CN102211837A - Method for treating urban sewage through water step-feed multi-stage aeration biological denitrification and biological filter - Google Patents

Abstract

The invention relates to a multi-stage aeration biological denitrification method for treating sewage by subsection water inflow and a biofilter. The biofilter of the present invention is divided into three sections, each section includes anoxic zone and aerobic zone, the upper part of each zone is a packing zone, the bottom is a supporting layer, and ceramsite filter material is filled in the packing zone; between the zones Connected through the water-passing area, the aeration device in each space is an aerobic area, and the others are anaerobic areas, and the bottoms of the three anoxic areas have inlets. The defect that the aerated biological filter requires a relatively large reflux ratio is solved. The present invention integrates the technical advantages of the multi-stage AO activated sludge process and the biological aerated filter process, overcomes the shortcomings of each, obtains a more efficient sewage denitrification effect, and preferentially uses the sewage carbon source for denitrification denitrification Nitrogen reduces the aeration volume of the aeration system and reduces power consumption. For urban sewage with a COD of 150-200 mg/L and a TN (total nitrogen) of 40-50 mg/L, the effluent COD can be kept below 40 mg/L, TN can be kept below 13 mg/L, and ammonia nitrogen can be kept at 3 mg/L. Below L.

Description

Multi-stage aeration biological denitrification treatment method of urban sewage by subsection water inflow and biofilter

technical field

The invention relates to a method and device for biological denitrification treatment of urban sewage, in particular to a method for biological denitrification treatment of sewage by segmented water inflow and multi-stage aeration and a biological filter.

Background technique

The key to controlling water eutrophication and improving urban water environment is to control the discharge of pollutants, and urban sewage treatment plays a vital role. The main indicators of water eutrophication are TN and TP. Since the effect of chemical phosphorus removal is stable, how to solve the problem of biological nitrogen removal more effectively is imminent.

Before the present invention, there has been a multi-stage AO activated sludge process with multi-stage water inflow. This process has obvious denitrification effect, and the treated water can reach the first-class A standard in the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002). However, one is that the multi-stage AO activated sludge process of multi-stage water inflow has higher requirements on the carbon-nitrogen ratio of sewage, and the carbon-nitrogen ratio of sewage is generally required to be greater than 5; First, there is a problem that the utilization efficiency of sewage carbon sources is lower than that of the biofilm method; third, a sedimentation tank needs to be set up in the process, and the suspended solids (SS) in the sedimentation water is higher than that of the filtration method; Although the filter does not require sedimentation tanks and sludge return, it cannot achieve segmented water intake like the AO segmented water intake process, which effectively solves the problem of denitrification carbon source utilization. Similarly, before the present invention, there has been a biological aerated filter process, which has a strong ability to remove organic matter in sewage and has the effect of denitrification of sewage, but requires a larger reflux ratio (≥2) to have a better denitrification effect.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects, design and develop a multi-stage aerated biological denitrification method for urban sewage treatment and a biofilter.

Technical scheme of the present invention is:

The main technical steps of the multi-stage aeration biological denitrification treatment method for urban sewage by subsection water inflow are as follows:

(1) The sewage is divided into three parts and enters three sections of the biofilter, each section includes anoxic zone and aerobic zone;

(2) The first part of sewage and the return sewage are merged at the bottom of the first anoxic zone, and the effect of removing nitrate nitrogen in the return sewage occurs in the first anoxic zone;

(3) Then the sewage flows into the first aerobic zone through the first water-passing zone to remove sewage organic matter and ammonia nitrogen and convert them into nitrate nitrogen;

(4) The first part of sewage and the return sewage are merged into the second anoxic zone at the bottom of the second anoxic zone through the second water passing zone and the second part of the sewage to remove nitrate nitrogen in the sewage;

(5) Then the first part of the sewage, the return sewage and the second part of the sewage flow into the second aerobic zone through the third water passing zone, and remove the sewage organic matter and ammonia nitrogen and convert them into nitrate nitrogen;

(6) Then the first part of sewage, return sewage and the second part of sewage enter the bottom of the third anoxic zone through the fourth water passing zone and merge with the third part of sewage, enter the third anoxic zone, and remove nitrate nitrogen in the sewage ;

(7) Then the first part of the sewage, the return sewage, the second part and the third part of the sewage flow into the third aerobic zone through the fifth water passing zone, and the organic matter and ammonia nitrogen of the sewage are removed and converted into nitrate nitrogen;

(8) After the above treatment, part of the sewage is discharged through the outlet pipe, and the other part is returned to the bottom of the first anoxic zone through the return pipe.

