Chemical sewage treatment process

Abstract

The invention relates to the technical field of wastewater treatment, and discloses a chemical wastewater treatment process which comprises the following steps: S1, pretreatment: removing large impurities and suspended solids in wastewater by adopting a mechanical grid, and adjusting the pH value of the wastewater; s2, adding a coagulant to coagulate and precipitate the chemical sewage; s3, biological treatment: decomposing organic matters in the sewage by using a bioreactor; s4, oxidation treatment: removing refractory organic matters by using an ozone reactor; s5, sedimentation: removing residual suspended matters by using a sedimentation tank; and S6, disinfection treatment: through multi-stage treatment steps such as pretreatment, coagulating sedimentation, biological treatment and oxidation treatment, suspended solids, organic matters and refractory pollutants in the sewage are effectively removed, it is ensured that the effluent quality meets the environmental protection standard, and in the biological treatment stage, the optimal growth environment is provided for microorganisms by regulating and controlling dissolved oxygen, temperature and pH value, so that the quality of the microorganisms is improved. The removal efficiency of the organic matters is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a chemical wastewater treatment process. Background Art

[0002] Pure water changes its original physical or chemical properties after use, and becomes wastewater containing different types of impurities. Chemical wastewater is wastewater discharged in chemical production, such as process wastewater, cooling water, exhaust gas washing water, equipment and site flushing water, etc. If these wastewaters are discharged without treatment, they will cause different properties and different degrees of pollution in the water body, thereby endangering human health and affecting industrial and agricultural production.

[0003] Chemical wastewater refers to wastewater produced in the process of producing products in chemical plants, such as oily wastewater from the production of ethylene, polyethylene, rubber, polyester, methanol, ethylene glycol, oil tank area, air separation and air compressor station, etc. After biochemical treatment, it can generally meet the national secondary emission standards. Due to the shortage of water resources, the water that meets the emission standards needs to be further deeply treated to meet the recycling requirements of industrial water replenishment. Since the impurities in the water are mainly suspended particles and fine fibers, the impurities are removed by mechanical filtration principle and microporous filtration technology. The working condition of the filter equipment is controlled by PLC or time relay to realize automatic backwashing and automatic operation, and the lifting pump provides the required water head for the filter, and the outlet water is directly introduced into the production system.

[0004] Wastewater generated during chemical production usually contains a large amount of suspended solids, organic matter and difficult-to-degrade pollutants. If it is discharged directly without proper treatment, it will have a serious impact on the environment and ecosystem. Traditional chemical wastewater treatment processes often have problems such as low treatment efficiency, substandard effluent quality and possible secondary pollution to the environment. Therefore, a chemical wastewater treatment process is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a chemical wastewater treatment process to solve the problem that the wastewater generated in the chemical production process mentioned in the above background technology usually contains a large amount of suspended solids, organic matter and difficult-to-degrade pollutants. If it is directly discharged without proper treatment, it will have a serious impact on the environment and ecosystem. Traditional chemical wastewater treatment processes often have problems such as low treatment efficiency, substandard effluent water quality, and possible secondary pollution to the environment.

[0006] To achieve the above object, the present invention provides the following technical solution: a chemical wastewater treatment process, comprising the following steps:

[0007] S1, pretreatment, using mechanical screens to remove large impurities and suspended solids in the wastewater and adjust the pH value of the wastewater;

[0008] S2, adding coagulant to make chemical wastewater coagulate and precipitate;

[0009] S3, biological treatment, using bioreactors to decompose organic matter in sewage;

[0010] S4, oxidation treatment, using an ozone reactor to remove refractory organic matter;

[0011] S5, sedimentation, using a sedimentation tank to remove the remaining suspended matter;

[0012] S6. Disinfection.

[0013] Preferably, in the above: in S1, an acid-base regulator is added to the sewage to make the pH of the sewage be 6.5-7.5.

[0014] Preferably, in the above: in S2, the coagulant is polyaluminium chloride, and the mixing volume ratio of the coagulant to the sewage is 0.8-1.2:19-21 / L.

