Rural black water harmlessness and recycling system and method based on microbial enhancement

Abstract

The invention discloses a rural black water harmless and recycling system and method based on microbial enhancement, and relates to the technical field of black water treatment. The treatment system adopts a multi-grid black water treatment tank structure, the multi-grid black water treatment tank structure at least comprises a first treatment grid, a second treatment grid and a third treatment grid, the first treatment grid is a black water pre-fermentation tank, the second treatment grid is a harmless treatment tank, and the third treatment grid is a liquid fertilizer storage tank; the second treatment grid is communicated with the third treatment grid; adding a fermentation inoculant and a spherical biological filler into the black water pre-fermentation tank; adding a spherical biological filler into the harmless treatment tank; black water is treated by the first treatment grid, the second treatment grid and the third treatment grid; the fermentation inoculant at least contains phylum firmicalis, bacteroides, proteobacteria, actinomycetes and cyanobacteria, and the abundance of the phylum firmicalis exceeds 50%. According to the method, the harmless and recycling effects of the black water are realized.

Description

Technical Field

[0001] The invention relates to the technical field of black water treatment, and in particular to a rural black water harmlessness and resource utilization system and method based on microbial enhancement. Background Art

[0002] Sewage treatment needs to be combined with rural toilet reform work, so that toilet sewage can be returned to the fields on site after harmless treatment, and feces and water can be treated ecologically. It is also encouraged to use rural domestic sewage through artificial wetlands and other means to realize nitrogen and phosphorus resource utilization and tail water reuse.

[0003] The black water contains a large amount of pathogenic microorganisms, organic matter, nitrogen, phosphorus and other components. If it is discharged directly without proper treatment, it will seriously pollute the soil, groundwater and surrounding environment. Because black water contains nutrients such as nitrogen, phosphorus and potassium, it can be used as liquid fertilizer for resource utilization after effective fermentation and harmlessness. At present, the treatment of black water (feces and urine sewage) in domestic sewage is still a major problem.

[0004] Traditionally, rural areas usually use simple septic tanks to treat black water, and farmers directly use the overflow after discharge. This method cannot eliminate pathogenic microorganisms such as fecal coliform bacteria and salmonella in black water, and the harmless sanitation requirements cannot be guaranteed. In some areas, the method of treating black water is to collect it through a pipe network and mix it with other domestic sewage before discharging it. This method consumes energy to remove nitrogen and phosphorus resources, which is an unsustainable treatment method. In response to these problems, it is necessary to propose a decentralized rural black water treatment process to harmlessly treat and utilize rural black water as a resource. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a black water harmless and resourceful treatment system and method.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A rural blackwater harmless treatment and resource utilization system based on microbial enhancement adopts a multi-format blackwater treatment tank structure, and the multi-format blackwater treatment tank structure at least includes a first treatment cell, a second treatment cell and a third treatment cell, wherein the first treatment cell is a blackwater pre-fermentation tank, the second treatment cell is a harmless treatment tank, and the third treatment cell is a liquid fertilizer storage tank; the harmless treatment tank is connected to the liquid fertilizer storage tank; a fermentation agent is added to the blackwater pre-fermentation tank; spherical biological fillers are added to the blackwater pre-fermentation tank and the harmless treatment tank; the blackwater is treated by the blackwater pre-fermentation tank, the harmless treatment tank and the liquid fertilizer storage tank; the fermentation agent contains at least Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Cyanobacteria, and the abundance of Firmicutes exceeds 50%.

[0008] Based on the above technical solution, further, the multi-format black water treatment tank structure is a three-format black water treatment tank; the black water pre-fermentation tank, harmless treatment tank, and liquid fertilizer storage tank in the three-format black water treatment tank are arranged sequentially, and the black water pre-fermentation tank and the harmless treatment tank are connected.

[0009] Based on the above technical solution, further, the black water pre-fermentation tank, the harmless treatment tank, and the liquid fertilizer storage tank are independently arranged and connected in series in sequence.

[0010] Based on the above technical solution, further, in the three-compartment black water treatment pool, spherical biological fillers are added to the first treatment compartment and the second treatment compartment, wherein the accumulated volume of the spherical biological fillers in the first treatment compartment accounts for 50%-80% of the volume of the first treatment compartment; the accumulated volume of the spherical biological fillers in the second treatment compartment accounts for 50%-80% of the volume of the second treatment compartment.

