A method for treating waste cutting fluid

Abstract

The application relates to the technical field of hazardous waste treatment, and particularly discloses a waste cutting fluid treatment method. The waste cutting fluid treatment method comprises the following steps: S1: primary treatment: S11: pretreatment: waste cutting fluid is subjected to oil separation, sedimentation and filtration to remove floating oil and large-particle impurities, and then is uniformly mixed in an adjusting tank; S12: acidification and electroflocculation: the uniformly mixed wastewater is transported to an acidification tank for acidification, and then is transported to an electroflocculation tank for demulsification treatment, and then is transported to a coagulation tank; S13: flocculation air flotation; S14: electrooxidation; S2: secondary treatment: the catalytically oxidized wastewater is subjected to biochemical treatment to obtain secondary treatment liquid; and S3: tertiary treatment: the secondary treatment liquid is transported into a sedimentation tank, an adsorbent and a flocculant are added, and after treatment, the wastewater can meet the discharge standard. The waste cutting fluid treatment method has the advantages of good comprehensive treatment effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hazardous waste treatment, more particularly, it relates to a treatment method of waste cutting fluid. BACKGROUND

[0002] Cutting fluid is widely used in mechanical processing, mainly playing the roles of cooling, lubrication, cleaning, rust prevention, etc. Cutting fluid can be divided into two categories: oil-based cutting fluid and water-based cutting fluid. The main pollutants in used waste cutting fluid are oil, surfactants and various additives, resulting in a high COD index of waste cutting fluid. In addition, some additives in waste cutting fluid are highly toxic, so waste cutting fluid needs to be treated before being discharged.

[0003] At present, the treatment processes of waste cutting fluid include flocculation sedimentation method, biochemical method, catalytic oxidation method, activated carbon adsorption method, etc. The flocculation sedimentation method is to add flocculants to waste cutting fluid and remove harmful substances by the principle of sedimentation separation. The biochemical method is to metabolically degrade organic matter through biological and chemical reactions, so as to produce small-molecule organic matter with no or low toxicity. The catalytic oxidation method is to use the oxidation effect of strong oxidizing substances to make organic matter undergo oxidation-reduction reaction, thereby reducing the toxicity of waste cutting fluid and meeting the discharge standard.

[0004] For the above treatment processes, the flocculation sedimentation method and the activated carbon adsorption method are simple to operate and low in cost, but the overall treatment effect is not good. The biochemical method and the catalytic oxidation method can achieve stable treatment effect, but they have high initial investment, high maintenance difficulty and high treatment cost. Therefore, how to develop a more suitable comprehensive treatment process for waste cutting fluid is a problem to be solved by technical personnel. SUMMARY

[0005] In order to improve the comprehensive treatment effect of waste cutting fluid, the present application provides a treatment method of waste cutting fluid.

[0006] The present application provides a treatment method of waste cutting fluid, which adopts the following technical scheme:

[0007] A treatment method of waste cutting fluid, comprising the following steps:

[0008] S1: primary treatment:

[0009] S11: pretreatment: oil separation, sedimentation and filtration are performed on the waste cutting fluid to remove floating oil and large-particle impurities, and then the waste cutting fluid is sent into a conditioning tank for homogenization;

[0010] S12: acidification and electroflocculation: the homogenized waste water is transported to an acidification tank for acidification, then sent to an electroflocculation tank for demulsification treatment, and then sent to a coagulation tank;

[0011] S13: flocculation air flotation: a coagulant and an alkali are added in the coagulation tank to perform a coagulation reaction, air is blown in to stir during the coagulation process, and a sludge-water mixture after coagulation is subjected to solid-liquid separation to obtain filter residue and filtrate;

[0012] S14: electro-oxidation: the filtrate is sent into an electro-catalytic oxidation device to perform electro-catalytic oxidation to obtain a primary treatment liquid;

[0013] S2: secondary treatment: the wastewater after catalytic oxidation is sequentially subjected to hydrolysis treatment, facultative treatment, anaerobic treatment, aerobic treatment, and MBR membrane biological reaction to obtain a secondary treatment liquid;

[0014] S3: tertiary treatment: the secondary treatment liquid is sent into a sedimentation tank, an adsorbent and a flocculant are added, and after treatment, the effluent standard is reached.

[0015] By adopting the above technical scheme, the composition of the waste cutting fluid is relatively complex, and is in a state of coexistence of oil, water and solid particles. The waste cutting fluid is pretreated, the free floating oil carried by the water body is removed through oil separation, the removed floating oil is further subjected to targeted harmless treatment, so as to reduce the subsequent treatment pressure. After the oil separation, the wastewater is subjected to sedimentation and filtration to remove large solid particle impurities, and then is sent into a conditioning tank to homogenize, so as to provide a stable wastewater physicochemical environment for the subsequent treatment process and reduce the water quality fluctuation.

