wastewater treatment system in aluminum product production comprises:

[0009] An oil separation tank is used to remove oil impurities and COD in the wastewater, and outputs a first liquid;

[0010] A gas flotation unit is used to perform gas flotation treatment on the first liquid to remove suspended solids, oil impurities and COD, and outputs scum and a second liquid;

[0011] A micro-electrolysis unit is used to remove COD and BOD in the second liquid, and outputs a third liquid;

[0012] A hydrogen production unit is used to perform electrolysis to produce hydrogen and remove organic matter using the third liquid, and outputs hydrogen and a fourth liquid.

[0013] As a further improvement of the above-mentioned oil-containing wastewater treatment system in aluminum product production: the removal rate of the oil separation tank for oil impurities is ≥ 82%, and the removal rate for COD is ≥ 8%.

[0014] As a further improvement of the above-mentioned oil-containing wastewater treatment system in aluminum product production: the removal rate of the gas flotation unit for suspended solids is ≥ 92%, the removal rate for oil impurities is ≥ 96%, and the removal rate for COD is ≥ 8%.

[0015] As a further improvement of the above-mentioned oil-containing wastewater treatment system in aluminum product production: the removal rate of the micro-electrolysis unit for COD is ≥ 55%, and the removal rate for BOD is ≥ 55%.

[0016] As a further improvement of the above-mentioned oil-containing wastewater treatment system in aluminum product production: the hydrogen production unit comprises a hydrogen production coupled oxidation reactor, hydrogen ions in the third liquid obtain electrons to become hydrogen gas at the cathode, chloride ions in the third liquid lose electrons to become chlorine gas at the anode, the chlorine gas is hydrolyzed into chloride ions and hypochlorous acid, and the hypochlorous acid generates hydroxyl radicals to oxidize and remove organic matter in the third liquid.

[0017] As a further improvement of the above-mentioned oil-containing wastewater treatment system in aluminum product production: the hydrogen production coupled oxidation reactor uses green electricity as electric energy, the removal rate for COD is ≥ 75%, and the removal rate for BOD is ≥ 75%.

[0018] As a further improvement of the oil-containing wastewater treatment system in the production of aluminum products: further comprising a heavy removal unit for removing calcium ions, magnesium ions, aluminum ions, suspended solids and oil impurities in the second liquid or the fourth liquid, and the output water enters the micro-electrolysis unit or is discharged.

[0019] As a further improvement of the oil-containing wastewater treatment system in the production of aluminum products: the heavy removal unit has a removal rate of calcium ions, magnesium ions and aluminum ions of ≥85%, a removal rate of suspended solids of ≥95%, and a removal rate of oil impurities of ≥60%.

[0020] As a further improvement of the oil-containing wastewater treatment system in the production of aluminum products: the COD content in the wastewater is 300-1000 mg / L, the BOD content is 50-200 mg / L, and the chloride ion content is 100-300 mg / L.

[0021] In order to achieve the above-mentioned purpose, the present application first provides a treatment method for oil-containing wastewater in the production of aluminum products, and the technical solution is as follows:

[0022] The treatment method for oil-containing wastewater in the production of aluminum products adopts the treatment system for oil-containing wastewater in the production of aluminum products described in the first aspect.

[0023] Firstly, in the treatment system and method for oil-containing wastewater in the production of aluminum products of the present application, the Fenton reaction system is no longer used to remove organic matter, and a hydrogen production unit is used to directly utilize the original chloride ions in the wastewater. On the one hand, the chloride ions lose electrons at the anode to become chlorine gas, which is hydrolyzed into chloride ions and hypochlorous acid, and the hypochlorous acid generates hydroxyl radicals (·OH) to deeply oxidize and remove organic matter. On the other hand, clean energy hydrogen gas is generated at the same time. It can be seen that compared with the advanced oxidation method of the Fenton reaction system, the hydrogen production unit of the present application has the following advantages: (1) no other metal ions are introduced, saving the cost of reagents and subsequent treatment; (2) the hydrogen production coupled oxidation reactor occupies a small area, does not need a sedimentation tank, and almost no sludge is generated; (3) the generated hydrogen gas can generate more economic benefits; (4) directly reusing the original chloride ions in the wastewater greatly reduces the corrosion of the anode metal; (5) the overall water quantity is small, and green electricity can fully meet the demand, so the electricity cost is low, and the overall economic benefit is significant. - The corrosion of the anode metal is greatly reduced; (5) the overall water quantity is small, and green electricity can fully meet the demand, so the electricity cost is low, and the overall economic benefit is significant.

