CN101074141A - Low-concentration organic wastewater regeneration and reuse process - Google Patents

Abstract

The low concentration organic waste water regenerating and reusing process includes biochemical process, physical and chemical process and membrane process, and features that: the low-concentration organic wastewater firstly passes through internal circulation in the combined biological oxidation tower and then enters an inclined plate sedimentation tank; in the low-concentration organic wastewater treatment process, the low-concentration organic wastewater firstly passes through a fiber bundle filter and then passes through a quartz sand filter; the method comprises the following steps: the low-concentration organic wastewater needs to be subjected to biological oxidation treatment; adding a flocculating agent into a water inlet pipe of the inclined plate sedimentation tank; precipitating and separating the wastewater in an inclined plate sedimentation tank, and filtering supernatant liquid of the wastewater in two stages through a fiber bundle filter and a quartz sand filter tank; the water from the quartz sand filter tank passes through a security filter and then a high-pressure pump and enters a reverse osmosis device for further separation, the produced water of the system is recycled for users, and the concentrated water is used as low-quality water. The method has the advantages of COD removal rate of more than 96 percent, ammonia nitrogen removal rate of more than 99 percent, stable operation, simple operation, convenient maintenance and capability of reducing the operation cost by 25 percent.

Description

Low-concentration organic wastewater regeneration and reuse process

technical field

The invention relates to a low-concentration organic wastewater regeneration and reuse process, and belongs to the technical field of advanced sewage treatment.

Background technique

With the rapid increase of the world's population, the rapid development of industrial and agricultural production, the acceleration of urbanization, and the increasingly serious pollution of natural water bodies such as rivers, rivers, and lakes, the amount of fresh water available is gradually decreasing, and the contradiction between supply and demand of water resources has become increasingly prominent. It is predicted that the water resource crisis in the 21st century will be at the top of all kinds of crises in the world. Therefore, people turned their attention to urban sewage and industrial wastewater. At present, this kind of sewage (waste) water is discharged into natural water bodies after being treated up to the standard, and a few are directly discharged into natural water bodies without treatment, which not only aggravates water body pollution, but also wastes a lot of fresh water resources. This phenomenon is in great contrast to the shortage of fresh water resources in the world today. In fact, this kind of sewage, especially the secondary standard effluent of urban sewage treatment plants, is available nearby. The water quality is stable, the quantity is large, easy to collect, and easy to regenerate. The effluent after regeneration can be used as low-quality water other than drinking water, or After multi-stage advanced treatment, it can be used as industrial circulating cooling water or boiler water with high water quality requirements, and even drinking water. Therefore, a large amount of urban sewage and industrial wastewater that has been treated up to the standard have become the second water source of the city.

In order to carry out advanced treatment of low-concentration organic wastewater, the technologies currently being used at home and abroad include: ① direct filtration and recycling. That is to add flocculants to low-concentration organic wastewater to stir and coagulate, then chlorinate and sterilize, and then filter directly through a fiber ball filter, and the effluent is only used as domestic miscellaneous water and agricultural irrigation water; Gas biofilter, fiber filtration, activated carbon adsorption, microfiltration and reverse osmosis processes. Its biological treatment part can effectively remove large suspended solids and macromolecular organic matter in sewage, filter and absorb to further remove small particles in water, and then the water after microfiltration and reverse osmosis treatment can be used as supplementary water for industrial circulating cooling water systems . However, because the effluent water quality of traditional biochemical treatment does not meet the requirements of reverse osmosis process, microfiltration is required as the pretreatment of reverse osmosis, so the whole process is long and the operation cost is high; Filtration, ultrafiltration, and reverse osmosis treatment, the water produced is supplied to the power plant boiler to make up water. The process adopts double-membrane method, and its technical core is ultrafiltration and reverse osmosis. Compared with traditional mechanical filtration, ultrafiltration has the advantages of good effluent quality, small footprint, and high degree of automation. However, due to the different types, materials, and processing techniques of ultrafiltration membranes, there are certain difficulties in selection and use. At the same time, impurities and colloids in the sewage will be enriched on the surface of the ultrafiltration membrane, causing the membrane pores to be blocked quickly, reducing the water yield and quality of the effluent, and increasing the burden on the reverse osmosis membrane. Therefore, it should be added before the ultrafiltration membrane. A set of pretreatment device, thus increasing the processing cost. These are the shortcomings of the double-membrane method, which should arouse the attention of users.

