Method for granulating photosynthetic bacteria by taking ferroferric oxide nano-particles as carrier

Abstract

The invention belongs to the technical field of biological sewage treatment and energy resource utilization, and particularly relates to a single pure photosynthetic bacterium granulation method with ferroferric oxide nanoparticles as a carrier. According to the method, the pure photosynthetic bacteria are granulated and clustered by taking the ferroferric oxide nanoparticles as the carrier and combining the hydraulic condition, and the granulated photosynthetic bacteria can be effectively separated from liquid in the reactor, so that the content of effective microorganisms in the sewage treatment reactor and the system stability are improved, and the sewage treatment and hydrogen production efficiency is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage biological treatment and energy resource utilization, and particularly relates to a method for granulating photosynthetic bacteria with magnetite nanoparticles as a carrier. Background Art

[0002] The wastewater treatment technology of photosynthetic bacteria ( Photosynthetic Bacteria , PSB) is a new type of sewage treatment and resource recovery technology, which can effectively convert pollutants in sewage into high-value resource products in cells and can also produce hydrogen using high-concentration wastewater.

[0003] However, in this system, since most types of photosynthetic bacteria have poor aggregation ability, during the process of hydrogen production using high-concentration sewage, most of the bacterial cells are in a suspended state and are difficult to separate by natural sedimentation. During the continuous operation of the hydrogen production reactor, the suspended microorganisms cannot be effectively separated from the supernatant and will continuously flush out with the effluent of the reactor, thereby reducing the content of effective microorganisms in the reactor and the system stability, resulting in problems such as poor shock load resistance of the system and low sewage treatment and hydrogen production effects. 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 the continuous and stable operation of photosynthetic bacteria hydrogen production.

[0004] The reasons why photosynthetic bacteria cells are not conducive to aggregation are as follows: (1) Most of the morphologies of photosynthetic bacteria are rod-shaped or spherical, with small cell volumes, smooth surfaces, and motility, and are mostly distributed dispersedly in liquid culture; (2) The negative charge on the cell surface makes aggregation difficult. The negative charge causes the formation of a repulsive energy peak on the surface of PSB cells and they cannot aggregate with each other; (3) The low yield of extracellular polymeric substances secreted by photosynthetic bacteria is not conducive to cell aggregation. Extracellular polymeric substances play an important role in the mutual adhesion and aggregates between cells. The extracellular polymeric substances secreted by photosynthetic bacteria in the stationary phase are mostly soluble and have a very low yield, and cannot adsorb and aggregate the cells; (4) The phototaxis of photosynthetic bacteria is not conducive to cell aggregation. Phototaxis is a directional movement of photosynthetic bacteria to adapt to environmental changes. Under the condition of uniform light source distribution, this characteristic of photosynthetic bacteria will make them exist in a dispersed state to obtain the largest light-receiving area, rather than aggregating together to form aggregates. These reasons result in the difficulty of separating PSB from water in the cultivation of wastewater resource utilization and a low recovery rate.

[0005] At present, in the treatment of sewage and hydrogen production using photosynthetic bacteria, immobilization techniques include entrapment, adsorption, cross-linking, etc. However, there are still many deficiencies in these immobilization techniques. Some entrapment agents and cross-linking agents used in the entrapment or cross-linking immobilization of photosynthetic bacteria are toxic to the activity of the bacteria; the large-scale production process of entrapment particles is relatively complex, the mass transfer performance of entrapment particles is insufficient, and the scouring effect of the fluid and the microbial metabolism will cause the entrapment particles to rupture and swell, making it difficult to maintain a long service life.

[0006] Therefore, there is an urgent need to develop a new method to overcome the problem of difficult immobilization of photosynthetic bacteria in the prior art. Summary of the Invention