[0011] Based on the above technical solution, further, the multi-format black water treatment tank structure is a four-format black water treatment tank; the four-format black water treatment tank is also provided with a fourth treatment compartment, and the fourth treatment compartment is a secondary fermentation tank; the secondary fermentation tank is located between the black water pre-fermentation tank and the harmless treatment tank, and the black water pre-fermentation tank is connected to the secondary fermentation tank, and the secondary fermentation tank is connected to the harmless treatment tank.

[0012] Based on the above technical solution, further, the black water pre-fermentation tank, the secondary fermentation tank, the harmless treatment tank, and the liquid fertilizer storage tank are independently arranged and connected in series in sequence.

[0013] Based on the above technical solution, further, in the four-grid black water treatment pool, spherical biological fillers are added to the first treatment grid, the second treatment grid and the third treatment grid, wherein the accumulated volume of the spherical biological fillers in the first treatment grid accounts for 50%-80% of the volume of the first treatment grid; the accumulated volume of the spherical biological fillers in the second treatment grid accounts for 50%-80% of the volume of the second treatment grid; the accumulated volume of the spherical biological fillers in the third treatment grid accounts for 50%-80% of the volume of the third treatment grid.

[0014] Based on the above technical solution, further, the volume ratio of the first treatment compartment, the second treatment compartment, the third treatment compartment and the fourth treatment compartment of the four-compartment black water treatment pool is 2:1:2:1.

[0015] A method for harmless treatment and resource utilization of rural black water based on microbial enhancement, comprising a rural black water harmless treatment and resource utilization system based on microbial enhancement, wherein in a three-compartment black water treatment pool, black water passes through a first treatment compartment and undergoes a hydrolysis reaction under the action of a fermentation agent, with a residence time of not less than 10 days, and solid matter and macromolecular organic matter in the first treatment compartment are preliminarily decomposed into soluble matter and small molecular organic matter, thereby realizing pre-fermentation of black water; black water passes through a second treatment compartment and resides for not less than 5 days, and pathogenic microorganisms in the black water in the second treatment compartment are inactivated, thereby realizing harmless treatment of black water; black water passes through a third treatment compartment and resides for not less than 15 days, and the treated black water becomes liquid fertilizer, which is stored in the third treatment compartment and applied to farmland for resource utilization.

[0016] A method for harmless and resource-based rural black water treatment based on microbial enhancement includes a rural black water harmless and resource-based rural black water treatment system based on microbial enhancement. In a four-compartment black water treatment pool, black water passes through a first treatment compartment and undergoes a hydrolysis reaction under the action of a fermentation agent, with a residence time of not less than 10 days. In the first treatment compartment, solid insoluble substances are preliminarily decomposed into soluble substances, thereby realizing pre-fermentation of black water; black water passes through a fourth treatment compartment and stays for not less than 5 days. In the fourth treatment compartment, macromolecular organic matter that has been preliminarily dissolved in the black water undergoes a hydrolysis reaction and is further decomposed into smaller molecular substances, thereby realizing secondary fermentation of black water; black water passes through a second treatment compartment and stays for not less than 5 days. In the second treatment compartment, pathogenic microorganisms in the black water are inactivated, thereby realizing harmless black water treatment; black water passes through a third treatment compartment and stays for not less than 10 days. The treated black water becomes liquid fertilizer, which is stored in the third treatment compartment and applied to farmland for resource utilization; wherein the total residence time of black water is not less than 30 days.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The system and method of the present invention can convert black water into liquid fertilizer to realize resource utilization; the entire treatment process is non-powered; black water is rendered harmless, ensuring hygienic and safe application; and avoiding the discharge of pollutants. In addition, a multi-stage black water treatment pool is used, and microbial carriers (spherical biological fillers) are added, and efficient fermentation agents are added at the same time to achieve harmlessness and humification of organic matter.