[0015] Preferably, in the above: in S3, the bioreactor selects an activated sludge process or a biofilm process.

[0016] Preferably, the above-mentioned: the dissolved oxygen concentration in the bioreactor is 2-4 mg / L, the reaction temperature is 20-30° C., and the reaction time is 20-28 hours.

[0017] Preferably, in the above: in S4, the ozone dosage of the ozone reactor is 1.5-2 mg / L, and the treatment time is 25-35 minutes.

[0018] Preferably, in the above step: in S5, the precipitation time is 1-3 hours.

[0019] Preferably, in the above-mentioned step S6, the disinfection treatment is carried out by ultraviolet light or chlorine gas disinfection.

[0020] Preferably, the above-mentioned ultraviolet disinfection dose is 28-32 mJ / cm 2 The contact time between the ultraviolet rays and the sewage is 15-25 seconds.

[0021] Preferably, in the above-mentioned chlorine disinfection, the amount of chlorine added is 1.3-1.7 mg / L, and the contact time between chlorine and sewage is 40-50 minutes.

[0022] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0023] 1. Through multi-stage treatment steps, such as pretreatment, coagulation and sedimentation, biological treatment and oxidation treatment, the suspended solids, organic matter and difficult-to-degrade pollutants in the sewage can be effectively removed to ensure that the effluent quality meets environmental protection standards. In the biological treatment stage, by regulating dissolved oxygen, temperature and pH value, the best growth environment is provided for microorganisms to improve the removal efficiency of organic matter.

[0024] 2. Use high-efficiency, low-toxic coagulants to reduce the impact on the environment. At the same time, take measures in the oxidation treatment and disinfection steps to avoid the leakage of harmful gases and the generation of residues. According to the water quality and cost requirements of the effluent, you can flexibly choose ultraviolet disinfection, chlorine disinfection or combined disinfection to ensure the safety of effluent and meet different usage requirements. This process design focuses on environmental friendliness and can protect water resources and the ecological environment while meeting industrial needs, which is in line with the concept of sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0029] Embodiment 1

[0030] See also Figure 1 The present invention provides a technical solution: a chemical wastewater treatment process, comprising the following steps:

[0031] S1. Pretreatment: Use mechanical screens to remove large impurities and suspended solids from wastewater and adjust the pH value of wastewater. Impurities may include but are not limited to plastic bags, branches, sand and stones. If they are not removed in time, they will cause blockage or wear to subsequent treatment equipment, affecting the overall treatment efficiency.

[0032] A rotary screen decontamination machine can be used, which can not only effectively remove large impurities and suspended solids, but also automatically adjust the working frequency according to the sewage flow rate to reduce energy consumption. Acid-base regulators are added to the sewage to make the pH of the sewage 7. After adjusting the pH value, a pre-aeration step is added to increase the dissolved oxygen content in the sewage through microbubbles, initially promote microbial activity, and prepare for subsequent biological treatment. Regularly clean the debris on the screen, check and replace worn parts to ensure the screen decontamination efficiency;

[0033] The rotary screen cleaner can not only cut and intercept large impurities in the wastewater with its sharp bars, but also automatically adjust its operating frequency according to the actual flow of sewage. When the wastewater flow is large, the screen cleaner will speed up its operation to ensure that all impurities can be removed in time; when the flow is small, it will reduce the operating speed, thereby saving energy and reducing equipment wear.

[0034] According to the properties of the sewage, select suitable acid-base regulators, such as sodium hydroxide, sulfuric acid, etc., to ensure that the adjusted sewage pH value is stable within the range of 7±0.2. You can install an online pH monitor to monitor the sewage pH value in real time. After adjusting the pH value, adding a pre-aeration step can further improve the efficiency of wastewater treatment. Pre-aeration is achieved by injecting microbubbles into the wastewater, which can increase the dissolved oxygen content in the wastewater and initially promote the activity of microorganisms.

