Method for preparing mycoprotein feed based on violet bacterium wastewater treatment and application

Abstract

The invention discloses a method for preparing a mycoprotein feed based on purple bacteria wastewater treatment and application, and the method comprises the following steps: S1, under illumination and anaerobic conditions, carrying out membrane separation treatment on purple non-sulfur bacteria and salt-containing wastewater, and collecting biomass and the treated salt-containing wastewater; s2, mixing and sterilizing the biomass and sodium alginate, mixing with a forming agent, and forming to obtain the mycoprotein feed, the method comprises the following steps: constructing a membrane bioreactor, treating high-nutrition type wastewater by utilizing PPB under an illumination anaerobic condition, and improving the PPB pollutant removal performance through salinity stress, so that various pollution indexes of effluent of the reactor reach the standard; according to the method, purple non-sulfur bacteria are used as a raw material, then microbial strains (PPB biomass) in the reactor are scraped, and the PPB biomass is efficiently converted into feed by means of gel addition, drying and the like, so that the dual purposes of wastewater treatment and resource utilization are achieved, and the feed production efficiency and the comprehensive utilization value of the purple non-sulfur bacteria are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater utilization, and in particular to a method for preparing bacterial protein feed based on purple bacteria wastewater treatment and application thereof. Background Art

[0002] Purple non-sulfur photosynthetic bacteria (PNSB) are a type of anoxic microorganisms that use light as energy. They have flexible metabolic pathways to adapt to a variety of growth environments, a short doubling time, and can use different carbon sources for growth metabolism and production of high-value products. They are rich in essential proteins, vitamins, and carotenoids, etc., and can produce proteins in wastewater highly selectively by controlling conditions, showing high potential as a nutritious feed.

[0003] Purple non-sulfur bacteria can be used as feed additives in two categories: aqueous solution and powder. The aqueous solution formulation is unstable and has a short shelf life because the bacteria can easily use the nutrients in the aqueous solution to continue metabolism, growth and fermentation. The powder formulation is to slowly dehydrate the living bacteria using low-temperature hot air, freezing and other drying methods to put the bacteria in a stable dry dormant state, and then use feedable substances as fillers to mix evenly to make a relatively stable powder-type biological feed additive, but the cost is high. In the related art, the stability and nutritional value of purple non-sulfur bacteria are ignored when purple non-sulfur bacteria are used as feed additives. At the same time, the cost of using purple non-sulfur bacteria as feed additives through light anaerobic cultivation is high, and the sewage treatment capacity of purple non-sulfur bacteria is not fully utilized, resulting in a waste of resources.

[0004] Therefore, it is necessary to provide a method that can utilize the sewage treatment capacity of purple non-sulfur bacteria and improve the nutritional value of purple non-sulfur bacteria feed, so as to improve the comprehensive utilization value of purple non-sulfur bacteria. Summary of the invention

[0005] In view of this, the present application provides a method and application for preparing bacterial protein feed based on purple bacteria wastewater treatment, which is used to solve the problem of how to improve the comprehensive utilization value of purple non-sulfur bacteria.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions: In a first aspect, a method for preparing bacterial protein feed based on purple bacteria wastewater treatment is provided, comprising the following steps: S1. Under light and anaerobic conditions, purple non-sulfur bacteria and saline wastewater are treated by membrane separation, and biomass and treated saline wastewater are collected; S2. After the biomass and sodium alginate are mixed and sterilized, they are mixed with a molding agent and molded to obtain bacterial protein feed.

[0007] Preferably, in step S1, the membrane separation treatment step is based on the operation of a purple bacteria membrane bioreactor; the purple bacteria membrane bioreactor includes: a reaction chamber provided with a water inlet, a water outlet and a mud discharge outlet, a PDVF flat membrane accommodated in the reaction chamber, an inlet peristaltic pump connected to the water inlet, a water outlet peristaltic pump connected to the water outlet, and a pressure monitoring gauge connected to the PDVF.

[0008] Preferably, in step S1, the specific steps of membrane separation treatment are as follows: S11. Inoculating and acclimating purple non-sulfur bacteria in a purple bacterial membrane bioreactor; S12. The salinity of the wastewater is adjusted to obtain saline wastewater, and the saline wastewater is input into the purple bacteria bioreactor through the water inlet and output through the water outlet to obtain treated saline wastewater. Meanwhile, the attached materials on the PDVF flat membrane in the purple bacteria membrane bioreactor are scraped to obtain biomass.

