WO2006041128A1

WO2006041128A1 - Organic wastewater treatment method and apparatus

Info

Publication number: WO2006041128A1
Application number: PCT/JP2005/018867
Authority: WO
Inventors: Hiroshi Tsuno; Masasumi Kawamura; Toshihiro Tanaka; Yasuhiro Honma; Kazuaki Shimamura; Minako Tanaka
Original assignee: Ebara Corporation
Priority date: 2004-10-13
Filing date: 2005-10-13
Publication date: 2006-04-20
Also published as: JP4428188B2; JP2006110424A; CN101132993A

Abstract

This invention provides anaerobic biological treatment method and apparatus that can stably treat hardly degradable component-containing organic wastewater in a high-performance manner for a long period of time. The anaerobic biological treatment method for organic wastewater comprises providing an upflow anaerobic reactor (2) packed with activated carbon, withdrawing a part of treatment water (9) from the top of the reactor (2), and circulating the withdrawn water to the reactor (2) in its bottom or raw water inflow part. In this method, the amount of the liquid circulated from the top of the reactor (2) to the bottom or raw water inflow part is regulated according to the treatment status of the reactor (2). For example, the concentration of inhibitory organic matter of the treatment water and/or the amount of methane gas in relationship with inflow CODcr in the reactor may be mentioned as the treatment status of the reactor (2). Seed sludge may be added to the reactor (2) simultaneously with or after packing of the activated carbon. A multistage gas-liquid-solid separation part (3) for separating the produced methane gas, the treatment water and the packing material provided in a vertical direction may be provided in the reactor (2), and, in addition, means for measuring the amount of the separated methane gas may be provided.

Description

Specification

Organic wastewater treatment method and treatment apparatus

Technical field

[0001] The present invention relates to an anaerobic treatment method and apparatus for detoxifying organic wastewater, and more particularly to a biological anaerobic treatment method and apparatus for organic wastewater containing a hardly decomposable component.

[0002] For the treatment of organic wastewater, an aerobic activated sludge method has been often used. However, in recent years, microbial decomposition under anaerobic conditions has been used from the viewpoint of energy saving and reduction of surplus sludge production. The present invention relates to a method and apparatus for anaerobically treating inhibitory organic-containing wastewater and dilute organic wastewater by charging activated carbon as an organic matter adsorbent microbial carrier in an upward flow reactor.

Background art

[0003] In the aerobic activated sludge method generally used in the treatment of organic wastewater, the amount of energy consumed for aeration is large and the amount of excess sludge is large. For this reason, microbial degradation under anaerobic conditions with little excess sludge and energy is being put into practical use. The mainstream reactor is an anaerobic upflow sludge blanket (UASB) reactor utilizing the self-granulating function of microorganisms, and an improved version thereof. However, in these reactors, it is essential to maintain self-granulating microorganisms (granules) in the reactor, and wastewater containing bioinhibiting organic substances, wastewater containing SS greater than lOOmgZL, and lOOOmgZL In the case of the following dilute organic wastewater such as COD, the amount of Dara-Yule dismantled is larger than the amount of anaerobic microorganisms grown in the reactor, and the amount of microorganisms in the reactor is reduced. Impossible.

[0004] Examples of anaerobic bioinhibitory organic substances include black mouth form, trichlorethylene, and P-toluic acid. As wastewater containing hardly decomposable and easily decomposable components, purified terephthalic acid wastewater is known. The main components are P-toluic acid and terephthalic acid, which are hardly degradable, and acetic acid and benzoic acid that are easily degradable [Sheng-Shung Cheng et al., Wat. Sci. Tech., Vol. 36, 73- 82 (1997)]. [0005] The method for anaerobically treating organic wastewater containing hardly decomposable components has the following problems.

[0006] (1) A hardly decomposable component for anaerobic microorganisms is a component that remains without being decomposed even after long-term treatment (approximately 3 months or more). Such persistent components are themselves inhibitory to anaerobic microorganisms (unless they are substrates), so COD removal rates are low in wastewater treatment, where high-degradable components account for a high percentage. there were.

[0007] (2) When processing difficult-to-decompose components by the UASB method, the granular sludge density decreases, and the granule sludge concentration decreases, and it tends to flow out of the reactor. «I will be difficult to continue.

