A method for granulating photosynthetic bacteria using ferroferric oxide nanoparticles as carriers

Abstract

The present invention belongs to the technical fields of wastewater biological treatment and energy resource utilization, and specifically relates to a method for granulating a single pure strain of photosynthetic bacteria using ferroferric oxide nanoparticles as a carrier. By using ferroferric oxide nanoparticles as a carrier and combining hydraulic conditions to granulate the pure strain of photosynthetic bacteria into agglomerates, the granulated photosynthetic bacteria can be effectively separated from the liquid in the reactor, increasing the content of effective microorganisms in the wastewater treatment reactor and the stability of the system, thereby improving the efficiency of wastewater treatment and hydrogen production.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage biological treatment and energy resource utilization, and particularly relates to a photosynthetic bacteria granulation method using ferrosoferric oxide nanoparticles as carriers. Background Art

[0002] Photosynthetic bacteria ( 光合细菌 , PSB) wastewater treatment technology is a new type of sewage treatment and resource recovery technology that can effectively convert pollutants in sewage into high-value-added resource products in cells, and can also use high-concentration wastewater to produce hydrogen.

[0003] However, in this system, since most types of photosynthetic bacteria have poor aggregation ability, during the process of producing hydrogen using high-concentration sewage, most of the photosynthetic bacteria are in a suspended state and are difficult to separate through natural sedimentation. During the continuous operation of the hydrogen production reactor, the suspended microorganisms cannot be effectively separated from the supernatant and will continue to be flushed out with the effluent from the reactor, thereby reducing the content of effective microorganisms in the reactor and the stability of the system, resulting in poor resistance to shock loads, low sewage treatment and hydrogen production effects, and other problems. Therefore, in the photosynthetic bacteria hydrogen production technology, the research on the immobilization technology and separation technology of photosynthetic bacteria is one of the urgent needs to achieve continuous and stable operation of photosynthetic bacteria hydrogen production.

[0004] The reasons why photosynthetic bacteria are not conducive to aggregation are as follows: (1) Most photosynthetic bacteria are rod-shaped or spherical, with small size, smooth surface, and motility. They are mostly dispersed in liquid culture; (2) The negative charge on the surface of the bacteria makes aggregation difficult. The negative charge causes the formation of repulsive energy peaks on the surface of PSB bacteria, which prevents them from aggregating with each other; (3) The low production of extracellular polymers secreted by photosynthetic bacteria is not conducive to bacterial aggregation. Extracellular polymers play an important role in the mutual adhesion and aggregation between cells. The extracellular polymers secreted by photosynthetic bacteria in the stable period are mostly soluble and have very low production, which cannot adsorb and aggregate the bacteria; (4) The phototaxis of photosynthetic bacteria is not conducive to bacterial aggregation. Phototaxis is a directional movement that photosynthetic bacteria carry out to adapt to environmental changes. When the light source is evenly distributed, this characteristic of photosynthetic bacteria will allow them to exist in a dispersed state to obtain the largest area of ​​light exposure, rather than aggregating together to form aggregates. These reasons make it difficult to separate PSB from water in the cultivation of wastewater resource utilization, and the recovery rate is low.

[0005] Currently, immobilization technologies for photosynthetic bacteria treatment and hydrogen production include encapsulation, adsorption, and cross-linking. However, these technologies still have many shortcomings. Some encapsulation and cross-linking agents used in photosynthetic bacteria encapsulation or cross-linking can be toxic to bacterial activity. The large-scale production process of encapsulated particles is complex, and the mass transfer performance of the encapsulated particles is insufficient. Fluid erosion and microbial metabolism can cause the encapsulated particles to rupture and swell, making it difficult to maintain a long service life.

[0006] Therefore, it is urgent to develop a new method to overcome the difficulty in immobilizing photosynthetic bacteria in the existing technology. Summary of the Invention

[0007] The purpose of the present invention is to provide a granulation method for a pure photosynthetic bacteria hydrogen production and sewage degradation system using ferrosoferric oxide nanoparticles as a carrier. The method provided by the present invention can not only effectively granulate the photosynthetic bacteria into agglomerates and achieve the immobilization of the photosynthetic bacteria, but also further achieve effective separation from the supernatant in the reactor.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a granulation method for a pure photosynthetic bacteria hydrogen production and sewage degradation system using ferrosoferric oxide nanoparticles as a carrier, comprising the following steps:

[0010] S1, mixing ferroferric oxide nanoparticles with the wastewater to be treated and then introducing the mixture into a reactor, and inoculating photosynthetic bacteria;

