Bamboo product processing wastewater treatment system and treatment method

Abstract

The present invention relates to the field of wastewater treatment technology. To address the existing challenges of bamboo product processing wastewater treatment, including the difficulty and poor treatment results, a bamboo product processing wastewater treatment system is disclosed. The system comprises a water collection tank, an iron-carbon micro-electrolysis device, an oxidation tank, a regulating tank, a multi-electrolysis device, a biochemical treatment device, and a sludge treatment system. The multi-electrolysis device comprises a first-stage multi-electrolysis device, a first-stage reaction sedimentation tank, a second-stage multi-electrolysis device, and a second-stage reaction sedimentation tank, all connected in sequence. The biochemical treatment device comprises an anaerobic tank, a facultative oxic tank, and an aerobic tank, a membrane bioreactor located at the end of the aerobic tank, and an adsorption sedimentation tank. The system is efficient and stable. The present invention also provides a method for treating bamboo product processing wastewater using the wastewater treatment system. The wastewater treated by the method meets discharge standards.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a bamboo product processing wastewater treatment system and method. Background Art

[0002] To meet consumer demand, the bamboo products industry is experiencing increasing production volume and product variety. Consequently, the volume and complexity of wastewater generated during bamboo product processing are also increasing. Failure to treat this wastewater from bamboo product processing can place a significant burden on the aquatic environment. Wastewater generated by bamboo product processing primarily comes from the H2O2 cooking and carbonization processes. The wastewater produced by H2O2 cooking has a pH of 3-3.5 and a COD of approximately 30,000 mg / L. Carbonized wastewater from carbonization has a COD slightly lower than that of cooking wastewater, but still exceeding 20,000 mg / L. Overall, wastewater from bamboo product processing contains significant amounts of organic matter, including bamboo tar, polysaccharides, amino acid terpenes, phenolic acids, bamboo fiber, and bamboo acid liquid. This high COD, turbidity, and odor make it challenging to treat.

[0003] For example, the "System and Method for Treating Bamboo Carbonization Wastewater," published in Chinese patent literature with publication number CN105693030A, includes a sequentially connected physicochemical treatment system, a biochemical treatment system, and a deep treatment system. The physicochemical treatment system includes a steam exhaust tank, a regulating tank, a coagulation and sedimentation tank, and a Fenton oxidation tank. The boiler is connected to the steam exhaust tank, and a first heat exchanger is provided between the steam exhaust tank and the boiler water for cooling the tank and heating the boiler inlet water. The biochemical treatment system includes an anaerobic reactor and an aerobic biochemical tank, each connected to the other. A second heat exchanger is provided between the regulating tank and the anaerobic reactor. The deep treatment system includes a secondary sedimentation tank and an activated carbon adsorption tank, each connected to the other. This treatment system treats bamboo carbonization wastewater. However, H2O2 cooking wastewater has a higher COD value and a lower pH than bamboo carbonization wastewater. Therefore, the system is not very effective in treating H2O2 cooking wastewater or carbonization wastewater mixed with H2O2 cooking wastewater. Summary of the Invention

[0004] To overcome the difficulties and poor treatment results of bamboo processing wastewater in existing technologies, the present invention provides a bamboo processing wastewater treatment system. This system effectively degrades organic matter in the wastewater and decolorizes, denitrifies, and desulfurizes it. The treated wastewater meets discharge standards. The present invention also provides a method for treating bamboo processing wastewater, which requires a low dosage of chemicals and provides excellent treatment results.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A bamboo product processing wastewater treatment system, comprising

[0007] Collection tank for collecting wastewater from bamboo product processing;

[0008] Iron-carbon micro-electrolysis device, used to perform micro-electrolysis reaction on wastewater in the collection tank;

[0009] Oxidation tank, used to further oxidize the wastewater after micro-electrolysis;

[0010] Regulating tank, used to adjust the pH of wastewater after oxidation;

[0011] A multi-electrolysis device, used for electrolyzing the wastewater after pH adjustment, comprising a primary multi-electrolysis device, a primary reaction sedimentation tank, a secondary multi-electrolysis device and a secondary reaction sedimentation tank connected in sequence;

[0012] A biochemical treatment device for biochemically treating the wastewater after electrolysis, comprising an anaerobic tank, a facultative aerobic tank and an aerobic tank connected in sequence, a membrane bioreactor located at the end of the aerobic tank, and an adsorption sedimentation tank;

[0013] The sludge treatment system is used to receive the sludge generated in the treatment system and dewater it.