Disclosure of the invention

Problems to be solved by the invention

[0008] The present invention provides a biological anaerobic treatment method and apparatus capable of being stably treated with high performance for a long period of time, targeting organic wastewater containing a hardly decomposable component, in view of the above prior art. Is an issue.

Means for solving the problem

[0009] In order to solve the above problems, in the present invention, biological anaerobic treatment of organic wastewater is performed using an upflow anaerobic reactor of a fixed filter bed or fluidized bed filled with activated carbon. Then, a part of the treated water is extracted from the top of the reactor and circulated to the bottom of the reactor or the raw water inlet, and the reaction is performed according to the treatment status of the upward flow anaerobic reactor. The organic wastewater treatment method is characterized by adjusting the amount of circulating fluid to be circulated from the top of the vessel to the bottom or the raw water inflow point. In the above treatment method, the treatment status of the upflow anaerobic reactor is, for example, the concentration of the inhibitory organic matter in the treated water and Z or the inflow to the reactor c

The amount of biogas generated relative to ODcr. Seed sludge can be added to the upward flow anaerobic reactor at the same time as or after filling with activated carbon. In addition, the upward flow anaerobic reactor has gas-liquid solid-separation units that separate the generated methane gas, treated water, and filler in multiple stages in the vertical direction, and measures the amount of separated methane gas generated. It is possible to have a measuring means.

[0010] Further, in the present invention, an upflow type anaerobic reactor of a fixed filter bed or a fluidized bed filled with activated carbon. And a biological anaerobic treatment apparatus for organic wastewater having a circulating liquid line for circulating a part of the treated water from the top of the reactor to the bottom of the reactor or a raw water inflow portion. Using the data from the water COD measurement means and Z or biogas generation amount measurement means, and the data from the COD measurement means and Z or biogas generation amount measurement means, the processing status of the upward flow type anaerobic reactor is calculated, There is also provided an apparatus further comprising means for adjusting the amount of circulating fluid based on the calculation result.

[0011] In the processing apparatus, the upward flow type anaerobic reactor has an angle with the main body wall of the reactor of 35 degrees or less downward, and each occupied area is more than half of the cross-sectional area of the reactor It is possible to provide a gas generation amount measuring device that has baffle plates in multiple stages and measures the amount of methane gas separated by the baffle plates.

Industrial applicability

[0012] The present invention uses an anaerobic upflow reactor charged with activated carbon having a circulation line. The concentration of the bioinhibiting organic substance can be controlled below the inhibitory concentration by the adsorption ability of the filled activated carbon, and microorganisms capable of decomposing the organic substance are adhered and grown on the activated carbon to regenerate the activated carbon. In addition, by circulating a part of the treatment liquid from the top of the reactor to the bottom of the reactor, the concentration of bioinhibitory organic substances in the influent can be diluted, and the linear velocity of the upward flow in the reactor can be introduced. The activated carbon carrier can be controlled so that it swells moderately and can be blocked by SS in the influent water. Furthermore, because the microorganisms involved in decomposition adhere to and grow on activated carbon, they can be stably applied to dilute wastewater where stable self-granulation of microorganisms is difficult and wastewater such as high-concentration SS. Depending on the wastewater to be treated, GSS (gas, treated water, filler separation equipment) is installed in multiple stages in the vertical direction in the reactor, so that the contact reaction between the raw water and the microorganisms involved in decomposition occurs in the lower part of the reactor. In addition to facilitating, the outflow of decomposed microorganisms and activated carbon to the treated water is minimized, resulting in a reactor with a high cell concentration.

[0013] The present invention is directed to bioinhibitory organic substance-containing wastewater, SS-containing wastewater of lOOmgZL or higher, and dilute organic wastewater such as COO of lOOOmgZL or lower. As an anaerobic treatment method for these wastewaters, an anaerobic filter bed method using granular activated carbon as a carrier is effective.

[0014] At the beginning of treatment, the concentration of bioinhibitory organic substances is hindered by the adsorption capacity of the packed activated carbon. It is below the harmful concentration and can be controlled. Furthermore, before reaching the saturated adsorption amount, anaerobic bacteria supplied with seed sludge and anaerobic bacteria adhering to and proliferated on activated charcoal enable adsorptive decomposition that performs long-term treatment under anaerobic conditions. Biological regeneration is also possible.