[0009] Preferably, in step S11, the acclimation step is: continuously inputting untreated wastewater into the purple bacteria membrane bioreactor through the water inlet, and semi-continuously outputting it through the water outlet to form an acclimated residual liquid; wherein, the specific step of continuous input is: continuously inputting wastewater into the water inlet through the water inlet peristaltic pump, and setting the flow rate of the water inlet peristaltic pump to 1.5-2ml / h, and the hydraulic retention time to 20-25h; the specific step of semi-continuous output is: semi-continuously outputting wastewater to the water outlet through the water outlet peristaltic pump, and the setting of the water outlet peristaltic pump is 5min suction / 5min relaxation, and the working volume in the reaction chamber is maintained at 2L.

[0010] Preferably, in step S1, the salinity of the saline wastewater is 1-80 g NaCl / L.

[0011] Preferably, in step S1, the saline wastewater includes the following components: 0.19 g / L ammonium chloride, 0.1 g / L sodium bicarbonate, 1.98 g / L sodium acetate, 0.1 g / L magnesium chloride hexahydrate, 0.05-0.1 g / L potassium dihydrogen phosphate, and 1-2 mL / L trace element solution; wherein the trace element solution includes 1.8 g / L FeCl2·4H2O, 0.25 g / L CoCl2·6H2O, 0.01 g / L NiCl2·6H2O, 0.01 g / L CuCl2·2H2O, 0.07 g / L MnCl2·4H2O, 0.1 g / L ZnCl2, 0.5 g / L H3BO3, and 0.03 g / L Na2MoO4·2H2O. Preferably, in step S2, the molding agent includes 3-5 parts of calcium lactate, 1-3 parts of calcium chloride, and 100 parts of water.

[0012] Preferably, in step S2, the mass concentration of the sodium alginate solution is 3-5%.

[0013] In a second aspect, the present application provides a bacterial protein feed.

[0014] In a third aspect, the present application provides an application of bacterial protein feed in the field of shrimp farming.

[0015] The beneficial effects of this application are as follows: The present invention constructs a membrane bioreactor, utilizes PPB to treat high-nutrient wastewater under light anaerobic conditions, and improves the pollutant removal performance of PPB through salinity stress, so that various pollution indexes of the reactor effluent meet the standards; then the microbial strains (PPB biomass) inside the reactor are scraped, and the PPB biomass is efficiently converted into feed by adding a gelling agent, drying, etc., achieving the dual purposes of wastewater treatment and resource utilization, and greatly improving the feed production efficiency and the comprehensive utilization value of purple non-sulfur bacteria. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the purple bacteria membrane bioreactor of this application; Figure 2 Comparison of the removal effect of NaCl / L on COD; Figure 3 This is a graph showing the changing trend of biomass production; Figure 4 For feed product pictures; Figure 5 Comparison results of black shrimp growth. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] Based on the problem of insufficient utilization of purple non-sulfur bacteria wastewater treatment and resource utilization capacity, this application proposes the following technical solutions.

[0019] A method for preparing bacterial protein feed based on purple bacteria wastewater treatment, comprising the following steps: S1. Under light and anaerobic conditions, purple non-sulfur bacteria and saline wastewater are treated by membrane separation, and biomass and treated saline wastewater are collected; S2. After the biomass and sodium alginate are mixed and sterilized, they are mixed with a molding agent and molded to obtain bacterial protein feed.

[0020] The purple non-sulfur bacteria used in the present application are well-known species, which are derived from the strain prepared in the document Optimizing light sources for selective growth of purple bacteria and efficient formation of value-added products. The purple non-sulfur bacteria are Rhodobacter sphaeroides, which are purple-red in color, spherical in shape, and belong to Gram-negative bacteria.