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

[0008] In order to achieve the above purpose, the present invention provides the following technical solutions: The present invention provides a granulation method for a hydrogen production and sewage degradation system of pure photosynthetic bacteria with magnetite nanoparticles as the carrier, comprising the following steps: S1. Mix magnetite nanoparticles with the sewage to be treated and then enter the reactor, and inoculate photosynthetic bacteria; S2. The granulation process includes the pre-flocculation stage, the particle formation stage, and the stable stage after particle formation; When the total dosage of nano-magnetite is 0.05 - 1.0 g / L, in the pre-flocculation stage, the initial COD concentration is 500 - 1000 mg / L, the organic loading is 0.1 - 0.5 kg COD / m 3 / d, the upward flow velocity is 2 - 5 m / h, and the hydraulic retention time is 2 - 5 d; in the particle formation stage, adjust the COD concentration to 1000 - 3000 mg / L, the organic loading is 0.1 - 1.0 kg COD / m 3 / d, the upward flow velocity is 2 - 8 m / h; in the stable stage after particle formation, adjust the initial COD concentration to 2500 - 8000 mg / L, the organic loading is 0.5 - 1.5 kgCOD / m 3 / d, the upward flow velocity is 5 - 10 m / h, and the hydraulic retention time is 3 - 5 d; When the total dosage of nano-magnetite is 1.0 - 2.0 g / L, in the pre-flocculation stage, the initial COD concentration is 500 - 2000 mg / L, the organic loading is 0.1 - 0.5 kg COD / m 3 / d, the upward flow velocity is 3 - 6 m / h, and the hydraulic retention time is 2 - 5 d; during the particle formation period, adjust the COD concentration to 2000 - 6500 mg / L, and the organic loading is 0.5 - 1.5 kg COD / m 3 / d, the upward flow velocity is 3 - 8 m / h; during the stable period after particle formation, adjust the COD concentration to 6000 - 8000 mg / L, and the organic loading is 1.2 - 1.5 kg COD / m 3 / d, the upward flow velocity is 8 - 10 m / h, and the hydraulic retention time is 3 - 5 d; The photosynthetic bacteria are pure single photosynthetic bacteria.

[0009] Preferably, the photosynthetic bacteria are Rhodopseudomonas palustris for hydrogen production R. palsutris .

[0010] Preferably, the particle size of the magnetite nanoparticles is 10 - 100 nm.

[0011] Preferably, the total dosage of the magnetite nanoparticles is 0.05 - 2.0 g / L, the single dosage is 0.01 - 0.2 g / L, and it is added once every 10 days.

[0012] Preferably, the inoculation concentration of the photosynthetic bacteria is 0.5 - 2.0 g / L dry weight.

[0013] Preferably, the overall upward flow velocity range during the granulation process is 2.0 - 10.0 m / h. The influent COD concentration is 500 - 8000 mg / L, and the organic loading is 0.1 - 1.5 kg COD / m 3 / d, the hydraulic retention time is 2 - 5 d, and the bacterial particle formation time is 80 - 112 days.

[0014] Preferably, the reactor is an up - flow photobioreactor; the light source of the up - flow photobioreactor is a mixed light of red light and green light with a ratio of 4:1. The effective volume V of the reactor is approximately 1 L, the diameter d = 0.06 m, and the cross - sectional area A = 0.0028 m 2 ; The reactor adopts a bottom - in and top - out mode. The feed enters from the feed port at the bottom of the reactor, and the outlet is located at the top. A peristaltic pump is set to control the flow rate of the inlet and outlet and the reflux circulation.

[0015] The present invention also provides the application of the above - mentioned method in wastewater treatment.

[0016] Preferably, the method promotes the production of hydrogen in wastewater.

[0017] The beneficial effects of the present invention: The present invention uses iron oxide nanoparticles (Fe3O4 NPs) as a carrier, and for the first time, a technology for granulating and hydrogen-producing by pure photosynthetic bacteria with the carrier as the core in a high-concentration wastewater treatment and hydrogen-producing system is developed.

[0018] The present invention takes iron oxide nanoparticles (Fe3O4 NPs) carrier material as the core, and realizes granulation by using the upward flow velocity, water quality composition, hydraulic load, hydraulic retention time, etc. of the wastewater. Finally, the diameter of the granulated particles is mostly 400-800 microns, and the total time for forming stable particle clusters stays at about 80-112 d.

