CN106219754B - A method for the removal and recovery of phosphorus in sewage based on aerobic granular sludge - Google Patents

Abstract

The invention discloses a method for removing and recovering phosphorus from sewage based on aerobic granular sludge, forming magnesium ammonium phosphate precipitation in the granular sludge in the anaerobic reaction zone, and adding a granular sludge selection zone after the secondary settling tank to select Magnesium ammonium phosphate is recovered from the discharge system for particles with a large precipitation rate. The aerobic granular sludge enriched in phosphorus accumulating bacteria is returned to the anaerobic zone to release phosphorus, and ammonium magnesium phosphate precipitates are formed inside the particles. Subsequently, the granular sludge mixture passes through the aerobic zone, and the granular sludge excessively absorbs phosphorus in the sewage through phosphorus-accumulating bacteria. After the sludge and water are separated in the secondary settling tank, the particles enter the granular sludge selection area, so that the granular sludge containing magnesium ammonium phosphate with a high sinking rate is selected and discharged from the system to recover phosphorus. The method of the invention simplifies the phosphorus recovery system; realizes the application of the aerobic granular sludge technology for phosphorus recovery; the system is simple, energy-saving, and has practical application and popularization value for the transformation of sewage phosphorus removal process.

Description

A method for the removal and recovery of phosphorus in sewage based on aerobic granular sludge

technical field

The invention relates to a method for removing and recovering phosphorus from sewage based on aerobic granular sludge, and belongs to the technical field of wastewater biological treatment.

Background technique

As a non-renewable resource, phosphate rock resources are facing the problem of depletion. The domestic and foreign estimates of phosphate rock resources are 30 to 350 years of exploitable utilization. Therefore, rational mining and recycling of phosphate rock resources have become more and more popular at home and abroad more attention. Phosphorus is an important component of living matter and an indispensable nutrient element in the ecosystem. On the one hand, the phosphorus discharged with sewage causes a huge waste of phosphorus resources. On the other hand, the eutrophication of water caused by excessive discharge of phosphorus is an urgent need. Environmental problems solved. Phosphorus discharged into water bodies by people in daily life accounts for 34% of the total phosphorus discharge, and industrial discharge is 7%. Therefore, the recovery of phosphorus in sewage treatment plants is of great significance for the recycling of phosphorus resources and the protection of water environment. However, the phosphorus removal and phosphorus recovery process of sewage treatment plants using flocculent sludge has problems such as complex operation, high cost, large land occupation, and large sludge output. Aerobic granular sludge is a dense microbial self-flocculation aggregate. As a new type of sewage treatment method, it has some advantages that traditional flocculent sludge does not have, such as: high microbial concentration, small reactor footprint, good settling performance, and at the same time Due to the limitation of matrix and dissolved oxygen transport in the particles, the layered structure can provide corresponding ecological niches for different microorganisms and realize different functions of the particles. With the metabolic reaction of microorganisms, different micro-environments are formed inside the particles, such as the change of pH value at different depths inside the particles, which can induce the crystal precipitation or enrichment of phosphorus inside the particles. Therefore, the invention discloses a method for removing and recovering phosphorus in sewage based on anaerobic and aerobic phosphorus removal technology and aerobic granular sludge technology.

Contents of the invention

Purpose of the invention: Aiming at the problems existing in the prior art, the present invention provides a method for the removal and recovery of phosphorus in sewage based on aerobic granular sludge, which combines the anaerobic and aerobic phosphorus removal process of traditional sewage treatment plants with aerobic granular sewage Sludge technology improves the efficiency of phosphorus recovery in sewage, and at the same time simplifies the complexity of the operation of the traditional phosphorus recovery process, reduces the energy consumption of the sewage phosphorus recovery process, reduces the sludge output, and reduces the area occupied by the process.