[0011] S2. The granulation process includes the early stage of floc formation, the particle formation stage and the stable stage after particle formation;

[0012] When the total dosage of nano-ferroferric oxide is 0.05-1.0 g / L, in the early stage of floc formation, the initial COD concentration is 500-1000 mg / L, and the organic load is 0.1-0.5 kg COD / m 3 / d, rising velocity 2-5 m / h, hydraulic retention time 2-5 d; during the particle formation period, adjust the COD concentration to 1000-3000 mg / L, organic load 0.1-1.0 kg COD / m 3 / d, with an upward flow rate of 2-8 m / h; during the stabilization period after particle formation, the initial COD concentration is adjusted to 2500-8000 mg / L, and the organic load is 0.5-1.5 kgCOD / m 3 / d, rising velocity 5-10 m / h, hydraulic retention time 3-5 d;

[0013] When the total dosage of nano-ferroferric oxide is 1.0-2.0 g / L, the initial COD concentration is 500-2000 mg / L and the organic load is 0.1-0.5 kg COD / m 3 / d, rising velocity 3-6 m / h, hydraulic retention time 2-5d; during the particle formation period, adjust the COD concentration to 2000-6500 mg / L, organic load 0.5-1.5 kg COD / m 3 / d, with an upward flow rate of 3-8 m / h; during the stable period after particle formation, the COD concentration is adjusted to 6000-8000 mg / L and the organic load is 1.2-1.5 kg COD / m 3 / d, rising velocity 8-10 m / h, hydraulic retention time 3-5 d;

[0014] The photosynthetic bacteria are pure single photosynthetic bacteria.

[0015] Preferably, the photosynthetic bacteria is hydrogen-producing Rhodopseudomonas palustris 沼泽红假单胞菌 .

[0016] Preferably, the particle size of the ferrosoferric oxide nanoparticles is 10-100 nm.

[0017] Preferably, the total dosage of the ferrosoferric oxide nanoparticles is 0.05-2.0 g / L, the single dosage is 0.01-0.2 g / L, and the dosage is once every 10 days.

[0018] Preferably, the inoculation concentration of the photosynthetic bacteria is 0.5-2.0 g / L dry weight.

[0019] Preferably, the overall upward flow rate during the granulation process is in the range of 2.0-10.0 m / h. The influent COD concentration is 500-8000 mg / L, and the organic load is 0.1-1.5 kg COD / m 3 / d, hydraulic retention time is 2-5 days, and bacterial granule formation time is 80-112 days.

[0020] Preferably, the reactor is an upflow photobioreactor; the light source of the upflow photobioreactor is a mixture of red light and green light with a ratio of 4:1, the effective volume of the reactor is V≈1 L, the diameter d=0.06 m, and the cross-sectional area A=0.0028 m 2 The reactor adopts bottom-in and top-out, with the feed entering from the feed port at the bottom of the reactor and the water outlet located at the top. A peristaltic pump is set to control the feed and discharge flow rate and reflux circulation.

[0021] The invention also provides application of the method in wastewater treatment.

[0022] Preferably, the method promotes the production of hydrogen in wastewater.

[0023] Beneficial effects of the present invention:

[0024] The present invention uses ferroferric oxide nanoparticles (Fe3O4 NPs) as a carrier and for the first time creates a technology in which pure photosynthetic bacteria are granulated into clusters and produce hydrogen in a high-concentration wastewater treatment and hydrogen production system with the carrier as the core.

[0025] The present invention uses ferroferric oxide nanoparticles (Fe3O4 NPs) as the carrier material and utilizes the rising flow rate, water quality composition, hydraulic load, hydraulic retention time and other factors of the wastewater to achieve granulation and agglomeration. The final agglomerated particles have a diameter of mostly 400-800 microns, and the overall time for forming stable particle agglomerates is mostly around 80-112 days.