Contents of the invention

Purpose and _task of the present invention are to overcome existing technology: 1. investment cost is high; 2. technological process is long; 3. outlet water quality is on the low side; Petroleum), dissolved inorganic substances (ammonia nitrogen, NO ^- ₃ -N) and further removal of pathogenic microorganisms are insufficient. It also provides a waste water recycling process and technology that can meet the water quality requirements of industrial cooling water or boiler supplementary water, and its water quality is better than that of domestic miscellaneous water, landscape water and agricultural irrigation water, and has a simple process and is easy to operate and manage. The technological solution for the regeneration and reuse of low-concentration organic wastewater of the present invention is proposed.

The low-concentration organic wastewater regeneration and reuse process proposed by the present invention includes: biochemical method, physicochemical method and membrane method, and is characterized in that:

a) Low-concentration organic wastewater enters the combined biological oxidation tower equipped with fillers after being mediated by the sump, and enters the inclined plate sedimentation tank after the internal circulation treatment of aerobic reaction-facultative reaction;

b) After the biochemically treated wastewater is settled in the inclined plate sedimentation tank, it enters the fiber bundle filter, and after intercepting and filtering the unprecipitated flocs, the wastewater containing only fine precipitated particles enters the quartz sand filter tank;

c) The process steps are:

In the first step, the low-concentration organic wastewater enters the combined biological oxidation tower after being mediated by the sump, and under the action of aeration, it relies on the inner circulation diversion outer cylinder and the inner circulation diversion inner cylinder of the combined biological oxidation tower to carry out aerobic oxidation. Reaction - internal circulation of facultative oxygen reaction to form a three-phase fluidized bed of gas, water and packing; Microorganisms in contact with each other, conduct three-phase material exchange of microorganisms, wastewater, and gas phase, use the microorganisms on the biofilm on the carrier to oxidize organic substances into small molecular substances or completely oxidize them into carbon dioxide and water, so as to purify the wastewater;

In the second step, a flocculant with a content of 20 g/m ³ to 100 g/m ³ is added to the water inlet pipe from the combined biological oxidation tower to the inclined plate sedimentation tank. Under the action of turbulent water flow, the waste water is mixed , After flocculation, it enters the inclined plate sedimentation tank, and the flocs with a specific gravity greater than 1 are precipitated and removed, so that the water body can be further purified;

In the third step, after the turbidity of the wastewater is ≤20NTU, it enters the fiber bundle filter, intercepts and filters the unprecipitated flocs, and only the wastewater containing fine flocs or pollutants enters the quartz sand filter tank for further filtration and purification of the wastewater ,;

In the fourth step, the effluent from the quartz sand filter tank is pumped into the security filter through the clear water tank. After the turbidity of the effluent meets <1NTU, SDI ₁₅ ≤ 5, the waste water is pumped into the reverse osmosis device by a high-pressure lift pump, and the effluent is reused for industrial use. Circulating cooling water or boiler feed water; the concentrated water is used as low-quality water; the reverse osmosis device is composed of reverse osmosis membrane modules with high desalination rate and anti-pollution arrangement of 17:8~8:4.

Further features of the present invention are:

The filler in the combined biological oxidation tower is prismatic, with a volume of 1×1×1cm ³ , and the quantity ratio of hydrophilic soft filler to elastic filler is 3:4～5:6;

The internal circulation of the combined biological oxidation tower, the steps are: the wastewater evenly distributed through the water distribution pipe drives the filler and sludge settled at the bottom of the sedimentation area, enters the circulation channel, and then enters the aerobic reaction area; The air inlet pipe at the bottom of the oxygen reaction area enters the disc aeration pipe, and the air bubbles are evenly distributed to the aerobic reaction area through the aeration head, providing dissolved oxygen for the metabolism of microorganisms, and playing the role of mixing and stirring water and fillers, as well as providing The circulation in the aerobic reaction zone and the facultative reaction zone provides cyclic power; in the aerobic reaction zone and anaerobic reaction zone, under the diversion of the inner circulation diversion outer cylinder and the inner circulation diversion inner cylinder, the gas, water 1. The aerobic reaction of the three-phase fluidized bed with packing-anaerobic reaction internal circulation, during the internal circulation process, the waste water contacts the biofilm on the packing, and the three items of gas, waste water and microorganisms exchange materials, and the biofilm on the packing is used The microorganisms oxidize and decompose the organic matter to purify the wastewater; the inner circulation outlet is set under the outer cylinder of the inner circulation diversion, so that part of the treated water in the facultative reaction zone enters the sedimentation zone, and part of the water depends on the water purification pressure. Enter the filter area for further filtration treatment. The filtered water is discharged through the circular perforated outlet pipe above the filter area. The filler and sludge with a large specific gravity settle at the bottom of the sedimentation area and enter the circulation channel driven by the incoming water momentum. Carry out internal circulation; there is an emptying pipe at the bottom of the biological oxidation tower, which is equipped with a filter screen, which can intercept the carrier, discharge the excess sludge with a large specific gravity and poor activity, and transport it to the sludge landfill for landfill; biological oxidation The tail gas generated in the tower is discharged through the exhaust port; the effluent from the combined biological oxidation tower enters the inclined plate sedimentation tank;