[0021] In the present application, in step S1, the membrane separation treatment step is based on the operation of a purple bacteria membrane bioreactor; the purple bacteria membrane bioreactor includes: a reaction chamber provided with a water inlet, a water outlet and a mud discharge outlet, a PDVF flat membrane accommodated in the reaction chamber, an inlet peristaltic pump connected to the water inlet, a water outlet peristaltic pump connected to the water outlet, and a pressure monitoring meter connected to the PDVF; the connection method of the pressure monitoring meter: the pressure monitoring meter, the water outlet peristaltic pump, and the membrane reactor are connected through a three-way valve and a water pipe, and the position of the pressure monitoring meter is unified with the liquid level position inside the reactor. At this time, the reading of the pressure monitoring meter is the pressure difference across the membrane of the reactor.

[0022] In the examples of the present application, a purple bacteria membrane bioreactor (PPB-MBR) was first constructed for the implementation of the overall method, such as Figure 1 As shown, in the embodiment of the present application, the main body of the PPB-MBR is a reaction chamber (organic glass rectangular reactor) with a working volume of 2 L; a commercially available PDVF flat membrane is built into the reaction chamber, and the built-in method includes placement, embedding, etc. The effective membrane area of ​​the PDVF flat membrane is 0.1 m 2 ; At the same time, the reaction chamber is provided with a water inlet, a water outlet and a mud discharge port. The water inlet is connected to the water inlet peristaltic pump, the water outlet is connected to the water outlet peristaltic pump, and the mud discharge port is arranged below the water outlet; the water outlet and the mud discharge port are arranged at one end of the reaction chamber, and the water inlet is arranged at the other end of the reaction chamber; the pressure detection gauge is electrically connected to the PDVF to monitor the trans-membrane pressure difference, timely backwash to maintain the operating pressure of the membrane assembly, and ensure the consistency of the membrane contribution during the experiment; in order to maintain the lighting environment, the PPB-MBR is also equipped with an incandescent lamp with a power of ≥30W.

[0023] In step S1, the specific steps of membrane separation treatment are as follows: S11. Inoculating and acclimating purple non-sulfur bacteria in a purple bacterial membrane bioreactor; S12. The salinity of the wastewater is adjusted to obtain saline wastewater, and the saline wastewater is input into the purple bacteria bioreactor through the water inlet and output through the water outlet to obtain treated saline wastewater. Meanwhile, the attached materials on the PDVF flat membrane in the purple bacteria membrane bioreactor are scraped to obtain biomass.

[0024] In step S11, the acclimation step is: continuously inputting untreated wastewater into the purple bacteria membrane bioreactor through the water inlet, and semi-continuously outputting it through the water outlet to form an acclimated residual liquid; wherein, the specific step of continuous input is: continuously inputting wastewater into the water inlet through the water inlet peristaltic pump, and setting the flow rate of the water inlet peristaltic pump to 1.5-2ml / h, and the hydraulic retention time to 20-25h; the specific step of semi-continuous output is: semi-continuously outputting wastewater to the water outlet through the water outlet peristaltic pump, and the setting of the water outlet peristaltic pump is 5min suction / 5min relaxation, and the working volume in the reaction chamber is maintained at 2L. The PPB-MBR transmembrane pressure difference is monitored by a pressure detection gauge. When the pressure exceeds 0.05 Mpa, backwashing measures are taken (the water flow direction of the outlet peristaltic pump is changed, and 100 ml of the inlet solution is connected to the outlet pipe to reversely fill the membrane reactor with water); at the same time, the PPB-MBR uses a circulating diaphragm pump to fully mix the internal liquid, and the circulating pump flow rate is 2 L / min.

[0025] In some embodiments, in step S1, the salinity of the saline wastewater is 1-80 g NaCl / L, preferably, the salinity of the saline wastewater is 20-40 g NaCl / L. From the perspective of salinity stress, the pollutant removal performance and resource recovery capacity of the reactor are optimized to improve the operation effect of the reactor and the PPB biomass.