[0035] S2, adding coagulant to make chemical wastewater coagulate and precipitate;

[0036] The coagulant is polyaluminium chloride, and the mixing volume ratio of coagulant to sewage is 1:20 / L;

[0037] High-efficiency, low-toxic polyaluminium chloride is used as a coagulant to ensure the coagulation effect while reducing environmental pollution. A metering pump or automatic dosing device can be used to accurately control the amount of coagulant added according to the sewage flow and coagulant concentration.

[0038] After the coagulant is added, the two stages of rapid stirring and slow stirring are used to promote full contact and reaction between the coagulant and the colloidal particles in the sewage. An inclined plate sedimentation tank or a horizontal flow sedimentation tank can be used to improve sedimentation efficiency and reduce sedimentation time.

[0039] The coagulation and sedimentation process effectively converts the tiny suspended solids, colloidal substances and some soluble organic matter in the sewage into larger floccules, which is convenient for subsequent physical separation. Due to its unique molecular structure and charge characteristics, polyaluminium chloride can quickly neutralize and adsorb and bridge the colloidal particles in the sewage to form stable and easy-to-precipitate floccules. In this process, the mixed volume ratio of coagulant and sewage is precisely set to 1:20 / L. This ratio not only ensures the maximization of the coagulation effect, but also avoids the excessive use of coagulants, thereby achieving the dual optimization of cost-effectiveness and environmental benefits.

[0040] Inclined plate sedimentation tank or horizontal flow sedimentation tank. The sedimentation tank can significantly increase the sedimentation rate of flocs and reduce the sedimentation time by optimizing the water flow path and increasing the sedimentation area. At the same time, the sedimentation tank also takes into account the collection and discharge of sludge to ensure that the sedimentation process will not cause secondary pollution to the environment.

[0041] S3, biological treatment, using bioreactors to decompose organic matter in sewage;

[0042] The bioreactor selects the activated sludge method or the biofilm method. Combining the activated sludge method with the membrane separation technology can not only efficiently remove organic matter, but also achieve solid-liquid separation, reducing the load of the subsequent sedimentation tank. The bioreactor converts organic matter into harmless or low-toxic substances based on the metabolic activities of microorganisms, while purifying sewage. Combining the activated sludge method with the membrane separation technology can not only efficiently remove organic matter, but also achieve solid-liquid separation, effectively reducing the load of the subsequent sedimentation tank and improving the overall treatment efficiency.

[0043] The dissolved oxygen concentration in the bioreactor is 3 mg / L, the reaction temperature is 25°C, and the reaction time is 24 hours. An online dissolved oxygen monitor and aeration control system can be installed to accurately control the dissolved oxygen concentration in the bioreactor to ensure the normal growth and metabolism of microorganisms. A temperature sensor and a pH monitor can be installed to monitor and regulate the temperature and pH value in the bioreactor in real time to provide a suitable growth environment for microorganisms. The reaction temperature is 25°C, which is a suitable temperature range for microbial growth and reproduction. By installing a temperature sensor, the temperature in the reactor can be monitored in real time and adjusted as needed to maintain the best growth environment for microorganisms.

[0044] S4, oxidation treatment, using an ozone reactor to remove refractory organic matter;

[0045] The ozone reactor is dosed at 1.7 mg / L and the treatment time is 30 minutes. It adopts a segmented dosing method. The initial high concentration quickly removes most of the difficult-to-degrade organic matter, and the later low concentration maintains an oxidizing environment to ensure the treatment effect. The tail gas produced after the ozone reaction is collected and treated to avoid harm to the environment and human body caused by ozone leakage. Oxidation treatment further removes organic matter in the sewage that is difficult to degrade by biological treatment.