[0014] Bamboo product processing wastewater contains a large amount of bamboo tar, polysaccharides, amino acid terpenes, phenolic acid, bamboo fiber and bamboo acid liquid. Among them, bamboo tar can inhibit microbial reproduction, while the biochemical degradation efficiency of high-molecular organic matter such as polysaccharides and bamboo fiber is low. In the present invention, a micro-electrolysis device, an oxidation tank and a multi-electrolysis device are used to pre-treat and detoxify bamboo product processing wastewater. By pre-treating the bamboo product processing wastewater, biochemical toxic substances and difficult-to-degrade pollutants in the wastewater are removed to the greatest extent to ensure the subsequent biochemical water quality performance, and then the pre-treated wastewater is subjected to biochemical treatment. The iron-carbon micro-electrolysis + oxidation + multi-electrolysis process in the pretreatment stage can open the rings of biochemical toxic substances and difficult-to-degrade pollutants, open the long chains of bamboo fiber and lignin, improve the biodegradability of wastewater, improve the B / C ratio, further regulate water quality, improve the biodegradability of wastewater and microbial activity, enhance biochemical efficiency, control COD concentration, reduce the load of the biochemical system and meet the requirements of pipelining. After pretreatment, wastewater undergoes biochemical degradation in anaerobic, facultative, and aerobic tanks, followed by sludge-water separation in a membrane bioreactor. This further efficiently degrades pollutants while effectively intercepting microbial agents to prevent sludge loss. The effluent from the membrane bioreactor is precipitated by adsorbents and flocculants, and the supernatant, which meets standards, is discharged to surrounding water bodies. The physicochemical and biochemical sludge produced by the system enters the sludge treatment system for dehydration. The supernatant is then returned to the collection tank for further treatment, and the sludge cake is transported for disposal.

[0015] Preferably, the oxidation tank is provided with a hydrogen peroxide dosing device and an ozone generator.

[0016] After iron-carbon micro-electrolysis, the wastewater contains ferrous ions. Adding hydrogen peroxide can cause the wastewater to undergo a Fenton reaction, further decomposing organic matter. In addition, introducing ozone into the wastewater can improve the oxidation effect of hydrogen peroxide, reduce the amount of hydrogen peroxide added, and the enhanced oxidation effect can fully convert ferrous hydroxide into ferric hydroxide, avoiding the color reversal caused by ferrous ions in the subsequent treatment process.

[0017] Preferably, the activated sludge of the biochemical treatment device includes nitrite bacteria, nitrate bacteria, cellulose-degrading bacteria and lignin-degrading bacteria.

[0018] Bamboo product processing wastewater contains a large amount of cellulose, and cellulose-degrading bacteria and lignin-degrading bacteria can degrade cellulose into small molecular sugars that are easily decomposed.

[0019] Preferably, the biochemical treatment device is provided with a biological enzyme dosing device, and the biological enzymes include cellulase and hemicellulase.

[0020] Enzymes are protein molecules with catalytic functions that can catalyze specific compounds and biochemical reactions, reducing the activation energy of the reaction. Through their catalytic action, enzymes can enhance the degradation efficiency of the activated sludge microbiome, accelerate the biochemical degradation of degradable pollutants, increase reaction rates, and broaden the spectrum of biochemical reactions. This allows previously difficult-to-biodegrade organic matter to be degraded to varying degrees due to the enhanced effect of enzyme addition, significantly improving the treatment efficiency and load of the biochemical process, significantly reducing effluent COD and color, and enhancing biodegradability. Furthermore, low enzyme dosages can optimize the sludge microbial structure, enhancing the biochemical activity of the activated sludge while further improving its growth environment. This allows the biochemical treatment unit to operate stably under low B / C ratio conditions, maintaining stable effluent quality. During stable operation, only the enzyme consumption generated by the discharge water needs to be replenished, reducing the dosage of corresponding physicochemical agents and sludge production, further reducing treatment costs.

[0021] Preferably, a neutralization tank is provided between the oxidation tank and the regulating tank, and the neutralization tank is connected to the lime dosing device.

[0022] After iron-carbon micro-electrolysis and oxidation, the wastewater contains a large amount of flocculent suspended matter. Mixing the wastewater with lime can fully separate the flocculent suspended matter in the form of precipitation.

[0023] Preferably, the adsorption sedimentation tank is connected to an adsorbent dosing device and a flocculant dosing device.

[0024] Preferably, the primary reaction sedimentation tank and the secondary reaction sedimentation tank are respectively connected to a lime dosing device.