[0026] In some embodiments, in step S1, the saline wastewater includes the following components: 0.19 g / L ammonium chloride, 0.1 g / L sodium bicarbonate, 1.98 g / L sodium acetate, 0.1 g / L magnesium chloride hexahydrate, 0.05-0.1 g / L potassium dihydrogen phosphate, and 1-2 mL / L trace element solution; wherein the trace element solution includes 1.8 g / L FeCl2·4H2O, 0.25 g / L CoCl2·6H2O, 0.01 g / L NiCl2·6H2O, 0.01 g / L CuCl2·2H2O, 0.07 g / L MnCl2·4H2O, 0.1 g / L ZnCl2, 0.5 g / L H3BO3, and 0.03 g / L Na2MoO4·2H2O; in step S11, the wastewater includes the following components: 0.19 g / L ammonium chloride, 0.1 g / L sodium bicarbonate, 1.98 g / L sodium acetate, 0.1 g / L magnesium chloride hexahydrate, 0.05-0.1 g / L potassium dihydrogen phosphate, 1-2 mL / L trace element solution; wherein the trace element solution includes 1.8 g / L FeCl2·4H2O, 0.25 g / L CoCl2·6H2O, 0.01 g / L NiCl2·6H2O, 0.01 g / L CuCl2·2H2O, 0.07 g / L MnCl2·4H2O, 0.1 g / L ZnCl2, 0.5 g / L H3BO3, and 0.03 g / L Na2MoO4·2H2O; in step S12, the salt-containing wastewater includes 0.19 g / L ammonium chloride, 0.1 g / L sodium bicarbonate, 1.98 g / L sodium acetate, 0.1 g / L magnesium chloride hexahydrate, 0.05-0.1 g / L potassium dihydrogen phosphate, and 1-2 mL / L trace element solution. g / L potassium dihydrogen phosphate, 1-2mL / L trace element solution; wherein the trace element solution includes 1.8 g / L FeCl2·4H2O, 0.25 g / LCoCl2·6H2O, 0.01g / LNiCl2·6H2O, 0.01 g / LCuCl2·2H2O, 0.07g / L MnCl2·4H2O, 0.1 g / L ZnCl2, 0.5 g / LH3BO3, 0.03 g / L Na2MoO4·2H2O, and also includes 1-80g / L NaCl.

[0027] In some embodiments, in step S2, the molding agent includes 3-5 parts of calcium lactate, 1-3 parts of calcium chloride, and 100 parts of water.

[0028] In some embodiments, in step S2, the mass concentration of the sodium alginate solution is 3-5%.

[0029] The present application provides a bacterial protein feed.

[0030] The present application provides an application of bacterial protein feed in the field of shrimp farming.

[0031] The present solution is further described below through specific embodiments.