[0016] The homogenized wastewater is subjected to acidification treatment, under the action of acid-producing bacteria, the organic matter is decomposed into small molecular organic matter, the biodegradability of the wastewater is improved, and part of the COD is removed. During the whole acidification process, the pH value of the system decreases. Then, the acidified wastewater is subjected to electro-flocculation treatment, under the action of an external electric field, soluble cations are generated to form a coagulation effect on the pollutants, and after the auxiliary addition of a coagulant, under continuous stirring, the coagulant forms a large number of colloidal flocs, which can adsorb residual floating oil, solid particles and other impurities in the system. After solid-liquid separation, a filtrate with lower COD and easier treatment is obtained.

[0017] Then, the filtrate is subjected to electro-oxidation treatment, the strong electric field is used to further open the ring, break the bond and dissociate the organic matter in the wastewater, so as to further improve the biodegradability of the wastewater. Then, the wastewater is subjected to biochemical comprehensive treatment of hydrolysis treatment, facultative treatment, anaerobic treatment, aerobic treatment and MBR membrane biological reaction, under the degradation action of microorganisms, the small molecular organic matter is further decomposed, and very good treatment effect is obtained. Finally, after the deep treatment of the adsorbent and the flocculant, the pollutants in the wastewater are further adsorbed and degraded, so that the water quality reaches the effluent standard, and the comprehensive treatment effect is very ideal. At the same time, the combination of multiple processes not only ensures the treatment effect, but also reduces the treatment cost as much as possible, and is very suitable for popularization and application.

[0018] Further preferably, the base is added in the form of liquid alkali, the liquid alkali is sodium hydroxide solution with a mass fraction of 20%, and the addition amount of the liquid alkali is 0.055 t-0.06 t per ton of waste cutting fluid treated. The addition amount of the liquid alkali set in the present application can achieve the corresponding technical effects, and further preferably, the addition amount of the liquid alkali is 0.58 t.

[0019] Further preferably, the addition amount of the coagulant is 0.12 t-0.15 t per ton of waste cutting fluid treated. The addition amount of the coagulant set in the present application can achieve the corresponding technical effects, and further preferably, the addition amount of the coagulant is 0.127 t.

[0020] Further preferably, the addition amount of the adsorbent is 0.22 kg-0.25 kg per ton of waste cutting fluid treated. The addition amount of the adsorbent set in the present application can achieve the corresponding technical effects, and further preferably, the addition amount of the adsorbent is 0.238 kg.

[0021] Further preferably, the addition amount of the flocculating agent is 0.041 t-0.43 t per ton of waste cutting fluid treated. The addition amount of the flocculating agent set in the present application can achieve the corresponding technical effects, and further preferably, the addition amount of the flocculating agent is 0.426 t.

[0022] Preferably, in the step S13, the coagulant is mainly made of raw materials in the following weight fractions: 80-90 parts of polyaluminum chloride and 1-2 parts of polyacrylamide.

[0023] By adopting the above technical solution, after the coagulant is added, the base can adjust the pH value of the system to provide a pH environment conducive to flocculation and precipitation, then the polyaluminum chloride and the polyacrylamide form flocs in the system, and under the action of air stirring, the flocs float up, thereby realizing the separation of pollutants and the purification of water, improving the biodegradability of sewage, reducing the pressure of subsequent biochemical treatment, and obtaining better comprehensive treatment effect.

[0024] Preferably, the coagulant further includes 6-8.5 parts of activated micro powder, and the activated micro powder is prepared by a method including the following steps:

[0025] 1) adding polysaccharide, 2,7-diamino fluorene, 2-sodium mercaptoethanesulfonate and water into a container and mixing uniformly to prepare an intermediate material;

[0026] 2) adding metal micro powder into the intermediate material and stirring at high speed, and then drying and grinding to obtain the activated micro powder.

[0027] Further, in the preparation method, the mass ratio of the polysaccharide, 2,7-diaminofluorene, sodium 2-mercaptoethanesulfonate, and water is 1:(0.05-0.065):(0.1-0.25):(0.5-0.75). In step 2), the mass ratio of the metal powder and the intermediate material is 1:(0.8-1.2).

[0028] By adopting the technical solution, the polysaccharide, 2,7-diaminofluorene, sodium 2-mercaptoethanesulfonate, and water are uniformly mixed to form an intermediate material in the form of a viscous slurry. The polysaccharide can form a network gel structure adsorbent, thereby encapsulating 2,7-diaminofluorene and sodium 2-mercaptoethanesulfonate. Then, the intermediate material is uniformly mixed with the metal powder, so that the intermediate material slurry uniformly encapsulates the metal powder. After drying, a coating layer structure is formed. After grinding, a micro-nano-sized encapsulated ball is formed.

[0029] After the introduction of the activated powder into the coagulant, the encapsulation layer structure gradually disintegrates with the penetration of water molecules, so that the encapsulation layer structure on the surface of the encapsulated ball can slowly release a certain amount of sodium 2-mercaptoethanesulfonate, adjust the surface tension of the water body, and be beneficial to the formation of flocculation, accelerate the collision and fusion between colloids, thereby improving the separation efficiency of pollutants.