The filling capacity of the fiber bundle filter is 2/3~4/5 of the effective volume of the filter. The filter material is a kind of self-adaptive filter material, namely hydrophilic synthetic fiber filter material, which has high filtration accuracy and large sewage interception capacity. , which is 15-35kg/m ³ , which is more than 4 times that of ordinary sand filters; the filtration speed is 40m/h, the highest is 60m/h, which is more than 3 times that of ordinary sand filters; the flocculants used are aluminum sulfate and Polyaluminum Sulfate (PAC).

The effluent treated by the low-concentration organic wastewater regeneration and reuse process proposed by the present invention can be reused in an industrial circulating cooling water system.

The low-concentration organic wastewater mentioned in the present invention refers to: the secondary standard effluent of urban sewage treatment plants (hereinafter referred to as the secondary standard effluent) and the low-concentration organic wastewater discharged by industrial enterprises.

When the processing capacity is ≤600m ³ /h, the influent turbidity of the fiber bundle filter is approximately 20NTU, and the SDI ₁₅ of the effluent from the quartz sand filter tank is 5, it is better to take the upper limit of the value range of each parameter, and the effluent of the system meets the user's requirements; When the processing capacity is ≤150m ³ /h, the influent turbidity of the fiber bundle filter is about 15NTU, the SDI ₁₅ of the effluent from the quartz sand filter tank is between 4 and 5, and when the value range of each parameter takes the lower limit, the system effluent has It can meet the design requirements; when the processing capacity is 150m ³ /h～600m ³ /h, the influent turbidity of the fiber bundle filter is between 15～20NTU, and the SDI ₁₅ of the effluent of the quartz sand filter tank is <5, the parameters of each parameter It is better to take the middle value in the value range, and all indicators of the system effluent meet the water use standard.

Adopt above-mentioned technical scheme, the effect that the present invention obtains is: 1. under the situation of same scale, same treatment effect, combined type biological oxidation tower reduces 30% of floor area of activated sludge pool compared with conventional activated sludge method, reduces The occupied area is reduced; ②Because the filler in the combined biological oxidation tower is attached with a large number of highly active microorganisms, the process of adsorption, decomposition, digestion and absorption of pollutants in the sewage is fast, resulting in low output of residual sludge. The amount of excess sludge produced in the oxidation tower is only 25% to 30% of the activated sludge process; at the same time, it also increases the treatment load by 10% to 15%, and the BOD ₅ load is as high as 3 to 8kg BOD ₅ /m ³ ·h, which can Save 25% to 30% of the space of the biological oxidation tower; ③The fiber bundle filter has fast filtration speed, easy backwashing, small equipment volume, high mechanical strength of the fiber bundle, long service life, and low cost per ton of water; ④Because the pretreatment effect reaches Design requirements, and the operation is relatively stable, so the reverse osmosis device operates stably, the pure water production rate is more than 75%, and the operating cost and maintenance cost are low.

Schedule Notes

Attached Table 1 is the treatment effect of the secondary standard effluent regeneration and reuse process of the urban sewage treatment plant treated in Example 1

The table lists four main indicators required by users: COD, ammonia nitrogen, BOD ₅ , and turbidity. At the same time, it lists the measured values of secondary standard effluent, the measured value of effluent from regeneration and reuse treatment systems, and the effluent of industrial circulating cooling water. GB/T19923-2005 "Urban Sewage Reuse Industrial Water Quality" national standard value and pollutant removal rate. It can be seen from Table 1 that the treatment effect of the secondary standard effluent regeneration and reuse treatment system is excellent, and the removal rates of the four indicators are: 97.2% for COD, 99.6% for ammonia nitrogen, 98.9% for BOD ₅ , and 100% for turbidity . The water output of the system meets the user's requirements.