Another technical scheme of the present invention is:

The main technical feature of the biofilter is that the biofilter is divided into three sections, each section includes an anoxic zone and an aerobic zone, the upper part of each zone is a packing area, the bottom is a supporting layer, and the filling area is filled with Put the ceramsite filter material; each area is connected through the water area, and the aeration device in each space is an aerobic area, and the others are anaerobic areas, and the bottom of the three anoxic areas has inlets.

The patent of the present invention is a segmented multi-stage aerated biological filter, which has three sections, each section is composed of anoxic zone and aerobic zone, and the raw sewage is divided into three parts to enter water from the bottom of the anoxic zone of each section; The three-stage biological aerated filter all enters water from the bottom and leaves water from the upper part; the anoxic zone consists of water distribution area, support plate and filter material layer from bottom to top. The support plate is equipped with filter head, support plate and filter material layer The support layer is in between; the aerobic area is the water distribution area, the support plate, and the filter layer from bottom to top. The filter head is installed on the support plate, and the support layer is between the support plate and the filter material layer. The water distribution area Perforated aeration tubes are installed at the bottom. After the sewage flows through the first-level anoxic zone, it flows into the first-level aerobic zone through the connecting zone, and then enters the second and third-level treatment zones in turn to complete the purification of sewage.

The essence of the technical innovation of the present invention is to integrate the technical advantages of the multi-stage AO activated sludge process of water inflow and the biological aerated filter process. The biological filter can't denitrify the sewage deeply. By combining the advantages of the two, the deficiencies of the two can be eliminated, and a more efficient sewage denitrification effect can be obtained. In particular, the denitrification effect of sewage with a carbon-to-nitrogen ratio between 3 and 5 is still significant, and the technical effect of 1 plus 1 greater than 2 has been achieved, and a sewage biological denitrification process technology with better treatment effect has been produced.

The invention solves the problem of the denitrification carbon source of urban sewage with low nitrogen-to-carbon ratio, preferentially uses the sewage carbon source for denitrification and denitrification, reduces the aeration volume of the aeration system, and reduces power consumption. For urban sewage with a COD of 150-200mg/L and a TN (total nitrogen) of 40-50mg/L, the effluent COD can be kept below 40mg/L, TN can be kept below 13mg/L, and ammonia nitrogen can be kept at 3mg/L. Below L, lower than the Class A standard in the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002).

Description of drawings

Fig. 1 ——Schematic diagram of multi-stage biological aerated filter with multi-stage water inflow in the present invention.

Each label in the figure shows:

The first anoxic zone 1, the first water-passing zone 2, the first aerobic zone 3, the second water-passing zone 4, the second anoxic zone 5, the third water-passing zone 6, the second aerobic zone 7, the second water-passing zone Four passing areas 8, the third anoxic area 9, the fifth passing area 10, the third aerobic area 11, the first supporting layer 12, the second supporting layer 13; the third supporting layer 14, the fourth Supporting layer 15, fifth supporting layer 16, sixth supporting layer 17, water inlet system 18, aeration system 19, outlet pipe 20, return pipe 21, return pump 22, backwashing system 23.

Detailed ways

The technical idea of the present invention is based on the principle of nitrification and denitrification of biological denitrification, and draws lessons from the concept of supplementing the denitrification carbon source in the anoxic section of the AO process, so as to combine with the biological aerated filter, and the two complement each other to produce Synergistic effect, so as to achieve better biological denitrification effect.

The details are as follows.

As shown in Figure 1:

The biofilter in the present invention is divided into three sections, each section has anoxic zone and aerobic zone; Oxygen zone 3, second supporting layer 13, second water passing zone 4; second section includes second anoxic zone 5, third supporting layer 14, third water passing zone 6, second aerobic zone 7, The fourth supporting layer 15, the fourth water-passing area 8; the third section includes the third anoxic area 9, the fifth supporting layer 16, the fifth water-passing area 10, the third aerobic area 11, and the sixth supporting layer 17; the water inlet system 18 is respectively connected to the bottom of each section; the aeration system 19 is arranged downwards from the top of each water passing zone respectively to the first aerobic zone 3, the second aerobic zone 7, and the third aerobic zone 11 The outlet pipe 20 is arranged on the top of the third aerobic zone 11; the return pipe 21 is connected to the bottom of the first anoxic zone 1 from the top of the third aerobic zone 11 through the backflow pump 22; the backwash system 23 communicates with each bottom of the segment. The above structure constitutes a biofilter.