[0030] Moreover, due to the very small size of the encapsulated ball, after filtration, the encapsulated ball can enter the electro-catalytic equipment together with the filtrate. At this time, the encapsulation structure has been basically released completely, and the released 2,7-diaminofluorene and sodium 2-mercaptoethanesulfonate molecules can be oxidized to form cationic radicals on the anode. The use of electron transfer can further promote the degradation reactions such as ring opening and C-C bond breaking of organic molecules in wastewater, thereby improving the degradation speed and effect of organic matter.

[0031] In addition, with the disintegration of the encapsulation layer structure, the metal powder is gradually exposed. Under the action of a strong electric field, the metal powder can be electrolyzed to generate metal cations to form an electroactive body, which can exhibit strong catalytic oxidation ability to dissolved organic matter in water, further assisting the catalytic effect, so that more macromolecular organic matter is degraded, and the comprehensive treatment effect of wastewater is improved.

[0032] Preferably, the polysaccharide is one or more of starch, dextrin, and hydroxypropyl cellulose.

[0033] The polysaccharides listed in the present application can achieve the corresponding technical effects. Further preferably, the polysaccharide is dextrin.

[0034] By adopting the technical solution, the types and compositions of polysaccharides are optimized and adjusted to balance the adsorption performance and adhesion performance of the intermediate material slurry, so as to obtain an encapsulation layer structure with moderate adhesion and drug loading. The disintegration speed of the encapsulation layer structure and the release speed of the drug components are more suitable.

[0035] Preferably, the metal micro-powder is one or more of copper powder, tin powder, and nickel powder.

[0036] The metal micro-powder listed in the present application can achieve the corresponding technical effects. The types and compositions of the metal micro-powder are tested and screened, the cost and use effect are considered, and further preferably, the metal micro-powder is copper powder.

[0037] Preferably, the mass ratio of the activated micro-powder to polyaluminum chloride is (0.066-0.08):1.

[0038] By adopting the above technical solution, introducing more activated micro-powder can easily increase the COD index of the water body, and at the same time, it can also easily cause systematic abnormalities and reduce the biodegradability of the sewage. Introducing less activated micro-powder cannot well play the corresponding degradation assisting effect, so the mass ratio of the activated micro-powder to polyaluminum chloride is optimized and adjusted to further improve the treatment effect of the sewage.

[0039] Preferably, in the step S2, the hydrolysis treatment is divided into two-stage hydrolysis treatment, the DO control in the first-stage hydrolysis treatment process is 0.5-0.6 mg / L, and the DO control in the second-stage hydrolysis treatment process is 0.35-0.45 mg / L.

[0040] The control ranges of the DO in the first-stage hydrolysis treatment process and the DO in the second-stage hydrolysis treatment process set in the present application can achieve the corresponding technical effects, and further preferably, the DO control in the first-stage hydrolysis treatment process is 0.5 mg / L, and the DO control in the second-stage hydrolysis treatment process is 0.4 mg / L.

[0041] By adopting the above technical solution, the double hydrolysis treatment process is used, and the DO parameters in the two hydrolysis treatment processes are adjusted, a high-low control process is adopted, the microbial decomposition and metabolism are in a suitable dissolved oxygen environment, and the demand of the nitrification reaction for dissolved oxygen is met, so that better hydrolysis treatment effect is obtained.

[0042] Preferably, in the step S11, the filtration is divided into coarse filtration and fine filtration, the coarse filtration adopts a bag filter, and the fine filtration adopts a metal filter screen with a mesh number of 80-100.

[0043] By adopting the above technical solution, the bag filter is used for coarse filtration first to filter out large-particle solid impurities, and then the metal filter screen is used for fine filtration, which can improve the filtration effect, prolong the filtration life of the bag filter and the metal filter screen, and reduce the influence of the solid impurities on the subsequent treatment process.

[0044] Preferably, in the step S3, the flocculant is made from the following raw materials in parts by weight: polyaluminum chloride 12-18 parts, polyacrylamide 0.5-1 part, and calcium chloride 10-15 parts.

[0045] The weight percentage composition range of the flocculant component set in the present application can achieve the corresponding technical effect, and further preferably, the flocculant is made from the following raw materials by weight percentage: 15.2 parts of polyaluminum chloride, 0.8 parts of polyacrylamide, and 12.6 parts of calcium chloride.

[0046] By adopting the above technical solution, polyaluminum chloride, polyacrylamide and calcium chloride are added to the flocculant to form a flocculation system, adsorb sludge, organic matter degradation and other impurities generated in the biochemical treatment stage, and further improve the water quality.

[0047] Preferably, in the step S3, the adsorbent is one or more of activated carbon, silica gel, alumina, and zeolite.

[0048] The adsorbents listed in the present application can achieve the corresponding technical effect, and further preferably, the adsorbent is activated carbon.

