CN1151085C - Process for treating sewage with zeolite filler in aerated biologic filter pool and zeolite filler - Google Patents

Abstract

The present invention discloses a method for treating domestic sewage by using a zeolite filter material in an aeration biologic filter pool and a zeolite filter material, which relates to reuse of low concentration domestic sewage and a domestic sewage advanced treatment technique. The present invention is characterized in that when COD of the domestic sewage in a sewage treatment process is from 40 mg/L to 120 mg/L, and the ammonia nitrogen is from 10 mg/L to 40 mg/L, the water-gas ratio is 1: 1-1: 3, the height of the filter material is from 2m to 4m, and the hydraulic load is from 2 m/h to 5 m/h; the gas flush strength of the gas-water combined backflushing process is from 12 L/m<2>s to 18 L/m<2>s, the water flush strength is from 8 L/m<2>s to 12 L/m<2>s, and the water rinsing strength is from 8 L/m<2>s to 12 L/m<2>s. The grain size of the zeolite filter material used in the method is from 3mm to 6mm, the density is from 1900 kg/m<3> to 2200 kg/m<3>, the hardness is the mohs hardness from 3 to 5, and the ammonia ion exchange capacity is from 3 kg/m<3> to 6 kg/m<3>. The method has good effects of removing suspended matters, COD and ammonia nitrogen, has high capability of resisting the shock load of the ammonia nitrogen and has less invest and low operation cost.

Description

A method for treating sewage in a biological aerated filter with zeolite filter material

technical field

The invention relates to a low-concentration domestic sewage reuse treatment and domestic sewage advanced treatment technology, in particular to a method for treating sewage in a zeolite filter material aerated biological filter.

Background technique

There is currently no suitable method for the reuse and treatment of low-concentration domestic sewage. If biological treatment processes such as activated sludge method and biological contact oxidation method are used, the treatment efficiency is low due to the low organic matter load, and secondary sedimentation is required, so the treatment cost is high. In addition, the effect of ammonia nitrogen removal is poor, and the effluent is difficult to reach the sewage. Reuse as a requirement of circulating cooling water quality standards. If physical and chemical processes such as coagulation, sedimentation, and filtration are used, ammonia nitrogen cannot be removed, and the amount of sludge generated is not easy to handle, and the operating cost is high.

The technologies currently used in the advanced treatment of urban sewage generally have the disadvantages of large floor area and low treatment load. Moreover, the concentration of ammonia nitrogen in urban domestic sewage fluctuates greatly. According to statistics, the maximum load of ammonia nitrogen concentration is only 2 to 3 hours a day. The ground area is large, and it is easy to cause the equipment not to operate under the best working conditions, which will affect the treatment effect.

Biological aerated filter (BAF) is a sewage treatment process that emerged in the late 1980s and early 1990s. It was initially used as a tertiary treatment, and later developed into a direct secondary treatment. It uses rough and porous granular filter material. Biofilm grows on the surface of the filter material, and aeration is provided at the bottom of the pool. When the sewage flows through the filter bed, the pollutants are first filtered and adsorbed, and then oxidized and decomposed by the microorganisms on the surface of the filter material. Its biggest feature is that it integrates biological oxidation and interception of suspended solids, saves subsequent sedimentation tanks, has the advantages of large volume load, short hydraulic retention time, low infrastructure investment, and high effluent quality.

The filter material has a great influence on the one-time investment, operating cost and normal operation of BAF. The selection mainly considers the specific surface area, mechanical strength, density, physical and chemical stability, particle size and shape, porosity and film-hanging characteristics. In addition, low price and wide range of sources are also important factors to be considered. The most widely used are spherical clay ceramsite and irregular shale ceramsite.

Zeolite is a widely distributed and highly mined natural ion exchange material. Clinoptilolite is the most productive natural zeolite, which has the characteristics of high porosity and large specific surface area. In addition, it has a strong selective ion exchange capacity for ammonia nitrogen, and is often used in the chemical treatment of sewage to remove ammonia nitrogen. However, there is no report of using it as a biological aerated filter filter material to treat sewage in China.