[0026] The granular form of the hydrogen-producing photosynthetic bacteria in this invention effectively separates the hydraulic retention time (HRT) from the sludge retention time (SRT), allowing for the accumulation of high concentrations of organisms. This overcomes the problem of bacterial colony loss and reduced hydrogen production efficiency caused by the inability to separate the HRT from the SRT in traditional photosynthetic biohydrogen production systems. Furthermore, the granules formed by the photosynthetic bacteria absorb light well, further improving hydrogen production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 The figure is a curve diagram showing the ratio of COD concentration in sewage of Comparative Example 1-2 and Example 5 over time;

[0029] Figure 2 The figure is a curve diagram showing the ratio of the average particle size of photosynthetic bacteria in sewage of Comparative Examples 1-2 and Example 5 as the stages change;

[0030] Figure 3 The sludge volume index SVI in the reactor changes with time in comparative examples 1-2 and example 5 30 Ratio curve graph. DETAILED DESCRIPTION

[0031] The present invention provides a method for granulating photosynthetic bacteria using ferroferric oxide nanoparticles as carriers. The method uses ferroferric oxide nanoparticles as carriers and combines water conservancy conditions including rising flow rate, water quality composition, hydraulic load and hydraulic retention time to granulate pure single photosynthetic bacteria into agglomerates. The pure single photosynthetic bacteria of the present invention is hydrogen-producing Rhodopseudomonas palustris. 沼泽红假单胞菌。

[0032] The granulation method of photosynthetic bacteria of the present invention is carried out in an upflow photobioreactor (UPBR), wherein the UPBR is made of transparent organic glass, and each reactor has an effective volume V≈1 L, a diameter d=0.06 m, and a cross-sectional area A=0.0028 m 2 . The light source is a mixture of red light (620-780 nm) and green light (492-560 nm), with a ratio of 4:1, to ensure the strain dominance of photosynthetic bacteria. The reactor adopts bottom-in and top-out, with the feed entering from the feed port at the bottom of the reactor and the outlet at the top. A peristaltic pump is set to control the inlet and outlet flow rates, and a reflux system is set up, using a peristaltic pump to control the reflux cycle. Prepare 1.5 L of artificial wastewater for each reactor every 3 days to supplement the feed. Use a fish tank brush to regularly clean the biofilm attached to the wall every week. The initial inoculation concentration of photosynthetic bacteria is 0.5-2.0 g / L dry weight, without any additions in the middle.

[0033] The granulation conditions of the photosynthetic bacteria of the present invention are that the particle size of the ferroferric oxide nanoparticles used is 10-100 nm, the total dosage is 0.05-2.0 g / L, the single dosage is 0.01-0.2 g / L, and the material is added once every 10 days, for a total of 3-10 additions; the overall rising flow rate range of the granulation process is 2.0-10.0 m / h. The influent COD concentration is 500-8000 mg / L, and the organic load is 0.1-1.5 kg COD / m 3 / d, hydraulic retention time is 2-5 d, and it takes 80-112 days for photosynthetic bacteria to form particles.

[0034] The photosynthetic bacteria granulation and agglomeration of the present invention utilizes pure photosynthetic bacteria. Currently, there is no technology or related research on the granulation and agglomeration of pure photosynthetic bacteria in high-concentration wastewater and the production of hydrogen. Other granulation and agglomeration processes for photosynthetic bacteria are all for treating wastewater and bacterial accumulation, while the main purpose of the present invention is to produce hydrogen, and its material metabolic pathways are different. Different metabolic pathways mean that the systems associated with them are different, which determines the properties and quality of the metabolic products and even the extracellular secretions, resulting in different results. The wastewater hydrogen production efficiency of the present invention refers to the ability to convert organic matter in wastewater into hydrogen by biological or chemical methods during the wastewater treatment process. The level of hydrogen production efficiency directly affects the effect of wastewater treatment and the output of hydrogen.

[0035] The present invention utilizes a different principle and process for granulation and agglomeration. It utilizes factors such as rising flow rate, water composition, hydraulic load, and hydraulic retention time to achieve granulation and agglomeration. With the carrier material as the core, the resulting agglomerated particles have a diameter of 450-700 microns, and the overall granulation time is typically around 80 days.

[0036] The granular form of the hydrogen-producing photosynthetic bacteria in this invention effectively separates the HRT from the SRT and allows for the accumulation of high concentrations of organisms. This overcomes the problem of bacterial colony loss and reduced hydrogen production efficiency caused by the inability to separate the hydraulic retention time and solid retention time in traditional photosynthetic biohydrogen production systems. Furthermore, the granules formed by the photosynthetic bacteria absorb light well, further improving hydrogen production efficiency.

[0037] The organic load in this invention refers to the amount of organic matter (measured in chemical oxygen demand (COD)) that can be processed or tolerated per cubic meter of reactor volume in a sewage treatment system per day. The organic load is proportional to the COD concentration of the influent. The higher the COD concentration, the greater the organic load at the same flow rate. Conversely, the lower the COD concentration, the smaller the organic load. Organic load (kg COD / m 3 / d) = water inlet flow (m 3 / day)×COD concentration (g / m 3 ).

