High-efficiency sewage treatment process

Abstract

The present application relates to the field of sewage treatment, mainly for a kind of " four high wastewater" of high salinity, high COD, high suspended solids concentration, high nitrogen and phosphorus content, the treatment, the treatment process mainly includes the following steps: first, raw water is filtered through 19-74um filter bag filter for security filtration, the filtrate is treated by 100-500nm ceramic membrane separation system again, the water produced by ceramic membrane separation system is treated by traditional anaerobic process and aerobic process again, and the water produced by fenton micro-electrolysis treatment can be discharged up to standard.The treatment process combines membrane filtration technology with traditional biochemical technology process, reduces the biochemical treatment load, and compared with traditional biochemical treatment process, the treatment process is more efficient for high-concentration wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and can efficiently treat "four-high wastewater" characterized by high salinity, high COD, high suspended solids concentration, and high nitrogen and phosphorus content. Background Technology

[0002] Currently, my country mostly uses traditional biological treatment ponds for wastewater treatment, and most of these ponds are built underground. This traditional treatment process involves a large amount of engineering work and has very low efficiency in treating high-concentration wastewater. Furthermore, the unstable temperature due to seasonal changes makes it impossible to guarantee the stable operation of the entire system. When the influent concentration increases or the temperature is low in winter, the biological treatment pond system needs to reduce its treatment capacity to allow the entire system to recover.

[0003] Membrane treatment technology is a relatively new technology that emerged in recent years. When it first appeared, it faced challenges such as high cost, low throughput, and inability to operate stably for extended periods. However, after several years of development, membrane treatment is now widely used in many areas of the water treatment industry. Currently, membrane treatment technology is extensively used in wastewater reuse, and its operation and maintenance costs are continuously decreasing through process optimization. Ceramic membranes are porous filter materials made from alumina, silicon carbide, mullite, etc., sintered at high temperatures. The separation process involves the feed liquid flowing at high speed inside the membrane. Under pressure, the clarified permeate containing small molecular components permeates outwards in a direction perpendicular to the membrane, while the turbid concentrate containing large molecular components is retained by the membrane, thus achieving separation, concentration, and purification. Ceramic membranes can withstand various complex water qualities (strong acids, strong alkalis, high temperatures, etc.), making them widely applicable to wastewater treatment in many industries. Combining ceramic membrane filtration with traditional biological treatment tanks can reduce the pressure on downstream biological treatment processes, making the entire treatment process more efficient.

[0004] Because the microorganisms are sensitive to temperature, the operation of biochemical treatment is easily affected by temperature changes. This often leads to a decrease in the treatment capacity of the biochemical tank system in winter, while the sewage discharge only increases. Therefore, sewage treatment plants can only increase the treatment capacity by increasing the area of ​​the biochemical treatment tank, which greatly increases the construction and operation and maintenance costs of sewage treatment. This invention treats light sewage that has undergone biochemical treatment but has not met the discharge standards using Fenton micro-electrolysis technology, which greatly reduces the treatment time and the building area of ​​the sewage treatment system. The entire operation and maintenance work is also simplified. Summary of the Invention

[0005] To address the shortcomings of current wastewater treatment processes, this invention provides a highly efficient wastewater treatment process that combines membrane treatment technology, traditional biological treatment pond technology, and Fenton micro-electrolysis technology.

[0006] The application provides a high-efficiency sewage treatment process, and the process steps are as follows:

[0007] 1) The sewage to be treated is filtered through a filter bag filter, the pore size of the filter bag selected for the filter bag filter is 19-74um, and the filter bag filter is connected in parallel with 2-5 groups in order to improve the filtering efficiency. The filter bag filter mainly filters the particles in the sewage and serves as a security filtering device for the next step of the ceramic membrane system. The raw water parameters are as follows: salinity <4%, SS <10000mg / L, COD <20000mg / L, and ammonia nitrogen <400mg / L.