[0032] Example 1 A method for preparing bacterial protein feed based on purple bacteria wastewater treatment, comprising the following steps: S1. First, build a purple bacteria membrane bioreactor, including a reaction chamber with a water inlet, a water outlet, and a mud outlet. The reaction chamber is a plexiglass rectangular reactor with a working volume of 2 L. The effective membrane area contained in the reaction chamber is 0.1 m 2 PDVF flat membrane, a water inlet peristaltic pump connected to the water inlet, a water outlet peristaltic pump connected to the water outlet, and a pressure monitoring meter connected to PDVF; Secondly, the purple bacteria membrane bioreactor was inoculated with purple non-sulfur bacteria (high-purity Rhodobacters phaeroides bacterial solution, and the culture solution was supplemented to 2L), and then two 30W incandescent lamps were used as light sources to irradiate the purple bacteria membrane bioreactor in a closed space. At the same time, the wastewater was continuously input into the water inlet through the water inlet peristaltic pump, and the flow rate of the water inlet peristaltic pump was set to 1.67ml / h, the hydraulic retention time was 20h, and the wastewater was semi-continuously output to the water outlet through the water outlet peristaltic pump. The water outlet peristaltic pump was set to 5min suction / 5min relaxation, and the working volume in the reaction chamber was maintained at 2L. The reactor transmembrane pressure difference was monitored by a pressure monitoring gauge. When the pressure exceeded 0.05 MPa, backwashing measures were taken. The reactor used a circulating diaphragm pump to fully mix the internal liquid. The flow rate of the circulating pump was 2 L / min to complete the process of acclimating purple non-sulfur bacteria. The wastewater included the following components: 0.19 g / L ammonium chloride, 0.1 g / L sodium bicarbonate, 1.98 g / L sodium acetate, 0.1 g / L magnesium chloride hexahydrate, 0.05 g / L potassium dihydrogen phosphate, 1mL / L trace element solution, wherein the trace element solution includes 1.8 g / LFeCl2·4H2O, 0.25 g / LCoCl2·6H2O, 0.01 g / LNiCl2·6H2O, 0.01 g / LCuCl2·2H2O, 0.07g / LMnCl2·4H2O, 0.1 g / L ZnCl2, 0.5 g / L H3BO3, 0.03 g / L Na2MoO4·2H2O; Then, before the wastewater is input into the purple bacteria membrane bioreactor, the salinity of the wastewater is adjusted to obtain saline wastewater, and the components of the obtained saline wastewater include 20g / L NaCl, 0.19g / L ammonium chloride, 0.1g / L sodium bicarbonate, 1.98g / L sodium acetate, 0.1g / L magnesium chloride hexahydrate, 0.05g / L potassium dihydrogen phosphate, and 1mL / L trace element solution, wherein the trace element solution includes 1.8g / L FeCl2·4H2O, 0.25g / L CoCl2·6H2O, 0.01g / L NiCl2·6H2O, 0.01g / L CuCl2·2H2O, 0.07g / L MnCl2·4H2O, 0.1g / L ZnCl2, 0.5g / L H3BO3, 0.03g / L Na2MoO4·2H2O; using two 30W incandescent lamps as light sources, irradiating the purple bacteria membrane bioreactor in a closed space at 25°C, while continuously inputting saline wastewater into the water inlet through the water inlet peristaltic pump, and setting the flow rate of the water inlet peristaltic pump to 1.67ml / h, and semi-continuously outputting wastewater to the water outlet through the water outlet peristaltic pump, the water outlet peristaltic pump is set to 5min suction / 5min relaxation, and keeping the working volume in the reaction chamber at 2L, processing according to the operating parameters in Table 1, after processing, collecting biomass and treated saline wastewater; S2. Dissolve 3g of calcium lactate and 1g of calcium chloride in 100ml of water to obtain a molding agent. Centrifuge the collected biomass, dry the surface moisture at 40℃, centrifuge the biomass in a centrifuge at 3800 rpm for 30 min, mix the biomass with sodium alginate (mass fraction of 3%), place it in a high-pressure steam sterilizer, set the temperature to 121℃, and sterilize it for 30 min. After sterilization, cool it on a sterile operating table for 3 h, pour the resulting mixture into the molding agent, and use a wooden stick to tear the purple bacteria in the mixture into pieces. Let it stand for 12 h. After molding, take it out and use a crusher, mortar or blade to make the solid into 2 mm granular material, and put it into a -20℃ refrigerator for freezing to obtain bacterial protein feed.

[0033] Embodiment 2-6 A method for preparing bacterial protein feed based on purple bacteria wastewater treatment, the other contents are the same as those in Example 1, except that the content of NaCl in the saline wastewater is 1, 10, 40, 60, and 80 g / L, respectively, and membrane separation treatment is performed according to the operating parameters in Table 1.

[0034] Comparative Example 1 A method for preparing bacterial protein feed based on purple bacteria wastewater treatment, the other contents are the same as those in Example 1, except that the content of NaCl in the saline wastewater is 0 g / L, and membrane separation treatment is performed according to the operating parameters in Table 1.

[0035] Table 1 Reactor operating parameters at each stage

[0036] Test and Evaluation Reactor operation performance test: During the entire reactor operation process, the COD removal rate is maintained above 77%, and the ammonia nitrogen removal rate is above 75%. Figure 2 Among them, 10-40 g NaCl / L has the highest COD removal rate, which has been maintained at more than 90%. Compared with 1 g NaCl / L, the salinity pressure of 10-40 g NaCl / L and 60-80 g NaCl / L makes NH 4+ The removal rate increased by 19%, reaching a maximum of 93% at 40g NaCl / L. This may be due to the fact that PPB is stimulated by high salinity to produce more pigments, resulting in stronger photoheterotrophic ability and better pollutant removal. The results show that suitable salinity is beneficial to COD and NH 4+ removal; while the PPB-MBR rate was maintained in the range of 0.53-0.67 g biomass / g COD removal during wastewater treatment, Figure 3 It can be clearly seen that as the salinity increases to 40 g NaCl / L, the yield and biomass production show the same growth trend. When the salinity continues to increase from 40g NaCl / L to 80g NaCl / L, both show a decreasing trend, that is, the optimal salinity range for PPB-MBR to produce PPB biomass is 20-40 g NaCl / L. In addition, due to the retention of the membrane, the biomass produced by PPB-MBR can be effectively recovered almost 100%. Combining the above two aspects, it can be seen that the wastewater treatment performance and resource utilization capacity of PPB-MBR can be optimized under the appropriate salinity (20-40 g NaCl / L). In subsequent experiments, the salinity was controlled within this range to achieve optimal wastewater treatment and resource utilization.