[0038] The hydraulic retention time of the present invention ( 水力停留时间 HRT, refers to the average residence time of the sewage to be treated in the reactor. The tank volume / water flow rate is the hydraulic retention time; the sludge retention time ( 污泥 停留时间 , referred to as SRT) is the sludge age, which refers to the average residence time of microbial cells in the aeration tank.

[0039] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] The hydrogen-producing Rhodopseudomonas palustris of the present invention 沼泽红假单胞菌 Source: purchased from China General Microbiological Culture Collection Center (strain number: JCM 2524), and ferroferric oxide nanoparticles (Fe3O4 NPs) were commercially available (Zhongke Leiming Technology Co., Ltd.).

[0041] Unless otherwise specified, the production processes, experimental methods or detection methods involved in the embodiments of the present invention are all conventional methods in the prior art, and their names and / or abbreviations are conventional names in the field and are very clear and unambiguous in the relevant fields of use. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment to implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0042] The various instruments, equipment, raw materials or reagents used in the embodiments of the present invention are not particularly limited in their sources and are all conventional products that can be purchased through regular commercial channels or prepared according to conventional methods well known to those skilled in the art.

[0043] Example 1: Method for granulating photosynthetic bacteria using ferroferric oxide nanoparticles as carriers

[0044] The bacterial community is hydrogen-producing Rhodopseudomonas palustris R. 沼泽红假单胞菌 , ferroferric oxide nanoparticles (Fe3O4 纳米颗粒 , Fe3O4 NPs) as the added material to promote the sedimentation performance and aggregation of photosynthetic bacteria.

[0045] Upflow photobioreactor ( 上流式光生物反应器 UPBR) is made of transparent organic glass. Each reactor has an effective volume of V≈1 L, a diameter of d=0.06 m, and a cross-sectional area of ​​A=0.0028 m 2 . The light source is a mixture of red light (620-780 nm) and green light (492-560 nm), with a ratio of 4:1, to ensure the strain dominance of photosynthetic bacteria. The reactor adopts bottom-in and top-out, with the feed entering from the feed port at the bottom of the reactor and the outlet at the top. A peristaltic pump is set up to control the inlet and outlet flow rates. A reflux system is set up, and a peristaltic pump is used to control the reflux cycle. Prepare 1.5 L of artificial wastewater for each reactor every 3 days to supplement the feed. Use a fish tank brush to regularly clean the biofilm attached to the wall every week. The initial inoculation concentration of photosynthetic bacteria is 0.5-2.0 g / L dry weight, and no additions are made in the middle.

[0046] The particle size of ferroferric oxide nanoparticles is 10-100 nm, the total dosage is 0.05-2.0 g / L, the single dosage is 0.01-0.2 g / L, and the material is added once every 10 days, for a total of 6-10 additions. The overall rising velocity range is 2.0-10.0 m / h. The influent COD concentration is 500-8000 mg / L, and the organic load is 0.1-1.5 kg COD / m 3 / d, with a hydraulic retention time of 2-5 days. The granulation process lasts approximately 140 days, with mature granules formed after 80-112 days. The total duration is 270 days. After 140 days, the system COD load is varied to study pollutant removal effectiveness at COD concentrations of 3000-8000 mg / L. Example 2

[0047] When the single addition amount of ferroferric oxide nanoparticles is 40 mg / L, the addition time is once every 10 days, and the addition time is 6 times, with a total amount of 0.24 g / L. The concentration of inoculated photosynthetic bacteria is 0.5-1.0 g / L. The overall granulation conditions are as follows: the influent COD concentration is 500-3100 mg / L, the organic load is 0.13-1.0 kg COD / m 3 / d, with an upward flow velocity of 2.0-8.0 m / h and a hydraulic retention time of 3-5 days. The entire granulation process lasts about 120 days, with mature activated sludge flocs forming around the 42nd to 84th day, granules forming on the 104th day, and mature granules after 112 days.

[0048] In the early stage of floc formation (0-8 days), the influent COD concentration is 500-1000 mg / L and the organic load is 0.13-0.25 kgCOD / m 3 / d, the rising velocity is 2-5 m / h, and the hydraulic retention time is 4 days.