[0024] Secondly, the present application uses an oil separation tank, a flotation unit and a micro-electrolysis unit in sequence before the hydrogen production unit to remove easily removable organic matter and other impurities such as suspended solids and oil impurities in the wastewater, effectively reducing the treatment capacity of the hydrogen production unit and improving the hydrogen production efficiency.

[0025] The oil-containing wastewater treatment system for aluminum product production has simple structure, low investment and operation cost, can realize deep removal of organic matters, can recover hydrogen resources, effectively solves the technical problem of high wastewater treatment cost in the prior art, and has strong practicability.

[0026] The embodiments of the application provided in the specification are further described below in conjunction with the drawings and specific embodiments. Additional aspects and advantages of the embodiments of the application provided in the specification will be partially given in the following description, partially become obvious from the following description, or be understood by practice of the embodiments of the application provided in the specification. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings constituting part of the embodiments of the application provided in the specification serve to assist understanding of the embodiments of the application provided in the specification, and the contents provided in the drawings and the related description in the embodiments of the application provided in the specification can be used to explain the embodiments of the application provided in the specification, but do not constitute improper limitation on the embodiments of the application provided in the specification. In the drawings:

[0028] Figure 1 The structure schematic view of the first embodiment of the oil-containing wastewater treatment system for aluminum product production.

[0029] Figure 2 The structure schematic view of the second embodiment of the oil-containing wastewater treatment system for aluminum product production.

[0030] Figure 3 The structure schematic view of the third embodiment of the oil-containing wastewater treatment system for aluminum product production. DETAILED DESCRIPTION

[0031] The embodiments of the application provided in the specification are clearly and completely described below in conjunction with the drawings. The person skilled in the art can implement the embodiments of the application provided in the specification based on these descriptions. Before the embodiments of the application provided in the specification are described in conjunction with the drawings, it needs to be particularly pointed out that:

[0032] The technical solutions and technical features provided in each part of the embodiments of the application provided in the specification, including the following description, can be combined with each other without conflict.

[0033] Moreover, the embodiments of the application provided in the specification are generally only a part of the embodiments of the application provided in the specification rather than all the embodiments of the application provided in the specification, and therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the application provided in the specification without creative labor shall fall within the scope of protection of the embodiments of the application provided in the specification.

[0034] Regarding the terms and units in the embodiments of the application provided in the specification: the terms "include", "contain", "have" and any variants thereof in the specification and claims of the embodiments of the application provided in the specification and related parts are intended to cover non-exclusive inclusion. In addition, other related terms and units in the embodiments of the application provided in the specification can be reasonably interpreted based on the related content of the embodiments of the application provided in the specification.

[0035] Figure 1 Structure diagram of a first embodiment of the oil-containing wastewater treatment system in the production of aluminum products.

[0036] As Figure 1 shown, the oil-containing wastewater treatment system in the production of aluminum products comprises an oil separation tank, a flotation unit, a micro-electrolysis unit and a hydrogen production unit; the oil-containing wastewater is any of the three wastewaters generated in the three traditional oil removal process sections.

[0037] The oil separation tank is used to remove oil impurities and COD in the wastewater, and outputs a first liquid; the removal rate of the oil separation tank for oil impurities is ≥82%, and the removal rate for COD is ≥8%.

[0038] The flotation unit is used to perform flotation treatment on the first liquid to remove suspended solids, oil impurities and COD, and outputs scum and a second liquid; the removal rate of the flotation unit for suspended solids is ≥92%, the removal rate for oil impurities is ≥96%, and the removal rate for COD is ≥8%.

[0039] The micro-electrolysis unit is used to remove COD and BOD in the second liquid, and outputs a third liquid; the removal rate of the micro-electrolysis unit for COD is ≥55%, and the removal rate for BOD is ≥55%.

[0040] The hydrogen production unit is used for electrolysis of hydrogen production with the third liquid and removal of organic matters, and outputs hydrogen and a fourth liquid; the hydrogen production unit comprises a hydrogen production coupling oxidation reactor, hydrogen ions in the third liquid become hydrogen at the cathode by obtaining electrons, chlorine ions in the third liquid become chlorine at the anode by losing electrons, the chlorine is hydrolyzed into chlorine ions and hypochlorous acid, and the hypochlorous acid generates hydroxyl radicals to oxidize and remove the organic matters in the third liquid; the hydrogen production coupling oxidation reactor uses green electricity as electric energy, the removal rate of COD is greater than or equal to 75%, and the removal rate of BOD is greater than or equal to 75%.

[0041] Figure 2 The structure diagram of the second embodiment of the oil-containing wastewater treatment system in the production of aluminum products.