[0019] In the present invention, the morphology of the hydrogen-producing photosynthetic bacteria is granulated, which can effectively separate the hydraulic retention time (HRT) and the sludge retention time (SRT), and accumulate high-concentration organisms, overcoming the problems of bacterial loss and decreased hydrogen-producing efficiency caused by the inseparability of the hydraulic retention time and the solid retention time in the traditional photosynthetic biological hydrogen production system. In addition, the particles formed by photosynthetic bacteria have good light-receiving effects, which is more conducive to improving the hydrogen-producing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a ratio curve graph of the COD concentration in the sewage of Comparative Examples 1-2 and Example 5 over time; Figure 2 It is a ratio curve graph of the average particle size of photosynthetic bacteria in the sewage of Comparative Examples 1-2 and Example 5 over stages; Figure 3 It is a ratio curve graph of the sludge volume index SVI in the reactor of Comparative Examples 1-2 and Example 5 over time 30 of. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention provides a method for granulating photosynthetic bacteria with iron oxide nanoparticles as a carrier. This method uses iron oxide nanoparticles as a carrier and combines hydraulic conditions including upward flow velocity, water quality composition, hydraulic load, and hydraulic retention time, etc., to enable pure single photosynthetic bacteria to granulate into clusters. The pure single photosynthetic bacteria in the present invention is Rhodopseudomonas palustris for hydrogen production R. palustris。

[0023] The granulation method of the photosynthetic bacteria in the present invention is carried out in an upflow photobioreactor (UPBR), which is made of transparent plexiglass. The effective volume V of each reactor is approximately 1 L, the diameter d = 0.06 m, and the cross-sectional area A = 0.0028 m 2 . The mixed light of red light (620 - 780 nm) and green light (492 - 560 nm) is used as the light source, and the ratio is 4:1 to ensure the species advantage of the photosynthetic bacteria. The reactor adopts a bottom-in and top-out mode. The feed enters from the feed port at the bottom of the reactor, and the water outlet is located at the top. A peristaltic pump is set to control the flow rate of the inlet and outlet materials, and a reflux system is set up. A peristaltic pump is used to control the reflux circulation. 1.5 L of artificial wastewater is prepared for each reactor every 3 days to supplement the feed. The biofilm attached to the wall is regularly cleaned with an aquarium brush every week. The initial inoculation concentration of the photosynthetic bacteria is 0.5 - 2.0 g / L dry weight, and no addition is made in the middle.

[0024] The particle size of the iron tetroxide nanoparticles used in the granulation conditions of the photosynthetic bacteria in the present invention 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 dosing time of the material is once every 10 days, with a total of 3 - 10 doses; the overall upward flow velocity range in the granulation process is 2.0 - 10.0 m / h. The influent COD concentration is 500 - 8000 mg / L, the organic load is 0.1 - 1.5 kg COD / m 3 / d, the hydraulic retention time is 2 - 5 d, and the time for the photosynthetic bacteria to form particles is 80 - 112 days.

[0025] The granulation of the photosynthetic bacteria in the present invention uses pure photosynthetic bacteria. At present, there is no technology and related research on the granulation and hydrogen production of pure photosynthetic bacteria in high-concentration wastewater. Other granulation processes of photosynthetic bacteria are all for wastewater treatment and cell accumulation, while the main purpose of the present invention is for hydrogen production, and its material metabolic pathways are different. Different metabolic pathways mean that the associated systems are different, which determines the properties and quality of the metabolites and even extracellular secretions, resulting in different results. The hydrogen production efficiency of the wastewater in the present invention refers to the ability to convert organic substances in the wastewater into hydrogen through biological or chemical methods during the wastewater treatment process. The level of hydrogen production efficiency directly affects the effect of wastewater treatment and the yield of hydrogen.

[0026] The principle and process of the granulation in the present invention are different. The present invention uses the upward flow velocity, water quality composition, hydraulic load, hydraulic retention time, etc. to achieve granulation. With the carrier material as the core, the diameter of the finally formed particles is 450 - 700 microns, and the overall granulation time mostly stays around 80 d.

[0027] In the present invention, the hydrogen-producing photosynthetic bacteria are granulated, which can effectively separate the HRT and SRT, and accumulate high concentrations of organisms, overcoming the problems of bacterial loss and decreased hydrogen production efficiency caused by the inability to separate the hydraulic retention time and solid retention time in traditional photosynthetic hydrogen production systems. In addition, the granules formed by photosynthetic bacteria have good light-receiving effects, which are more conducive to improving the hydrogen production efficiency.

[0028] The organic load in the present invention refers to the amount of organic matter (measured by chemical oxygen demand COD) that can be treated or tolerated per cubic meter of reactor volume per day in a sewage treatment system. The organic load is directly 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) = influent flow rate (m 3 / day) × COD concentration (g / m 3 ).