[0049] The particle formation stage is divided into the floc formation stage and the particle formation stage;

[0050] The floc formation period (9-84 days) is divided into four stages, and the water conditions are adjusted according to the status of photosynthetic bacteria in the reactor. In the first stage (9-29 days), the influent COD concentration is 1000-1600 mg / L and the organic load is 0.25-0.4 kg COD / m 3 / d, the rising velocity is 2-5 m / h, and the hydraulic retention time is 4 days; in the second stage (30-42 days), the influent COD concentration is 1600-2000 mg / L, the rising velocity is 2-6 m / h, and the organic load is 0.4-0.5 kg COD / m 3 / d, hydraulic retention time is 4 days; in the third stage (43-63 days), the influent COD concentration is 2000-2300 mg / L, and the organic load is 0.5-0.58 kg COD / m 3 / d, the rising velocity is 2-5 m / h, and the hydraulic retention time is 4 days. The fourth stage (64-84 days) is the mature stage, with the influent COD concentration of 2300-2500 mg / L and the organic load of 0.46-0.6 kg COD / m 3 / d, the rising velocity is 3-8 m / h, and the hydraulic retention time is 5 days.

[0051] During the particle formation stage (85-97 days), the influent COD concentration is 2500-2800 mg / L and the organic load is 0.8-1.0 kg COD / m 3 / d, the rising velocity is 5-8 m / h, the hydraulic retention time is 3 days. (98-134 days), the influent COD concentration is 2800-3100 mg / L, and the organic load is 1.2 kg COD / m 3 / d, with an upward flow velocity of 5-10 m / h and a hydraulic retention time of 3-5 days. The total duration was 270 days. After 140 days, the system COD load was increased to study the pollutant removal effect, with COD concentrations ranging from 3000-6000 mg / L. Example 3

[0052] When the single addition amount of ferroferric oxide nanoparticles is 60 mg / L, the addition time is once every 10 days, for a total of 10 additions, the total addition amount is 0.6 g / L, and the dry weight of the inoculated photosynthetic bacteria is 1.0-2.0 g / L.

[0053] The entire granulation process lasts about 100 days. Mature flocs can be formed on the 9th to 46th day, granules can be formed on the 64th to 72nd day, and mature granules can be formed after 80 days. The influent COD concentration is 500-5000 mg / L and the organic load is 0.25-1.3 kg COD / m 3 / d, the rising velocity is 2-10 m / h, and the hydraulic retention time is 2-5 d.

[0054] In the early stage of floc formation (0-8 days), the influent COD concentration is maintained at 500-1000 mg / L and the organic load is maintained at 0.25-0.5 kg COD / m 3 / d, the rising velocity is 2-4 m / h, and the hydraulic retention time is 2d;

[0055] The particle formation stage is divided into the floc formation stage and the particle formation stage;

[0056] The floc formation period (9-46 days) is divided into four stages, and the water conditions are adjusted according to the status of photosynthetic bacteria in the reactor. In the first stage (9-29 days), the influent COD concentration is 1000-1600 mg / L and the organic load is 0.25-0.4 kg COD / m 3 / d, the rising velocity is 2-5 m / h, and the hydraulic retention time is 4 days; in the second stage (30-45 days), the influent COD concentration is 1600-2000 mg / L, and the organic load is 0.32-0.4 kg COD / m 3 / d, the rising velocity is 2-5 m / h, and the hydraulic retention time is 5 d.

[0057] Particle formation stage: In the first stage (46-66 days), the influent COD concentration is 2000-2200 mg / L and the organic load is 0.5-0.55 kg COD / m 3 / d, the rising velocity is 5-8 m / h, and the hydraulic retention time is 4 days. In the second stage (67-85 days), the influent COD concentration is 2200-3000 mg / L, and the organic load is 0.73-1.0 kg COD / m 3 / d, the rising velocity is 5-8 m / h, and the hydraulic retention time is 3 days.

[0058] After particle formation (86-98 days), the influent COD concentration is 3000-4000 mg / L and the organic load is 1.0-1.3 kgCOD / m 3 / d, the rising velocity is 6-10 m / h, the hydraulic retention time is 3 days; (99-135 days), the influent COD concentration is 4000-5000 mg / L, and the organic load is 1.0-1.3 kg COD / m 3 The study lasted 270 days, with a flow rate of 6-10 m / h and a hydraulic retention time of 4 days. Pollutant removal was studied after 140 days, with COD concentrations ranging from 3000 to 6000 mg / L. Example 4

[0059] When the single addition amount of ferrosoferric oxide nanoparticles is 150 mg / L, the addition time is once every 10 days, for a total of 10 additions, the total addition amount is 1.5 g / L, and the dry weight of photosynthetic bacteria is inoculated at 1.0-2.0 g / L. The entire granulation stage lasts for about 100 days. Mature flocs can be formed on the 7th to 10th day, granules can be formed on the 16th to 20th day, and mature granules can be formed after 80 days. The influent COD concentration is 1000-8000 mg / L, and the organic load is 0.25-1.5 kg COD / m 3 / d, the rising velocity is 3-10 m / h, and the hydraulic retention time is 2-5 d.