[0049] By adopting the above technical solution, the addition of the adsorbent can adsorb harmful components such as heavy metal ions and toxic organic matter in the wastewater, reduce the toxicity of the wastewater, and facilitate subsequent treatment.

[0050] In summary, the present application has the following beneficial effects:

[0051] 1. Since the present application adopts a multi-stage treatment process of primary, secondary and tertiary stages, physical, biochemical and electrical treatment methods are organically combined to treat different pollutants in the wastewater, gradually improve the biodegradability of the wastewater, and reduce the treatment difficulty. And in the stages of electroflocculation and electrocatalysis, auxiliary reagents are introduced, which greatly improves the organic matter degradation effect of electroflocculation and electrocatalysis, improves the treatment effect and speed of the subsequent biochemical treatment stage, and ultimately achieves very good comprehensive treatment effect, while also appropriately reducing production costs.

[0052] 2. In the present application, the activated micro powder is preferably introduced into the coagulant, which can improve the flocculation effect in the electroflocculation treatment stage, and generate cationic free radicals and metal cationic electric active bodies in the electrocatalysis stage, thereby playing a good decomposition and catalysis role, allowing more organic macromolecules to be decomposed into small molecular organic matter, further improving the biodegradability of the wastewater and improving the treatment effect.

[0053] 3. The waste cutting fluid treatment method of the present application can perform deep harmless treatment on various types of waste cutting fluid, and has good comprehensive treatment effect. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 : The comprehensive data diagram of the water quality test indexes after treatment of the present application examples 1-9, comparative examples 1-5 and comparative examples 1-2. DETAILED DESCRIPTION

[0055] The present application will be further described in detail below with reference to the embodiments.

[0056] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available. Example

[0057] In this embodiment, the waste cutting fluid to be treated is selected from a machine processing plant. Its main components are: oil content 5%, solid content 3%, water content 92%, and COD range of 150,000-156,000 mg / L.

[0058] In this embodiment of the application, the waste cutting fluid treatment capacity is 67 t / d.

[0059] Example 1

[0060] The waste cutting fluid treatment method of this embodiment includes the following steps:

[0061] S1: Level 1 processing:

[0062] S11: Pretreatment: The waste cutting fluid wastewater to be treated is pumped into the oil separator. The free floating oil carried in the wastewater is skimmed off by the oil skimmer and then transported to the sedimentation tank. The skimmed floating oil is further treated to render it harmless. The wastewater undergoes preliminary sedimentation in the sedimentation tank and is then filtered and intercepted by a bar screen to remove large solid impurities before entering the equalization tank for homogenization.

[0063] S12: Acidification and electrocoagulation: The homogenized wastewater is pumped to the acidification tank for acidification and the pH value is adjusted to 3. Then it flows by gravity into the electrocoagulation tank for demulsification. After demulsification, the pH value of the wastewater is 6. Then it flows by gravity into the coagulation tank.

[0064] S13: Flocculation and air flotation: Coagulant and liquid alkali are added to the coagulation tank to carry out the coagulation reaction, and the pH is adjusted to 6.8-7.5. During the coagulation process, air is introduced to stir and form a mud-water mixture. The coagulated mud-water mixture is first passed through an oil conveyor to remove the residual floating oil, and then pumped to the No. 1 plate and frame filter press for primary filtration by a screw pump. The filtrate flows into the filtrate tank for temporary storage, and the filter residue is sent to the No. 2 plate and frame filter press for secondary pressing and drying for further processing. The press liquid from the secondary pressing is discharged into the filtrate tank.

[0065] S14: Electro-oxidation: The filtrate in the filtrate tank is sent to the electrocatalytic oxidation equipment by a booster pump for electrocatalytic oxidation. After catalytic oxidation, the primary treated liquid is obtained and stored in the intermediate tank.

[0066] S2: Secondary treatment: The catalytically oxidized wastewater is sequentially passed through a hydrolysis reactor for hydrolysis, and then through an anaerobic tank, an anaerobic tank, an aerobic tank, and an MBR membrane biological reactor to obtain the secondary treated liquid.

[0067] The setting parameters of the hydrolysis reactor are as follows: pH is 6.5, DO is 0.5 mg / L, and temperature is 20℃;

[0068] The operation parameters of the facultative pond are as follows: pH is 6.5-8, hydraulic retention time is 3.5 h, and sludge concentration is 4000-4200 mg / L;

[0069] The operation parameters of the anaerobic pond are as follows: pH is 6.5-7.8, temperature is 32-35℃, BOD5:N:P=200-300, and alkalinity (calculated as calcium carbonate) is 2000-4000 mg / L;

[0070] The operation parameters of the aerobic pond are as follows: pH is 6.5-8.5, temperature is 28-30℃, DO=2-4 mg / L, intermittent aeration, and the time of the muffled exposure is not less than 8 h;

[0071] The operation parameters of the MBR membrane biological reaction tank are as follows: pH is 7-7.5, temperature is 30-35℃, sludge concentration is 6-9 g / L, aeration amount is 0.025 m³ / min, sludge load is 0.2-0.25 kgCOD / (kgMLSS·d), hydraulic retention time is 48 h, and sludge age (SRT) is 30 d;

[0072] S3: tertiary treatment: the secondary treatment liquid is sent into a sedimentation tank, adsorbent and flocculant are added, and the wastewater after the treatment of sedimentation and filtration can reach the discharge standard.