Attached table 2 is the advanced treatment effect of petrochemical low-concentration organic wastewater treated in Example 2

The table lists the four main indicators required by users: COD, ammonia nitrogen, petroleum, turbidity, and also lists the measured values of petrochemical low-concentration organic wastewater, the measured values of effluent from regeneration and reuse treatment systems, and industrial circulating cooling water. The national standard value of GB/T19923-2005 "Urban Sewage Recycling Industrial Water Quality" and the removal rate of pollutants. It can be seen from Table 2 that the treatment effect of the recycling treatment system is excellent, and the removal rates of the four indicators are: 98.6% for COD, 99.2% for ammonia nitrogen, 98.2% for petroleum, and 100% for turbidity. The water output of the system meets the user's requirements.

Attached table 3 is the treatment effect of secondary standard effluent regeneration of urban sewage treatment plant treated in embodiment 3 and reuse in chemical plant

The table lists four main indicators required by users: COD, ammonia nitrogen, BOD ₅ , and turbidity. At the same time, it lists the measured values of secondary standard effluent, the measured value of effluent from regeneration and reuse treatment systems, and the effluent of industrial circulating cooling water. GB/T19923-2005 "Urban Sewage Reuse Industrial Water Quality" national standard value and pollutant removal rate. It can be seen from Table 3 that the secondary standard effluent regeneration and reuse treatment system has an excellent treatment effect, and the removal rates of the four indicators are: 98.4% for COD, 99.6% for ammonia nitrogen, 99.4% for BOD ₅ , and 100% for turbidity . The effluent from the regeneration and reuse system meets the user's requirements.

Description of drawings

Figure 1 Schematic diagram of the low-concentration organic wastewater regeneration and reuse process

This figure indicates that the low-concentration organic wastewater regeneration process of the present invention is mainly completed by 9 sets of equipment and device combinations, which are: sump, combined biological oxidation tower, dispensing tank, inclined plate sedimentation tank, fiber bundle filter , quartz sand filter tank, clean water tank, security filter, reverse osmosis device; equipment and devices are connected by pipes, valves and pumps; low-concentration organic wastewater is input into the sump from the outlet pipe of the sewage treatment plant, and pumped into the combined The biological oxidation tower is internally circulated, and the organic matter in the wastewater is oxidized and decomposed; before the oxidized wastewater enters the inclined plate sedimentation tank, the flocculant in the dispensing tank is added to the combined biological oxidation tower and the inclined plate sedimentation tank through the dosing pipeline In the pipeline between them, coagulation and adsorption are carried out, and the fine flocs are condensed into large flocs, and then enter the inclined plate sedimentation tank for sedimentation and separation; the sludge generated by the sedimentation separation is transported to the landfill, and the upper layer of wastewater After entering the fiber bundle filter through the pipeline, more than 95% of the suspended solids in the wastewater are intercepted by the fiber bundle, and can remove impurities such as macromolecular organic matter, viruses, colloids, iron, etc., and the effluent enters the quartz sand filter tank through the pipeline for secondary treatment. Secondary filtration to make the SDI ₁₅ of wastewater <5; the clean water after secondary filtration enters the clean water pool, and the clean water in the pool is pumped into the security filter to filter out particles with a particle size > 5 μm, and then the clean water is pumped into the reaction tank through a high-pressure pump. The osmosis device is filtered again, and the effluent is sent to the user's reuse system, and the concentrated water produced is used as low-quality water; the reverse osmosis membrane in the reverse osmosis device is a semi-permeable membrane, and the membrane pore size is very small, only about 1nm. Under the action of higher than the osmotic pressure of the solution, water molecules can pass through, but other substances cannot. Therefore, it can effectively remove dissolved salts, colloids, microorganisms, organic matter, etc. in water, and its removal rate is as high as 97% to 99%. It has the advantages of good system effluent quality, low energy consumption, no pollution, simple process, and easy operation. The direction of the arrow is the flow direction of the pipeline.