[0060] In the early stage of floc formation (0-7 days), the influent COD concentration is maintained at 1000-2000 mg / L and the organic load is maintained at 0.25-0.5 kg COD / m 3 / d, the rising velocity is 3-6 m / h, and the hydraulic retention time is 4 days;

[0061] During the particle formation stage, water conditions are adjusted according to the status of photosynthetic bacteria in the reactor. In the first stage (9-29 days), the influent COD concentration is 2000-3000 mg / L and the organic load is 0.5-1.5 kg COD / m 3 / d, the rising velocity is 3-5 m / h, and the hydraulic retention time is 2 days; in the second stage (30-42 days), the influent COD concentration is 3000-4500 mg / L, and the organic load is 1.0-1.5 kg COD / m 3 / d, the rising velocity is 3-6 m / h, and the hydraulic retention time is 3 days; in the third stage (43-63 days), the influent COD concentration is 4500-6000 mg / L, and the organic load is 0.9-1.2 kg COD / m 3 / d, the rising velocity is 6-8 m / h, and the hydraulic retention time is 5 days. In the fourth stage (64-84 days), the influent COD concentration is 6000-6500 mg / L, and the organic load is 1.2-1.3 kg COD / m 3 / d, the rising velocity is 6-8 m / h, and the hydraulic retention time is 5 days.

[0062] After particle formation (85-105 days), the influent COD concentration is 6500-7000 mg / L and the organic load is 1.3-1.4 kgCOD / m 3 / d, the rising velocity is 8-10 m / h, and the hydraulic retention time is 5 days; on the 106th-136th day, the influent COD concentration is 7000-7800 mg / L, and the organic load is 1.4-1.5 kg COD / m 3 The study lasted 270 days, with a flow rate of 8-10 m / h and a hydraulic retention time of 5 days. Pollutant removal was studied after day 140, with COD concentrations ranging from 3000 to 6000 mg / L.

[0063] Example 5: Method for granulating photosynthetic bacteria using ferroferric oxide nanoparticles as carriers

[0064] The treated wastewater was inoculated with 1.5 g / L of photosynthetic bacteria. The dosage of ferroferric oxide nanoparticles was 10 mg / L, and the dosage was once every 10 days, for a total of 5 times, with a total dosage of 0.05 g / L. The influent COD concentration was 900-3000 mg / L, and the organic load was 0.18-1.0 kg COD / m 3 / d, the rising flow velocity is 3-8 m / h, and the hydraulic retention time is 3-5d.

[0065] Adjust the water conditions according to the status of photosynthetic bacteria in the reactor. In the first stage (0-10 days), maintain the influent COD concentration at 900 mg / L and the organic load at 0.18 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 5 d; in the second stage (11-31 days), the influent COD concentration is 2000 mg / L, and the organic load is 0.5 kg COD / m 3 / d, the rising velocity is 3m / h, and the hydraulic retention time is 5 days; in the third stage (32-47 days), the influent COD concentration is 2500 mg / L, and the organic load is 0.6kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 5 d; in the fourth stage (48-69 days), the influent COD concentration is 3000 mg / L, the organic load is 0.7 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 3 days. In the fifth stage (70-85 days), the influent COD concentration is 3500 mg / L and the organic load is 0.8 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 3 days.

[0066] In the sixth stage, photosynthetic bacteria in the flocs began to form particles, and in the seventh stage, stable photosynthetic bacteria particles were formed. In the sixth stage (86-101 days), the influent COD concentration was 4000 mg / L and the organic load was 0.9 kg COD / m 3 / d, the rising velocity is 6 m / h, and the hydraulic retention time is 3 days. In the seventh stage (102-138 days), the influent COD concentration is 3000 mg / L, the organic load is 1.2 kg COD / m 3 / d, with an upward flow velocity of 8 m / h and a hydraulic retention time of 3 days. The total duration was 270 days. After the 140th day, the system COD load was increased to study the pollutant removal effect. The COD concentration was 3000-6000 mg / L. Comparative Example 1

[0067] Comparative Example 1 was set up based on Example 5. Comparative Example 1 was a treatment system in which no nano-ferroferric oxide was added, and granulation was performed solely by relying on organic load, rising flow rate, etc.

