CN101250006A - A fluidized bed reactor for aerobic and anaerobic circulation treatment of landfill leachate - Google Patents

Abstract

The invention discloses a fluidized bed reactor for aerobic and anaerobic circulation treatment of landfill leachate. The fluidized bed reactor comprises a reactor inner cylinder (8), a reactor outer cylinder (9) and a three-phase separator (10); the reactor inner cylinder (8) is located at the lower end of the fluidized bed reactor, and the fluidized bed reactor The upper end of the inner cylinder (8) is connected with the cone (11), and the reactor outer cylinder (9) is composed of the peripheral space of the lower reactor inner cylinder (8) and the upper cone (11); the reactor outer cylinder (9) The upper and lower ends of all communicate with the reactor inner cylinder (8). With this reactor, after the waste water enters the inner cylinder of the reactor, it enters the aerobic zone, the anoxic zone, and the anaerobic zone successively, and undergoes a process similar to the inverted A ² /O process to achieve efficient removal of COD and simultaneous nitrification and denitrification The denitrification effect realizes the cyclic complementarity of the aerobic and anaerobic processes, greatly simplifies the process flow, saves floor space, and has the advantages of low investment and operating costs.

Description

A fluidized bed reactor for aerobic and anaerobic circulation treatment of landfill leachate

technical field

The invention belongs to waste water treatment, in particular to the treatment of landfill leachate.

Background technique

At present, about 93% of municipal solid waste in my country is disposed of by landfill. As time goes by, under the action of compaction and the biochemical action of microorganisms in these landfills, the pollutants contained in the landfill will dissolve with water and form landfill leachate together with rainfall. Since the composition of landfill waste in my country is much more complex than that in advanced countries, the composition of landfill leachate in my country is more complex, the pollution load is higher, and the treatment is more difficult. A small amount of landfill leachate will cause serious pollution to groundwater, surface water and the surrounding environment of landfills, directly threatening the safety of drinking water and industrial and agricultural water sources.

Due to the extremely complex composition of landfill leachate, including organic pollution components, inorganic pollution components, and some heavy metal pollution components, it shows strong comprehensive pollution characteristics, and the concentration of pollutants in landfill leachate is particularly high. The filtrate is difficult to treat it up to the standard. Therefore, a combination of different types of process methods is widely used at home and abroad to meet the requirements of emission standards. Usually, the combination of different types of methods is generally to use biological method or land method as pretreatment, and then use physicochemical method as posttreatment. In order to meet the increasingly stringent discharge standards for leachate treatment, the combination of this process has become a trend. The current research focus is mainly on the matching and coordination of various processes.

Regarding how to treat landfill leachate, there are mainly the following main problems:

(1) The amount of leachate varies greatly. In particular, the seasonal variation is very large, and the amount of water is relatively large in the rainy season. To solve this problem, the leachate collection and adjustment tanks are generally set up in landfills to carry out water quantity regulation and water quality homogenization treatment.

(2) The characteristics of leachate water quality vary greatly. Different landfills have great differences in water quality due to many factors, so the treatment method suitable for one landfill leachate may not necessarily be suitable for another landfill leachate treatment.

(3) The concentration of ammonia nitrogen in the leachate is high. And with the increase of landfill age, the content of other components is also very high. Especially old garbage wastewater has the characteristics of high ammonia nitrogen content, complex and high content of non-biodegradable COD substances.

(4) Landfill infiltration water contains a large amount of toxic organic matter, even including some environmental hormones.

(5) Insufficient carbon source in leachate. When the traditional biological denitrification treatment is adopted, the treatment effect is not ideal.

(6) The biodegradability of leachate from old landfills is poor.

(7) It is expensive.

In view of the greater harm of landfill leachate, the leachate of domestic waste sanitary landfills should meet higher discharge standards. Judging from the current treatment technology, the relatively mature treatment process that can make the treated effluent stably meet the national standard "Standards for Pollution Control of Domestic Waste Landfill Sites" (GB16889-1997) first-level discharge standard mainly includes anaerobic (UASB) + aerobic (SBR or MBR) + membrane (NF or RO) technology and evaporation or combustion technology. However, these processes have problems such as high cost, large investment, serious membrane fouling, high concentrate yield (approximately 30%) and intractability, which limit their popularization and application. Therefore, how to reduce costs and improve processing efficiency is becoming the main research direction of the industry. If the simultaneous aerobic anaerobic treatment and biological denitrification of landfill leachate can be realized in the same reactor system, the development is of great significance.

Contents of the invention

The purpose of the present invention is to provide a solution for the shortcomings of domestic and foreign landfill leachate anaerobic and aerobic treatment separated in different reactors, and need to combine sedimentation tanks and other advanced treatment technologies (such as membrane treatment: ultrafiltration, reverse osmosis, etc.) The landfill leachate realizes Oxic, Anoxic and Anaerobic cycles in the same bioreactor, and realizes activated sludge, gas, and treated water through the action of a three-phase separator. separation.