[0029] The hydraulic retention time ( Hydraulic Retention Time , abbreviated as HRT) in the present invention refers to the average residence time of the sewage to be treated in the reactor. The pool volume divided by the influent flow rate is the hydraulic retention time; the sludge retention time ( Sludge Retention Time , abbreviated as SRT) is the sludge age, which refers to the average residence time of the microorganisms in the aeration tank.

[0030] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0031] The hydrogen-producing Rhodopseudomonas palustris in the present invention R. palustris was purchased from the China General Microbiological Culture Collection Center (strain number: JCM 2524), and the iron oxide nanoparticles (Fe3O4 NPs) were obtained commercially (Zhongke Leiming Technology Co., Ltd.).

[0032] For the production processes, experimental methods or detection methods involved in the embodiments of the present invention, unless otherwise specified, they are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the field, and are very clear and definite in the relevant application fields. Those skilled in the art can understand the conventional process steps according to the name and apply the corresponding equipment, and implement them under conventional conditions or conditions recommended by the manufacturer.

[0033] For the various instruments, equipment, raw materials or reagents used in the embodiments of the present invention, there are no special restrictions on the sources. They are all conventional products that can be obtained through regular commercial channels, and can also be prepared according to the conventional methods well-known to those skilled in the art. Example 1: Photosynthetic Bacteria Granulation Method with Magnetite Nanoparticles as Carrier

[0034] The bacterial strain is Rhodopseudomonas palustris for hydrogen production R. palustris , and magnetite nanoparticles (Fe3O4 nanoparticles , Fe3O4 NPs) are used as dosing materials to promote the sedimentation performance and aggregation of photosynthetic bacteria into clusters.

[0035] The upflow photobioreactor ( Up-flow Photobioreactors , UPBR) is made of transparent plexiglass. The effective volume of each reactor is V≈1 L, the diameter d = 0.06 m, and the cross-sectional area A = 0.0028 m 2 . The mixed light of red light (620 - 780 nm) and green light (492 - 560 nm) is used as the light source, with a ratio of 4:1 to ensure the species dominance of photosynthetic bacteria. The reactor has a bottom-in and top-out design. The feed enters from the bottom feed port of the reactor, and the water outlet is located at the top. A peristaltic pump is set to control the flow rate of the inlet and outlet. A reflux system is set up, and a peristaltic pump is used to control the reflux circulation. 1.5 L of artificial wastewater is prepared every 3 days for each reactor to supplement the feed. The biofilm attached to the wall is regularly cleaned with an aquarium brush every week. The initial inoculation concentration of photosynthetic bacteria is 0.5 - 2.0 g / L dry weight, and no addition is made in the middle.

[0036] The particle size of the magnetite nanoparticles is 10 - 100 nm, the total dosing amount is 0.05 - 2.0 g / L, the single dosing amount is 0.01 - 0.2 g / L, and the dosing time of the material is once every 10 days, with a total of 6 - 10 doses. The overall upward flow rate range is 2.0 - 10.0 m / h. The influent COD concentration is 500 - 8000 mg / L, the organic loading is 0.1 - 1.5 kg COD / m 3 / d, the hydraulic retention time is 2 - 5 d, and the granulation process lasts for about 140 days, with mature particles formed after 80 - 112 days. The overall duration is 270 days. After 140 days, the system COD load is changed to study the pollutant removal effect, and the COD concentration is 3000 - 8000 mg / L. Example 2

[0037] When the single addition amount of magnetite nanoparticles is 40 mg / L, the dosing time is once every 10 days, with 6 doses, and the total amount is 0.24 g / L. The inoculation concentration of 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, and the organic loading is 0.13 - 1.0 kg COD / m 3 / d, the upward flow rate is 2.0 - 8.0 m / h, and the hydraulic retention time is 3 - 5 days. The overall granulation process lasts about 120 days. Activated sludge-like mature flocs can form around the 42nd - 84th day, granules form on the 104th day, and mature granules are formed after the 112th day.

[0038] In the early stage of floc formation (0 - 8 days), the influent COD concentration is 500 - 1000 mg / L, the organic loading is 0.13 - 0.25 kgCOD / m 3 / d, the upward flow rate is 2 - 5 m / h, and the hydraulic retention time is 4 days.

