BIOAUGMENTATION TREATMENT PROCESS FOR LITHIUM BATTERY PRODUCING WASTEWATER

Abstract

The present invention relates to the technical field of wastewater treatment, and discloses a bioaugmentation treatment process for lithium battery producing wastewater. The method comprises the following steps: 1) introducing wastewater into a hydrolytic acidification tank, and adding Enterobacter sp. NJUST50 and activated sludge to the hydrolytic acidification tank for hydrolytic acidification treatment; 2) introducing the effluent into an anoxic tank, and adding Enterobacter sp. NJUST50 and anaerobic activated sludge for anoxic treatment; 3) introducing the effluent into an aerobic tank, and adding Enterobacter sp. NJUST50 and aerobic activated sludge for aerobic treatment; 4) introducing the effluent into an anoxic filter tank, and adding Enterobacter sp. NJUST50 and anaerobic activated sludge to the filter tank for treatment; and 5) introducing the effluent into a biological aerated filter tank, and adding a sludge mixture of Enterobacter sp. NJUST50 with aerobic activated sludge to the filter tank for treatment.

Claims

1. A bioaugmentation treatment process for lithium battery producing wastewater, comprising the following steps: 1) introducing lithium battery producing wastewater into a hydrolytic acidification tank, and adding a sludge mixture of Enterobacter sp. NJUST50 and anaerobic activated sludge to the hydrolytic acidification tank for hydrolytic acidification treatment, wherein the Enterobacter sp. NJUST50 is deposited in China Center for Type Culture Collection under CCTCC Accession NO: M2019128; 2) introducing the wastewater after treatment in step 1) into an anoxic tank, and adding a sludge mixture of the Enterobacter sp. NJUST50 with anaerobic activated sludge to the tank for anoxic treatment; 3) introducing the wastewater after treatment in step 2) into an aerobic tank, and adding a sludge mixture of the Enterobacter sp. NJUST50 and aerobic activated sludge to the tank for aerobic treatment; 4) introducing the wastewater after treatment in step 3) into an anoxic filter tank, and adding a sludge mixture of the Enterobacter sp. NJUST50 with anaerobic activated sludge to the filter tank for anoxic treatment; and 5) introducing the wastewater after treatment in step 4) into a biological aerated filter tank, and adding a sludge mixture of the Enterobacter sp. NJUST50 with aerobic activated sludge to the filter tank for aerobic treatment.

2. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 1, further comprising step 6) that is specifically: 6) entering the effluent after treatment in step 5) into a membrane bioreactor for solid-liquid separation treatment.

3. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 1 wherein the mixing ratio of the Enterobacter sp. NJUST50 and the anaerobic activated sludge in steps 1), 2) and 4) is 1:5 on basis of dry weight of the sludge, and/or the mixing ratio of the Enterobacter sp. NJUST50 and the aerobic activated sludge in steps 3) and 5) is 1:5 on basis of dry weight of the sludge.

4. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 3, wherein the hydraulic retention time in the hydrolytic acidification tank in step 1) is set as 16-24 hrs, and the organic load is 3.50-5.30 kgCOD/m.sup.3/d; and/or the hydraulic retention time in the anoxic tank in step 2) is set as 48-72 hrs, and the organic load is 0.23-0.35 kgCOD/m.sup.3/d; and/or the hydraulic retention time in the aerobic tank in step 3) is set as 48-72 hrs, and the organic load is 0.07-0.11 kgCOD/m.sup.3/d; and/or the hydraulic retention time in the anoxic filter tank in step 4) is set as 16-24 hrs, and the organic load is 0.34-0.51 kgCOD/m.sup.3/d; and/or the hydraulic retention time in the biological aerated filter tank in step 5) is set as 8-10 hrs, and the organic load is 0.14-0.17 kgCOD/m.sup.3/d.

5. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 4, wherein the sludge mixture inoculated in the hydrolytic acidification tank in step 1) is 5 kg/m.sup.3; and/or the sludge mixture inoculated in the anoxic tank in step 2) is 5 kg/m.sup.3; and/or the sludge mixture inoculated in the aerobic tank in step 3) is 3 kg/m.sup.3; and/or the sludge mixture inoculated in the anoxic filter tank in step 4) is 1 kg/m.sup.3; and/or the sludge mixture inoculated in the biological aerated filter tank in step 5) is 1 kg/m.sup.3.

6. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 1, wherein the lithium battery producing wastewater in step 1) has been pretreated by sedimentation-coagulation-precipitation.

7. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 6, wherein in the anoxic tank, a diluted sulfuric acid solution is required to be added to adjust the pH to 6.5-7.0, and in the aerobic tank, a sodium hydroxide solution needs to be added to adjust the pH to 7.5-8.0.

8. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 7, wherein ZVI could be added into the anoxic tank, and the amount of ZVI is 6 kg/m.sup.3.

9. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 8, wherein glucose is added in the anoxic filter tank, and the amount of glucose is 0.2 kg/m.sup.3.

10. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 8, wherein the effluent after treatment in step 3) is refluxed to the anoxic tank in step 2), and the effluent after treatment in step 5) is refluxed to the anoxic filter tank in step 4).

11. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 2, wherein the mixing ratio of the Enterobacter sp. NJUST50 and the anaerobic activated sludge in steps 1), 2) and 4) is 1:5 on basis of dry weight of the sludge, and/or the mixing ratio of the Enterobacter sp. NJUST50 and the aerobic activated sludge in steps 3) and 5) is 1:5 on basis of dry weight of the sludge.

12. The bioaugmentation treatment process for lithium battery producing wastewater according to claim 2, wherein the lithium battery producing wastewater in step 1) has been pretreated by sedimentation-coagulation-precipitation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1 shows a bioaugmentation combined process for lithium battery producing wastewater in Example 1; and

[0051] FIG. 2 shows a combined process for lithium battery producing wastewater in the comparative example.

DETAILED DESCRIPTION

[0052] The present invention is further described below with reference to specific embodiments.

[0053] The terms used in the present invention, unless otherwise stated, generally have the meaning commonly understood by a person of ordinary skill in the art. The present invention is further described in detail below with reference to specific embodiments and data. It should be understood that, the embodiments are only for describing the present invention by using examples, but do not limit the scope of the present invention in any manner. In the following embodiments, various processes and methods that are not described in detail are common conventional methods in the art.

Example 1

[0054] The wastewater pretreated by sedimentation-coagulation-precipitation in a lithium battery production plant is taken as an example, in which the COD concentration is in the range of 3200-3500 mg/L, the N-methylpyrrolidone concentration is in the range of 2100-2400 mg/L, the ammonia nitrogen concentration is in the range of 4-10 mg/L, and the total nitrogen concentration is in the range of 300-400 mg/L. The bioaugmentation combined process of “hydrolytic acidification-anoxic treatment-aerobic treatment-anoxic filter tank-biological aerated filter tank-membrane bioreactor” in the present invention is shown in FIG. 1. The specific steps are as follows.

[0055] 1) The wastewater pretreated by sedimentation-coagulation-precipitation is entered into a hydrolytic acidification tank, where the hydraulic retention time is set as 16-24 hrs, and the organic load is 3.50-5.30 kgCOD/m.sup.3/d; and a sludge mixture of the Enterobacter sp. NJUST50 (deposited under CCTCC Accession NO: M2019128) with anaerobic activated sludge is added to the hydrolytic acidification tank, where the sludge mixture is inoculated at 5 kg/m.sup.3 (the sludge concentration is on dry weight basis, and the dry weight ratio of Enterobacter sp. NJUST50 to the anaerobic activated sludge is 1:5), and the activated sludge comprises anaerobic and facultative anaerobic bacteria. Through hydrolysis by anaerobic or facultative anaerobic bacteria, refractory macromolecular substances in the wastewater are hydrolyzed into readily biodegradable small molecular substances through the hydrolysis and acidification, and then the small molecular substances are converted into volatile fatty acids through acidification by anaerobic bacteria.