Similar foreign technologies include the following:

(1) Japan's Tsuno et al. used zeolite as the filter material of the biological filter to conduct experiments in 1994. He found that the adsorption of ammonia nitrogen and biological nitrification occurred simultaneously. When the load of ammonia nitrogen exceeded the load that could be removed by nitrification, ammonia nitrogen The adsorption of the zeolite will be inhibited, but when the nitrifying bacteria on the filter material are fully grown, the ammonia nitrogen released after the adsorption will be nitrated, and the ion exchange capacity of the zeolite will be regenerated at this time (Tsuno, Hiroshi Nishimura, Fumitake et.al.Removalof ammonium nitrogen in bio-zeolite reactor.In: Proceedings of the Japan Society of Civil Engineers.Japan Soc of Civil Engineers, 1994.159-166), but the author only used a general biofilter, not an aerated biofilter, so ammonia nitrogen was removed Load capacity is limited. (2) Germany's Oldenburg, Martin and Sekoulov, Ivan. published in 1995 the test of mixing zeolite and other filter materials as a biological aerated filter filter, using the ion exchange of zeolite to remove the impact load of ammonia nitrogen in sewage result. It is found that when the concentration of ammonia nitrogen in the influent water is high, zeolite can enrich ammonia nitrogen; when the concentration of ammonia nitrogen in influent water decreases, ammonia nitrogen is desorbed from the zeolite and is removed by nitrifying bacteria on other filter materials through nitrification (Oldenburg, Martin, Sekoulov, Ivan. Multipurpose filters with ion-exchanger for the equalization of ammonia peaks. Water Science and Technology, 1995, 32(7): 199-206). This technology utilizes two kinds of filter materials, which will inevitably cause the problem of backwash stratification caused by the different density and particle size of the filter materials. In addition, the ion exchange capacity of zeolite is not fully utilized. (3) Norway's Gisvold, B. et al. published the test results of using expanded ceramsite containing zeolite powder as a nitrification filter filter (Filtralite ZL) in 1999 to remove the impact load of ammonia nitrogen. This filter utilizes the joint action of nitrification and adsorption to remove ammonia nitrogen in domestic sewage, and the filter is continuously regenerated through biological action, and its performance has not decreased after ten months of operation (Gisvold, B., Odegaard, H., Follesdal, M..Enhanced removal ofammonium by combined nitrification/adsorption in expanded clay aggregate filters. Water Science and Technology, 1999, 41(4):409-416). The disadvantage of this technology is that the expanded ceramsite containing zeolite powder needs to be fired at high temperature, which increases the cost. (4) Lahav, O. and Green, M. of Israel published in 2000 the experimental results of using zeolite as the filter material of biological aerated filter for primary and secondary treatment of domestic sewage. The process adopted is: the wastewater is first filtered through zeolite until ammonia nitrogen leaks, then the filtration is stopped, and the zeolite is biologically regenerated with nitrifying bacteria, and then the next cycle of filtration is started (Lahav, O., Green, M..Ammonium removal from primary and secondary efffluents using a bioregenerated ion-exchange process. Water Science and Technology, 2000, 42(1): 179-185). The disadvantage of this method is that it needs to be stopped for special regeneration after running for a period of time, which reduces the effective utilization time of the equipment.

Contents of the invention

The purpose of the present invention is to provide a method for treating sewage with a zeolite filter material aerated biological filter with strong ability to resist impact load of ammonia nitrogen and low equipment investment and operation cost.