[0042] On the basis of the first embodiment, the oil-containing wastewater treatment system in the production of aluminum products of the present embodiment further has the difference that, as shown in Figure 2 the removal unit is further included, the removal unit is used for removing COD, calcium ions, magnesium ions, aluminum ions, suspended solids and petroleum impurities in the fourth liquid, and output water is discharged. The removal unit uses a precipitating agent and a flocculating agent to remove the above-mentioned ions and impurities, the removal rate of COD is greater than or equal to 8%, the removal rate of calcium ions, magnesium ions and aluminum ions is greater than or equal to 85%, the removal rate of suspended solids is greater than or equal to 95%, and the removal rate of petroleum impurities is greater than or equal to 60%.

[0043] Figure 3 The structure diagram of the third embodiment of the oil-containing wastewater treatment system in the production of aluminum products.

[0044] On the basis of the first embodiment, the oil-containing wastewater treatment system in the production of aluminum products of the present embodiment further has the difference that, as shown in Figure 3 the removal unit is further included, the removal unit is used for removing COD, calcium ions, magnesium ions, aluminum ions, suspended solids and petroleum impurities in the fourth liquid, and output water is discharged. The removal unit uses a precipitating agent and a flocculating agent to remove the above-mentioned ions and impurities, the removal rate of COD is greater than or equal to 8%, the removal rate of calcium ions, magnesium ions and aluminum ions is greater than or equal to 85%, the removal rate of suspended solids is greater than or equal to 95%, and the removal rate of petroleum impurities is greater than or equal to 60%.

[0045] Compared with the second embodiment, the removal unit is used to treat the second liquid, and part of COD, suspended solids impurities and petroleum impurities can be removed, which not only effectively reduces the treatment capacity of the hydrogen production unit, but also improves the hydrogen production efficiency.

[0046] The embodiment of the oil-containing wastewater treatment method in the production of aluminum products of the present application is the oil-containing wastewater treatment system in the production of aluminum products described in any one of the above embodiments.

[0047] The following is an application example of the present application.

[0048] The oil-containing wastewater treatment system and method of the third embodiment are used to treat the oil-containing wastewater in the production of aluminum products, and the wastewater has a COD content of 500 mg / L, a BOD content of 100 mg / L, and a chloride ion content of 150 mg / L, and other water quality indicators and water quality indicators of each unit are shown in Table 1.

[0049] Table 1

[0050]

[0051] As can be seen from Table 1, the COD of the produced water (the fourth liquid output by the hydrogen production unit) treated by the oil-containing wastewater treatment system and method of the aluminum product production of the present application is as low as 25 mg / L, and the BOD is as low as 5 mg / L, meeting the discharge standard and having practical use value.

[0052] Some terms in the present application are explained as follows:

[0053] Chemical oxygen demand (COD) refers to the amount of reducing substances that need to be oxidized in a water sample measured by a chemical method.

[0054] Biochemical oxygen demand (BOD) refers to the amount of dissolved oxygen consumed by microorganisms in the decomposition of certain oxidizable substances (especially organic substances) in a certain volume of water within a certain period of time.

[0055] Green electricity refers to the process of producing electricity with zero or close to zero carbon dioxide emissions, which has lower environmental impact than other methods (such as thermal power generation). The main sources of green electricity are solar energy, wind power, biomass energy, and geothermal energy, with solar energy and wind power being the main sources in China.

[0056] The oil separation tank is a wastewater pretreatment structure that uses the density difference between oil droplets and water to remove floatable oil substances in oil-containing wastewater. Common types of oil separation tanks include horizontal flow oil separation tanks, parallel plate oil separation tanks, and inclined plate oil separation tanks.

[0057] The working principle of the air flotation unit is as follows: a large amount of highly dispersed micro-bubbles (usually requiring the addition of coagulants such as PMA and / or PAC) are introduced into the wastewater using a micro-bubble generating device, which acts as a carrier and adheres to the particles (oil droplets) or flocs suspended in the wastewater, forming a floating body with a density less than the wastewater, which is removed by floating to the surface of the wastewater, forming a floating sludge, and ultimately achieving the purpose of purifying the wastewater. The air flotation unit mainly includes an air flotation machine, which is preferably a high-efficiency shallow air flotation machine, and the treatment capacity is 5 m3 / h, total power is 2.2kW, configured with a micro-bubble generating device, a slag removal device and a coagulant feeding device.