[0008] 2) The filtrate of step (1) is subjected to 100-500nm ceramic membrane filtration, and the ceramic membrane filtration system is equipped with a feed tank, a feed high-pressure pump, a water-cooled cooling pipe, a ceramic membrane, a pressure gauge, and a water storage tank. The main body material of the device is 304 stainless steel, the membrane inlet pressure should be set to 2-10bar during the operation of the equipment, the membrane outlet pressure should be set to 2-10bar, the membrane filtration system flux should be 5-60L / h.m2, and the operation temperature is <70oC. This step can retain and concentrate the macromolecular components in the sewage, and a large amount of small molecular components can pass through.

[0009] 3) The macromolecular substances that are difficult to be decomposed and metabolized by microorganisms are retained in step (2), and the large amount of permeate liquid that can pass through the membrane can be improved in biodegradability and directly enters the anaerobic treatment system. The anaerobic treatment system mainly comprises a water distributor, active flocculent anaerobic sludge, anaerobic low-speed vortex stirring, and two-stage three-phase separation devices. The COD of the sewage can be removed by 60%-80% after the sewage passes through the hydrolysis, acidification, and gas production stages, the anaerobic treatment system retention time is 12-18h, the anaerobic low-speed vortex stirring speed is 20-80r / min, the water salinity should be <4.0%, and the pH should be controlled within the range of 6-9.

[0010] 4) The water produced after the treatment in step (3) is punched into the anoxic-aerobic reaction system, the sewage is subjected to continuous nitrification and denitrification reaction through the anoxic-aerobic system in this stage, the COD and ammonia nitrogen can be reduced to close to the standard, the flow rate of the anoxic system backflow to the aerobic system is 3-6 times of the water inflow of the whole system. The HRT of the anoxic-aerobic system is 8-16h, the dissolved oxygen of the anoxic system is controlled to be 0.4-0.8mg / L, the dissolved oxygen of the aerobic system is 4-6mg / L, the salinity should be <4.0%, and the pH should be controlled within the range of 6-9.

[0011] 5) when the water produced in step (4) is treated by Fenton micro-electrolysis reaction, including acid adjustment, iron-carbon micro-electrolysis reaction (aeration is needed), Fenton reaction, neutral adjustment and natural precipitation, etc. The pH of the water is controlled in the range of 3-5 during the acid adjustment, the volume ratio of the iron-carbon filler to the wastewater to be treated is 1:1-5, the steam-water ratio during the iron-carbon micro-electrolysis reaction and the Fenton reaction is 3:1-1.5, the micro-electrolysis reaction time is 10-30 min, the Fenton reaction time is 10-30 min, and the hydrogen peroxide addition amount is 0.2-0.5 ‰. The final natural precipitation time is 1-3 h.

[0012] Preferably, the pore size of the filter bag of the filter bag type filter is 19-48 um.

[0013] Preferably, the membrane pore size of the ceramic membrane filtration system is 100-300 nm, the membrane inlet pressure is 3-6 bar, and the membrane outlet pressure is 2-4 bar.

[0014] Preferably, the HRT of the anaerobic system is 15-18 h, and the anaerobic low-speed vortex stirring speed is 40-80 r / min.

[0015] Preferably, the HRT of the anoxic-aerobic system is 10-16 h.

[0016] Preferably, the pH of the anaerobic system and the anoxic-aerobic system should be controlled in the range of 6-8.5, the dissolved oxygen of the anoxic system is controlled in the range of 0.4-0.6 mg / L, and the dissolved oxygen of the aerobic system is 5-6 mg / L.

[0017] Preferably, the pH of the Fenton micro-electrolysis is controlled in the range of 3-4 during the acid adjustment, the volume ratio of the iron-carbon filler to the wastewater to be treated is 1:1-3, the micro-electrolysis reaction time is 20-30 min, the Fenton reaction time is 20-30 min, the hydrogen peroxide addition amount is 0.3-0.5 ‰. The final natural precipitation time is 2-3 h.