[0046] As the core equipment of this process, the ozone reactor produces high-concentration ozone gas and uses its strong oxidizing property to oxidize and decompose organic matter in sewage. The dosage of ozone is 1.7 mg / L. This concentration can not only ensure efficient organic matter removal rate, but also avoid cost waste and possible by-product generation caused by excessive dosage. The treatment time is set to 30 minutes, based on the rate and efficiency of the reaction between ozone and organic matter, as well as actual engineering application considerations. In order to maximize the utilization efficiency and treatment effect of ozone, a staged addition method is adopted. In the early stage of the reaction, most of the difficult-to-degrade organic matter in the sewage is quickly removed with a higher ozone concentration, and the organic load is quickly reduced; then, the ozone concentration is reduced to maintain a relatively stable oxidation environment to ensure that the remaining organic matter is thoroughly oxidized, while avoiding the negative impact of excessive oxidation on water quality.

[0047] The ozone reaction process produces tail gas, which may contain incompletely reacted ozone and other potentially harmful substances. In order to prevent ozone leakage from causing harm to the environment and human body, it is treated by catalytic decomposition, absorption or other appropriate methods to ensure that tail gas emissions meet environmental protection requirements and protect the surrounding environment and the health of workers.

[0048] S5, sedimentation, using a sedimentation tank to remove the remaining suspended matter;

[0049] The sedimentation time is 2 hours. After sedimentation, deep filtration units such as sand filtration and carbon filtration are added to further remove fine suspended matter and some soluble organic matter.

[0050] The settling time is carefully set to 2 hours, based on the sedimentation rate of suspended matter, the volume of the sedimentation tank and the actual operating experience. During this period of time, the suspended matter has enough time to settle in the sedimentation tank to achieve the ideal removal effect.

[0051] S6. Disinfection.

[0052] Disinfection is done by ultraviolet light or chlorine. Ultraviolet disinfection is widely used for its high efficiency, environmental protection and no chemical residue.

[0053] The UV disinfection dose is 30mJ / cm 2The contact time between ultraviolet rays and sewage is 20 seconds. The contact time between ultraviolet rays and sewage is precisely controlled at 20 seconds, ensuring that ultraviolet rays can fully act on the microorganisms in the sewage and achieve ideal disinfection effect.

[0054] The comparison of water quality index data before and after treatment by the process of the present invention is as follows:

[0055] Water quality indicators Concentration before treatment (mg / L) Concentration after treatment (mg / L) Removal rate (%) COD 2000 60 97 BOD5 1000 15 98.5 NH3-N 150 3 98 Total Phosphorus 50 0.5 99 Total amount of heavy metals 10 0.05 99.5 pH 4.5 7 -

[0056] Based on the above data, we can calculate:

[0057] The COD removal rate is over 95%; the BOD5 removal rate is over 95%; the NH3-N removal rate is over 95%; the total phosphorus removal rate is over 95%; and the total heavy metal removal rate is over 95%.

[0058] The removal rate calculation formula is:

[0059]

[0060] The above formula is used to calculate the removal efficiency of a certain water quality indicator;

[0061] Calculation of heavy metal removal:

[0062] Heavy metal removal amount = total amount of heavy metals before treatment - total amount of heavy metals after treatment

[0063] The above formula is used to calculate the reduction of heavy metal ions during the treatment process.

[0064] In summary, through multi-stage treatment steps, such as pretreatment, coagulation and sedimentation, biological treatment and oxidation treatment, suspended solids, organic matter and difficult-to-degrade pollutants in sewage can be effectively removed to ensure that the effluent quality meets environmental protection standards. In the biological treatment stage, by regulating dissolved oxygen, temperature and pH value, an optimal growth environment is provided for microorganisms to improve the removal efficiency of organic matter.

[0065] High-efficiency, low-toxic coagulants are used to reduce the impact on the environment. At the same time, measures are taken in the oxidation treatment and disinfection steps to avoid the leakage of harmful gases and the generation of residues. According to the effluent water quality and cost requirements, ultraviolet disinfection, chlorine disinfection or combined disinfection can be flexibly selected to ensure effluent safety and meet different usage requirements. This process design focuses on environmental friendliness and can protect water resources and the ecological environment while meeting industrial needs, in line with the concept of sustainable development.

