CN108996672A - A kind of membrane pollution of membrane bioreactor and sludge yield control method - Google Patents

Abstract

The present invention relates to a kind of membrane bioreactor (MBR) control membrane fouling and sludge yield control method, include the following steps: 1) to prepare multi-functional composite bacteria agent with the one or more of Bdellovibrio class bacterium, yellow myxococcus, saccharomycete, bacillus, actinomyces；2) by multi-functional composite bacteria agent directly or after situ activation according to water, water quality, system temperature, stream plus investment aerobic membrane bioreactor.By adding a kind of multi-functional composite bacteria agent with the characteristics such as microorganism predation and extracellular hydrolase secretion capacity be strong into MBR reactor, cleavable microorganism wall simultaneously destroys sludge structure, inhibit biofilm formation on membrane reactor, reduce the content of extracellular polymeric (EPS) and dissolved phenols (SMP) in mud mixed liquid, promote muddy water synchronous degradation, effectively slow down the fouling membrane and control system sludge yield of MBR, achieve the effect that sludge concentration in stable reactor, mitigate sewage and Treatment of Sludge pressure, and on water quality treatment without influence.

Description

Membrane bioreactor membrane fouling and sludge yield control method

technical field

The invention relates to a control method, in particular to a method for controlling membrane pollution and sludge yield of a membrane bioreactor, and belongs to the technical field of sludge treatment by biotechnology.

Background technique

In recent years, membrane bioreactor (MBR), as an innovative and promising wastewater treatment process, has attracted increasing attention. It combines the physical separation of membranes with the biodegradation of activated sludge, and replaces the secondary settling tank in traditional activated sludge reactors with membrane separation devices to achieve efficient solid-liquid separation. Compared with the traditional wastewater biological treatment process, it has many advantages, including: good effluent quality, small footprint, etc. However, the membrane fouling problem generated during the operation of MBR will cost a lot of money, which greatly restricts its promotion.

Membrane fouling refers to the solute macromolecules, tiny particles and colloidal particles in water forming a filter cake layer on the membrane surface during the membrane filtration process. The accumulation of these pollutants will increase the filtration resistance, thereby increasing the energy consumption of the entire system. The causes of membrane fouling are complex. Some studies have found that the precipitation of soluble and refractory small molecule organic matter and the combination of sludge mixed liquid suspended solids (MLSS) on the membrane surface will form a gel layer, causing membrane fouling and membrane clogging. At the same time, it is believed that Extracellular polymeric substances (EPS) and soluble microbial products (SMP) are the most critical substances that cause membrane fouling.

At the same time, at present, the amount of excess sludge produced in the biochemical treatment of sewage in my country is huge. The sludge with a water content of 80% produced by China's urban sewage treatment plants exceeds 30 million tons every year, and the cost of sludge treatment is high, accounting for about 10% of sewage treatment. 25-40% of the plant's operating cost, which brings a lot of burden to the operation of the sewage treatment plant. At the same time, the pollution problem caused by improper sludge disposal in practical applications is relatively serious. Therefore, it is necessary to accelerate the transformation of sludge treatment and disposal methods. Only by controlling and reducing the amount of sludge generated from the source to the greatest extent is the best direction to meet the requirements of ecological environment protection and sustainable development.

Contents of the invention

The present invention aims at the technical problems existing in the prior art and provides a membrane bioreactor membrane fouling and sludge yield control method. The technical problem to be solved is to provide a membrane bioreactor membrane fouling mitigation and sludge yield control method. Yield control biotechnology, comprehensively using the principles of microbial lysis, EPS and SMP degradation, and inhibition of biofilm formation structure, etc., to achieve synchronous degradation of mud and water, reduce gel layer formation, alleviate membrane fouling and control system sludge yield, to achieve stable reactors The effect of internal sludge concentration reduces the cost of sewage and sludge treatment, and there is no secondary pollution and health and safety issues.

In order to achieve the above object, the technical scheme of the present invention is as follows: a membrane bioreactor membrane fouling and sludge yield control method, the method comprises as follows: One or more of Bacillus, Bacillus, and Actinomycetes to prepare multifunctional composite bacterial agents;

2) Feed the multifunctional composite microbial agent into the membrane bioreactor after direct or on-site activation.