[0015] As an example of raw water, there is organic wastewater containing a substance that exhibits an inhibitory effect on anaerobic treatment depending on its concentration.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram of a processing flow of the present invention.

FIG. 2 is a graph showing the experimental results of Example 1.

FIG. 3 is a graph showing the experimental results of Example 2.

In FIG. 1, each symbol has the following meaning.

1: Raw water pipe, 2: Reactor, 3: Baffle plate, 4a, 4b: Separate sludge zone, 5: GSS section,

5a, 5b: Gas phase section, 6: Generated gas recovery piping, 7: Water seal tank, 8: Gas meter, 9: Treated water piping, 1

0: Antifoaming agent, 11: Gas holder, 12: Upper end of activated carbon, 15: Circulating fluid piping, 16: Circulating pump.

FIG. 1 illustrates a schematic configuration diagram of a processing flow in the present invention, and the present invention will be described in detail based on this diagram.

In FIG. 1, a cylindrical reactor 2 in which the raw water supply pipe 1 communicates and is closed at the top and bottom is fixed to one of the left and right side walls, and the other end is opposite to the other side. There is a baffle plate 3 extending while descending in the direction of the side wall. The baffle plates 3 are provided alternately at two left and right locations in the vertical direction, and form acute slanted segment sludge zones 4a to 4b between the reactor side walls. The downward angle Θ between the side wall of the reactor 2 and the baffle plate 3 is an acute angle of 35 degrees or less, and the occupied area is preferably 1/2 or more of the cross-sectional area of the cylindrical reactor. When the angle Θ exceeds 35 degrees, sludge or activated carbon carrier accumulates on the upper part of the baffle plate 3 in the sludge zones 4a and 4b, resulting in insufficient fluidity, and a dead space is formed. If the area force of the baffle plate 3 is less than or equal to that of the baffle plate 3, trapping of the generated gas becomes insufficient, causing problems in gas-liquid solid separation. In other words, the gas escapes upward from the center of the reactor 2, and the gas cannot be sufficiently accumulated in the GSS part (gas * liquid * solid separation part) 5 described later. [0020] The upper part of the divided sludge zones 4a, 4b forms a GSS section 5. The gas phase part 5a where the generated gas collects when the reaction starts is provided with an outlet of the generated gas recovery pipe 6 that communicates with the outside. Reference numeral 12 denotes the upper end surface of the filled activated carbon.

It should be noted that the discharge port of the generated gas recovery pipe 6 connected from the gas phase part 5a opens in the water of the water sealing tank 7 filled with water. The opening position is at an appropriate water depth with different water pressures, and the water seal tank 7 is provided with a gas meter 8 for measuring the flow rate of the gas discharged from the generated gas recovery pipe 6. A gas holder 11 is provided at the tip of the gas meter 8. A treated water pipe 9 for discharging the supernatant liquid is opened at the upper end of the reactor 2. The circulating liquid pipe 15 is connected to the treated water outflow part or the treated water pipe 9 at the top of the reactor, and is connected to the bottom of the reactor 2 through the circulating pump 16.

[0022] The reactor 2 is filled with activated carbon having an arbitrary particle diameter, and granular sludge or digested sludge made of anaerobic bacteria is used as seed sludge.

[0023] The activated carbon can be any of granular coal, pulverized coal, and pulverized coal, but since it is used over a long period of time, granular or crushed activated carbon that can maintain its shape even at a pressure of at least lkgZcm ³ is used as the crushing strength. preferable. The particle size of the activated carbon used is determined by the flow conditions in the reactor and the amount of microorganisms required. In other words, when the organic matter concentration in the raw water is low (COD: 3000 mgZL or less), the flow rate in the reactor can be increased, and a relatively large size, activated carbon with a particle size can be selected. In this case, activated carbon with a small particle size is selected. The activated carbon used in the present invention has an effective diameter of 0.05 mn! It is possible to use a material having a uniformity coefficient in the range of 1.2 to 2 in a range of ˜3 mm, preferably 0.2 mm to 0.7 mm.