[0066] Embodiment 2

[0067] This embodiment is different from the first embodiment in that:

[0068] The following steps are involved:

[0069] S1. Pretreatment: Use mechanical screens to remove large impurities and suspended solids in the wastewater and adjust the pH value of the wastewater; add acid-base regulators to the wastewater to make the pH value of the wastewater 6.9.

[0070] S2. Add a coagulant to coagulate and precipitate the chemical wastewater; the coagulant is polyaluminium chloride, and the mixed volume ratio of the coagulant to the wastewater is 1.1:21 / L.

[0071] S3, biological treatment, using a bioreactor to decompose organic matter in sewage; the bioreactor selects activated sludge method or biofilm method. The dissolved oxygen concentration in the bioreactor is 2.9 mg / L, the reaction temperature is 26°C, and the reaction time is 25 hours.

[0072] S4, oxidation treatment, using an ozone reactor to remove refractory organic matter;

[0073] The ozone dosage of the ozone reactor is 1.8 mg / L, and the treatment time is 29 minutes.

[0074] S5. Sedimentation: Use a sedimentation tank to remove the remaining suspended matter; the sedimentation time is 1.8 hours.

[0075] S6. Disinfection.

[0076] In chlorine disinfection, the amount of chlorine added is 1.5 mg / L, and the contact time between chlorine and sewage is 45 minutes. According to the effluent water quality requirements and operating costs, ultraviolet disinfection, chlorine disinfection or chlorine dioxide disinfection can be flexibly selected. For high-demand occasions, ultraviolet + chlorine combined disinfection can be considered to ensure effluent safety.

[0077] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways, even if such combinations and / or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All of these combinations and / or combinations fall within the scope of the present invention.

Claims

1. A chemical wastewater treatment process, characterized in that: The following steps are involved: S1, pretreatment, using mechanical screens to remove large impurities and suspended solids in the wastewater and adjust the pH value of the wastewater; S2, adding coagulant to make chemical wastewater coagulate and precipitate; S3, biological treatment, using bioreactors to decompose organic matter in sewage; S4, oxidation treatment, using an ozone reactor to remove refractory organic matter; S5, sedimentation, using a sedimentation tank to remove the remaining suspended matter; S6. Disinfection.

2. A chemical wastewater treatment process according to claim 1, characterized in that: In S1, an acid-base regulator is added to the sewage to make the pH value of the sewage be 6.5-7.

5.

3. A chemical wastewater treatment process according to claim 1, characterized in that: In S2, the coagulant is polyaluminium chloride, and the mixing volume ratio of the coagulant to the sewage is 0.8-1.2:19-21 / L.

4. A chemical wastewater treatment process according to claim 1, characterized in that: In S3, the bioreactor selects an activated sludge process or a biofilm process.

5. A chemical wastewater treatment process according to claim 4, characterized in that: The dissolved oxygen concentration in the bioreactor is 2-4 mg / L, the reaction temperature is 20-30° C., and the reaction time is 20-28 hours.

6. A chemical wastewater treatment process according to claim 1, characterized in that: In S4, the ozone dosage of the ozone reactor is 1.5-2 mg / L, and the treatment time is 25-35 minutes.

7. A chemical wastewater treatment process according to claim 1, characterized in that: In S5, the precipitation time is 1-3 hours.

8. A chemical wastewater treatment process according to claim 1, characterized in that: In S6, the disinfection treatment is disinfection by ultraviolet rays or chlorine gas.

9. A chemical wastewater treatment process according to claim 8, characterized in that: The ultraviolet disinfection dose is 28-32mJ / cm 2 The contact time between the ultraviolet rays and the sewage is 15-25 seconds.

10. A chemical wastewater treatment process according to claim 8, characterized in that: In the chlorine disinfection, the amount of chlorine added is 1.3-1.7 mg / L, and the contact time between the chlorine and the sewage is 40-50 minutes.

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