As an improvement of the present invention, the concentration range of microorganisms in the multifunctional composite bacterial agent in the step 1) is 10 ⁶ -10 ¹³ pfu/mL.

As an improvement of the present invention, the dosage of the multifunctional composite bacterial agent in the step 2) is 0.05-0.5‰ of the treated water in the membrane bioreactor.

As an improvement of the present invention, the dosing frequency of the multifunctional composite bacterial agent in the step 2) is 2-10d.

As an improvement of the present invention, the membrane bioreactor in step 2) is an aerobic-membrane reactor, and the dosing point is set near the water inlet of the membrane bioreactor.

As an improvement of the present invention, in the membrane bioreactor, the initial sludge mass concentration needs to be controlled at 5-22 g/L, preferably 6-18 g/L, and phage microorganisms can prey by adhesion (Epibiotic predation ), invasive predation ( Endobiotic predation), wolf pack predation (Wolfpack group), etc. kill and degrade bacteria, such as Bdellovibrio -and-like organisms and Myxococcus xanthus . For example, Bdellovibrio is a small parasitic Gram-negative aerobic bacterium that preys on host bacteria, and it exists widely in nature. It can lyse most Gram-negative bacteria and a small number of Gram-positive bacteria, but not It can infect eukaryotic cells and is non-pathogenic to animals and humans. Bdellovibrio has been included in the list of microorganisms and beneficial bacteria allowed to be used in feed drug additives in the "Catalogue of Allowed Species of Feed Drug Additives". Myxococcus xanthus can prey on various prokaryotes, including cyanobacteria, various Gram-positive strains, and various Gram-negative bacteria such as Escherichia coli and Rhizobium. The conditions of high sludge concentration (5-22 g/L) and aeration and high dissolved oxygen environment (1-2mg/L) in the membrane bioreactor ensure the full contact between this type of bacteria and the host bacteria and are suitable for their growth. The Bdellovibrio and Myxococcus xanthus in the MBR reactor can proliferate and grow by preying on the host cells, and at the same time effectively slow down the increasing trend of the sludge concentration in the reactor with the extension of the sewage treatment time, so that the system sewage can be controlled. Sludge yield, greatly reducing the need and cost of subsequent treatment and disposal of excess sludge, and reducing the operation and treatment costs of the sewage treatment system. At the same time, the investment and operation costs of MBR are high, the cost of MBR membrane modules is high, and membrane fouling is prone to occur during the operation of the reactor. Proteins, polysaccharides and humic acids in sludge cell extracellular polymers (EPS) and soluble microbial products (SMP), these degradable refractory organics are precipitated and combined with sludge mixed liquid suspended solids (MLSS) It is enriched to the surface of the membrane to form a gel layer and biofilm, so it needs to be cleaned regularly. Bdellovibrio and Myxococcus xanthus in the multifunctional composite bacterial agent can hydrolyze proteins, sugars, nucleic acids and fatty acids in sludge by secreting extracellular proteases, polycanases, etc., and cooperate with their phagocytosis to reduce Sludge yield, while maintaining the sludge concentration in the reactor stably within the range of optimal control conditions, degrade the precursors and components generated by the gel layer on the surface of the membrane, effectively preventing the adhesion of microorganisms and the formation of the gel layer , Avoid membrane fouling, prolong the service life of the membrane, ensure the stability and long-term operation of MBR, and reduce its operating costs.