[0037] The harmlessness and bioavailability of the PPB feed in this application were verified through the black-shell shrimp feeding experiment. The breeding experiment used black-shell shrimp, and the young shrimp were purchased from the Central and Southern Aquatic Breeding Base. Before the experiment, the corresponding feed was used for pre-cultivation for 7 days, and sick shrimp, dead shrimp and non-juvenile shrimp were removed, and all shrimp were initially measured. The equipment required in the experiment included a breeding glass tank, an aeration pump, an oxygen pump, a temperature control device, and a timer. The breeding experiment was carried out in a shrimp breeding tank with a volume of 30L. A total of 3 breeding tanks were set up, and different feed combinations were added in equal amounts: PPB gel feed, commercial feed, and PPB gel feed + commercial feed. The breeding density in all tanks was 50 per tank. The experiment lasted 28 days, during which the temperature and illumination were controlled at 25°C and 12 h light / 12 h dark. During the experiment, the residual material was cleaned once a day, and the water lost by aeration and evaporation was replenished; water was changed and monitored every 7 days. The feed amount is adjusted in time through the shrimp weight gain, growth, survival rate, feed conversion ratio (FCR), and shrimp specific growth rate (SFG), and relevant charts are drawn to determine the breeding effect. The preparation effect of PPB feed: The sodium alginate-calcium ion embedded gel forming system combined with the PPB scraped out of the reactor produces a feed with moderate texture. After drying, it is easy to further process and grind. The product picture is as follows Figure 4 As shown, Figure 4 a is a microscopic picture, Figure 4 b is a diagram of the powder morphology of the product. The PPB feed ingredients produced in Example 1 of the present application were compared with the ingredients of commercial feed (purchased from Zhongnan Aquaculture Farm), and the results are shown in Table 2.

[0038] Table 2 Composition of PPB feed and commercial feed

[0039] The dry weight of the PPB gel feed obtained in Example 1 is slightly lower than that of the commercial feed, which is attributed to the high water retention capacity of the gel feed itself. However, the protein content of each gram of dry weight of the PPB gel feed can reach 181.16 mg / g, which is basically consistent with the 189.8 mg / g of the commercial feed. At the same time, the PPB gel feed shows a lower fat content, and its lipid content is about 64% of that of the commercial feed. In addition, the ash content of the PPB gel feed is also low, only about 4.3%, indicating that the energy of the PPB gel feed is higher. Therefore, through component analysis, the PPB gel feed has the potential to compete with commercial feed and has certain feasibility.

[0040] The application effect of the PPB feed obtained in Example 1: Figure 5It can be seen that after the end of the breeding experiment, the final results of the length and weight of the three feed groups were not much different. The average weight of black-shell shrimp was about 0.17g and the average length was about 2cm. However, the adult speed of the PPB feed group and the mixed feed group was faster, especially the PPB feed group had the fastest speed, and the specific growth rate (SGR) was the highest among the three feed experimental groups, about 3.7 per day. At the same time, the feed conversion rate (FCR) also showed the same results. The commercial feed group was about 7.7 g dry feed / g shrimp weight gain, which was about 1.7 times higher than the PPB feed group. This shows that the addition of PPB-containing feed can achieve a better feeding effect with a small amount of feed. This may be because PPB bacteria can enhance the intestinal peristalsis of the fed organisms and improve the digestive capacity of the fed animals, thereby increasing the FCR and SGR. This proves that PPB bacteria feed has the potential to replace traditional feed and even achieve better feeding effects.

[0041] The present invention adopts PPB-MBR to treat wastewater, and under the stress of salinity, achieves good pollutant removal effect while producing sufficient PPB biomass, providing a large amount of raw materials for the preparation of PPB feed, achieving the dual purposes of wastewater treatment and resource utilization.

[0042] The process used in the preparation method of the PPB gel feed obtained in Example 1 of the present invention is simple and has low requirements on equipment. At the same time, by comparing the ingredients of the PPB gel feed with those of commercial feed, the PPB gel feed has the potential to compete with commercial feed and has certain feasibility.