Technical solution: A method for the removal and recovery of phosphorus in sewage based on aerobic granular sludge. In the system, aerobic granular sludge is mixed with influent water and granular sludge in sequence—anaerobic phosphorus release and magnesium ammonium phosphate precipitation— —Aerobic excess phosphorus uptake by granular sludge—sedimentation and separation of mud and water—selective area for granular sludge—6-stage operation of particle backflow and discharge;

(1) In the anaerobic zone of the method, aerobic granular sludge produces phosphorus release under the induction of influent volatile fatty acids, and by adjusting the hydraulic retention time of the anaerobic zone for 1 to 3 hours, the mixed solution in the anaerobic zone The concentration of phosphorus is 50-110 mg/L, the pH inside the particles is 0.2-0.8 higher than that of the mixed solution, and the greater the distance from the surface of the particles, the higher the pH value. When the solubility product of ammonium magnesium phosphate inside the particles is greater than its conditional solubility product, the formation Crystals precipitate inside the particles;

(2) After the reaction in the anaerobic reaction zone is over, the mixed solution enters the aerobic zone, and the phosphorus accumulating bacteria in the granular sludge excessively absorb phosphorus in the mixed solution under aerobic conditions;

(3) After the aerobic phosphorus absorption is completed, the mixed solution enters the sedimentation tank for mud-water separation, the supernatant is discharged as treated water, and the precipitated and separated particles enter the granular sludge selection area;

(4) In the granular sludge selection area, since the granular sludge contains more phosphate precipitation, its sinking speed is relatively large (2.5-3.4m/min), and the sedimentation rate of the particles with less phosphate in the particles is relatively high. The velocity is relatively small (1.5-2.4m/min). Therefore, according to the difference in their sinking speed, different granular sludges are selected in the granular sludge selection area. Magnesium ammonium phosphate precipitates are recovered by the larger particulate removal system containing more phosphate precipitates.

The system includes an anaerobic zone, an aerobic zone, a sedimentation tank and an influent mixing zone, the influent mixing zone is adjacent to the anaerobic zone, the anaerobic zone is adjacent to the aerobic zone, the aerobic zone is connected to the sedimentation tank, and the sedimentation tank is connected to the particle The sludge selector and the granular sludge selector are connected to the influent mixing area through the granular sludge return system; among them, the agitator is installed in the anaerobic area, and the aeration system is installed in the aerobic area, and the aeration system is connected with the blower. The granular sludge selector is provided with a granular sludge discharge port.

Based on the traditional anaerobic and aerobic dephosphorization process, the present invention applies the granular sludge technology and increases the granular sludge selection area to realize the removal and recovery of phosphorus in sewage, simplifies the complexity of the traditional phosphorus recovery process, and reduces the process In the granular sludge selection area, the granular sludge containing more phosphate in the particles is selectively discharged for forest recovery; the phosphorus content of the granular sludge can reach 9% to 15%; it is different from the traditional flocculent The sludge phosphorus recovery process reduces sludge digestion and phosphate precipitation equipment, saves 40% of chemical costs and 25% of operating costs, and realizes energy-saving and efficient operation of the process.

Description of drawings

Fig. 1 is the removal and recovery system of sewage phosphorus based on aerobic granular sludge according to the embodiment of the present invention, in the figure: 01. anaerobic zone; 02. aerobic zone; 03. sedimentation tank; 04. granular sludge selector ;05. Granular sludge return system; 06. Inlet mixing zone; 07. Agitator; 08. Aeration system; 09. Blower; 10. Granular sludge discharge;

Figure 2 is the SEM photo and elemental analysis of phosphorus-containing granular sludge;

Figure 3 is the SEM photo and elemental analysis of phosphorus-containing granular sludge.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention, should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention, after having read the present invention, those skilled in the art will understand various equivalent forms of the present invention All modifications fall within the scope defined by the appended claims of the present application.