The patent of the invention mainly uses the principles of microbial cracking, EPS and SMP degradation, and sludge floc structure destruction to achieve the effects of alleviating membrane fouling and controlling the sludge yield of the system in an economical and efficient manner. By adding bacteriophage microorganisms (Bdellovibrio organisms and Myxococcus xanthus, etc.), the cracking of some microorganisms in the sludge and the simultaneous degradation of sludge and water are promoted, the sludge production rate is inhibited, and the sludge concentration in the reactor can be kept stable for a long time. Design the optimum concentration range, slow down the adhesion of microorganisms on the membrane and inhibit the formation of gel layer at the same time, effectively control membrane fouling. At the same time, the multifunctional composite bacterial agent proposed by the present invention can be used as high-efficiency protease and polycanase producing bacteria to strengthen the hydrolysis of EPS and SMP by compounding other strains, mainly including yeast, bacillus, and actinomycetes, and synergistically improve the The biological predation of bacteria and microorganisms can accelerate the cracking of sludge flocs and strengthen the degradation of EPS and SMP, which can greatly improve the effect of slowing down membrane fouling and prolong the action time of multifunctional composite bacteria agents. The components work synergistically to jointly improve the control effect of membrane fouling and sludge concentration. Compared with the existing technology, the multi-functional composite bacterial agent has the advantages of economy and universality, simple operation and long-lasting effect, which can significantly reduce sludge discharge and discharge frequency, reduce the pressure of sludge treatment and disposal, and have no secondary pollution and health and safety problems , reduce sludge discharge from the source and effectively slow down membrane fouling, which has multiple economic and environmental benefits.

Compared with the prior art, the advantages of the present invention are as follows: 1) The invention strengthens the self-lysis of endogenous microorganisms by adding multifunctional composite bacterial agents, promotes the synchronous degradation of mud and water, and effectively controls the sludge production rate of the system to ensure Control the sludge concentration in the reactor to be stable within the design concentration range for a long time without discharging the sludge, so as to operate normally for a long time; 2) This scheme inhibits the formation of biofilm and reduces the content of EPS and SMP in the sludge mixture, Effectively slow down membrane fouling, prolong the service life of the membrane, and reduce the operating cost of the MBR membrane process; 3) This scheme does not need to add chemical preparations such as enzyme preparations, chemical uncoupling agents, and oxidants, and is easy to operate and has no environmental, ecological, and health issues; 4 ) This scheme significantly reduces the amount and frequency of sludge discharge, reduces the pressure on sludge treatment and disposal, and reduces the cost of sludge treatment and disposal; 5) The effluent quality of the process is stable and good.

Description of drawings

Fig. 1 is the schematic diagram of embodiment 1 blank group and experimental group membrane fouling state;

Fig. 2 is a schematic diagram of the state of the daily sludge discharge of the system in Example 1.

Fig. 3 is the schematic diagram of the sludge growth state of the experimental group and the control group within 60 days of the embodiment 2 operation;

Fig. 4 is the schematic diagram of the effluent up-to-standard situation of 2 groups of experiments in the continuous operation of embodiment 2;

Detailed ways

In order to enhance the understanding and recognition of the present invention, the present invention will be further described and introduced below in conjunction with the drawings and specific embodiments.

Embodiment 1: a kind of membrane bioreactor membrane fouling and sludge yield control method, described method comprises as follows specifically: 1) with Bdellovibrio class organism, xanthococcus, Stoop Bdellovibrio, Starr One or more of Bdellovibrio, yeast, bacillus, and actinomycetes to prepare multifunctional composite bacterial agents;

2) Feed the multifunctional composite microbial agent into the membrane bioreactor after direct or on-site activation.

The concentration range of microorganisms in the multifunctional composite bacterial agent in the step 1) is 10 ⁶ -10 ¹³ pfu/mL.

The dosage of the multifunctional composite bacterial agent in the step 2) is 0.05-0.5‰ of the treated water in the membrane bioreactor.

The dosing frequency of the multifunctional composite bacterial agent in the step 2) is 2-10 days.

The membrane bioreactor in step 2) is an aerobic-membrane reactor, and the dosing point is set at the entrance of the membrane bioreactor.

In the membrane bioreactor, the initial sludge mass concentration needs to be controlled at 5-22 g/L, preferably 6-18 g/L6-10 g/L.

The multifunctional composite bacterial agent in the step 2) is added to the membrane bioreactor, and the final number of phage microorganisms in the system reaches more than 10 ³ pfu/mL.

Application Example 1

By simulating the MBR process in the laboratory, the effect of this method on mitigating membrane fouling and controlling sludge yield was verified.