In order to achieve the above object, a method for treating sewage in a zeolite filter material aerated biological filter proposed by the present invention includes a sewage treatment process and a gas-water combined backwashing process, and is characterized in that: the chemical oxygen demand of sewage in the sewage treatment process When the amount of COD is (40-120) mg/L, ammonia nitrogen is (10-40) mg/L, the water-air ratio is 1:1-1:3, the height of the filter material is 2-4m, and the hydraulic load is (2- 5) m/h; the gas flushing intensity in the first stage of the air-water combined backwashing process is (12-18) L/m ² ·s, and the gas flushing intensity in the second stage is (12-18) L/m ² ·s, The water flushing intensity is (8-12) L/m ² ·s, and the water rinsing intensity in the third stage is (8-12) L/m ² ·s; the biological aerated filter is mainly composed of a porous plate water distribution device (6), support layer (7), zeolite filter material layer (1), process aeration device (2), backwash air distribution device (3); during operation, sewage enters from the water inlet (11), and passes through the inlet The water distribution device (3) passes through the support layer (7), removes suspended solids, COD, BOD ₅ and ammonia nitrogen through the zeolite filter layer (1), and then discharges from the water outlet (8), while the compressed air is discharged from the (4 ) enters through (2) aeration to provide oxygen for microbial growth; during backwashing, compressed air enters from the air inlet (5), clean water enters from the backwash water inlet (10), and backwash water is discharged from the drain outlet (9) The equipment is continuous operation. When the head loss of the filter reaches 1.5m, backwashing is carried out jointly with compressed air and outlet water, and the backwash outlet water can be put into operation after clarification; the zeolite filter material is a natural clinoptilolite filter material, and its The effective particle size is (3-6) mm, the density is (1900-2200) kg/m ³ , the hardness is Mohs hardness 3-5, and the ammonia ion exchange capacity is (3-6) kg/m ³ .

A method for treating sewage with a zeolite filter material aerated biological filter proposed by the present invention is used to treat low-concentration domestic sewage. After sedimentation and removal of most of the suspended matter, it can directly enter the equipment, and the effluent can be reused after disinfection. Secondary precipitation; when used for advanced treatment of domestic sewage, the secondary effluent can directly enter the equipment to remove the remaining COD and NH ₄ ⁺ -N. This method is easy to hang film, has good effect of removing suspended matter, COD and ammonia nitrogen, has strong resistance to ammonia nitrogen impact load, can reduce the volume of the filter tank, reduce the cost of the filter tank, and make the equipment operate in the optimal working condition, reducing equipment investment and operating costs Low. In addition, the use of zeolite is more economical, and the zeolite filter material is easy to process and has sufficient supply, which is conducive to protecting the environment.

Description of drawings

Fig. 1 is a structural schematic diagram of a biological aerated filter with zeolite filter material used in the present invention.

Detailed ways

A method for treating sewage in a biological aerated filter with zeolite filter material and the zeolite filter material according to the present invention will be described in detail below in conjunction with the accompanying drawings.

The upflow biological aerated filter used in the present invention is mainly composed of a porous plate water distribution device 6 , a support layer 7 , a zeolite filter material layer 1 , a process aeration device 2 , and a backwash air distribution device 3 . During operation, the sewage enters from the water inlet 11, passes through the water inlet distribution device 3, passes through the support layer 7, passes through the zeolite filter material layer 1 to remove suspended solids, COD, BOD ₅ and ammonia nitrogen, and is discharged from the water outlet 8, while compressing the air It enters through 4 and aerates through 2 to provide oxygen for microbial growth; during backwashing, compressed air enters from air inlet 5, clean water enters from backwash inlet 10, and backwash water is discharged from drain 9. The equipment is in continuous operation. When the water head loss of the filter reaches a certain height (generally about 1.5m), the compressed air and water outlet are combined for backwashing. After the backwashing water is clarified, it can be put into operation. This process can also adopt the downward flow operation mode.