[0073] In step S13, the liquid alkali is sodium hydroxide solution with a mass fraction of 20%, and the addition amount is 0.058 t / t of the cutting fluid treated; the coagulant is polyaluminum chloride, and the addition amount is 0.127 t / t of the cutting fluid treated. In step S3, the adsorbent is activated carbon, and the addition amount is 0.238 kg / t of the cutting fluid treated; the flocculant is calcium chloride, and the addition amount is 0.426 t / t of the cutting fluid treated.

[0074] Example 2

[0075] The difference between the treatment method of the waste cutting fluid of the present example and that of Example 1 is that, in step S13, the coagulant is uniformly mixed from the following weights of raw materials: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, and the rest is the same as in Example 1.

[0076] Example 3

[0077] The difference between the treatment method of the waste cutting fluid of the present example and that of Example 1 is that, in step S13, the coagulant is uniformly mixed from the following weights of raw materials: 80 kg of polyaluminum chloride, 2 kg of polyacrylamide, and the rest is the same as in Example 1.

[0078] Example 4

[0079] The processing method of the waste cutting fluid of the present embodiment is different from that of Embodiment 1 in that, in step S13, the coagulant is made of the following raw materials mixed uniformly in the following weights: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 6 kg of activated micro powder, and the rest is the same as in Embodiment 1.

[0080] The activated micro powder of the present embodiment is made by the following steps:

[0081] 1) 1 kg of polysaccharide, 50 g of 2,7-diamino fluorene, 250 g of 2-mercaptoethanesulfonic acid sodium, and 500 g of water are added into a stirring kettle to be mixed uniformly at 500 rpm / min to obtain an intermediate material;

[0082] 2) The metal micro powder and the intermediate material are put into a disperser at a mass ratio of 1:0.8 for high-speed stirring, and then put into an oven for drying at a temperature of 120°C, and then ground to obtain the activated micro powder, the average particle size of which is 50 μm.

[0083] The polysaccharide is dextrin. The metal micro powder is copper powder.

[0084] Embodiment 5

[0085] The processing method of the waste cutting fluid of the present embodiment is different from that of Embodiment 1 in that, in step S13, the coagulant is made of the following raw materials mixed uniformly in the following weights: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 6 kg of activated micro powder, and the rest is the same as in Embodiment 1.

[0086] The activated micro powder of the present embodiment is made by the following steps:

[0087] 1) 1 kg of polysaccharide, 65 g of 2,7-diamino fluorene, 100 g of 2-mercaptoethanesulfonic acid sodium, and 750 g of water are added into a stirring kettle to be mixed uniformly at 500 rpm / min to obtain an intermediate material;

[0088] 2) The metal micro powder and the intermediate material are put into a disperser at a mass ratio of 1:1.2 for high-speed stirring, and then put into an oven for drying at a temperature of 120°C, and then ground to obtain the activated micro powder, the average particle size of which is 50 μm.

[0089] The polysaccharide is dextrin. The metal micro powder is copper powder.

[0090] Embodiment 6

[0091] The processing method of the waste cutting fluid of the present embodiment is different from that of Embodiment 5 in that, in step S13, the coagulant is made of the following raw materials mixed uniformly in the following weights: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 8.5 kg of activated micro powder, and the rest is the same as in Embodiment 5.

[0092] Example 7

[0093] The difference between the treatment method of the waste cutting fluid of the present example and that of Example 5 is that in step S13, the coagulant is made of the following raw materials mixed uniformly by weight: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 7.2 kg of activated micro powder, and the rest is the same as in Example 5.

[0094] Example 8

[0095] The difference between the treatment method of the waste cutting fluid of the present example and that of Example 7 is that in step S2, the hydrolysis treatment is divided into two-stage hydrolysis treatment, the DO control is 0.5 mg / L in the first-stage hydrolysis treatment, and the DO control is 0.4 mg / L in the second-stage hydrolysis treatment, and the rest is the same as in Example 7.

[0096] Example 9

[0097] The difference between the treatment method of the waste cutting fluid of the present example and that of Example 8 is that in step S3, the flocculating agent is made of the following raw materials mixed uniformly by weight: 15.2 parts of polyaluminum chloride, 0.8 parts of polyacrylamide, 12.6 parts of calcium chloride, and the rest is the same as in Example 8.

[0098] Comparative Example

[0099] Comparative Example 1

[0100] The difference between the treatment method of the waste cutting fluid of the present comparative example and that of Example 1 is that in step S13, the coagulant is made of the following raw materials mixed uniformly by weight: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 6 kg of activated micro powder, and the rest is the same as in Example 1.