The MBR process simulation device is mainly composed of water inlet tank; peristaltic pump, two parallel membrane bioreactor devices (including membrane modules); aeration system (air pump, air flow meter and aeration tube).

The inoculum sludge was taken from the thickening tank of a sewage treatment plant in Jiangsu Province. The test water is artificially distributed to simulate domestic sewage. The water quality parameters are COD 300-400 mg/L, NH ₄ ⁺ -N 30-40 mg/L, and pH 6.5-8.0. The membrane module is a polyvinylidene fluoride (PVDF) hollow fiber membrane with an average pore size of 0.1 μm. The hydraulic retention time is 10h, and the aeration intensity is 0.6m ³ /h. Run at room temperature. After 20-30 days of cultivation, the sludge concentration and properties in the reactor are basically stable. The MLSS concentration of the sludge in the test was kept around 8g/L.

After the operation is stable, set up the laboratory and the blank group. The experimental group was dosed with a multifunctional compound bacterial agent every 4 cycles, and the dosing ratio was 0.1‰ of the influent

Its ratio is as follows:

Bdellovibrio organisms, 80%;

Bacillus, 10%;

Actinomycetes, 10%.

Among them, the number of live bacteria of Bdellovibrio was 8×10 ¹⁰ pfu/mL.

Membrane fouling can be represented by transmembrane pressure (TMP). According to the design requirements of the membrane module, under the condition of constant flow suction, the suction pressure of the pipeline must be kept in the range of 5-50kPa to prolong the service life of the membrane. When the TMP exceeds 50kPa, the membrane module needs to be cleaned. When running the MBR under the action of constant pumping, the TMP will continue to rise as the membrane fouling increases.

The transmembrane pressure difference (TMP) value reflected in the membrane reactor can intuitively express the status of membrane fouling. The higher the transmembrane pressure difference value, the worse the filterability of the membrane and the lower the membrane flux.

As can be seen from Figure 1, the membrane fouling of the blank control group was serious after 12 days, and the TMP reached 50kPa; and the membrane fouling occurred after 31 days after the experimental group was inoculated with the multifunctional composite bacterial agent. The sustainable filtration performance is greatly enhanced, and the membrane service life is extended by nearly 2 times.

The control effect of sludge yield can generally reflect the growth of sludge through the daily sludge discharge, and it can be characterized by the change of sludge yield. The daily sludge discharge of the two groups of systems during the operation of the system is shown in Figure 4, and the sludge yield is shown in Table 1.

The daily sludge discharge of the system is shown in Figure 2. During the 30 days of operation, the system of the experimental group has always maintained a low daily sludge discharge, which is always lower than that of the blank group. It shows that the experimental group can maintain a low daily sludge growth, which can effectively control the sludge concentration of the system. As shown in Table 1, the sludge yields of the two groups of systems were 0.311 and 0.162 kg MLSS/kg COD, respectively, confirming that the sludge yield can be effectively controlled by adding multifunctional composite bacterial agents. The previous patent writing did not mention the amount of sludge discharge, but only explained the maintenance of sludge concentration, but here it is used as an indicator, whether to make corresponding adjustments to reduce the sludge production rate and residual sludge discharge.

Table 1

Application Example 2:

The experiment was carried out by adding multifunctional compound bacterial agent to the aerobic-membrane bioreactor of a certain urban sewage treatment plant. The water treatment capacity of the sewage plant is 10,000 m ³ /d. There are 2 groups of parallel membrane-bioreactor processes. As the experimental group, in the membrane bioreactor (aerobic pool) of the experimental group, a mixed multifunctional compound bacterial agent of Bdellovibrio, Myxococcus xanthus, Bacillus and Actinomycetes was added.

Among them, the ratio of multifunctional compound bacterial agent is as follows:

Bdellovibrio-like organisms, 65%;

Myxococcus xanthus, 15%;

Bacillus, 12%;

Actinomycetes, 8%.

Among them, the number of viable bacteria of Bdellovibrio and Myxococcus xanthus was (6~9)×10 ¹¹ pfu/mL.

First add multi-functional compound bacterial agent to 5 times of tap water to aerate and activate for 4 h, then feed it to the water inlet of the membrane bioreactor with a peristaltic pump.