[0039] The granulation period is divided into a floc formation stage and a granule formation stage; The floc formation period (9 - 84 days) is divided into four stages, and the hydraulic conditions are adjusted according to the state of photosynthetic bacteria in the reactor. In the first stage (9 - 29 days), the influent COD concentration is 1000 - 1600 mg / L, the organic loading is 0.25 - 0.4 kg COD / m 3 / d, the upward flow rate 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 - 2000mg / L, the upward flow rate is 2 - 6 m / h, and the organic loading is 0.4 - 0.5 kg COD / m 3 / d, and the 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 loading is 0.5 - 0.58 kg COD / m 3 / d, the upward flow rate is 2 - 5 m / h, and the hydraulic retention time is 4 days. In the fourth stage (64 - 84 days), which is the mature stage, the influent COD concentration is 2300 - 2500 mg / L, and the organic loading is 0.46 - 0.6 kg COD / m 3 / d, the upward flow rate is 3 - 8 m / h, and the hydraulic retention time is 5 days.

[0040] In the granule formation stage (85 - 97 days), the influent COD concentration is 2500 - 2800 mg / L, and the organic loading is 0.8 - 1.0kg COD / m 3 / d, the upward flow rate is 5 - 8 m / h, and the hydraulic retention time is 3 days. (98 - 134 days), the influent COD concentration is 2800 - 3100 mg / L, and the organic loading is 1.2 kg COD / m 3 / d, the upward flow rate is 5 - 10 m / h, and the hydraulic retention time is 3 - 5 days. The total duration lasts 270 days. After 140 days, the COD load of the system is increased to study the pollutant removal effect, and the COD concentration is 3000 - 6000 mg / L. Example 3

[0041] When the single addition amount of iron oxide nanoparticles is 60 mg / L, the dosing time is once every 10 days, with a total of 10 doses, and the total dosage is 0.6 g / L. The photosynthetic bacteria are inoculated at a dry weight of 1.0 - 2.0 g / L.

[0042] The overall granulation process lasts about 100 days. Mature flocs can be formed approximately from the 9th to the 46th day, granules are formed from the 64th to the 72nd day, and mature granules are formed after 80 days. The influent COD concentration is 500 - 5000 mg / L, the organic loading is 0.25 - 1.3 kg COD / m 3 / d, the upflow velocity is 2 - 10 m / h, and the hydraulic retention time is 2 - 5 d.

[0043] In the early stage of floc formation (0 - 8 days), the influent COD concentration is maintained at 500 - 1000 mg / L, the organic loading is 0.25 - 0.5 kg COD / m 3 / d, the upflow velocity is 2 - 4 m / h, and the hydraulic retention time is 2 d; The granulation period is divided into a floc formation stage and a granule formation stage; The floc formation period (9 - 46 days) is divided into four stages, and the hydraulic conditions are adjusted according to the state of photosynthetic bacteria in the reactor. In the first stage (9 - 29 days), the influent COD concentration is 1000 - 1600 mg / L, the organic loading is 0.25 - 0.4 kg COD / m 3 / d, the upflow velocity is 2 - 5 m / h, and the hydraulic retention time is 4 d; in the second stage (30 - 45 days), the influent COD concentration is 1600 - 2000 mg / L, the organic loading is 0.32 - 0.4 kg COD / m 3 / d, the upflow velocity is 2 - 5 m / h, and the hydraulic retention time is 5 d.

[0044] Granule formation stage: In the first stage (46 - 66 days), the influent COD concentration is 2000 - 2200 mg / L, the organic loading is 0.5 - 0.55 kg COD / m 3 / d, the upflow 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, the organic loading is 0.73 - 1.0 kg COD / m 3 / d, the upflow velocity is 5 - 8 m / h, and the hydraulic retention time is 3 days.