[0068] The wastewater to be treated is inoculated with 1.5 g / L of dry weight of photosynthetic bacteria. The influent COD concentration is 900-3000 mg / L and the organic load is 0.18-1.0 kg COD / m 3 / d, the rising velocity is 3-8 m / h, and the hydraulic retention time is 3-5 d.

[0069] In the first stage (0-10 days), the influent COD concentration was maintained at 900 mg / L and the organic load was 0.18 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 5 d; in the second stage (11-31 days), the influent COD concentration is 2000 mg / L, and the organic load is 0.5 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 5 d; in the third stage (32-47 days), the influent COD concentration is 2500 mg / L, and the organic load is 0.6 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 5 d; in the fourth stage (48-69 days), the influent COD concentration is 3000 mg / L, the organic load is 0.7 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 3 days. In the fifth stage (70-85 days), the influent COD concentration is 3500 mg / L and the organic load is 0.8 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 3 days. In the sixth stage (86-101 days), the influent COD concentration is 4000 mg / L and the organic load is 0.9 kg COD / m 3 / d, the rising velocity is 6 m / h, and the hydraulic retention time is 3 days. In the seventh stage (102-138 days), the influent COD concentration is 3000 mg / L, the organic load is 1.2 kg COD / m 3 / d, with an upward flow velocity of 8 m / h and a hydraulic retention time of 3 days. The total duration was 270 days. After the 140th day, the system COD load was increased to study the pollutant removal effect. The COD concentration was 3000-6000 mg / L.

[0070] Comparative Example 1 is only a process of forming single homozygous photosynthetic bacteria particles. Although its hydraulic conditions are the same as those of Example 5, it lacks the assistance of the ferroferric oxide nanoparticle carrier. Therefore, the formation of stable photosynthetic bacteria particles in this comparative example requires a long wait. Comparative Example 2

[0071] Comparative Example 2 was set up based on Example 5. In this comparative example, the dosage of the ferrosoferric oxide nanoparticles was higher than the implementation range, and the hydraulic conditions remained unchanged.

[0072] The treated wastewater was inoculated with 1.5 g / L of dry weight of photosynthetic bacteria. The dosage of ferroferric oxide nanoparticles was 200 mg / L, and the dosage was once every 5 days, for a total of 15 times, with a total dosage of 3.0 g / L. The influent COD concentration was 900-3000 mg / L, and the organic load was 0.18-1.0 kg COD / m 3 / d, the rising velocity is 2-8 m / h, and the hydraulic retention time is 3-5 d.

[0073] In the first stage (0-10 days), the influent COD concentration was maintained at 900 mg / L and the organic load was 0.18 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 5 d; in the second stage (11-31 days), the influent COD concentration is 2000 mg / L, and the organic load is 0.5 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 5 d; in the third stage (32-47 days), the influent COD concentration is 2500 mg / L, and the organic load is 0.6 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 5 d.

[0074] The formation of photosynthetic bacteria granules was advanced and began in the fourth stage. In the fourth stage (48-69 days), the influent COD concentration was 3000 mg / L and the organic load was 0.7 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 3 days. In the fifth stage (70-85 days), the influent COD concentration is 3500 mg / L and the organic load is 0.8 kg COD / m 3 / d, the rising velocity is 3 m / h, and the hydraulic retention time is 3 days.

[0075] Over time, the photosynthetic bacteria granules of this comparative example became unstable in the sixth stage. In the sixth stage (86-101 days), the influent COD concentration was 4000 mg / L and the organic load was 0.9 kg COD / m 3 / d, the rising velocity is 6 m / h, and the hydraulic retention time is 3 days. In the seventh stage (102-138 days), the influent COD concentration is 3000 mg / L, the organic load is 1.2 kg COD / m 3 / d, with an upward flow velocity of 8 m / h and a hydraulic retention time of 3 days. The total duration was 270 days. After the 140th day, the system COD load was increased to study the pollutant removal effect. The COD concentration was 3000-6000 mg / L.

[0076] While Comparative Example 2 employed the same carrier and hydraulic conditions as Example 5, the amount of ferrosoferric oxide nanoparticles used exceeded the limits of the present invention. Although photosynthetic bacterial particles appeared to form briefly, the stability of the formation process was much lower than that of Example 5.