The present invention uses natural clinoptilolite as the filter material of the biological aerated filter. The surface of the natural zeolite is rough and porous, and there are many irregular small holes with a diameter of 20-30 μm, which are larger than the size of the bacteria. The charge is opposite, which is conducive to bacterial attachment, so the zeolite filter material BAF has the functions of filtration, biosorption and biooxidation, and can remove suspended solids, chemical oxygen demand COD, biochemical oxygen demand BOD ₅ and ammonia nitrogen and other pollutants. But because clinoptilolite has a strong selective exchange capacity for ammonia nitrogen (the selective exchange order for common ions is: K ⁺ >NH ₄ ⁺ >Na ⁺ >Ca ²⁺ >Fe ³⁺ >Al ³⁺ >Mg ²⁺ >Li ⁺ ), so when the concentration of ammonia nitrogen in the influent is high, the zeolite can enrich the ammonia nitrogen, and when the concentration of ammonia nitrogen in the influent decreases, the ammonia nitrogen can be exchanged from the zeolite by Na ⁺ and other cations, and the nitrifying bacteria on the filter material It is removed by nitrification, so the zeolite filter material BAF has a strong ability to resist the impact load of ammonia nitrogen, which is a unique feature of the zeolite bed BAF.

The natural clinoptilolite filter material selected by the present invention has an effective particle diameter of (3-6) mm, a density of (1900-2200) kg/m ³ , a hardness of 3-5 on the Mohs scale, and an ammonia ion exchange capacity of (3-2200) kg/m 3 . 6) kg/m ³ . Determine the particle size and filling height of the filter material according to the concentration of COD and NH ₄ ⁺ -N in the influent water and the quality requirements of the effluent water. The filling height of the filter material is 2-4m. Low-concentration domestic sewage can directly enter the equipment after preliminary precipitation to remove most of the suspended matter, and the effluent can be reused after disinfection without secondary precipitation; the secondary effluent can directly enter the equipment to remove the remaining COD and NH ₄ ⁺ -N.

This process method can achieve the following technical effects:

(1) The effect of removing suspended solids, COD and ammonia nitrogen is good. When the biological aerated filter with zeolite filter material treats low-concentration domestic sewage, the heterotrophic zone and the nitrification zone are separated, and the inhibitory effect of heterotrophic bacteria on nitrifying bacteria is not obvious. In addition, the zeolite filter material after the film has a good filtering effect, so in a zeolite filter material aerated biological filter, suspended solids, COD and ammonia nitrogen can be removed at the same time, and the quality of the effluent can reach domestic miscellaneous water or sewage recycling. It is used as the water quality standard for suspended solids, COD, BOD ₅ and ammonia nitrogen in circulating cooling water of power plants. When the suspended matter in the influent is 10-30mg/L, the COD is 80-120mg/L, and the ammonia nitrogen is 7-15mg/L, the water-air ratio is 1:2-1:3, the height of the filter material is 3m, and the hydraulic load The removal rate of suspended solids is about 90%, the removal rate of COD is about 80%, and the removal rate of ammonia nitrogen is 80-90%.

(2) Strong resistance to ammonia nitrogen impact load. In this way, the volume of the filter tank can be reduced, the cost of the filter tank can be reduced, and the equipment can be operated in an optimal working condition. The filtration rate is 4m/h, the residence time is 40min, the concentration of ammonia nitrogen in the influent is increased from 10mg/L to 20mg/L for 2 hours, and the maximum concentration of ammonia nitrogen in the outlet is no more than 3mg/L.

(3) Easy to hang film. Since natural clinoptilolite is a rough and porous granular filter material with a large specific surface area, the surface is positively charged, and the pore diameter is larger than the size of the bacteria, it is conducive to the attachment of microorganisms, easy to form a film, and biofilm during backwashing. Not easy to fall off. When the temperature is 20-30°C, the inoculation film is used, and the heterotrophic bacteria are mature in about 10 days, and the nitrifying bacteria are mature in about 20 days.

(4) Low equipment investment and operating costs. The price of zeolite filter material is about 300 yuan/m ³ , while the price of clay ceramsite is about 1200 yuan/m ³ , and the price of zeolite is only about 1/4 of that of ceramsite, so it is more economical to use zeolite, and zeolite The filter material is easy to process, and the supply is sufficient, which is conducive to protecting the environment.