[0043] In the feeding experiment, compared with the commercial feed, the PPB feed obtained in Example 1 increased the specific growth rate of black-shell shrimp and achieved a lower feed conversion ratio, that is, the PPB feed required for the black-shell shrimp to grow to a certain mass was less than the commercial feed, thereby lowering the actual feeding cost.

[0044] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing bacterial protein feed based on purple bacteria wastewater treatment, characterized in that: The following steps are involved: S1. Under light and anaerobic conditions, purple non-sulfur bacteria and saline wastewater are treated by membrane separation, and biomass and treated saline wastewater are collected; S2. After the biomass and sodium alginate are mixed and sterilized, they are mixed with a molding agent and molded to obtain the bacterial protein feed.

2. The method for preparing bacterial protein feed based on purple bacteria wastewater treatment according to claim 1, characterized in that: In step S1, the membrane separation treatment step is based on the operation of a purple bacteria membrane bioreactor; the purple bacteria membrane bioreactor includes: a reaction chamber provided with a water inlet, a water outlet and a mud discharge outlet, a PDVF flat membrane accommodated in the reaction chamber, an inlet peristaltic pump connected to the water inlet, a water outlet peristaltic pump connected to the water outlet, and a pressure monitoring gauge connected to the PDVF.

3. The method for preparing bacterial protein feed based on purple bacteria wastewater treatment according to claim 2, characterized in that: In step S1, the specific steps of the membrane separation treatment are as follows: S11. Inoculating and acclimating purple non-sulfur bacteria in the purple bacterial membrane bioreactor; S12. adjusting the salinity of the wastewater to obtain saline wastewater, inputting the saline wastewater into the purple bacteria bioreactor through the water inlet, and outputting it through the water outlet to obtain treated saline wastewater, and at the same time scraping the attachments on the PDVF flat membrane in the purple bacteria membrane bioreactor to obtain the biomass.

4. The method for preparing bacterial protein feed based on purple bacteria wastewater treatment according to claim 3, characterized in that: In the step S11, the acclimation step is: continuously inputting untreated wastewater into the purple bacteria membrane bioreactor through the water inlet, and semi-continuously outputting it through the water outlet to form an acclimated residual liquid; wherein the specific step of continuous input is: continuously inputting wastewater into the water inlet through the water inlet peristaltic pump, and setting the flow rate of the water inlet peristaltic pump to 1.5-2ml / h, and the hydraulic retention time to 20-25h; the specific step of semi-continuous output is: semi-continuously outputting wastewater to the water outlet through the water outlet peristaltic pump, and the setting of the water outlet peristaltic pump is 5min suction / 5min relaxation, and the working volume in the reaction chamber is maintained at 2L.

5. The method for preparing bacterial protein feed based on purple bacteria wastewater treatment according to claim 1, characterized in that: In step S1, the salinity of the saline wastewater is 1-80 g NaCl / L.

6. The method for preparing bacterial protein feed based on purple bacteria wastewater treatment according to claim 1, characterized in that: In step S1, the saline wastewater includes the following components: 0.19 g / L ammonium chloride, 0.1 g / L sodium bicarbonate, 1.98 g / L sodium acetate, 0.1 g / L magnesium chloride hexahydrate, 0.05-0.1 g / L potassium dihydrogen phosphate, and 1-2 mL / L trace element solution; wherein the trace element solution includes 1.8 g / L FeCl2·4H2O, 0.25 g / L CoCl2·6H2O, 0.01 g / L NiCl2·6H2O, 0.01 g / L CuCl2·2H2O, 0.07 g / L MnCl2·4H2O, 0.1 g / L ZnCl2, 0.5 g / L H3BO3, and 0.03 g / L Na2MoO4·2H2O.

7. The method for preparing bacterial protein feed based on purple bacteria wastewater treatment according to claim 1, characterized in that: In step S2, the molding agent includes 3-5 parts of calcium lactate, 1-3 parts of calcium chloride, and 100 parts of water.

8. The method for preparing bacterial protein feed based on purple bacteria wastewater treatment according to claim 1, characterized in that: In step S2, the mass concentration of the sodium alginate solution is 3-5%.

9. A bacterial protein feed obtained by the method according to any one of claims 1 to 8.

10. Use of the bacterial protein feed according to claim 9 in shrimp farming.

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