[0056] 2) The effluent from the hydrolytic acidification tank is introduced to an anoxic tank, where the hydraulic retention time is set as 48-72 hrs, and the organic load is 0.23-0.35 kgCOD/m.sup.3/d; and a sludge mixture of the Enterobacter sp. NJUST50 with activated sludge is added to the tank, where the sludge mixture is inoculated at a concentration of 5 kg/m.sup.3 (the sludge concentration is on dry weight basis, and the dry weight ratio of Enterobacter sp. NJUST50 to the activated sludge is 1:5). Dilute sulfuric acid is added in the tank to adjust the pH to 6.5-7.0 to maintain a proper pH value. By taking advantage of nitrate generated from aerobic tank denitrification and biodegradation of N-methylpyrrolidone are carried out.

[0057] 3) The effluent is introduced into an aerobic tank, where the hydraulic retention time is set as 48-72 hrs, and the organic load is 0.07-0.11 kgCOD/m.sup.3/d; and a sludge mixture of the Enterobacter sp. NJUST50 with activated sludge is added to the tank, where the sludge mixture is inoculated at 3 kg/m.sup.3 (the sludge concentration is on dry weight basis, and the dry weight ratio of Enterobacter sp. NJUST50 to the activated sludge is 1:5). Because the nitrification of ammonia nitrogen will release acidity, a sodium hydroxide solution is added in the aerobic tank to adjust the pH to 7.5-8.0 to maintain a proper pH value. This step functions to further degrade residual COD in the wastewater in the aerobic tank, and oxidize ammonia nitrogen into nitrate under the action of nitrifying bacteria, which is then refluxed to the anoxic tank, to achieve the biological nitrogen removal by a combination with denitrifying bacteria.

[0058] 4) The effluent from the aerobic tank is introduced into an anoxic filter tank, where the hydraulic retention time is set as 16-24 hrs, the organic load is 0.34-0.51 kgCOD/m.sup.3/d, and spherical polyurethane is contained in the anoxic filter tank as a filter material; and a sludge mixture of the Enterobacter sp. NJUST50 with activated sludge is added, where the sludge mixture is inoculated at 1 kg/m.sup.3 (the sludge concentration is on dry weight basis, and the dry weight ratio of the Enterobacter sp. NJUST50 to the activated sludge is 1:5). Through using nitrate generated from nitration, this step mainly to further degrade pollutants such as N-methylpyrrolidone, and simultaneously realize the nitrogen removal by denitrification and the release of ammonia nitrogen. In this step, in order to ensure the removal of total nitrogen, 0.2 kg/m.sup.3 of glucose needs to be added as an auxiliary electron donor.

[0059] 5) The effluent from the anoxic filter tank is introduced into a biological aerated filter tank, where the hydraulic retention time is set as 16-24 hrs, the organic load is 0.05-0.08 kg COD/m.sup.3/d, and spherical polyurethane is contained in the biological aerated filter tank as a filter material; and a sludge mixture of the Enterobacter sp. NJUST50 with activated sludge is added and inoculated at 1 kg/m.sup.3 (the sludge concentration is on dry weight basis, and the dry weight ratio of the Enterobacter sp. NJUST50 to the activated sludge is 1:5). This step in order to further remove residual organic matter and COD in the wastewater, and oxidize ammonia nitrogen into nitrate, which is then refluxed to the anoxic filter tank, to realize the function of biological nitrogen removal.

[0060] 6) The effluent from the biological aerated filter tank is introduced to a membrane bioreactor, where the hydraulic retention time is set as 8-10 hrs, and the organic load is 0.14-0.17 kgCOD/m.sup.3/d. This step aims to trap biological membrane and other suspended substances carried in the wastewater. The sludge is refluxed to the front biological aerated filter tank, and the effluent is discharge up to standard. The removal efficiencies of various procedures in the bioaugmentation combined process of “hydrolytic-acidification-anoxic treatment-aerobic treatment-anoxic filter tank-biological aerated filter tank-membrane bioreactor” under stable working conditions are shown in Table 1.