Example 1:

Treatment of low-concentration domestic sewage: select a particle size of 4-6 mm, a density of (1900-2100) kg/m ³ , a hardness of 4-5 on the Mohs scale, and an ammonia ion exchange capacity of (3-4) kg/m ³ . When the COD in the sewage is (80-120) mg/L, and the ammonia nitrogen is (10-15) mg/L, the water-air ratio is 1:2-1:3, the height of the filter material is (2-3) m, and the hydraulic load (2~4) m/h; this process adopts air-water combined backwashing method, the air flushing intensity in the first stage is (15~18)L/(m ² ·s), and the flushing time is (3~7)min; the second stage The intensity of air flushing in the second stage is (15-18) L/(m ² ·s), the intensity of water flushing is (10-12) L/(m ² ·s), and the flushing time is (10-15) min; The rinsing intensity is (10-12) L/(m ² ·s), and the time is (5-10) min. The removal rate of suspended solids is about 90%, the removal rate of COD is about 80%, and the removal rate of ammonia nitrogen is 80-90%.

Example 2:

Advanced treatment of domestic sewage: choose a particle size of (3-4) mm, a density of (2000-2200) kg/m ³ , a hardness of 3-4 on the Mohs scale, and an ammonia ion exchange capacity of (5-6) kg/m3 m ³ . When the COD in the sewage is (40-90) mg/L, and the ammonia nitrogen is (15-40) mg/L, the water-air ratio is 1:1-1:2, and the hydraulic load is (4-6) m/h. The height of the material is (2-4) m. This process adopts the air-water combined backwash method, the air flushing intensity in the first stage is (12~15) L/(m ² ·s), and the flushing time is (3~7) min; the air flushing intensity in the second stage is (12~15) L/(m ² ·s), the water flushing intensity is (8～10)L/( ^m2 ·s), the flushing time is (10～20)min; the third stage water rinsing intensity is (8～10)L/ (m ² ·s), time (5-10) min. The removal rate of suspended solids is about 90%, the removal rate of COD is about 70-80%, and the removal rate of ammonia nitrogen is 90%.

Claims (1)

1. A method for treating sewage in a zeolite filter material aerated biological filter, comprising a sewage treatment process and a gas-water combined backwashing process, characterized in that: the chemical oxygen demand COD of sewage in the sewage treatment process is (40～120 ) mg/L, when the ammonia nitrogen is (10-40) mg/L, the water-air ratio is 1:1-1:3, the filter material height is 2-4m, and the hydraulic load is (2-5)m/h; The air flushing intensity in the first stage of the air-water combined backwashing process is (12-18) L/m ² ·s, the air flushing intensity in the second stage is (12-18) L/m ² ·s, and the water flushing intensity is (8-18) L/m 2 ·s. 12) L/m ² ·s, the water rinsing intensity in the third stage is (8-12) L/m ² ·s; the biological aerated filter is mainly composed of a porous plate water distribution device (6), a supporting layer (7), composed of zeolite filter material layer (1), process aeration device (2), and backwash air distribution device (3); during operation, sewage enters from the water inlet (11), passes through the water inlet distribution device (3), Pass through the supporting layer (7), pass through the zeolite filter material layer (1) to remove suspended solids, COD, BOD ₅ and ammonia nitrogen, and then discharge from the water outlet (8), while the compressed air enters through (4) and passes through (2) Aeration provides oxygen for microbial growth; compressed air enters from the air inlet (5) during backwashing, clean water enters from the backwashing water inlet (10), and backwashing water is discharged from the drain (9); the equipment operates continuously, when After the water head loss of the filter reaches 1.5m, backwashing is carried out jointly with compressed air and effluent, and the backwashing effluent can be put into operation after clarification; the zeolite filter material is a natural clinoptilolite filter material, and its effective particle size is (3～ 6) mm, the density is (1900-2200) kg/m ³ , the hardness is 3-5 on the Mohs scale, and the ammonia ion exchange capacity is (3-6) kg/m ³ .