Figure 2 Schematic diagram of the process flow in the combined biological oxidation tower

This figure shows the internal circulation process in the combined biological oxidation tower. Low-concentration organic wastewater (secondary standard effluent) first enters the bottom of the aerobic reaction zone located in the inner diversion tube from the top of the tower through the inner pipe of the composite pipe. , at the same time, the air also enters the bottom of the aerobic zone from the top through the outer tube of the composite tube for aeration, and an aerobic zone is formed in the inner guide tube, and a prismatic small piece of filler is installed as a biological carrier. Water and packing three-phase fluidized bed, the macromolecular organic matter in the wastewater is intercepted by the biological carrier, and a biological oxidation reaction occurs, and the macromolecular organic matter is decomposed into small molecular substances or completely mineralized into carbon dioxide and water; in the aerobic reaction zone In the three-phase fluidized bed, air, water, and fillers continuously rise, collide, and roll, and flow down through the upper edge of the inner guide tube to the aerobic zone between the inner guide tube and the outer guide tube. The nitrogen compounds are completely converted into harmless substances, thereby completing the nitrification reaction; after the nitrification reaction, part of it returns to the bottom of the aerobic zone along the direction of the water flow, and part of it enters the sedimentation zone from the water outlet at the end of the outer diversion tube, and the upstream water enters the filter layer for filtration. The effluent is discharged from the ring-shaped water collection pipe at the top of the tower, and then this part of the effluent flows out of the tower and enters the inclined plate sedimentation tank; while the sludge and filler produced by the sedimentation flow down from the baffle at the bottom of the tower and return to the bottom of the aerobic zone , to participate in the biological oxidation reaction again; the other part of the sludge is discharged from the bottom of the tower due to gravity, and transported to the sludge landfill; the tail gas during the reaction is discharged from the top of the tower, from the combined biological The effluent from the oxidation tower enters the inclined plate sedimentation tank.

Detailed ways

Embodiment one

The 600m ³ /h secondary standard effluent of a city's sewage treatment plant is regenerated and reused in a thermal power plant

Adopt the inventive method to process, and its process is as follows:

The first step, influent water quality, national standards and removal rate

The secondary standard effluent water quality requirements are COD ≤ 100mg/L, BOD ₅ ≤ 30mg/L, ammonia nitrogen ≤ 25mg/L, turbidity (no requirement) (GB 18918-2002). The technology of the present invention requires that the influent water quality is controlled within this standard. The water quality required by the user should meet the GB/T19923-2005 standard: COD≤50mg/L, BOD _5≤10mg /L, turbidity≤3NTU, ammonia nitrogen≤10mg/L (when the heat exchanger of the circulating cooling water system is made of copper , the ammonia nitrogen index of circulating cooling water should be less than 1mg/L).

The second step of processing:

a) The secondary standard effluent of the urban sewage treatment plant passes through the sump, first enters the aerobic zone of the combined biological oxidation tower, and relies on the diversion tube of the reactor for internal circulation reaction under the action of aeration. At the same time, the organic matter and nitrogen compounds in the sewage are intercepted by the packing in the tower, and are decomposed into small molecular substances or completely mineralized into carbon dioxide and water by the microorganisms attached to the packing; the tower is filled with hydrophilic soft packing and elastic packing, The filler is suspended during operation; the volume ratio of hydrophilic soft filler and elastic filler in the tower is 5:6;

b) Add polyaluminum chloride (PAC) to the inlet pipe of the inclined plate sedimentation tank for coagulation, adsorption, and sedimentation in the inclined plate sedimentation tank to reduce the chemical oxygen consumption and ammonia nitrogen content in the sewage; polychlorination Aluminum was added in an amount of 100 g/m ³ . Sewage with polyaluminum chloride is separated from solid and liquid in the inclined plate sedimentation tank, and the supernatant liquid passes through the fiber bundle filter and quartz sand filter tank to further intercept fine suspended solids and colloidal particles, so that the turbidity of the effluent is less than 1NTU , SDI ₁₅ <5; wherein the filling capacity of the filter material in the fiber bundle filter is 4/5 of the effective volume of the filter;

c) The effluent from the quartz sand filter tank enters the clear water tank, and then is pumped into the reverse osmosis device through the security filter, wherein the arrangement of the membrane modules in each reverse osmosis device is 17:8; the effluent (product water) enters the industrial circulation cooling of the thermal power plant The water system is used, and the concentrated water produced is used as slag flushing water in thermal power plants;

The third step is to check and accept

After being treated by the above technical solutions, the average purification efficiency of sewage is 97.2% for COD, 99.6% for ammonia nitrogen, 98.9% for BOD ₅ , and 100% for turbidity, see Table 1 for details.