Example 1: The removal and recovery system of sewage phosphorus based on aerobic granular sludge, as shown in Figure 1, mainly includes anaerobic-aerobic-sedimentation-granular sludge selection four parts, using continuous operation; influent mixing zone 06 is adjacent to anaerobic zone 01, anaerobic zone 01 is adjacent to aerobic zone 02, aerobic zone 02 is connected to sedimentation tank 03, sedimentation tank 03 is connected to granular sludge selector 04, and granular sludge selector 04 flows back through granular sludge The system 05 is connected to the influent mixing zone 06; among them, the agitator 07 is set in the anaerobic zone 01, the aeration system 08 is set in the aerobic zone 01, the aeration system 08 is connected with the blower 09, and the granular sludge selector 04 There are 10 discharge outlets for granular sludge.

As shown in Figure 1, the anaerobic zone 01 maintains an anaerobic state, and a stirring device—agitator 07 is installed to keep the particles in a suspended state and mix them evenly with the influent; the aerobic zone 02 is equipped with an aeration system 08 to stir and ensure the particles Sludge dephosphorization requires mixed dissolved oxygen concentration; sedimentation tank 03 separates granular sludge and some flocculent sludge in the mixed solution; separated granular and flocculent sludge enters granular sludge selection area 04, and according to the sinking speed Different choices are made, the particles with higher sinking speed are discharged through the discharge system for phosphorus recovery, and the particles with smaller sinking speed and part of floc are returned to the anaerobic zone 01 for the next cycle of reaction. The specific operation process of this example is as follows: the reactor is inoculated with mature granular sludge and flocculent sludge with good phosphorus removal ability, and inoculated into the reactor according to the TSS ratio of 1:1, and the MLSS is 3500mg/L; C: N: P is 100:10:4, the hydraulic retention time of the anaerobic zone is controlled to 1-3 hours, the hydraulic retention time of the aerobic zone is 2-6 hours, and the hydraulic retention time of the granular sludge selection zone is 0.2-1 hour; The volume ratio of anaerobic zone to aerobic zone is 1:2～1:6.

Start the reactor and control the anaerobic state strictly in the anaerobic zone. Due to the release of phosphorus, the concentration of phosphorus in the mixed solution in the anaerobic zone 01 gradually approaches twice the concentration of ammonia nitrogen with the prolongation of the operation time. Due to the release of phosphorus and the volatile organic The acid was absorbed by the phosphorus accumulating bacteria, and the pH value of the solution gradually increased from 7.2 to 7.6; the dissolved oxygen concentration of the 02 mixed solution in the aerobic zone was controlled at 2-3 mg/L. After the system operated for 1 month, more white granular sludge appeared in the reactor, the particle density increased from 1.035g/mL of inoculated granules to 1.079mg/L, and the particle settling speed increased from 1.5m/min of inoculated granular sludge to 3.4m/min; the average phosphorus content in the particles measured by the digestion method increased from 3% to 6-1%; the phosphorus concentration in the effluent was lower than 0.5mg/L. Particles entering the granular sludge selection zone 04, through different settling speeds, the granular sludge with the highest settling speed is selected to discharge 3-5% of the granular sludge, and the rest of the particles and part of the flocculent sludge are returned to the anaerobic zone. The system has been running stably for 2 months, and the average particle size is 2.2mm. As shown in Figure 2, cocci and bacilli are the main particles in the particles, and some filamentous bacteria exist as the particle skeleton; there are many material transmission channels inside the particles; The interior of the granules is relatively dense, and the discharged granules have high phosphorus and magnesium content, and the local phosphorus content is as high as 15.8%. More than 90% of the phosphorus in the sewage can be recovered through the granular sludge, of which. Since there is no need for sludge digestion and chemical precipitation facilities, 40% of chemical usage is saved, sludge production is reduced, and 25% of operating costs are saved.

Example 2: The method used in this example is as in Example 1, wherein the nutrient ratio C:N:P in the influent water is 100:20:4, the hydraulic retention time of the anaerobic zone 01 is controlled for 1 to 3 hours, and the aerobic zone 02 is controlled. The hydraulic retention time is 3-6 hours, and the hydraulic retention time of granular sludge selection zone 04 is 0.2-1 hour; the pH of anaerobic zone 01 and aerobic zone 02 is controlled to be 7.5-7.8. At this time, the system excludes high concentrations of phosphorus and calcium in the granular sludge. As shown in Figure 3, the interior of the granules is denser, with cocci and brevibacteria as the mainstay. The phosphorus content of the sludge is 16.25%, and the calcium content is 25.28%. %.