[0045] After granulation (86 - 98 days), the influent COD concentration is 3000 - 4000 mg / L, the organic loading is 1.0 - 1.3 kgCOD / m3 / d, the upflow velocity is 6 - 10 m / h, and the hydraulic retention time is 3 days; (99 - 135 days), the influent COD concentration is 4000 - 5000 mg / L, and the organic loading is 1.0 - 1.3 kg COD / m 3 / d, the upflow velocity is 6 - 10 m / h, and the hydraulic retention time is 4 days. The overall duration lasts for 270 days. The pollutant removal effect is studied after 140 days, and the COD concentration is 3000 - 6000 mg / L. Example 4

[0046] When the single addition amount of iron oxide nanoparticles is 150 mg / L, the addition time is once every 10 days, and a total of 10 times are added, with a total addition amount of 1.5 g / L. Photosynthetic bacteria are inoculated at a dry weight of 1.0 - 2.0 g / L. The overall process of the granulation stage lasts for about 100 days. Mature flocs can be formed around the 7th - 10th day, granules are formed on the 16th - 20th day, and mature granules are formed after 80 days. The influent COD concentration is 1000 - 8000 mg / L, and the organic loading is 0.25 - 1.5 kg COD / m 3 / d, the upflow velocity is 3 - 10 m / h, and the hydraulic retention time is 2 - 5 d.

[0047] During the early stage of floc formation (0 - 7 days), the influent COD concentration is maintained at 1000 - 2000 mg / L, and the organic loading is 0.25 - 0.5 kg COD / m 3 / d, the upflow velocity is 3 - 6 m / h, and the hydraulic retention time is 4 d; During the granule formation stage, the hydraulic conditions are adjusted according to the state 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 loading is 0.5 - 1.5 kg COD / m 3 / d, the upflow velocity is 3 - 5 m / h, and the hydraulic retention time is 2 d; in the second stage (30 - 42 days), the influent COD concentration is 3000 - 4500 mg / L, and the organic loading is 1.0 - 1.5 kg COD / m 3 / d, the upflow velocity is 3 - 6 m / h, and the hydraulic retention time is 3 d; in the third stage (43 - 63 days), the influent COD concentration is 4500 - 6000 mg / L, and the organic loading is 0.9 - 1.2 kg COD / m 3 / d, the upflow 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 loading is 1.2 - 1.3 kg COD / m 3 / d, the upflow velocity is 6 - 8 m / h, and the hydraulic retention time is 5 days.

[0048] After granulation (85 - 105 days), the influent COD concentration is 6500 - 7000 mg / L, and the organic loading is 1.3 - 1.4 kgCOD / m 3 / d, the upflow velocity is 8 - 10 m / h, and the hydraulic retention time is 5 days; during the period of (106 - 136 days), the influent COD concentration is 7000 - 7800 mg / L, and the organic loading is 1.4 - 1.5 kg COD / m 3 / d, the upflow velocity is 8 - 10 m / h, and the hydraulic retention time is 5 days. The total duration is 270 days. After the 140th day, the pollutant removal effect is studied, and the COD concentration is 3000 - 6000 mg / L. Example 5 Photosynthetic bacteria granulation method using magnetite nanoparticles as a carrier

[0049] In the wastewater to be treated, photosynthetic bacteria are inoculated at a dry weight of 1.5 g / L. The dosage of magnetite nanoparticles is 10 mg / L, and the dosing time is once every 10 days, with a total of 5 doses, and the total dosage is 0.05 g / L. The influent COD concentration is 900 - 3000 mg / L, and the organic loading is 0.18 - 1.0 kg COD / m 3 / d, the upflow velocity is 3 - 8 m / h, and the hydraulic retention time is 3 - 5 d.

[0050] Adjust the hydraulic conditions according to the state of photosynthetic bacteria in the reactor. In the first stage (0 - 10 days), keep the influent COD concentration at 900 mg / L, and the organic loading at 0.18 kg COD / m 3 / d, the upflow 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 loading is 0.5 kg COD / m 3 / d, the upflow velocity is 3m / 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 loading is 0.6kg COD / m 3 / d, the upflow 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, and the organic loading is 0.7 kg COD / m 3 / d, the upflow 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 loading is 0.8 kg COD / m 3 / d, the upflow velocity is 3 m / h, and the hydraulic retention time is 3 days.

[0051] In the sixth stage, photosynthetic bacteria in the flocs begin to form granules, and stable photosynthetic bacteria granules are formed in the seventh stage; in the sixth stage (86 - 101 days), the influent COD concentration is 4000 mg / L, the organic loading is 0.9 kg COD / m 3 / d, the upflow 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 loading is 1.2 kg COD / m 3 / d, the upflow velocity is 8 m / h, and the hydraulic retention time is 3 days. The total duration is 270 days. After the 140th day, the COD loading of the system is increased to study the pollutant removal effect, and the COD concentration is 3000 - 6000 mg / L. Comparative Example 1

[0052] Based on Example 5, Comparative Example 1 is set up. Comparative Example 1 is a treatment system without adding nano-ferroferric oxide, and granulation is carried out only relying on organic loading, upflow velocity, etc.