[0018] Compared with the traditional sewage treatment process, the treatment efficiency of the high COD, high ammonia nitrogen, high salinity and high suspended solid wastewater is greatly improved. Due to the improvement of the treatment efficiency, the HRT is shortened, so the comprehensive treatment cost is basically the same as that of the traditional sewage treatment process. DETAILED DESCRIPTION

[0019] Example 1

[0020] Take 120 kg of animal tissue to raise amino acid sewage (salinity 3.1%), filter the sewage through a 25 um filter bag type filter to remove visible particles in the water, obtain 119.58 kg of water, which mainly reduces suspended solids. The water passing through the filter enters the ceramic membrane system, the membrane pore size is 300 nm, the membrane inlet pressure is adjusted to 4 bar, the membrane outlet pressure is 3 kg, and the liquid temperature is controlled to be less than 70℃. Finally, 115.21 kg of water is obtained, which can reduce COD and SS. The water filtered by the ceramic membrane is further introduced into the anaerobic reaction system, the reaction pH is controlled at 7.5-8, the low-speed vortex stirring speed is 50 r / min, and 40 kg of active flocculent anaerobic sludge is added. Reaction for 16 h. After the reaction is completed, about 100 kg of supernatant is obtained by siphoning. The obtained 100 kg of supernatant is introduced into the anoxic-aerobic system to control the reaction pH at 7.5-8, the dissolved oxygen in the anoxic system is controlled at 0.4-0.6 mg / L, and the dissolved oxygen in the aerobic system is 5-6 mg / L. The flow rate of the aerobic system backflow to the anoxic system is 3 times the flow rate of the entire system. The control retention time is 12 h. The obtained water is adjusted to pH 3, and an equal volume of iron-carbon is added. Start aeration at the bottom of the iron-carbon, after 20 min of reaction, take the upper clear liquid and add 0.3‰ hydrogen peroxide to continue aeration for 25 min. The entire aeration process ensures that the steam-water ratio is 3:1-1.5. After the reaction is completed, natural sedimentation for 2 h.

[0021] The main pollutant indicators of the water quality before and after treatment are shown in the following table:

[0022]

[0023]

[0024] Example 2

[0025] Take 120 kg of animal tissue protein extraction wastewater (salinity 4.5%), filter the wastewater through a 45 um filter bag filter to remove visible particles in the water, obtain 119.08 kg of water, this stage mainly reduces suspended solids. The water passing through the filter enters the ceramic membrane system, the membrane pore size is 100 nm, the membrane inlet pressure is adjusted to 5 bar, the membrane outlet pressure is 4 kg, and the liquid temperature is controlled to be less than 70℃. Finally, 110.39 kg of water is obtained, this stage can reduce COD and SS. The water filtered by the ceramic membrane enters the anaerobic reaction system, the reaction pH is controlled at 7.5-8, the low-speed vortex stirring speed is 60 r / min, and 40 kg of active flocculent anaerobic sludge is added for 16 h of reaction. After the reaction is completed, about 89 kg of supernatant is obtained by siphoning. The 89 kg of supernatant is introduced into the anoxic-aerobic system, the reaction pH is controlled at 7.5-8, the dissolved oxygen in the anoxic system is controlled at 0.4-0.6 mg / L, and the dissolved oxygen in the aerobic system is 5-6 mg / L. The flow rate of the aerobic system backflow to the anoxic system is 3 times the flow rate of the entire system. The control retention time is 15 h. The obtained water is adjusted to pH 3, and 2 times the volume of iron-carbon is added, and aeration is started at the bottom of the iron-carbon. After 30 min of reaction, the upper clear liquid is taken and 0.5‰ hydrogen peroxide is added for 30 min of continuous aeration. The entire aeration process guarantees a steam-water ratio of 3:1-1.5. After the reaction is completed, natural sedimentation is carried out for 3 h.