Example 3: The method used in this example is as in Example 1. Granular sludge and flocculent sludge are inoculated into the reactor according to the TSS ratio of 2:1, and the MLSS is 3500 mg/L; the nutrient ratio in the influent is C: N: P is 100:10:4, the hydraulic retention time of control anaerobic zone 01 is 1-3 hours, the hydraulic retention time of aerobic zone 02 is 3-6 hours, and the hydraulic retention time of granular sludge selection zone 04 is 0.2-1 hour.

Example 4: The method used in this example is the same as in Example 1. The granular sludge and flocculent sludge are inoculated into the reactor according to the TSS ratio of 2:1, and the MLSS is 5000mg/L; the influent C:N:P is 100: 20:8, control the hydraulic retention time of anaerobic zone 01 to 1 to 2 hours, the hydraulic retention time of aerobic zone 01 to 2 to 6 hours, and the hydraulic retention time of granular sludge selection zone 04 to 0.2 to 1 hour.

Claims (3)

1. A method for removal and recovery of sewage phosphorus based on aerobic granular sludge, characterized in that: (1) Adopt continuous anaerobic-aerobic-sedimentation-sludge selective discharge and reflux in four stages of operation; in the anaerobic zone, aerobic granular sludge produces phosphorus release under the induction of volatile fatty acids in the influent, By adjusting the hydraulic retention time in the anaerobic zone, the concentration of phosphorus in the mixed solution in the anaerobic zone is 50-110mg/L, the pH inside the particles is 0.2-0.8 higher than that of the mixed solution, and the greater the distance from the particle surface, the higher the pH value. When the internal ammonium magnesium phosphate solubility product is greater than its conditional solubility product, crystals are formed and precipitated inside the particles; (2) After the reaction in the anaerobic reaction zone is over, the mixed solution enters the aerobic zone, and the phosphorus accumulating bacteria in the granular sludge excessively absorb phosphorus in the mixed solution under aerobic conditions; (3) After the aerobic phosphorus absorption is completed, the mixed solution enters the sedimentation tank for mud-water separation, the supernatant is discharged as treated water, and the precipitated and separated particles enter the granular sludge selection area; (4) In the granular sludge selection area, since the granular sludge contains more phosphate precipitation, its settling velocity is relatively large, and the phosphate precipitation in the particles is relatively small, so the settling velocity is relatively small. Therefore, according to its Different sedimentation speeds, different granular sludges are selected in the granular sludge selection area, the particles with smaller sedimentation speeds are returned to the anaerobic zone, and the particles with larger sedimentation speeds containing more phosphate precipitation are excluded from the system, and the Phosphorus recovery. 2. The removal and recovery method of sewage phosphorus based on aerobic granular sludge as claimed in claim 1, characterized in that: the hydraulic retention time in the anaerobic zone is controlled for 1 to 3 hours, and the hydraulic retention time in the aerobic zone is 2 to 6 hours. Hours, the hydraulic retention time of the granular sludge selection zone is 0.2 to 1 hour; the volume ratio of the anaerobic zone to the aerobic zone is 1:2 to 1:6. 3. A system for the removal and recovery method of sewage phosphorus based on aerobic granular sludge as claimed in claim 1, characterized in that: said system comprises anaerobic zone, aerobic zone, settling tank and influent Mixing area, the influent mixing area is adjacent to the anaerobic area, the anaerobic area is adjacent to the aerobic area, the aerobic area is connected to the sedimentation tank, the sedimentation tank is connected to the granular sludge selector, and the granular sludge selector is connected to the granular sludge return system through the granular sludge return system. The influent mixing area is connected; among them, an agitator is provided in the anaerobic area, an aeration system is provided in the aerobic area, the aeration system is connected with a blower, and a granular sludge discharge port is provided at the granular sludge selector.