The specific method is as follows:

The sewage is divided into three parts through the water inlet system 18 and enters the biofilter respectively. The first part of sewage enters the bottom of the first anoxic zone 1, the second part of sewage enters the bottom of the second anoxic zone 5, and the third part of sewage enters the third anoxic zone. The bottom of the oxygen zone 9; the first part of the sewage and the return sewage are merged at the bottom of the first anoxic zone 1, and the action of removing nitrate nitrogen in the return sewage occurs in the first anoxic zone 1; then it is treated in the first anoxic zone 1 The treated sewage flows into the first aerobic zone 3 through the first water-passing zone 2 to remove sewage organic matter and ammonia nitrogen into nitrate nitrogen. Here, the dissolved oxygen concentration in the water is kept at 2mg/L by the aeration system 19; the first part Sewage and backflow sewage are merged into the second anoxic zone 5 at the bottom of the second anoxic zone 5 through the second passing zone 4 and the second part of sewage to remove nitrate nitrogen in the sewage; then the first part of sewage, backflow sewage and The second part of sewage flows into the second aerobic zone 7 through the third water-passing zone 6, removes sewage organic matter and ammonia nitrogen and converts it into nitrate nitrogen, and keeps the dissolved oxygen concentration in water at 2 mg/L by the aeration system 19 here; then the second part A part of sewage, backflow sewage and the second part of sewage enter the bottom of the third anoxic zone 9 through the fourth water passing zone 8 and merge with the third part of sewage, enter the third anoxic zone 9, and remove nitrate nitrogen in the sewage; then The first part of sewage, the return sewage, the second part and the third part of sewage flow into the third aerobic zone 11 through the fifth water passing zone 10 to remove organic matter and ammonia nitrogen in the sewage and convert them into nitrate nitrogen. The aeration system 19 maintains dissolved oxygen in the water The concentration is 2 mg/L; after the above treatment, part of the sewage is discharged through the outlet pipe, and the other part is returned to the bottom of the first anoxic zone 1 through the return pipe 21 .

Claims (3)

1. The method for treating urban sewage with multi-stage aeration biological denitrification by subsections, the steps of which are as follows: (1) The sewage is divided into three parts through the water inlet system and enters the multi-stage biological filter respectively. The first part of sewage enters the bottom of the first anoxic zone, the second part of sewage enters the bottom of the second anoxic zone, and the third part of sewage enters the first anoxic zone. The bottom of the three anoxic zones is composed of three biofilters connected in series, and each section includes anoxic zone and aerobic zone; (2) The first part of sewage and the return sewage are merged at the bottom of the first anoxic zone, and the effect of removing nitrate nitrogen in the return sewage occurs in the first anoxic zone; (3) Then the sewage flows into the first aerobic zone through the first water-passing zone to remove sewage organic matter and ammonia nitrogen and convert them into nitrate nitrogen; (4) The first part of sewage and the return sewage are merged into the second anoxic zone at the bottom of the second anoxic zone through the second water passing zone and the second part of the sewage to remove nitrate nitrogen in the sewage; (5) Then the first part of the sewage, the return sewage and the second part of the sewage flow into the second aerobic zone through the third water passing zone, and remove the sewage organic matter and ammonia nitrogen and convert them into nitrate nitrogen; (6) Then the first part of sewage, return sewage and the second part of sewage enter the bottom of the third anoxic zone through the fourth water passing zone and merge with the third part of sewage, enter the third anoxic zone, and remove nitrate nitrogen in the sewage ; (7) Then the first part of the sewage, the return sewage, the second part of the sewage and the third part of the sewage flow into the third aerobic zone through the fifth water passing zone, and remove the sewage organic matter and ammonia nitrogen and convert them into nitrate nitrogen; (8) After the above treatment, part of all the sewage is discharged through the outlet pipe, and the other part is returned to the bottom of the first anoxic zone as backflow sewage through the return pipe. 2. The method according to claim 1, characterized in that the dissolved oxygen concentration in water in steps (3), (5), and (7) is 2 mg/L. 3. According to the biofilter used in the above method, it is characterized in that the biofilter is divided into three sections, each section includes anoxic zone and aerobic zone, the top in each zone is a packing zone, and the bottom is a supporting layer, The filling area is filled with ceramsite filter material; each area is connected through the water area, and the aeration device in each space is an aerobic area, and the rest is an aerobic area. There are inlets at the bottom of the three anoxic areas. .

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