Embodiment two

Regeneration and reuse treatment of 150m ³ /h petrochemical low-concentration wastewater in a petrochemical plant

The first step, influent water quality, national standards and removal rate

The effluent water quality requirements of petrochemical plant wastewater treatment workshops are COD≤100mg/L, ammonia nitrogen≤25mg/L, petroleum ≤5mg/L, and turbidity (no requirement) (GB 18918-2002). The process of the present invention requires that the influent water quality be controlled within this standard; the water quality required by the user should meet the GB/T19923-2005 standard: COD≤50mg/L, BOD _5≤10mg /L, turbidity≤3NTU, ammonia nitrogen≤10mg/L L (when the heat exchanger of the circulating cooling water system is made of copper, the ammonia nitrogen index of the circulating cooling water should be less than 1mg/L);

The second step of the process

a) Firstly, pump the standard outlet water from the wastewater purification workshop of the petrochemical plant into the combined biological oxidation tower, and the organic matter and nitrogen compounds in the water are oxidized and decomposed by microorganisms; the volume ratio of the hydrophilic soft filler to the elastic filler in the tower is 3:4;

b) adding aluminum sulfate to the wastewater after biological oxidation treatment to carry out coagulation, adsorption, precipitation, decolorization, sterilization, removal of microorganisms and algae. The SDI ₁₅ of the effluent of the subsequent quartz sand filter tank is <5, and 20 g/m ³ of aluminum sulfate is added;

c) The sewage added with aluminum sulfate enters the inclined plate sedimentation tank for precipitation, and the supernatant liquid passes through the fiber bundle filter and the quartz sand filter tank, and further intercepts fine suspended solids and colloidal particles, so that the effluent turbidity <1NTU, SDI ₁₅ <5; The filling capacity of the filter material in the fiber filter is 2/3 of the effective volume of the filter;

d) The effluent from the quartz sand filter tank enters the clear water tank, and then is pumped into the reverse osmosis device through the security filter. The arrangement of the membrane modules in each reverse osmosis device is 8:4; the effluent (produced water) is used as a primary Water replenishment and replenishment of the "central circulating water plant" in the plant. Concentrated water from the device is used as workshop floor flushing water and toilet flushing water;

The third step is to check and accept

After being treated by the above technical scheme, the average purification efficiency of sewage is 98.6% for COD, 99.2% for ammonia nitrogen, 98.2% for petroleum, and 100% for turbidity, see Table 2 for details.

Embodiment three

The 400m ³ /h secondary standard effluent of a sewage treatment plant in a city is regenerated and reused in a chemical plant

Adopt the inventive method to process, and its process is as follows:

The first step, influent water quality, national standards and removal rate

The secondary standard effluent water quality requirements are COD ≤ 100mg/L, BOD ₅ ≤ 30mg/L, ammonia nitrogen ≤ 25mg/L, turbidity (no requirement) (GB 18918-2002). The technology of the present invention requires that the influent water quality is controlled within this standard. The water quality required by the user should meet the GB/T19923-2005 standard: COD≤50mg/L, BOD _5≤10mg /L, turbidity≤3NTU, ammonia nitrogen≤10mg/L (when the heat exchanger of the circulating cooling water system is made of copper , the ammonia nitrogen index of the circulating cooling water should be less than 1mg/L);

The second step of the process

a) The secondary standard effluent of the urban sewage treatment plant passes through the sump, first enters the aerobic zone of the combined biological oxidation tower, and relies on the diversion tube of the reactor for internal circulation reaction under the action of aeration. At the same time, the organic matter and nitrogen compounds in the sewage are intercepted by the packing in the tower, and are decomposed into small molecular substances or completely mineralized into carbon dioxide and water by the microorganisms attached to the packing; the tower is filled with hydrophilic soft packing and elastic packing, The filler is suspended during operation; the volume ratio of hydrophilic soft filler and elastic filler in the tower is 4:5;