[0024] If the amount of seed sludge is small, the treatment becomes unstable due to insufficient anaerobic bacteria growing on the surface of the activated carbon. Conversely, if the amount is too large, the amount of activated carbon is insufficient and the treatment at the start point is poor. Hesitate. Therefore, in order to maintain a stable treatment situation, it is clear from experimental results that it is preferable to cover 5% to 30%, preferably 10% to 20%, of seeded sludge with respect to the charged activated carbon capacity. It was.

[0025] Anaerobic treatment subject to the present invention includes medium temperature methane fermentation treatment with an optimum temperature of 30 ° C to 37 ° C, high temperature methane fermentation treatment with an optimum temperature of 50 ° C to 55 ° C, etc. Hate all temperature ranges Intended for temper treatment.

[0026] Raw water such as organic waste water containing a substance that inhibits anaerobic treatment also introduces a feeding pipe 1 into the reactor 2. The water flow rate inside reactor 2 is preferably 0.1 to 1 Om / h, including the circulating fluid! /.

[0027] In the reactor 2, bioinhibitory organic substances are decomposed by anaerobic bacteria, and decomposition gas is generated. The generated gas gathers separately in the GSS section 5 at the upper end of each of the sludge zones 4a to 4b, forms a gas phase section 5a in each, and reaches the water seal tank 7 through the generated gas recovery pipe 6. The amount of such generated gas is recorded by the gas meter 8 and sent to the gas holder 11. Part of the generated gas adheres to the biological carrier in the divided sludge zones 4a to 4b, reduces its apparent specific gravity, and accompanies sludge or activated carbon carrier to the water surface of the GSS section 5. Such generated gas forms bubbles and temporarily stays in the water surface gas phase portion 5b. The bubbles gathered in the water surface gas phase part 5b eventually burst, and the generated gas and sludge or activated carbon carrier were separated, and the sludge or activated carbon carrier recovered its original specific gravity and settled in water. It is discharged out of the system from the recovery pipe 6 via the water seal tank 7. Water that has been clarified by the decomposition of organic matter is discharged from the top of the reactor via the treated water pipe 9 and the circulating fluid is discharged to the bottom of the reactor via the circulating pump 16 via the circulating pump 16. Supplied.

[0028] Since the gas pressure in the gas phase portion 5a of each GSS portion 5 is different, the differential pressure may be adjusted in the water-sealed tank 7. The water seal pressure needs to be kept higher in the order closer to the raw water feed side. There are many ways to adjust the pressure of gas recovery besides using the water-sealed tank 7. For example, a pressure valve may be used

[0029] In the case of foaming raw water, the gas phase part 5a and the generated gas recovery pipe 6 in the GSS 5 are blocked, making it difficult to recover the generated gas. In such a case, foaming in GSS5 can be suppressed by adding antifoaming agent 10 to the inflow water of reactor 2 in advance. Compared to the method of dripping and spraying an antifoam in GSS5, this method is more effective for defoaming in a closed space. Anti-foaming agent 10 has anti-foaming effect according to raw water condition, and defoaming at medium temperature (30 ~ 35 ° C) or high temperature (50 ~ 55 ° C) suitable for defoaming of fermentation broth An antifoaming agent that does not lose its effect can be used. Types of antifoaming agents include silicone-based antifoaming agents and alcohol-based antifoaming agents Any of these can be applied.

[0030] When scum is likely to be formed due to the influence of the raw water state or the like, scum is formed on the surface and inside of the gas phase portion 5b in GSS5, making it difficult to recover the generated gas. In such a case, connect the generated gas blow-in pipe (not shown) to the generated gas recovery pipe 6 and supply the generated gas in the gas holder 11 to the GSS5 to destroy the scum or form the scum. Prevention can be performed.

[0031] The amount of circulating fluid, which is an important matter of the present invention, is adjusted by using the following methods alone or in combination.

[0032] (1) Method by concentration measurement

(a) Measure the biological inhibition concentration (C) of the target organic substance in advance by a batch experiment, etc.

0

Determine.

[0033] (b) Measure the concentration of the inhibitory organic matter flowing into the reactor with the raw water (C) and treated water (C).

In out, based on the following formula (1), the concentration of the inhibitory organic substance (C) at the reactor inlet

0 Set the circulating water volume Q so that it is in the lower range. Inhibitor organic concentration (C) is the same as C

r Less than 0 degrees is necessary, and in practice, C = lZ2C is preferable.