[0101] The activated micro powder of the present comparative example is made by the following steps:

[0102] 1) Put 1 kg of polysaccharide, 250 g of 2-mercaptoethanesulfonic acid sodium, and 550 g of water into a stirred tank to mix uniformly at 500 rpm / min to obtain an intermediate material;

[0103] 2) Put the metal micro powder and the intermediate material into a disperser at a mass ratio of 1:0.8 and stir at high speed, then dry in an oven at a temperature of 120°C, and grind to obtain the activated micro powder, the average particle size of which is 50 μm.

[0104] Among them, the polysaccharide is dextrin. The metal micro powder is copper powder.

[0105] Comparative Example 2

[0106] The difference between the waste cutting fluid treatment method of the present comparative example and that of example 1 is that in step S13, the coagulant is made of the following raw materials mixed uniformly by weight: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 6 kg of activated powder, and the rest is the same as in example 1.

[0107] The activated powder of the present comparative example is made by the following steps:

[0108] 1) 1 kg of polysaccharide, 50 g of 2,7-diamino fluorene, and 750 g of water are added to a stirring kettle to mix uniformly at 500 rpm / min to obtain an intermediate material;

[0109] 2) The metal powder and the intermediate material are placed in a disperser at a mass ratio of 1:0.8 and stirred at high speed, then placed in an oven and dried at a temperature of 120°C, and then ground to obtain the activated powder, the average particle size of which is 50 μm.

[0110] The polysaccharide is dextrin, and the metal powder is copper powder.

[0111] Comparative example 3

[0112] The difference between the waste cutting fluid treatment method of the present comparative example and that of example 1 is that in step S13, the coagulant is made of the following raw materials mixed uniformly by weight: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 6 kg of activated powder, and the rest is the same as in example 1.

[0113] The activated powder of the present comparative example is made by the following steps:

[0114] 1) 50 g of 2,7-diamino fluorene, 250 g of 2-mercaptoethanesulfonic acid sodium, and 500 g of water are added to a stirring kettle to mix uniformly at 500 rpm / min to obtain an intermediate material;

[0115] 2) The metal powder and the intermediate material are placed in a disperser at a mass ratio of 1:0.8 and stirred at high speed, then placed in an oven and dried at a temperature of 120°C, and then ground to obtain the activated powder, the average particle size of which is 50 μm.

[0116] The metal powder is copper powder.

[0117] Comparative example 4

[0118] The difference between the waste cutting fluid treatment method of the present comparative example and that of example 1 is that in step S13, the coagulant is made of the following raw materials mixed uniformly by weight: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 6 kg of activated powder, and the rest is the same as in example 1.

[0119] The activated powder of the present comparative example is made by the following steps:

[0120] 1) 1 kg of polysaccharide, 500 g of water were added into a stirred tank to mix evenly at 500 rpm / min to obtain an intermediate material;

[0121] 2) The metal powder and the intermediate material were placed into a disperser at a mass ratio of 1:0.8 and stirred at high speed, then dried in an oven at a temperature of 120°C, and ground to obtain the activated powder, the average particle size of the ground activated powder being 50 μm.

[0122] In the formula, the polysaccharide is dextrin, and the metal powder is copper powder.

[0123] Comparative Example 5

[0124] The difference between the treatment method of the waste cutting fluid of the present comparative example and that of Example 1 is that in step S13, the coagulant is prepared by mixing the following raw materials evenly by weight: 90 kg of polyaluminum chloride, 1 kg of polyacrylamide, 6 kg of metal powder, and the rest is the same as in Example 1.

[0125] In the formula, the metal powder is copper powder.

[0126] Comparative Example

[0127] Comparative Example 1

[0128] The treatment method of the waste cutting fluid of the present comparative example comprises the following steps:

[0129] S1: Pretreatment: the waste cutting fluid to be treated is pumped into an oil separation tank, and after the free floating oil carried by the waste water is removed by an oil skimmer, it is transported to a sedimentation tank, and the removed floating oil is further treated for harmless treatment; the waste water is preliminarily settled in the sedimentation tank, and then filtered and intercepted by a grid to remove large solid impurities into a conditioning tank;

[0130] S2: Coagulation air flotation: the conditioned waste water is transported into a coagulation tank by a booster pump, a demulsifier is added for demulsification in the coagulation tank, and air is blown in for stirring to form a mud-water mixture, the coagulated mud-water mixture is first brought out by an oil removal machine, and then transported to a 1# plate and frame filter press for primary pressure filtration, the filtrate flows into a filtrate tank for temporary storage, and the filter residue is sent to a 2# plate and frame filter press for secondary squeezing and blowing dry for further treatment, and the squeezed liquid of the secondary squeezing is discharged into the filtrate tank;

[0131] S3: Membrane filtration treatment: the filtrate is subjected to membrane separation treatment by a vibrating membrane filtration device to obtain a membrane filtration treatment liquid;

[0132] S4: Adsorption and sedimentation: the membrane filtration treatment liquid is sent into a sedimentation tank, an adsorbent and a flocculant are added, and after treatment, sedimentation and filtration, a treated waste water is obtained.