In order to achieve the above-mentioned purpose of the invention, the present invention has taken the following technical solutions:

A fluidized bed reactor for aerobic and anaerobic circulation treatment of garbage leachate, including a regulating tank, a sewage pump, air compression equipment, a microporous aeration head and a fluidized bed reactor, the upper port of the fluidized bed reactor has a large diameter , The diameter of the lower port is small, and there is a cone connecting the upper end and the lower end in the middle. The reactor inner cylinder, the reactor outer cylinder and the three-phase separator are arranged in the fluidized bed reactor; the reactor inner cylinder is located at the lower end of the fluidized bed reactor , there is a microporous aeration head at the bottom, and the microporous aeration head is connected with the air compression equipment; the bottom of the inner cylinder of the reactor is also connected with the regulating tank through the sewage pump; the upper end of the inner cylinder of the fluidized bed reactor is connected with the cone, and the reactor The outer cylinder is composed of the peripheral space of the inner cylinder of the lower end reactor and the cone at the upper end; the upper and lower ends of the outer cylinder of the reactor are connected with the inner cylinder of the reactor; the three-phase separator is fixed on the top of the fluidized bed reactor, and the lower end is connected with the outer cylinder. The upper end of the cylinder is connected, and the top of the fluidized bed reactor is located on the outside of the three-phase separator, and an overflow weir outlet is provided.

Compared with prior art, the present invention has the advantage:

(1) At the same time, the aerobic-anaerobic circulating fluidized bed (three-phase) bioreactor is designed to realize the three-phase flow by absorbing the structural advantages of the aerobic fluidized bed, UASB three-phase separator, and air-lift bioreactor. Integration of chemical bed functions.

(2) The treatment of wastewater by the aerobic-anaerobic circulating fluidized bed reactor passes through the aerobic zone, anoxic zone, anaerobic zone, and sedimentation zone in sequence, which is similar to the inverted (A ² /O) process in terms of technology. However, structurally, it overcomes the disadvantage that the traditional (A ² /O) process or the inverted (A ² /O) process requires at least three separate reactors, and greatly simplifies the process flow, saves floor space and investment costs.

(3) The present invention can realize the functions of highly efficient removal of organic matter and denitrification and dephosphorization in a single reactor. In particular, it can realize simultaneous nitrification and denitrification biological denitrification, so that the two processes can complement each other in terms of COD and oxygen supply and consumption, alkalinity production and consumption, and save operating costs.

(4) The present invention solves the difficult problem of A2/O process integration and simultaneous nitrification and denitrification in the field of waste water treatment in the world. It has important engineering application value for landfill leachate and other high ammonia nitrogen organic wastewater.

Description of drawings

Fig. 1 is aerobic anaerobic circulating fluidized bed bioreactor structure schematic diagram and flow process used in the present invention;

Fig. 2 is the removal effect of the method used in the present invention to waste water COD;

Fig. 3 is the rapid removal effect of the method used in the present invention to ammonia nitrogen;

Figure 4 shows the NO ₃ ^- -N removal effect of the method used in the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings, but the scope of protection claimed by the present invention is not limited to the scope described in the specific embodiments.

As shown in Figure 1, the aerobic anaerobic circulation treatment fluidized bed reactor of landfill leachate comprises regulating tank 1, sewage pump 2, air compression equipment 5, microporous aeration head 7 and fluidized bed reactor; The upper port of the fluidized bed reactor has a large diameter and the lower port has a small diameter, and there is a cone connecting the upper end and the lower end in the middle. The fluidized bed reactor includes a reactor inner cylinder 8, a reactor outer cylinder 9 and a three-phase separator 10; the reactor The inner cylinder 8 is located at the lower end of the fluidized bed reactor, and the bottom is provided with a microporous aeration head 7, which is connected to the air compression equipment 5; the bottom of the reactor inner cylinder 8 is also connected to the regulating tank 1 through the sewage pump 2 The upper end of the fluidized bed reactor inner cylinder 8 is connected with the cone 11, and the reactor outer cylinder 9 is composed of the peripheral space of the lower reactor inner cylinder 8 and the inner cavity of the upper cone 11; the upper and lower ends of the reactor outer cylinder 9 are all It communicates with the inner cylinder 8 of the reactor; the three-phase separator 10 is fixed on the top of the fluidized bed reactor, and the lower end is connected with the upper end of the outer cylinder 9, and the top of the fluidized bed reactor is located on the outside of the three-phase separator 10 and is provided with an overflow The weir outlet 12, the overflow weir outlet 12 is connected with the drainage pool 13, and the drainage pool is connected with the drain valve 14. A gas flow meter 6 is provided on the pipe connecting the microporous aeration head 7 and the air compression equipment 5; a water inlet valve 4 and a liquid flow meter 3 are respectively provided on the pipe connecting the reactor inner cylinder 8 and the regulating tank 1 . The lower part of the reactor inner cylinder 8 is equipped with activated sludge and landfill leachate.