b) Add polyaluminum chloride (PAC) to the inlet pipe of the inclined plate sedimentation tank for coagulation, adsorption, and sedimentation in the inclined plate sedimentation tank to reduce the chemical oxygen consumption and ammonia nitrogen content in the sewage; polychlorination Aluminum (PAC) was added in an amount of 60 g/m ³ . The SDI ₁₅ of the quartz sand filter effluent is <5. Sewage with polyaluminum chloride is separated from solid and liquid in the inclined plate sedimentation tank, and the supernatant liquid passes through the fiber bundle filter and quartz sand filter tank to further intercept fine suspended solids and colloidal particles, so that the turbidity of the effluent is less than 1NTU , SDI ₁₅ <5; wherein the filling amount of the filter material in the fiber bundle filter is 3/4 of the effective volume of the filter;

c) The effluent from the quartz sand filter tank enters the clear water tank, and then is pumped into the reverse osmosis device through the security filter, wherein the arrangement of the membrane modules in each reverse osmosis device is 13:7; the effluent (product water) enters the industrial cycle of the chemical plant Used in the cooling water system, the concentrated water produced is used as ground water and toilet flushing water in the chemical plant washing workshop;

The third step is to check and accept

After being treated by the above technical scheme, the average purification efficiency of sewage is 98.4% for COD, 99.6% for ammonia nitrogen, 99.4% for BOD ₅ , and 100% for turbidity, see Table 3 for details.

Table 1 is the secondary standard effluent water regeneration and reuse treatment effect of the urban sewage treatment plant treated in Example 1 COD (mg/L) Ammonia nitrogen (mg/L) _BOD5 (mg/L) Turbidity (NTU) Secondary standard effluent 115.2 25.8 30.7 18.6 Recycling system effluent 3.3 0.1 0.3 0 Water quality requirements for industrial circulating cooling water ≤50 ≤10(1) ≤10 ≤3 Pollutant removal rate (%) 97.2 99.6 98.9 100

Note: When the heat exchanger of the circulating cooling water system is made of copper, the ammonia nitrogen index of the circulating cooling water should be less than 1mg/L.

Table 2 is the effect of regeneration and reuse of petrochemical low-concentration organic wastewater treated in Example 2 COD (mg/L) Ammonia nitrogen (mg/L) Petroleum (mg/L) Turbidity (NTU) Sewage treatment workshop effluent 102.2 24.5 10.7 20.5 Recycling system effluent 2.5 0.2 0.2 0 Water quality requirements for industrial circulating cooling water ≤50 ≤10(1) ≤10 ≤3 Pollutant removal rate (%) 98.6 99.2 98.2 100

Note: When the heat exchanger of the circulating cooling water system is made of copper, the ammonia nitrogen index of the circulating cooling water should be less than 1mg/L.

Table 3 is the treatment effect of the secondary standard effluent regeneration of the urban sewage treatment plant treated in Example 3 and reused in the chemical plant COD (mg/L) Ammonia nitrogen (mg/L) _BOD5 (mg/L) Turbidity (NTU) Sewage treatment workshop effluent 108.5 25.2 30.5 27.4 Recycling system effluent 1.8 0.1 0.2 0 Water quality requirements for industrial circulating cooling water ≤50 ≤10(1) ≤10 ≤3 Pollutant removal rate (%) 98.4 99.6 99.4 100

Note: When the heat exchanger of the circulating cooling water system is made of copper, the ammonia nitrogen index of the circulating cooling water should be less than 1mg/L.

Claims (5)

1. process for regenerating, recovering and reutilizing low-concentration organic waste water, comprising: biochemical process physico-chemical process and embrane method is characterized in that:

A) low-concentration organic waste water enters the combined bio oxidizing tower that filler is housed after water collecting basin is reconciled, and carries out the internal recycle of the aerobic reaction-oxygen reaction of holding concurrently and handles, and its water outlet enters inclined-plate clarifying basin;

B) waste water after the biochemical treatment enters fiber bundle filter through the inclined-plate clarifying basin post precipitation, and after unprecipitated flco interception was filtered, the waste water that only contains trickle deposit seeds entered the quartz sand filtration pond;

C) processing step is:

The first step, low-concentration organic waste water is after water collecting basin is reconciled, enter the combined bio oxidizing tower, under the effect of aeration, rely on the internal recycle water conservancy diversion urceolus of combined bio oxidizing tower and internal recycle water conservancy diversion inner core to carry out the internal recycle that aerobic reaction-oxygen of holding concurrently reacts, form air water filler three-phase fluidized bed; In inner cyclic process, prismatic wetting ability soft-filler in organic nitride in the waste water and the tower contacts with the microorganism in the elastic filler, carry out the three-phase material exchange of organism waste water gas phase, the interior microorganism of microbial film that utilization is attached on the carrier is oxidized to organic substance small-molecule substance or is completely oxidized to carbonic acid gas and water, makes waste water obtain to purify;