[0026] The main pollutant indicators of the water quality before and after treatment are shown in the following table:

[0027]

[0028] Example 3

[0029] Take 120 kg of landfill leachate, filter the sewage through a 25 um filter bag filter to remove visible particles in the water, obtain 113.29 kg of water, which mainly reduces suspended solids. The water passing through the filter enters the ceramic membrane system, the membrane pore size is 100 nm, the membrane inlet pressure is adjusted to 3 bar, the membrane outlet pressure is 2 kg, and the liquid temperature is controlled to be less than 70℃. Finally, 108.81 kg of water is obtained, which can reduce COD and SS. The water filtered by the ceramic membrane is then introduced into the anaerobic reaction system, the reaction pH is controlled at 7.5-8, the low-speed vortex stirring speed is 55 r / min, and 30 kg of active flocculent anaerobic sludge is added for 15 h of reaction. After the reaction is completed, about 78 kg of supernatant is obtained by siphoning. The obtained 78 kg of supernatant is introduced into the anoxic-aerobic system to control the reaction pH at 7.5-8, the dissolved oxygen in the anoxic system is controlled at 0.4-0.6 mg / L, and the dissolved oxygen in the aerobic system is 5-6 mg / L. The flow rate of the aerobic system backflow to the anoxic system is 3 times the flow rate of the entire system. The control retention time is 10 h. The obtained water is adjusted to pH 4, an equal volume of iron-carbon is added, aeration is started at the bottom of the iron-carbon, after 20 min of reaction, the upper clear liquid is taken and 0.3‰ hydrogen peroxide is added for continued aeration for 20 min, the entire aeration process ensures that the steam-water ratio is 3:1-1.5. After the reaction is completed, natural sedimentation is carried out for 3 h.

[0030] The main pollutant indicators of the water quality before and after treatment are shown in the following table:

[0031]

[0032] It is apparent to those skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments, and that the application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered as exemplary and not limiting, and the scope of the application is defined by the appended claims rather than the above description, and all changes falling within the meaning and range of equivalency of the essential elements of the claims are intended to be embraced therein. Any mark in the claims should not be considered as limiting the involved right.

Claims

1. A sewage treatment process, the process flow is as follows: Take 120 kg of landfill leachate, filter the sewage through a filter bag type filter with a mesh size of 25 μm to remove visible particles in the water, obtain 113.29 kg of water, this stage mainly reduces suspended solids; the water passing through the filter enters the ceramic membrane system, the membrane pore size is 100 nm, the membrane inlet pressure is adjusted to 3 bar, the membrane outlet pressure is 2 kg, and the liquid temperature is controlled to be less than 70℃; finally, 108.81 kg of water is obtained, this stage can reduce COD and SS; then the water filtered by the ceramic membrane enters the anaerobic reaction system, the reaction pH is controlled at 7.5-8, the low-speed vortex stirring speed is 55 r / min, 30 kg of active flocculent anaerobic sludge is added, and the reaction is carried out for 15 h; after the reaction is completed, about 78 kg of supernatant is obtained by siphoning; the obtained 78 kg of supernatant enters the anoxic-aerobic system, the reaction pH is controlled at 7.5-8, the dissolved oxygen in the anoxic system is controlled at 0.4-0.6 mg / L, and the dissolved oxygen in the aerobic system is 5-6 mg / L; the flow rate of the aerobic system backflowing to the anoxic system is 3 times the water inflow of the entire system; the residence time is controlled at 10 h; the obtained water is adjusted to pH 4, an equal volume of iron-carbon is added, aeration is started at the bottom of the iron-carbon, the upper clear liquid is taken after 20 min of reaction, 0.3‰ hydrogen peroxide is added, and the aeration reaction is continued for 20 min, the whole aeration process guarantees the steam-water ratio of 3:1~1.5; after the reaction is completed, natural sedimentation is carried out for 3 h; the raw water parameters are: COD=25000 mg / L, NH3-N=298 mg / L, SS=10000 mg / L, BOD5=18141 mg / L.

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