After continuous operation for 2 months, the effluent quality and sludge concentration of the experimental group and the control group were detected every 5 days, and no sludge was discharged during the period. At the same time, the membrane fouling was measured every 10 days, and the membrane fouling was mainly characterized by the growth trend of the sequencing transmembrane pressure (TMP).

From the results in Table 2, it can be known that the addition of the multifunctional composite bacterial agent in the present invention can greatly slow down the fouling of the MBR membrane and prolong the service life of the membrane.

It can be seen from Figure 3 that after 10 days of continuous operation, the sludge properties of the experimental group were significantly improved, and the amount of sludge production began to decrease, and remained at 9000-1000 mg/L in the late stage of operation, while the sludge concentration of the control group showed a continuous increase trend, and finally reached 14000~15000mg/L, which shows that the addition of multifunctional compound bacterial agents can significantly reduce the growth rate of sludge in the biochemical treatment system and reduce the sludge production, which can effectively control the sludge production rate in the system and reduce the discharge of excess sludge reduce the pressure on the treatment and disposal of excess sludge in sewage treatment plants.

It can be seen from Figure 4 that during continuous operation, the effluent COD, NH ₄ ⁺ -N, TN, and TP of the two groups of experiments can all reach the first-class A standard. In the process of controlling membrane fouling and sludge yield by using multifunctional compound bacteria agent, the removal effect of the system on COD, total nitrogen and total phosphorus will not be affected, and the quality of the effluent is good, which can be used as reclaimed water.

Table 2

It should be noted that the above-mentioned embodiments are not used to limit the protection scope of the present invention, and equivalent replacements or substitutions made on the above-mentioned basis all belong to the protection scope of the claims of the present invention.

Claims (9)

1. a kind of membrane pollution of membrane bioreactor and sludge yield control method, which is characterized in that the method includes specifically such as Under: 1) with Bdellovibrio class biology, yellow myxococcus, saccharomycete, bacillus, actinomyces one or more prepare it is multi-functional multiple Combined bacteria agent；2) by multi-functional composite bacteria agent, directly or after situ activation stream adds investment membrane bioreactor.

2. membrane pollution of membrane bioreactor according to claim 1 is alleviated and sludge yield control method, it is characterised in that: In the step 1) in multi-functional composite bacteria agent microorganism concn range 10⁶—10¹³pfu/mL。

3. membrane pollution of membrane bioreactor according to claim 1 is alleviated and sludge yield control method, it is characterised in that: Multi-functional composite bacteria agent dosage in the step 2 is 0.05 ~ 0.5 ‰ of processing water in membrane bioreactor.

4. membrane pollution of membrane bioreactor according to claim 1 is alleviated and sludge yield control method, it is characterised in that: It is 2-10d that multi-functional composite bacteria agent in the step 2, which adds frequency,.

5. membrane pollution of membrane bioreactor according to claim 1 is alleviated and sludge yield control method, it is characterised in that: Membrane bioreactor in the step 2 is aerobic-membrane reactor, and the water inlet that membrane bioreactor is arranged in toss area is attached Closely.

6. membrane pollution of membrane bioreactor according to claim 1 is alleviated and sludge yield control method, it is characterised in that: The membrane bioreactor, initial sludge quality concentration need to be controlled in 5 ~ 22 g/L.

7. membrane pollution of membrane bioreactor according to claim 1 is alleviated and sludge yield control method, it is characterised in that: In the step 1) in multi-functional composite bacteria agent the toatl proportion of Bdellovibrio class biology and yellow myxococcus 70% or more.

8. membrane pollution of membrane bioreactor according to claim 1 is alleviated and sludge yield control method, it is characterised in that: Multi-functional composite bacteria agent dosage in the step 2 is 0.15 ~ 0.35 ‰ of processing water in membrane bioreactor.

9. membrane pollution of membrane bioreactor according to claim 1 is alleviated and sludge yield control method, it is characterised in that: The membrane bioreactor, initial sludge quality concentration need to be controlled in 6 ~ 18 g/L.