When treating the landfill leachate, the waste water to be treated is first placed in the regulating tank 1, and then the waste water is introduced into the inner cylinder 8 of the reactor through the action of the sewage pump, and its flow is controlled by the liquid flow meter 3; Equipment 5, introduce air into the lower part of the reactor inner cylinder 8, control the flow rate of the compressed air through the gas flow meter, and blow the compressed air into the reactor inner cylinder 8 evenly through the microporous aeration head 7; the temperature control of the waste water It is 26-36°C. The compressed air moves upwards in the inner cylinder 8 of the reactor, driving the liquid between the inner cylinder 8 and the outer cylinder 9 of the reactor to cause a circular flow; after the waste water enters the inner cylinder of the reactor, it first enters the aerobic zone of the inner cylinder 8 of the reactor (Oxiczone), after that, at the top of the reactor due to the effect of the three-phase separator 10, the gas is removed by the three-phase separator 10, and the cone at the top of the reactor outer cylinder 9 forms an anoxic zone (Anoxic zone), and the waste water flows through After the anoxic zone, due to the consumption of oxygen by microorganisms, an anaerobic zone (Anaerobic zone) is formed between the inner cylinder 8 and the lower end of the outer cylinder 9 of the reactor. After passing through the anaerobic zone, due to the circulation of the fluid, the sewage enters the inner cylinder 8 At the lower end of the bioreactor, it enters the aerobic zone again. In this way, the sewage goes through a similar inverted (A ² /O) process in the same bioreactor. Therefore, it has a good effect of simultaneous nitrification and denitrification and denitrification. phosphorus removal effect. Since the top of the main reactor is equipped with a three-phase separator 10, and the upper part of the outer cylinder 9 is a cone structure, after the wastewater-activated sludge-gas three-phase suspension passes through the three-phase separator 10, an anoxic zone and sedimentation are formed in the cone part. After sedimentation, the wastewater passes through the overflow weir at the top of the reactor, and is discharged into the drainage pool through the outlet 12. Sediment is suspended in the cone section. If the influent water is fresh landfill leachate, the effluent water can meet the national primary or secondary discharge standards for secondary wastewater. If the influent is old waste landfill wastewater, it is difficult to meet the national second-level discharge standard, and advanced treatment methods can be adopted to make it meet the national first-level discharge standard.

The fluidized bed reactor for aerobic and anaerobic circulation treatment of landfill leachate above is used to treat landfill leachate from a distribution pool in a landfill in Guangzhou. The fluidized bed reactor for aerobic anaerobic circulation treatment of landfill leachate is made of stainless steel , the effective reaction volume is 0.52m ³ . The sludge in the inner cylinder 8 of the reactor is taken from the activated sludge of the leachate treated in the landfill through the combined anaerobic-aerobic process. The water quality of the percolation water has been monitored, tracked and studied for 5 years, and its main characteristics are shown in Table 1.

Table 1 Main properties of percolation water from a landfill in Guangzhou

project Percolation water in the reservoir area below the landfill Fresh percolation water from landfill outlet color dark grey Yellow-dark gray pH 7.5～8.5 6.0～9.0 Alkalinity (mg/l) 7739～12661 9039～22072 COD(mg/l) 8379～24288 31200～58050 BOD5(mg/l) 4300～11250 - NH ₃ -N (mg/l) 1604～2904 2041～3554 SS(mg/l) 1046～2424 -

COD _cr /NH ₃ -N ratio 4.02～9.52 8.95～32.1 BOD ₅ /NH ₃ -N ratio 2.66～4.19 - Biodegradability (BOD ₅ /COD _cr ) 0.43～0.68 -

During the treatment, the garbage wastewater to be treated was placed in the adjustment pool 1. Considering the domestication of various microorganisms of nitrification and denitrification at the same time, it is more advantageous to use wastewater with a lower concentration. diluted. Through the effect of the pump 2, the diluted waste water is introduced into the bottom of the aerobic anaerobic circulating fluidized bed (the lower part of the reactor inner cylinder 8) equipped with activated sludge and landfill leachate, and its flow is controlled by the liquid flow meter 3; Simultaneously, by air compressor 5, air is introduced into the bottom of the aerobic-anaerobic circulating fluidized bed (the bottom of reactor inner cylinder 8), the flow rate of compressed air is controlled by gas flow meter 6, and by microporous aeration head 7, Blow the compressed air evenly into the bottom of the aerobic-anaerobic circulating fluidized bed (the lower part of the reactor inner cylinder 8); the temperature of the waste water is controlled between 26-36°C. During the domestication and operation period of more than 140 days in the test, it was observed that the treatment effect has been stable and efficient, so the stock solution of landfill leachate (COD concentration of nearly 24000mg/l, ammonia nitrogen concentration range of 1500-2041mg/l) was used instead, and it was directly pumped without dilution. The aerobic anaerobic circulating fluidized bed of the present invention has been operated for more than 30 days, and the COD removal and simultaneous nitrification and denitrification denitrification effects have been kept stable and efficient. The specific conditions are as follows:

1. Treatment effect of COD _cr in landfill infiltration water

As shown in Figure 2: the concentration of COD _cr in the influent water of the reactor fluctuates between 568.6 and 3228mg/l most of the time (the stock solution of landfill leachate was used for appropriate dilution in the early stage), and the concentration in the later stage is nearly 24000mg with the stock solution (fast change) /l; the concentration of COD _cr in the reactor effluent has been relatively stable, generally below 250mg/l, with an average of 136.3mg/l, which has reached the national secondary discharge standard for similar wastewater (COD _cr <300mg/l), and reached It complied with the requirements of "one control and two standards" in Guangdong Province. The average removal rate of COD _cr is about 95.2% when the reactor tends to run stably, and the removal rate of COD _cr is less affected by system impact and other factors. This shows that the aerobic-anaerobic circulating fluidized bed reactor has a high and stable removal rate of COD _cr in landfill infiltration water.

2. Ammonia nitrogen treatment effect of landfill leachate

As shown in Figure 3: the concentration of ammonia nitrogen in the influent and effluent water of the reactor was between 108 and 200 mg/l at the beginning, and when the reactor operation tended to be stable, the concentration of influent water in the later period was 1500-2041 mg/l, but the concentration of ammonia nitrogen in the effluent was always at 25 mg/l Below l, the average is 8.46mg/l, reaching the national secondary discharge standard for similar wastewater (NH ₃ -N<25mg/l). During the process of reactor tending to stable operation, the removal rate of ammonia nitrogen has been above 90%, the highest is close to 100%, and the average removal rate during stable operation is 95.8%.

3. Effect of denitrification treatment on landfill leachate

As shown in Figure 4: at a low dissolved oxygen concentration (kept below 1.0mg/l), maintaining the same high concentration of ammonia nitrogen in the water, the concentration of ammonia nitrogen and nitrate nitrogen in the effluent can be controlled to a very low level, and the effluent Situations where the nitrate nitrogen concentration is lower than that of the influent. This shows that there is an obvious simultaneous nitrification and denitrification denitrification process in the reactor, and the denitrification rate exceeds 100%.

Claims (4)

1, a kind of percolate aerobic-anaerobic cycling treatment fluidized bed reactor comprises equalizing tank (1), sump pump (2), compressed air unit (5), micro porous aeration head (7) and fluidized-bed reactor; It is characterized in that described fluidized-bed reactor upper end bore is big, the lower end bore is little, the centre is provided with the cone-shaped body that connects top and bottom, is provided with reactor inner core (8), reactor urceolus (9) and triphase separator (10) in the fluidized-bed reactor; Reactor inner core (8) is positioned at the fluidized-bed reactor lower end, and the bottom is provided with micro porous aeration head (7), and micro porous aeration head (7) is connected with compressed air unit (5); Reactor inner core (8) bottom also is communicated with equalizing tank (1) by sump pump (2); Fluidized-bed reactor inner core (8) upper end is connected with cone (11), and reactor urceolus (9) is made up of the peripheral space of lower end reactor inner core (8) and the cone (11) of upper end; The upper and lower ends of reactor urceolus (9) all communicates with reactor inner core (8); Triphase separator (10) is fixed on the top of fluidized-bed reactor, and lower end and urceolus (9) upper end links, and the outside that the top of fluidized-bed reactor is positioned at triphase separator (10) is provided with overflow weir water port (12).

2, percolate aerobic-anaerobic cycling treatment fluidized bed reactor according to claim 1 is characterized in that the described connection micro porous aeration head 7 and the pipeline of compressed air unit 5 are provided with gas meter 6.

3, percolate aerobic-anaerobic cycling treatment fluidized bed reactor according to claim 1 and 2 is characterized in that also being respectively equipped with water intaking valve (4) and liquid meter (3) on the pipeline of described ligation device inner core (8) and equalizing tank (11).

4, percolate aerobic-anaerobic cycling treatment fluidized bed reactor according to claim 3 is characterized in that described overflow weir water port (12) is connected with blowoff basin (13), and blowoff basin (13) links to each other with water discharge valve (14).

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