[0133] Comparative Example 2

[0134] The treatment method of the waste cutting fluid of the present comparative example comprises the following steps:

[0135] S1: primary treatment:

[0136] S11: pretreatment: the waste cutting fluid sewage to be treated is pumped into an oil separation tank, and the free floating oil carried in the sewage is removed by an oil skimmer and then delivered to a sedimentation tank. The removed floating oil is further treated for harmless treatment. The wastewater is preliminarily precipitated in the sedimentation tank, and then filtered and intercepted by a grid to remove large solid impurities into a conditioning tank for uniformity;

[0137] S12: acidification and electroflocculation: the uniform wastewater is delivered to an acidification tank by a lifting pump for acidification, and the pH value is adjusted to 3. Then, the wastewater is self-flowed into an electroflocculation tank for demulsification treatment. After demulsification, the pH value of the wastewater is 6. Then, the wastewater is self-flowed into a coagulation tank;

[0138] S13: electro-oxidation: the filtrate in the filtrate tank is delivered to an electro-catalytic oxidation equipment by a lifting pump for electro-catalytic oxidation. The primary treatment liquid obtained after catalytic oxidation is stored in an intermediate tank;

[0139] S2: secondary treatment: the wastewater after catalytic oxidation is sequentially subjected to hydrolysis reaction in a hydrolysis reactor, and then subjected to facultative pond, anaerobic pond, aerobic pond and MBR membrane biological reaction tank. The secondary treatment liquid is obtained after treatment;

[0140] The set parameters of the hydrolysis reactor are: pH 6.5, DO 0.5 mg / L, and temperature 20°C;

[0141] The operation parameters of the facultative pond are: pH 6.5-8, hydraulic retention time 3.5 h, and sludge concentration 4000-4200 mg / L;

[0142] The operation parameters of the anaerobic pond are: pH 6.5-7.8, temperature 32-35°C, BOD5:N:P=200-300, and alkalinity (calculated as calcium carbonate) in the range of 2000-4000 mg / L;

[0143] The operation parameters of the aerobic pond are: pH 6.5-8.5, temperature 28-30°C, DO=2-4 mg / L, intermittent aeration, and the muffled exposure time is not less than 8 h;

[0144] The operation parameters of the MBR membrane biological reaction tank are: pH 7-7.5, temperature 30-35°C, sludge concentration 6-9 g / L, aeration amount 0.025 m³ / min, sludge load 0.2-0.25 kgCOD / (kgMLSS·d), hydraulic retention time 48 h, and sludge age (SRT) 30 d;

[0145] S3: tertiary treatment: the secondary treatment liquid is sent into a sedimentation tank, adsorbent and flocculant are added, and after treatment, sedimentation and filtration, treated wastewater is obtained.

[0146] Detection method

[0147] The treated wastewater of Examples 1-9, Comparative Examples 1-5 and Comparative Example 1-2 is tested for COD, BOD5, ammonia nitrogen, petroleum, and suspended solids, and the comprehensive test results are shown in Table 1. Figure 1

[0148] Examples 1 and Comparative Example 1-2 are analyzed and combined with Figure 1 It can be seen that the treatment method of the waste cutting fluid of the present application uses a process combining pretreatment, acidification, electrocoagulation, coagulation treatment, electrooxidation, multi-stage biochemical treatment, and tertiary deep treatment, greatly improving the biodegradability of the waste cutting fluid. The final effluent meets the 3rd level discharge water quality requirement of the wastewater comprehensive discharge standard, and has very good treatment effect. In Comparative Example 1, the conventional treatment method of coagulation, membrane filtration and adsorption precipitation is used, the biodegradability of the wastewater is poor, and the COD content in the effluent is very high, which cannot meet the discharge standard. In Comparative Example 2, no coagulant is added, and the macromolecular organic matter cannot be well degraded in the electrocoagulation and electrocatalytic oxidation stages, resulting in poor biochemical treatment effect.

[0149] Examples 2-3, Examples 4-7, and Comparative Examples 1-5 are analyzed and combined with Figure 1 It can be seen that after introducing activated micro powder into the coagulant, in the coagulation stage, with the slow disintegration of the polysaccharide coating layer structure, the activated micro powder can release 2,7-diamino fluorene and 2-mercaptoethanesulfonic acid sodium in an appropriate amount, which can form cationic radicals under the oxidation of the anode, thereby promoting the cleavage of macromolecular organic matter. In addition, it can also adjust the surface tension of the wastewater to a certain extent, promoting the formation of flocculation. In the electrooxidation stage, the metal micro powder can generate electroactive bodies under the action of a strong electric field, thereby showing very strong oxidation ability. The components of 2,7-diamino fluorene and 2-mercaptoethanesulfonic acid sodium that are not completely consumed in the electrocoagulation stage can be further oxidized, assisting the metal micro powder to play a very good oxidation cleavage effect, greatly improving the biodegradability of the wastewater.

