CN-117069329-B - Short-range pretreatment method for lithium battery production wastewater

Abstract

The invention discloses a short-range pretreatment method of lithium battery production wastewater, which comprises the steps of adjusting the pH value of the lithium battery production wastewater, respectively adding persulfate and ferrous sulfate into the wastewater, oxidizing and removing NMP, adding polyacrylamide into the NMP-removed wastewater for flocculation reaction, controlling the speed gradient of the flocculation reaction, precipitating, separating and removing nano graphite, and obtaining the pretreated lithium battery production wastewater. The method utilizes the nano graphite and Fe 2+ co-activated persulfate oxidation method to carry out oxidation treatment on NMP in the wastewater produced by the lithium battery, improves the removal rate and biodegradability of NMP, and carries out flocculation precipitation separation on nano-filtration graphite on the basis. According to the method, the nano graphite and Fe 2+ are used for jointly activating the persulfate oxidation method to perform oxidation treatment on NMP in the wastewater produced by the lithium battery, so that the removal rate and biodegradability of the NMP are improved, the flocculation precipitation separation effect is achieved on the nano-filtration graphite, the process flow is shortened, and the energy consumption is reduced.

Inventors

• LV YONGTAO
• ZHANG MENGDA
• WANG LEI
• SUN TING
• Lv Qinghu

Assignees

• 西安建筑科技大学

Dates

Publication Date

20260505

Application Date

20230927

Claims (7)

1. 1. The short-range pretreatment method for the lithium battery production wastewater is characterized by comprising the following steps of: Adjusting the pH value of the wastewater produced by the lithium battery to 9.0-11.0, respectively adding persulfate and ferrous sulfate into the wastewater to perform oxidation reaction, and jointly activating the persulfate to oxidize and remove NMP through Fe 2+ and nano graphite; the persulfate is one of sodium persulfate or potassium persulfate; the coagulation reaction removes colloid or colloid-like substances in water, and comprises two steps of coagulation and flocculation: The ferrous salt is oxidized into ferric salt by persulfate to carry out condensation reaction; adding polyacrylamide into NMP-removed wastewater to perform flocculation reaction, wherein the flocculation reaction time is 1-5 min, the speed gradient of the flocculation reaction is controlled to be 40-60s -1 , precipitation is performed, nano graphite is separated and removed, and the nano graphite separation efficiency is not lower than 96%, so that pretreated lithium battery production wastewater is obtained.
2. 2. The short-range pretreatment method for lithium battery production wastewater according to claim 1, wherein the pH is adjusted by sodium hydroxide with a concentration of 0.01-0.1 mmol/L.
3. 3. The short-range pretreatment method for lithium battery production wastewater according to claim 1, wherein the addition amount of ferrous sulfate is 10-15 mmol/L and the addition amount of persulfate is 18-22 mmol/L.
4. 4. The short-range pretreatment method for lithium battery production wastewater according to claim 1, wherein the time for oxidizing NMP is 20-30 min.
5. 5. The short-range pretreatment method for lithium battery production wastewater according to claim 1, wherein the concentration of the polyacrylamide is 0.5-1%, and the adding amount of the polyacrylamide is 90-100 mg/L.
6. 6. The short-range pretreatment method for lithium battery production wastewater according to claim 1, wherein the precipitation time is 5-10 min.
7. 7. A short-range pretreatment method for lithium battery production wastewater according to any one of claims 1 to 6, wherein the removal rate of COD in the pretreated lithium battery production wastewater is not lower than 57%.

Description

Short-range pretreatment method for lithium battery production wastewater Technical Field The invention belongs to the field of wastewater treatment, and relates to a short-range efficient pretreatment method for wastewater in lithium battery production. Background Since the 21 st century, the global environmental load capacity has been continuously reduced, and energy sources are in shortage, so that development and application of new energy sources are gradually attracting attention from governments around the world, and lithium batteries have become key projects for new energy source development. With the vigorous development of the lithium battery industry, a large amount of production wastewater is inevitably generated. The method mainly originates from processes such as anode and cathode production, raw material storage tank cleaning and the like, and because the waste water from lithium battery production contains high-concentration nano graphite and Nitrogen Methyl Pyrrolidone (NMP), the concentration of Chemical Oxygen Demand (COD), total Suspended Solids (TSS) and Total Nitrogen (TN) is high, and the method has the characteristics of poor biodegradability and biotoxicity. Therefore, pretreatment is required for the contaminants nanographite and NMP. The prior pretreatment method respectively carries out independent treatment on two pollutants, which leads to the defects of high energy consumption and long flow. The method for evaporating nano graphite in wastewater is usually adopted, and has the advantages of good separation effect, high energy consumption, treatment cost of ton water approaching 200 yuan, easy blockage and damage of evaporating equipment and normal operation of a subsequent water treatment system. After separation of the graphite, advanced oxidation methods, such as Fenton oxidation, are often used, which, although improving biodegradability, have poor NMP removal, typically less than 30%. In summary, the pretreatment of the lithium battery production wastewater has the defects of high energy consumption and long process, and how to shorten the process flow, reduce the energy consumption and improve the treatment performance is a key point to be solved in the field. Disclosure of Invention In order to solve the defects in the prior art, the invention aims to provide a short-range and efficient pretreatment method for lithium battery production wastewater, which utilizes a nano graphite and Fe 2+ co-activated persulfate oxidation method to perform oxidation treatment on NMP in the lithium battery production wastewater, improves the NMP removal rate and biodegradability, and performs flocculation precipitation separation effect on nano-filtration graphite, shortens the process flow and reduces the energy consumption. The invention is realized by the following technical scheme. The invention provides a short-range pretreatment method for lithium battery production wastewater, which comprises the following steps: regulating the pH value of the wastewater produced by the lithium battery, respectively adding persulfate and ferrous sulfate into the wastewater, and oxidizing to remove NMP; adding polyacrylamide into the NMP-removed wastewater to perform flocculation reaction, controlling the speed gradient of the flocculation reaction, precipitating, separating and removing nano graphite, and obtaining pretreated lithium battery production wastewater. Preferably, the pH is adjusted to 9.0-11.0 by using sodium hydroxide with a concentration of 0.01-0.1 mmol/L. Preferably, the addition amount of ferrous sulfate is 10-15mmol/L, and the addition amount of persulfate is 18-22mmol/L. Preferably, the persulfate is one of sodium persulfate or potassium persulfate. Preferably, the time for oxidizing NMP is 20-30 minutes. Preferably, the concentration of the polyacrylamide is 0.5-1%, and the adding amount of the polyacrylamide is 90-100mg/L. Preferably, the flocculation reaction time is 1-5min. Preferably, the speed gradient of the flocculation reaction is 40-60s -1. Preferably, the precipitation time is 5-10min. Due to the adoption of the technical scheme, the invention has the following beneficial effects: The existing treatment technology of the lithium battery production wastewater carries out pretreatment on the nano graphite and the NMP independently, so the defects of long process flow, high treatment cost and poor treatment effect exist, and compared with the prior art, the invention has the beneficial effects that: 1. The removal effect is improved, namely the nano graphite is utilized to strengthen Fe 2+ to activate persulfate to oxidize NMP, namely, the synergistic effect between two pollutants is fully considered, so that the NMP oxidation removal effect and biodegradability of persulfate are improved, the removal rate can be improved by 20-30%, and the biodegradability is improved by 10-20%. COD removal rate of the pretreated lithium battery production wastewater is not lower than 57