[0077] Comparison of Example 5 with Comparative Examples 1-2 shows that mature and stable granules are formed after the 90th day. In Example 5, mature granules with a particle size of 450-700 μm are formed after the middle and late stages of the 6th stage (after 90 days) (the dominant particle size range of mature granular sludge is mostly between 450-3000 μm). Correspondingly, after the 90th day, the SVI of the granules is 30 The SVI of granular sludge is about 80-110 mL / g (the SVI of granular sludge is usually between 80-150 mL / g), reaching a stable level. As for the COD removal rate, after the 134th day, the COD removal rate reached more than 80%, and the COD content was significantly lower than the two comparative examples. In comparative example 1, the time when particles with a particle size of ≥450 μm were formed was about the beginning of the seventh stage (almost no particles with a particle size of ≥450 μm were formed), the overall particle size was significantly lower than that of the embodiment, and the SVI was 30 Basically lower than 60 mL / g. In comparative example 2, the time to form particles with a particle size of ≥450 μm is about the seventh stage (about 106 days), and the overall particle size is significantly lower than that of the embodiment, and SVI 30 It is basically lower than 60 mL / g, indicating that its sedimentation performance is poor.

[0078] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for granulating photosynthetic bacteria using ferroferric oxide nanoparticles as carriers, characterized in that: The following steps are involved: S1, mixing ferroferric oxide nanoparticles with the wastewater to be treated and then introducing the mixture into a reactor, and inoculating photosynthetic bacteria; S2. The granulation process includes the early stage of floc formation, the particle formation stage and the stable stage after particle formation; When the total dosage of nano-ferroferric oxide is 0.05-1.0 g / L, in the early stage of floc formation, the initial COD concentration is 500-1000 mg / L, and the organic load is 0.1-0.5 kg COD / m 3 / d, rising velocity 2-5 m / h, hydraulic retention time 2-5 d; during the particle formation period, adjust the COD concentration to 1000-3000 mg / L, organic load 0.1-1.0 kg COD / m 3 / d, with an upward flow rate of 2-8 m / h; during the stabilization period after particle formation, adjust the initial COD concentration to 2500-8000 mg / L and the organic load to 0.5-1.5 kg COD / m 3 / d, rising velocity 5-10 m / h, hydraulic retention time 3-5 d; When the total dosage of nano-ferroferric oxide is 1.0-2.0 g / L, the initial COD concentration is 500-2000 mg / L and the organic load is 0.1-0.5 kg COD / m 3 / d, rising velocity 3-6 m / h, hydraulic retention time 2-5 d; during the particle formation period, adjust the COD concentration to 2000-6500 mg / L, organic load 0.5-1.5 kg COD / m 3 / d, with an upward flow rate of 3-8 m / h; during the stable period after particle formation, the COD concentration is adjusted to 6000-8000 mg / L and the organic load is 1.2-1.5 kg COD / m 3 / d, rising velocity 8-10 m / h, hydraulic retention time 3-5 d; The photosynthetic bacteria are pure single hydrogen-producing photosynthetic bacteria; The photosynthetic bacteria is hydrogen-producing Rhodopseudomonas palustris R. palustris; The time for forming stable bacterial granules during the granulation process is 80-112 days.

2. The photosynthetic bacteria granulation method according to claim 1, characterized in that: The particle size of the ferrosoferric oxide nanoparticles is 10-100 nm.

3. The photosynthetic bacteria granulation method according to claim 1, characterized in that: The single dosage of the ferrosoferric oxide nanoparticles is 0.01-0.2 g / L, and the addition is performed every 6-10 days.

4. The photosynthetic bacteria granulation method according to claim 1, characterized in that: The inoculation concentration of the photosynthetic bacteria is 0.5-2.0 g / L dry weight.

5. The photosynthetic bacteria granulation method according to claim 1, characterized in that: The reactor is an upflow photobioreactor; the light source of the upflow photobioreactor is a mixture of red light and green light with a ratio of 4:1, the effective volume of the reactor is 1 L, the diameter d=0.06 m, and the cross-sectional area A=0.0028 m 2 The reactor adopts bottom-in and top-out, with the feed entering from the feed port at the bottom of the reactor and the water outlet located at the top. A peristaltic pump is set to control the feed and discharge flow rate and reflux circulation.

6. Use of the photosynthetic bacteria granulation method according to claim 1 in wastewater treatment.

7. The use according to claim 6, characterized in that The photosynthetic bacteria granulation method promotes the generation of hydrogen in wastewater.

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