[0053] The influent sewage is inoculated with 1.5 g / L dry weight of photosynthetic bacteria. The influent COD concentration is 900 - 3000 mg / L, the organic loading is 0.18 - 1.0 kg COD / m 3 / d, the upflow velocity is 3 - 8 m / h, and the hydraulic retention time is 3 - 5 d.

[0054] In the first stage (0 - 10 days), the influent COD concentration is maintained at 900 mg / L, the organic loading is 0.18 kg COD / m 3 / d, the upflow 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, the organic loading is 0.5 kg COD / m 3 / d, the upflow 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, the organic loading is 0.6 kg COD / m 3 / d, the upflow 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 loading is 0.7 kg COD / m 3 / d, the upflow 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, the organic loading is 0.8 kg COD / m 3 / d, the upflow 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 loading is 0.9 kg COD / m 3 / d, the upflow 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, and the organic loading is 1.2 kg COD / m 3 / d, the upflow velocity is 8 m / h, and the hydraulic retention time is 3 days. The overall duration is 270 days. After 140 days, the COD loading of the system is increased to study the pollutant removal effect, and the COD concentration is 3000 - 6000 mg / L.

[0055] Comparative Example 1 is only the process of forming a single pure photosynthetic bacteria granule. Although its hydraulic conditions are the same as those of Example 5, it lacks the assistance of the Fe₃O₄ nanoparticle carrier. The formation of the stable photosynthetic bacteria granule in this comparative example requires a long waiting time. Comparative Example 2

[0056] Based on Example 5, Comparative Example 2 is set. The dosage of Fe₃O₄ nanoparticles in this comparative example is higher than the implementation range, and the hydraulic conditions remain unchanged.

[0057] The photosynthetic bacteria are inoculated into the wastewater to be treated at a dry weight of 1.5 g / L. The dosage of Fe₃O₄ nanoparticles is 200 mg / L, and the addition time is once every 5 days, with a total of 15 additions, and the total dosage is 3.0 g / L. The influent COD concentration is 900 - 3000 mg / L, and the organic loading is 0.18 - 1.0 kg COD / m 3 / d, the upflow velocity is 2 - 8 m / h, and the hydraulic retention time is 3 - 5 d.

[0058] In the first stage (0 - 10 days), the influent COD concentration is maintained at 900 mg / L, and the organic loading is 0.18 kg COD / m 3 / d, the upflow 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 loading is 0.5 kg COD / m 3 / d, the upflow 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 loading is 0.6 kg COD / m 3 / d, the upflow velocity is 3 m / h, and the hydraulic retention time is 5 d.

[0059] The formation of photosynthetic bacteria particles is advanced, and photosynthetic bacteria particles begin to form in the fourth stage; in the fourth stage (48 - 69 days), the influent COD concentration is 3000 mg / L, the organic loading is 0.7 kg COD / m 3 / d, the upflow 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, the organic loading is 0.8 kg COD / m 3 / d, the upflow velocity is 3 m / h, and the hydraulic retention time is 3 days.

[0060] Over time, the photosynthetic bacteria particles in this comparative example show instability in the sixth stage. In the sixth stage (86 - 101 days), the influent COD concentration is 4000 mg / L, the organic loading is 0.9 kg COD / m 3 / d, the upflow 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 loading is 1.2 kg COD / m 3 / d, the upflow velocity is 8 m / h, and the hydraulic retention time is 3 days. The total duration is 270 days. After the 140th day, the COD load of the system is increased to study the pollutant removal effect, and the COD concentration is 3000 - 6000 mg / L.

[0061] Although Comparative Example 2 has the same carrier and hydraulic conditions as Example 5, the dosage of iron oxide nanoparticles exceeds the range defined in the present invention. Although the formation of photosynthetic bacteria particles seems to occur in a short time, the stability of its formation process is much lower than that of Example 5.