[0025] Lime is alkaline and can neutralize acidic wastewater, and it is low in cost.

[0026] Preferably, the sludge treatment system is also connected to the water collection tank through a pipeline.

[0027] The liquid removed from the sludge in the sludge treatment system can enter the collection tank through a pipe and thus enter the treatment cycle.

[0028] A method for treating bamboo product processing wastewater using a wastewater treatment system, comprising the following steps:

[0029] (1) The collected bamboo product processing wastewater is subjected to micro-electrolysis reaction, and then an oxidant is added for mixed oxidation, and after removing the precipitate, acid is added to adjust the pH of the wastewater to 3-4;

[0030] (2) The wastewater after pH adjustment is subjected to primary electrolysis treatment, a neutralizer is added to the wastewater after electrolysis to a pH of 7-9, the precipitate is removed, and then a secondary electrolysis treatment is performed, and a neutralizer is added to the wastewater to a pH of 7-8 and a secondary precipitation is performed;

[0031] (3) The wastewater after the precipitation is removed is subjected to anaerobic-facultative-aerobic biochemical treatment. After filtering through a membrane bioreactor, the wastewater is mixed with an adsorbent and a flocculant, and the resulting supernatant can be discharged.

[0032] H2O2 cooking wastewater is acidic, with a pH of 3-4, while carbonization wastewater is weakly acidic, with a pH of 5-7. Therefore, the combined bamboo product processing wastewater is generally acidic. Direct micro-electrolysis offers excellent decomposition results and minimizes the need for chemical addition. The wastewater after micro-electrolysis is then treated with hydrogen peroxide and ozone to catalytically generate hydroxyl radicals, opening polymer chains and rings. It then undergoes two-stage multi-electrolysis treatment to create optimal biochemical water quality. The wastewater is acidic upon entering the primary electrolysis process. The iron in the electrolysis unit has a strong reducing capacity in an acidic environment. After being oxidized to ferrous ions, it reacts with hydroxides produced by water electrolysis to form hydroxides. The hydroxides flocculate and adsorb impurity particles, forming flocs that adsorb and separate organic matter and suspended matter from the wastewater. After the primary electrolysis process and neutralization to remove precipitates, the wastewater becomes alkaline. The secondary electrolysis process, under alkaline conditions, dissociates or ionizes non-electrolytes such as humic acid and bamboo acid polycarboxylic acid compounds in the wastewater, thereby reducing COD and ammonia nitrogen. A regulating tank is installed between oxidation and multi-electrolysis to control the pH of wastewater entering the multi-stage electrolysis device, thereby improving the electrolysis effect. After electrolysis, the supernatant undergoes biochemical treatment. Under the combined action of microorganisms and enzymes, cellulose and other organic molecules in the wastewater are broken down, reducing COD and ammonia nitrogen levels. Under the action of adsorbents and flocculants, suspended solids in the wastewater are precipitated, and the supernatant meets discharge standards.

[0033] Preferably, the step (1) further comprises subjecting the bamboo product processing wastewater to a micro-electrolysis reaction, then mixing it with an oxidant for oxidation, adding lime, removing the precipitate, and then adding acid to adjust the wastewater pH to 3-4.

[0034] Preferably, in step (3), the adsorbent is one or more of activated carbon, diatomaceous earth, zeolite, resin adsorbent and humic acid adsorbent, and the flocculant is polyacrylamide.

[0035] Therefore, the present invention has the following beneficial effects: the bamboo product processing wastewater treatment method preliminarily decomposes organic matter that is difficult to biodegrade through pretreatment detoxification technology, and reduces the concentration of biotoxic substances in the wastewater, so as to improve the effect of subsequent biochemical treatment; the present invention also combines microbial treatment technology with bio-enzyme biochemical enhancement technology to improve the degradation effect of organic matter in bamboo product processing wastewater by biochemical treatment, and has a strong effect on reducing COD. The method has a good decomposition effect on bamboo leaf flavonoids, polysaccharides, amino acid terpenes, phenolic acids and bamboo fibers contained in the bamboo product wastewater, thereby realizing a high-efficiency and stable wastewater treatment system, and the treated wastewater meets the standards and can be discharged. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Flowchart of the processing method of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the accompanying drawings and specific implementation methods.