0

[0034] C <C = (C X Q + C X Q) Z (Q + Q) 'H (1)

0 in out r r

Q: Inflow water volume (m ³ Zd), Circulating water volume (m ³ Zd)

C, C, C, C: Inhibitor concentration or total organic concentration, unit (mgZ liter)

0 in out

(2) Gas generation method

(a) The amount of methane generated from the reactor (G) is calculated from the amount of gas generated from the gas meter and the methane concentration of the gas concentration meter, and the amount of COD removed (Δ COD) is calculated.

out

Calculate the residual organic matter concentration (C) of the treated water.

out

(b) The amount of COD removed can be obtained from the following equation (2).

(m ³ / d) ÷ 0.3 to 0.4 (kgZm ³ ) Equation (2)

(c) C is calculated by equation (3).

out

C = C-(A COD ÷ Q X 1000)

out in

(3) Formula force When the calculated C is introduced into Formula (1), the required circulating fluid volume is obtained.

out

Example Hereinafter, the present invention will be specifically described with reference to examples.

[0036] Example 1

Two series (A series and B series) of an upflow anaerobic reactor filled with activated carbon shown in Fig. 1 were used in the experiment.

[0037] The A-series and B-series apparatuses have the same structure. Two inclined baffle plates were attached, the angle between the apparatus side wall and the baffle plate 3 was 30 degrees, and an antifoaming agent was added to the raw water. The volume of the liquid layer was 100 liters. The temperature of the water in the reactor was controlled to 35 ° C. These two reactors were filled with 60 liters of granular activated carbon with an effective diameter of 0.3 mm and a uniformity coefficient of 1.5, and 10 liters of UASB granules (MLSS concentration 5%) treated with drinking wastewater as seed sludge. .

[0038] The raw water contains sodium acetate (750 mgZ liter in terms of COD) and terephthalic acid (CO cr

D is converted to 350mgZ liter) and added with inorganic nutrients (nitrogen, phosphorus, etc.) cr

Was used. In this mixed wastewater, the concentration range in which terephthalic acid, which is a hardly decomposable organic substance, is inhibitory, is 200 mgZ liters or more in terms of COD.

It has become clear.

[0039] In both series, the COD load of raw water (hereinafter simply referred to as COD load) was set at 3kgZm ³ Z days. Figure 2 shows the course of the experiment.

[0040] In the A series, from the start of treatment until the 90th day, the circulating water 15 was not allowed to flow into the reactor, but only the raw water (Q) was passed. In this case, the acetic acid was almost completely decomposed until the 60th day, whereas the removal of terephthalic acid gradually worsened, and on the 90th day, the terephthalic acid was converted to COD.

cr 80mgZ liter, residual concentration increased. After 91 days, less than the concentration range where terephthalic acid is inhibitory (170 mgZ liter cr in terms of COD)

The amount of treated water twice the amount of raw water (2Q) was circulated to the bottom of the reactor. As a result, the removal of terephthalic acid was improved, and on the 150th day, 10 mg / liter of COD was converted.

It became a tuttle.

[0041] In the B series, twice the amount of raw water treated water was circulated to the bottom of the reactor immediately after the start of the treatment. On the 30th day, terephthalic acid was 35mgZ liters, but the terephthalic acid of the treated water, which was less than the inhibitory concentration of terephthalic acid, also has high activity of anaerobic bacteria. lOmgZ liters or less could be maintained.

[0042] From the above results, when terephthalic acid, which is a hardly decomposable substance, is flowed into an upflow anaerobic reactor, the concentration range of terephthalic acid exhibits an inhibitory value as in the case of B series. When the treated water is circulated as described above, anaerobic decomposition is started in a short time.

[0043] On the other hand, in the A series of the period where the circulatory treatment was strong, the decomposition of terephthalic acid was slight. Thus, terephthalic acid was decomposed, and the effect of the present invention was confirmed.