[0150] ​The 2,7-diamino fluorene is not added in the comparative example 1, and cannot play a corresponding cracking promotion role. The sodium 2-mercaptoethanesulfonate is not added in the comparative example 2, and the oxidation catalysis effect is good compared with the comparative example 1 and the example 1, but the generation amount of the flocculation body is small, leading to poor indexes of the suspended matter. In the comparative example 3, the polysaccharide is not added, and the coating layer structure cannot be formed, leading to rapid release of the 2,7-diamino fluorene and the sodium 2-mercaptoethanesulfonate into the water body. Not only cannot the 2,7-diamino fluorene and the sodium 2-mercaptoethanesulfonate play a good cracking promotion role, but also cause systemic processing abnormalities, and the overall processing effect is poor. In the comparative example 4, only the polysaccharide and the metal powder are compounded, and in the comparative example 5, only the metal powder is used, and the overall processing effect of the sewage is poor, and some indexes such as COD and BOD5 increase.

[0151] The analysis examples 8-9 are combined Figure 1 It can be seen that the hydrolysis treatment process and the component composition of the flocculant are further optimized and adjusted, the degradation effect of the high COD wastewater in the hydrolysis stage is improved, and the deep treatment effect of the sewage is also improved, so that better water quality indexes are obtained.

[0152] The specific embodiment is only an explanation of the application, and is not a limitation of the application. Those skilled in the art can make modifications to the embodiment without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the application, and are protected by the patent law.

Claims

1. A method for treating waste cutting fluid, characterized by, Includes the following steps: S1: Level 1 processing: S11： Pretreatment: The waste cutting fluid is separated by oil separation, sedimentation, and filtration to remove floating oil and large particulate impurities, and then sent to the equalization tank for homogenization; S12: Acidification and electrocoagulation: The homogenized wastewater is transported to the acidification tank for acidification, then sent to the electrocoagulation tank for demulsification, and then sent to the coagulation tank. S13: Flocculation and air flotation: Coagulant and alkali are added to the coagulation tank to carry out coagulation reaction. Air is introduced to stir during the coagulation process. The sludge-water mixture after coagulation is separated into filter residue and filtrate through solid-liquid separation. S14: Electro-oxidation: The filtrate is fed into an electrocatalytic oxidation device for electrocatalytic oxidation to obtain the primary treated liquid; S2: Secondary treatment: The wastewater after catalytic oxidation is sequentially subjected to hydrolysis, facultative anaerobic treatment, anaerobic treatment, aerobic treatment, and MBR membrane biological reaction to obtain secondary treated liquid; S3: Tertiary treatment: The secondary treated liquid is sent into the sedimentation tank, and adsorbent and flocculant are added. After treatment, it can meet the discharge standards. In step S13, the coagulant is mainly made from the following raw materials in parts by weight: 80-90 parts of polyaluminum chloride and 1-2 parts of polyacrylamide. The coagulant also includes 6-8.5 parts of activated micro powder, which is prepared by a method comprising the following steps: 1) Add polysaccharide, 2,7-diaminofluorene, sodium 2-mercaptoethanesulfonate, and water to a container and mix evenly to obtain an intermediate material; 2) Add the metal micro powder to the intermediate material and stir at high speed, then dry and grind to obtain the metal micro powder, which is one or more of copper powder, tin powder and nickel powder.

2. The method for treating waste cutting fluid according to claim 1, characterized in that, The polysaccharide is one or more of starch, dextrin, and hydroxypropyl cellulose.

3. The method for treating waste cutting fluid according to claim 1, characterized in that, The mass ratio of the activated micro powder to polyaluminum chloride is (0.066-0.08):

1.

4. The method for treating waste cutting fluid according to claim 1, characterized in that, In step S2, the hydrolysis treatment is divided into two stages. During the first stage of hydrolysis treatment, the DO is controlled at 0.5-0.6 mg / L, and during the second stage of hydrolysis treatment, the DO is controlled at 0.35-0.45 mg / L.

5. The method for treating waste cutting fluid according to claim 1, characterized in that, In step S11, filtration is divided into coarse filtration and fine filtration. Coarse filtration uses a bag filter, and fine filtration uses a metal filter with a mesh size of 80-100.

6. The method for treating waste cutting fluid according to claim 1, characterized in that, In step S3, the flocculant is made from the following raw materials in parts by weight: 12-18 parts of polyaluminum chloride, 0.5-1 parts of polyacrylamide, and 10-15 parts of calcium chloride.

7. The method for treating waste cutting fluid according to claim 1, characterized in that, In step S3, the adsorbent is one or more of activated carbon, silica gel, alumina, and zeolite.

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