[0038] Example 1

[0039] A bamboo product processing wastewater treatment system comprises a water collection tank, an iron-carbon tower, an oxidation tank, a neutralization tank, a pH adjustment tank, a primary multi-electrolysis device, a primary reaction sedimentation tank, a secondary multi-electrolysis device, a secondary reaction sedimentation tank, an intermediate water tank, a UASB reactor, an anaerobic tank, an aerobic tank, and an adsorption sedimentation tank, wherein the iron-carbon tower contains coke filler and iron-carbon filler in a mass ratio of 2:5, the oxidation tank is provided with a hydrogen peroxide dosing device and an ozone generator, the neutralization tank, the primary reaction sedimentation tank, and the secondary reaction sedimentation tank are respectively connected to a lime dosing device, the adsorption sedimentation tank is connected to an adsorbent dosing device and a flocculant dosing device, a membrane bioreactor is provided between the end of the aerobic tank and the adsorption sedimentation tank, and a U The bacteria species in the ASB reactor, facultative aerobic tank, aerobic tank and membrane bioreactor are nitrite bacteria, nitrate bacteria, cellulose-degrading bacteria and lignin-degrading bacteria. The UASB reactor is connected to the cellulase and hemicellulase dosing device. A sludge pipe is connected between the bottom of the UASB reactor, facultative aerobic tank and aerobic tank. A flotation tank is provided between the UASB reactor and the facultative aerobic tank, and a flotation equipment is provided in the flotation tank. The system also includes a sludge thickening tank connected to the oxidation tank, neutralization tank, primary reaction sedimentation tank, secondary reaction sedimentation tank, UASB reactor, facultative aerobic tank, aerobic tank and adsorption sedimentation tank. The sludge thickening tank is connected to the filter press. The sludge thickening tank and the filter press are also respectively provided with pipes connected to the water collection tank.

[0040] The above wastewater treatment system is used to treat bamboo product processing wastewater. The process is as follows: Figure 1 As shown, the following steps are included:

[0041] (1) The bamboo product processing wastewater in the water collection tank is transported to the iron-carbon tower by a pump for micro-electrolysis reaction for 2 hours. The wastewater then flows into the oxidation tank and is mixed with hydrogen peroxide and ozone for oxidation for 2 hours. The wastewater then flows into the neutralization tank and is mixed with lime to a pH of 8. The supernatant flows into the pH adjustment tank, and sulfuric acid is added to the wastewater to a pH of 4.

[0042] (2) The wastewater after pH adjustment flows into the primary multi-electrolysis device for electrolysis for 1 hour, the wastewater flows into the primary reaction sedimentation tank and lime is added to the pH to 8, the supernatant enters the secondary multi-electrolysis device for reaction for 1 hour, and then flows into the secondary reaction sedimentation tank and is mixed with lime to a pH of 7;

[0043] (3) The supernatant is pumped to the intermediate water tank, and then flows from the intermediate water into the UASB reactor, the flotation tank, the facultative aerobic tank, the aerobic tank and the membrane bioreactor in sequence. The residence time in the UASB reactor is 40 hours, the residence time in the facultative aerobic tank is 20 hours, and the residence time in the aerobic tank is 60 hours. The dosage of cellulase and hemicellulase is 0.15% and 0.1% of the mass of the wastewater in the UASB reactor, respectively. After filtering through the membrane bioreactor, the wastewater is mixed with 0.1% of its mass of activated carbon and 0.02% of polyacrylamide in the adsorption sedimentation tank, and the obtained supernatant can be discharged;

[0044] (4) The precipitates in the oxidation tank, neutralization tank, primary reaction sedimentation tank, secondary reaction sedimentation tank, UASB reactor, facultative aerobic tank, aerobic tank and adsorption sedimentation tank are pumped to the sludge thickening tank. The supernatant of the sludge thickening tank is returned to the water collection tank. The sludge enters the filter press for filtration. The obtained mud cake is transported for disposal and the filtrate is returned to the water collection tank.

[0045] The water quality of the wastewater in the water collection tank of Example 1 and the water quality of the effluent obtained by treatment are shown in the following table:

[0046] Types of wastewater COD (mg / L) SS (mg / L) Chroma (times) Total nitrogen (mg / L) Ammonia nitrogen (mg / L) Total phosphorus (mg / L) Water quality of the collection pool 25030 890 200 261 168 38 Outlet water quality 87 52 30 / 9 0.2

[0047] The quality of the wastewater treated by the treatment system and treatment method of the invention meets the discharge standard.

[0048] Comparative Example 1

[0049] The difference from Example 1 is that the dosage of cellulase and hemicellulase in step (3) of the treatment process is both 0.