[0044] Example 2

The experiment was started again using the raw water of Example 1 using the B series used in Example 1 above. Figure 3 shows the experimental results. By the 90th day, the COD load was ³ kgZm ³ Z days, the raw water volume was 150 liters Z days, and the circulating fluid volume was 300 liters Z days. The amount of methane gas generated was 55 liters / day, and the COD concentration of treated water was 35 mg / liter. From the 91st day, the COD load was set to 6 kg / mV day, and only the raw water volume was increased to 300 liter Z days while the circulating fluid volume was 300 liters Z day. Until the 100th day, the COD concentration of the treated water remained almost the same as 35 mgZL as the load increased, and the gas generation amount of the treated water increased, but thereafter, the concentration of terephthalic acid was inhibited. On the 150th day, methane gas generation decreased to 90 liters per day. The methane gas generation capacity at this time was also calculated, and the concentration of terephthalic acid was 200 mg Z liter, and it was judged that the concentration range of terephthalic acid exceeded the inhibitory concentration range. In fact, the COD of treated water was 205mgZ liter. Therefore, when the circulating fluid volume was adjusted to 600 liters / day on the 151st day, an increase in gas generation volume and a decrease in the concentration of terephthalic acid in the treated water were confirmed. On the 210th day, the methane gas generation volume was 115 liters Z The COD concentration in the treated water was 35 mgZ liters.

[0045] Example 3

The upflow anaerobic reactor filled with activated carbon shown in Fig. 1 was used in the experiment. The internal structure of the reactor, filled activated carbon and seed sludge are the same as in Example 1. The raw water was ethylene glycol wastewater from a chemical factory. The COD concentration of this raw water is about 1,00 cr

OmgZ retort.

[0046] Two types of experiments, RUN1 and RUN2, were performed. RUN1 passes and treats only raw water While no water was circulated, RUN2 circulated four times the amount of raw water to the bottom of the reactor. In inhibitory batch experiments, the concentration range where ethylene glycol wastewater is inhibitory is

The result is 4000mgZL or more in cr conversion.

[0047] For both RUN1 and RUN2, we examined the removal rate when the COD load was set to 10 kgZm ³ Z days and the limit load at which a removal rate of 80% or more was obtained.

[0048] In the RUN1 experiment, the removal rate when the COD load was 10 kgZm ³ Z days was 65 to 70%. To maintain a removal rate of 80%, a COD load of 7 kg / m ³ / day was reasonable.

[0049] In contrast, in the RUN2 experiment, the removal rate at a COD load of 10 kgZm ³ Z days was 85-90%. In order to maintain the removal rate of 80%, 20kgZm ³ Z days were obtained with the maximum COD load.

Claims

The scope of the claims

[1] A method for performing biological anaerobic treatment of organic wastewater using an upflow type anaerobic reactor filled with activated carbon or a fluidized bed, which is treated from the top of the reactor. A part of the water is extracted and circulated to the bottom of the reactor or the raw water inflow point, and is circulated from the top of the reactor to the bottom or the raw water inflow point depending on the treatment status of the upward flow type anaerobic reactor. Adjusting the amount of circulating fluid to be adjusted.

[2] The treatment status of the upflow anaerobic reactor is the concentration of inhibitory organic substances in the treated water and Z or the amount of methane gas generated relative to Z or CODcr flowing into the reactor. Organic wastewater treatment method.

[3] The organic wastewater treatment method according to claim 1 or 2, wherein the upward flow anaerobic reactor is charged with seed sludge simultaneously with or after filling with activated carbon.

[4] In the upward flow anaerobic reactor, gas 'liquid' solid separation parts for separating the produced methane gas, treated water and filler are installed in multiple stages in the vertical direction, and the amount of separated methane gas generated The method for treating organic wastewater according to claim 1, 2 or 3, further comprising a measuring means for measuring water.

[5] An upflow type anaerobic reactor filled with activated carbon or a fluidized bed, and a circulating fluid that circulates a part of the treated water from the top of the reactor to the bottom of the reactor or the raw water inflow point A biological anaerobic treatment system for organic wastewater with a line

OD measurement means and Z or biogas generation amount measurement means, and data from the COD measurement means and Z or biogas generation amount measurement means are used to calculate the treatment status of the upflow anaerobic reactor, and And a device for adjusting the amount of circulating fluid based on the calculation result.

[6] The upward flow type anaerobic reactor has a baffle plate whose angle with the main body wall of the reactor is 35 degrees or less downward, and each occupied area is one half or more of the cross-sectional area of the reactor. 6. The organic wastewater treatment apparatus according to claim 5, wherein a gas generation amount measuring device is provided for measuring the amount of methane gas separated by the baffle plate.