[0062] When Example 5 is compared with Comparative Examples 1 - 2, the results show that after the 90th day, mature and stable particles are formed. In Example 5, mature particles with a particle size of 450 - 700 μm are formed after the middle and late stages of the sixth stage (after the 90th day) (the dominant particle size range of mature granular sludge is mostly between 450 - 3000 μm). Correspondingly, after the 90th day, the SVI of the particles 30 is approximately stable at 80 - 110 mL / g (the SVI of granular sludge is usually between 80 - 150 mL / g), reaching a stable level. For the COD removal rate, after the 134th day, the COD removal rate reaches more than 80%, and the COD content is significantly lower than that of the two comparative examples. In Comparative Example 1, the time to form particles with a particle size ≧450 μm is approximately at the beginning of the seventh stage (almost no particles with a particle size ≧450 μm are formed), the overall particle size is significantly lower than that of Example 5, and the SVI 30Basically lower than 60 mL / g. In Comparative Example 2, the time to form particles with a particle size ≧ 450 μm is approximately in the seventh stage (about 106 days), and the overall particle size is significantly lower than that of the examples, and the SVI 30 is basically lower than 60 mL / g, indicating poor sedimentation performance.

[0063] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for granulating photosynthetic bacteria using magnetite nanoparticles as a carrier, characterized in that, It includes the following steps: S1. Mix the magnetite nanoparticles with the wastewater to be treated and then enter the reactor, and inoculate photosynthetic bacteria; S2. The granulation process includes the pre-flocculation stage, 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, the organic load is 0.1 - 0.5 kg COD / m 3 / d, the upflow velocity is 2 - 5 m / h, and the hydraulic retention time is 2 - 5 d; in the particle formation period, adjust the COD concentration to 1000 - 3000 mg / L, and the organic load is 0.1 - 1.0 kg COD / m 3 / d, the upflow velocity is 2 - 8 m / h; in the stable period after particle formation, adjust the initial COD concentration to 2500 - 8000 mg / L, and the organic load is 0.5 - 1.5 kg COD / m 3 / d, the upflow velocity is 5 - 10 m / h, and the hydraulic retention time is 3 - 5 d; When the total dosage of nano-ferroferric oxide is 1.0 - 2.0 g / L, in the early stage of floc formation, the initial COD concentration is 500 - 2000 mg / L, the organic load is 0.1 - 0.5 kg COD / m 3 / d, the upflow velocity is 3 - 6 m / h, and the hydraulic retention time is 2 - 5 d; in the particle formation period, the COD concentration is adjusted to 2000 - 6500 mg / L, and the organic load is 0.5 - 1.5 kg COD / m 3 / d, the upflow velocity is 3 - 8 m / h; in 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, the upflow velocity is 8 - 10 m / h, and the hydraulic retention time is 3 - 5 d; The photosynthetic bacteria are pure single hydrogen-producing photosynthetic bacteria.

2. The method according to claim 1, wherein The photosynthetic bacterium is Rhodopseudomonas palustris that produces hydrogen R. palsutris .

3. The method according to claim 1, wherein The particle size of the magnetite nanoparticles is 10 - 100 nm.

4. The method according to claim 1, characterized in that The total dosage of the magnetite nanoparticles is 0.05 - 2.0 g / L, and the single dosage is 0.01 - 0.2 g / L, and it is added every 6 - 10 days.

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

6. The method according to claim 1, wherein The overall upward flow velocity range during the granulation process is 2.0 - 10.0 m / h; the influent COD concentration is 500 - 8000 mg / L, the organic loading is 0.1 - 1.5 kg COD / m 3 / d, the hydraulic retention time is 2 - 5 d, and the time required to form stable bacterial granules is 80 - 112 days.

7. The method according to claim 1, characterized in that, The reactor is an upflow photobioreactor; the light source of the upflow photobioreactor is a mixed light of red light and green light, with a ratio of 4:

1. The effective volume V of the reactor is approximately 1 L, the diameter d = 0.06 m, and the cross-sectional area A = 0.0028 m 2 ; The reactor operates with a bottom-in and top-out configuration. The feed enters through the feed inlet at the bottom of the reactor, and the outlet is located at the top. A peristaltic pump is set to control the flow rates of the inlet and outlet materials and the reflux circulation.

8. Application of the method according to claim 1 in wastewater treatment.

9. The application according to claim 8, wherein The method promotes the production of hydrogen in wastewater.

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