[0050] The water quality of the wastewater in the water collection tank of Comparative Example 1 and the water quality of the treated effluent are shown in the following table:

[0051] Types of wastewater COD (mg / L) SS (mg / L) Chroma (times) Total nitrogen (mg / L) Ammonia nitrogen (mg / L) Total phosphorus (mg / L) Water quality of the collection pool 25030 890 200 261 168 38 Outlet water quality 132 64 30 / 14 0.3

[0052] It can be seen from the above table that when biological enzymes are used to assist microorganisms in the biochemical treatment system, the treatment effect is better.

Claims

1. A bamboo product processing wastewater treatment system, characterized in that: include Collection tank for collecting wastewater from bamboo product processing; Iron-carbon micro-electrolysis device, used to perform micro-electrolysis reaction on wastewater in the collection tank; Oxidation tank, used to further oxidize the wastewater after micro-electrolysis; pH adjustment tank, used to adjust the pH of wastewater after oxidation; A multi-electrolysis device, used for electrolyzing the wastewater after pH adjustment, comprising a primary multi-electrolysis device, a primary reaction sedimentation tank, a secondary multi-electrolysis device and a secondary reaction sedimentation tank connected in sequence; The biochemical treatment device is used to biochemically treat the wastewater after electrolysis, including an anaerobic tank, a facultative aerobic tank and an aerobic tank connected in sequence, a membrane bioreactor located at the end of the aerobic tank, and an adsorption sedimentation tank; the anaerobic tank is connected to a cellulase and hemicellulase dosing device; an air flotation tank is provided between the anaerobic tank and the facultative aerobic tank; and a sludge pipe is provided at the bottom of the anaerobic tank, the facultative aerobic tank and the aerobic tank. The sludge treatment system is used to receive the sludge generated in the treatment system and dewater it.

2. A bamboo product processing wastewater treatment system according to claim 1, characterized in that: A hydrogen peroxide dosing device and an ozone generator are provided in the oxidation pool.

3. The bamboo product processing wastewater treatment system according to claim 1, characterized in that: The activated sludge of the biochemical treatment device includes nitrite bacteria, nitrate bacteria, cellulose degrading bacteria and lignin degrading bacteria.

4. A bamboo product processing wastewater treatment system according to claim 1 or 2, characterized in that: A neutralization tank is provided between the oxidation tank and the pH regulating tank, and the neutralization tank is connected to a lime dosing device.

5. The bamboo product processing wastewater treatment system according to claim 1, characterized in that: The primary reaction sedimentation tank and the secondary reaction sedimentation tank are respectively connected to the lime dosing device.

6. The bamboo product processing wastewater treatment system according to claim 1, characterized in that: The adsorption sedimentation tank is connected to the adsorbent dosing device and the flocculant dosing device.

7. A method for treating bamboo product processing wastewater using the wastewater treatment system according to claim 1, characterized in that: The steps include: (1) The collected bamboo product processing wastewater is subjected to micro-electrolysis reaction, and then an oxidant is added for mixed oxidation. After removing the precipitate, acid is added to adjust the pH of the wastewater to 3-4; (2) The wastewater after pH adjustment is subjected to primary electrolysis treatment, a neutralizer is added to the wastewater after electrolysis to a pH of 7-9, the precipitate is removed, and then a secondary electrolysis treatment is performed, and a neutralizer is added to the wastewater to a pH of 7-8 and a secondary precipitation is performed; (3) The wastewater after the sediment is removed flows into the UASB reactor, flotation tank, facultative aerobic tank and aerobic tank in sequence for anaerobic-facultative aerobic-aerobic biochemical treatment. Cellulase and hemicellulase are added to the UASB reactor. After filtering through the membrane bioreactor, the wastewater is mixed with adsorbent and flocculant, and the obtained supernatant can be discharged.

8. The method for treating bamboo product processing wastewater according to claim 7, wherein: The step (1) further comprises subjecting the bamboo product processing wastewater to a micro-electrolysis reaction, then mixing it with an oxidant for oxidation, adding lime, removing the precipitate, and then adding acid to adjust the pH of the wastewater to 3-4.

9. The method for treating bamboo product processing wastewater according to claim 7, wherein: In the step (3), the adsorbent is one or more of activated carbon, diatomaceous earth, zeolite, resin adsorbent and humic acid adsorbent.

10. The method for treating bamboo product processing wastewater according to claim 9, wherein: In the step (3), the flocculant is polyacrylamide.

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