Second step is to adding content at 20 gram/m by the combined bio oxidizing tower to the water inlet pipe of inclined-plate clarifying basin ³～100 gram/m ³Between flocculation agent, under the water turbulence effect, waste water enters inclined-plate clarifying basin behind mixed flocculation, and proportion is removed greater than 1 flco precipitation, and water body is further purified;

The 3rd step behind turbidity of wastewater≤20NTU, entered fiber bundle filter, and after unprecipitated flco interception was filtered, the waste water that only contains trickle flco or pollutent entered the quartz sand filtration pond, and waste water is carried out further filtration, purification;

In the 4th step, the water outlet of quartz sand filtration pond is pumped to security personnel's strainer through clean water basin, and delivery turbidity satisfies＜1NTU, SDI ₁₅After≤5, by the high-tension boost pump waste water is pumped into reverse osmosis unit, its effluent reuse is in industrial circulating cooling water or boiler feedwater; Its dense water is as the low-quality water; Reverse osmosis unit is that 17: 8～8: 4 reverse osmosis membrane assembly is formed by high desalination rate antipollution arrangement mode.

2. according to the described process for regenerating, recovering and reutilizing low-concentration organic waste water of claim 1, it is characterized in that: the filler in the combined bio oxidizing tower is that prismatic volume is 1 * 1 * 1cm ³Wetting ability soft with elasticity two in filler, its volume ratio is 3: 4～5: 6.

3. process for regenerating, recovering and reutilizing low-concentration organic waste water according to claim 1, it is characterized in that: the processing step in the combined bio oxidizing tower: the waste water that goes out through the even cloth of water distributor, drive falls to the filler and the mud of bottom, settling region, enters circulation passage, enters aerobic reactor zone subsequently; Air enters the disc type aeration tube by the inlet pipe that is arranged at the aerobic reactor zone bottom, by aeration head with the even cloth of bubble to aerobic reaction zone, for the metabolism of microorganism provides dissolved oxygen, and play mixing stirring action, and provide circulation power for aerobic reactor zone and double oxygen reaction interval internal recycle to water packing; In aerobic reactor zone and anaerobic reaction district, under the guide functions of internal recycle water conservancy diversion urceolus and internal recycle water conservancy diversion inner core, carry out the aerobic reaction-anaerobic reaction internal recycle of air water filler three-phase fluidized bed, in inner cyclic process, waste water contacts with microbial film on the filler, three in gas waste water microorganism carries out exchange of substance, utilizes microorganism in the microbial film on the filler with the organic substance oxygenolysis, makes waste water obtain to purify; Be arranged on the internal recycle water outlet of internal recycle water conservancy diversion urceolus below, make the part water outlet after handling in the oxygen reaction zone of holding concurrently enter the settling region, wherein a part of water relies on water purification pressure to enter filtrating area, carry out further filtration treatment, water after the filtration is distinguished the annular perforations rising pipe of top after filtration and is discharged, filler that proportion is bigger and sludge settling enter circulation passage in the bottom, settling region under the water inlet impulse force drives, proceed internal recycle; The bio-oxidation tower bottom is provided with evacuated tube, is provided with filter screen in it, and the carrier that can dam is discharged the big active relatively poor excess sludge of proportion, is transported to the sludge landfill landfill; The tail gas that produces in the Biological Oxidation Tower is discharged through venting port; Water outlet enters inclined-plate clarifying basin in the combined bio oxidizing tower.

4. process for regenerating, recovering and reutilizing low-concentration organic waste water according to claim 1 is characterized in that: the filtrate loadings of fiber bundle filter is 2/3～4/5 of a strainer useful volume; Its filtrate is that a kind of self-adaptation filtrate is the wetting ability synthetic fiber filter material, and the filtering accuracy height reaches more than 95% the clearance of suspended substance in the water, and its holding filth capacity is big simultaneously, is 15～35kg/m ³, be more than 4 times of normal sands filter; Filtration velocity is 40m/h, is up to 60m/h, is more than 3 times of normal sands filter.

5. process for regenerating, recovering and reutilizing low-concentration organic waste water according to claim 1 is characterized in that: used flocculation agent has Tai-Ace S 150 or polymerize aluminum chloride.

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