TABLE-US-00001 TABLE 1 Water quality index of effluent from various procedures of the combined process Treatment COD.sub.cr NMP NH.sub.3—N TN TP SS unit Index (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Hydrolysis Influent 3200-3500 2100-2400  4-10 300-400 0.4-0.5 40-50  acidification tank Effluent 2000-2100 1300-1450 240-270 300-320 0.3-0.4 85-100 Anoxic tank Influent 2000-2100 1300-1450 240-270 300-320 0.3-0.4 85-100 Effluent 550-650 350-440 330-360 400-430 0.3-0.4 85-100 Aerobic tank Influent 550-650 350-440 330-360 400-430 0.3-0.4 85-100 Effluent  90-110 61-75 35-45 55-65 0.2-0.3 85-100 Anoxic Influent  90-110 61-75 35-45 55-65 0.2-0.3 85-100 filter tank Effluent 25-35 17-25 3-4  5-10 0.2-0.3 40-50  Biological aerated Influent 25-35 17-25 3-4  5-10 0.2-0.3 40-50  filter tank Effluent 20-25 13-15 3-4  5-10 0.2-0.3 40-50  Membrane Influent 20-25 13-15 3-4  5-10 0.2-0.3 40-50  bio-reactor Effluent 15-19 10-13 1-2  5-10 0.2-0.3 2-4 

[0061] The costs in the treatment of wastewater by the bioaugmentation combined process of “hydrolytic acidification-anoxic-aerobic-anoxic filter tank-biological aerated filter tank-membrane bioreactor” mainly include chemical cost, electricity cost, and labor cost etc., which are 10.56 yuan/ton of wastewater in total. The chemical cost mainly includes dilute sulfuric acid, sodium hydroxide, glucose and other consumables, and is estimated to be 1.24 yuan/ton of wastewater. The consumption of electricity mainly is attributed to the operation of air compressors, dosing pumps, feed pumps and others, and the electricity cost is estimated to be 9.32 yuan/ton of wastewater. The on-site operators are part-time employees of the production department, and the labor cost is not included. If the wastewater from lithium battery production is treated by “Fenton oxidation-coagulation-precipitation-activated carbon filtration”, where the cost of chemicals alone is as high as 80-100 yuan/ton of water. The costs in the treatment of wastewater by the bioaugmentation combined process of “hydrolytic acidification-anoxic-aerobic-anoxic filter tank-biological aerated filter tank-membrane bioreactor” is far less than the cost of the combined process of Fenton oxidation-coagulation-precipitation-activated carbon filtration, and thus has significant economic benefits.

Comparative Example

[0062] In the comparative example, a combined process of “anaerobic treatment-anoxic treatment-aerobic treatment-membrane bioreactor” is used, and the process is as shown in FIG. 2. The influent water quality and operating parameters of each section are the same as those in Example 1, except that a common anaerobic sludge is inoculated in the anaerobic tank, and a common activated sludge is inoculated in the anoxic tank and the aerobic tank. The removal efficiencies of each procedure under stable operating conditions is shown in Table 2. COD in the anaerobic reaction procedure inoculated with anaerobic sludge is reduced from 3200-3500 mg/L to 2100-2300 mg/L, and N-methylpyrrolidone is reduced from 2100-2400 mg/L to 1400-1550 mg/L. COD in the anoxic reaction procedure inoculated with common activated sludge is reduced to 1600-1800 mg/L, and N-methylpyrrolidone is reduced to 1050-1250 mg/L. COD in the aerobic reaction procedure inoculated with common activated sludge is reduced to about 850-900 mg/L, and N-methylpyrrolidone is reduced to 540-610 mg/L. COD in the membrane bioreactor is further reduced to 520-550 mg/L, and N-methylpyrrolidone is reduced to 340-370 mg/L, The wastewater cannot be discharged up to standard.

TABLE-US-00002 TABLE 2 Water quality index of effluent from various procedures of the combined process Treatment COD.sub.cr NMP NH.sub.3—N TN TP SS unit Indicator (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Anaerobic Influent 3200-3500 2100-2400  4-10 300-400 0.4-0.5 40-50  tank Effluent 2100-2300 1400-1550 250-280 300-350 0.3-0.4 95-110 Anoxic Influent 2100-2300 1400-1550 250-280 300-350 0.3-0.4 95-110 tank Effluent 1600-1800 1050-1250 300-320 350-380 0.3-0.4 95-110 Aerobic Influent 1600-1800 1050-1250 300-320 350-380 0.3-0.4 95-110 tank Effluent 850-900 540-610 100-110 120-140 0.2-0.3 50-60  Membrane Influent 850-900 540-610 100-110 120-140 0.2-0.3 50-60  bio-reactor Effluent 520-550 340-370 55-70 70-80 0.2-0.3 30-40