[0058] The working principle of the micro-electrolysis unit is that the iron-carbon alloy (generally iron filings) and inert carbon particles (generally graphite, coke, activated carbon, graphite, etc.) are immersed in wastewater, the carbon particles are cathodes, and the iron-carbon alloy is anode; on the anode, iron loses electrons to generate Fe 2+ , and on the cathode, dissolved oxygen in the wastewater absorbs electrons to generate OH - . The cathode generates nascent hydrogen in a slightly acidic solution, and Fe 2+ and nascent hydrogen both have reducing properties and can undergo redox reactions with some organic matter such as nitro-containing organic matter. Fe 2+ In alkaline conditions, Fe(OH)2 and Fe(OH)3 are generated, and nascent Fe(OH)3 has a strong adsorption capacity and can adsorb a large amount of dispersed organic macromolecules in wastewater. The micro-electrolysis unit can use but is not limited to using an iron-carbon micro-electrolysis tank or an iron-carbon micro-electrolysis reaction tower, which is provided with filler water distribution and gas distribution pipelines, pipeline supports, etc., and is configured with a fan and a water inlet pump.

[0059] The working principle of the electrolytic hydrogen production unit is that after direct current is passed, hydrogen ions in water obtain electrons at the cathode to obtain hydrogen gas, and chloride ions in water lose electrons at the anode to become chlorine gas, which is hydrolyzed in water to form chloride ions and hypochlorous acid, Cl - can be repeatedly used; hypochlorous acid has strong oxidizing properties and reacts in water to form ·OH (hydroxyl radical) to complete the advanced oxidation process, using this principle to oxidize total organic matter in water into carbon dioxide and water and other inorganic elements, effectively reducing them to a lower level. The electrolysis unit mainly includes a hydrogen production coupled oxidation reactor, the anode is Ti alloy or Pt alloy, and the cathode is graphite. The hydrogen production coupled oxidation reactor can use but is not limited to using a bipolar pressure filtration type electrolytic cell or a PEM water electrolytic cell.

[0060] The above describes the content of the embodiments of the invention provided in the specification. Those skilled in the art will be able to implement the embodiments of the invention provided in the specification based on these descriptions. Based on the above content of the embodiments of the invention provided in the specification, all other preferred modes and embodiments obtained by those skilled in the art without creative labor shall belong to the scope of protection of the embodiments of the invention provided in the specification.

Claims

1. A system for the treatment of oily wastewater in the production of aluminium products, characterised in that: The processing system comprises: an oil separation tank for removing oil impurities and COD in wastewater and outputting a first liquid; an air flotation unit for air flotation treatment of the first liquid to remove suspended solids, oil impurities and COD and outputting scum and a second liquid; a micro-electrolysis unit for removing COD and BOD in the second liquid and outputting a third liquid; a hydrogen production unit for electrolytic hydrogen production using the third liquid and removing organic matter and outputting hydrogen and a fourth liquid; wherein the hydrogen production unit comprises a hydrogen production coupled oxidation reactor, hydrogen ions in the third liquid become hydrogen gas by obtaining electrons at a cathode, chloride ions in the third liquid become chlorine gas by losing electrons at an anode, the chlorine gas is hydrolyzed into chloride ions and hypochlorous acid, and the hypochlorous acid generates hydroxyl radicals to oxidize and remove organic matter in the third liquid; and further comprising a heavy substance removal unit for removing COD, calcium ions, magnesium ions, aluminum ions, suspended solids and oil impurities in the second liquid or the fourth liquid and outputting produced water into the micro-electrolysis unit or discharging.

2. The system for treating oily wastewater in the production of aluminum products according to claim 1, characterized by: The oil separation tank has an oil impurity removal rate of ≥82% and a COD removal rate of ≥8%.

3. The system for treating oily wastewater in the production of aluminum products according to claim 1, characterized by: The air flotation unit has a suspended solid removal rate of ≥92%, an oil impurity removal rate of ≥96% and a COD removal rate of ≥8%.

4. The system for treating oily wastewater in the production of aluminum products according to claim 1, characterized by: The micro-electrolysis unit has a COD removal rate of ≥55% and a BOD removal rate of ≥55%.

5. The system for treating oily wastewater in the production of aluminum products according to claim 1, characterized by: The hydrogen production coupled oxidation reactor uses green electricity as electric energy, has a COD removal rate of ≥75% and a BOD removal rate of ≥75%.

6. The system for treating oily wastewater in the production of aluminum products according to claim 1, characterized by: The heavy substance removal unit has a COD removal rate of ≥8%, a calcium ion removal rate of ≥85%, a magnesium ion removal rate of ≥85%, an aluminum ion removal rate of ≥85%, a suspended solid removal rate of ≥95% and an oil impurity removal rate of ≥60%.

7. The system for treating oily wastewater in the production of aluminum products according to claim 1, characterized by: The wastewater has a COD content of 300-1000 mg / L, a BOD content of 50-200 mg / L and a chloride ion content of 100-300 mg / L.

8. A method for treating oily wastewater in the production of aluminium products, characterised in that: The processing system is used for treating oil-containing wastewater in aluminum product production. The processing system is used for treating oil-containing wastewater in aluminum product production.

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