[0019] (2) The present invention uses anaerobic fermentation agents to strengthen the acid production process of black water anaerobic fermentation, promote the rapid hydrolysis of organic matter in black water and accumulate organic acids, inhibit the subsequent methanogenesis process, retain small molecular organic matter and nutrients in black water, obtain liquid fertilizer, and effectively control odor substances and pathogenic microorganisms such as fecal coliform group in black water, ensuring the safety of fermentation liquid returned to the field. Through batch experiments, the effects of anaerobic fermentation agent dosage and fermentation temperature on the transformation of organic matter in black water, accumulation of organic acids, odor control and inactivation of pathogenic microorganisms were investigated, the changes in the microbial community structure in the fermentation system were analyzed, and a suitable black water enhanced treatment method was proposed, providing a basis for realizing the safe utilization of rural black water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a three-format black water treatment pool of the present invention;

[0021] Figure 2 This is a schematic diagram of the structure of a four-compartment black water treatment pool of the present invention;

[0022] Figure 3 The figure is a curve diagram showing the effect of the dosage of the fermentation agent on SCOD of the present invention;

[0023] Figure 4 The figure is a curve diagram showing the effect of the dosage of the fermentation agent on TCOD of the present invention;

[0024] Figure 5 The figure is a curve diagram showing the effect of the dosage of the fermentation agent on ammonia nitrogen;

[0025] Figure 6 The figure is a curve diagram showing the effect of the dosage of the fermentation agent on the mass concentration of VFA in the present invention;

[0026] Figure 7 The figure is a curve diagram showing the effect of the dosage of the fermentation agent of the present invention on the total nutrients;

[0027] Figure 8 The graph is a graph showing the accumulation of SCOD, VFA and ammonia nitrogen in black water under different anaerobic fermentation agent dosages of the present invention;

[0028] Reference numerals:

[0029] 1. Black water pre-fermentation tank; 2. Harmless treatment tank; 3. Liquid fertilizer storage tank; 4. Secondary fermentation tank; 5. Water inlet pipe; 6. Overflow outlet pipe; 7. Spherical biological filler; 8. Perforated flower wall; 9. Inspection port. DETAILED DESCRIPTION

[0030] It is worth noting that the raw materials used in the present invention are all common commercially available products, and their sources are not specifically limited.

[0031] The following sources of raw materials are provided for illustrative purposes:

[0032] Example

[0033] The present embodiment provides a rural blackwater harmless treatment and resource utilization system based on microbial enhancement, which adopts a multi-format blackwater treatment tank structure, and the multi-format blackwater treatment tank structure at least includes a first treatment grid, a second treatment grid and a third treatment grid, wherein the first treatment grid is a blackwater pre-fermentation tank 1, the second treatment grid is a harmless treatment tank 2, and the third treatment grid is a liquid fertilizer storage tank 3; the harmless treatment tank 2 is connected to the liquid fertilizer storage tank 3; a fermentation agent is added to the blackwater pre-fermentation tank 1, and the fermentation agent and the black water can be mixed evenly by manual stirring; spherical biological fillers 7 are added to the blackwater pre-fermentation tank 1 and the harmless treatment tank 2; the black water is treated by the blackwater pre-fermentation tank 1, the harmless treatment tank 2, and the liquid fertilizer storage tank 3; the fermentation agent contains at least Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Cyanobacteria, and the abundance of Firmicutes exceeds 50%. Specifically, the fermentation agent is an anaerobic fermentation agent, and the properties of the anaerobic fermentation agent are: pH 7.6, total chemical oxygen demand (TCOD) value of 150000 mg / L, soluble chemical oxygen demand (SCOD) value of 270 mg / L, total solids concentration (TS) of 1500 mg / L, volatile solids concentration (Volatile Solids, VS) is 1480mg / L; among them, the main dominant bacterial phylum of the fermentation agent used is Firmicutes, and its relative abundance can reach 88.28%. Firmicutes is the main bacterial group that promotes cellulose hydrolysis; the main dominant genus is Lactobacillus, and its relative abundance is 87.40%. Lactobacillus can promote the process of anaerobic fermentation and acid production; the fermentation agent can effectively decompose protein, cellulose, and aliphatic groups in black water, and while hydrolyzing large molecular organic matter, retain small molecular organic matter and nutrients to realize the resource utilization of black water. At the same time, it can effectively inactivate fecal coliform bacteria, ascarid eggs, salmonella and other pathogenic microorganisms in black water to achieve harmlessness of black water. The specific fermentation agent composition formula and microbial community abundance are shown in Table 1 below:

[0034] Table 1 Abundance of microbial communities in anaerobic fermentation agents

[0035]

[0036] In one embodiment, in combination Figure 1As shown, the multi-format black water treatment tank structure is a three-format black water treatment tank; that is, the three-format black water treatment tank includes a first treatment grid, a second treatment grid and a third treatment grid, wherein the black water pre-fermentation tank 1, the harmless treatment tank 2, and the liquid fertilizer storage tank 3 in the three-format black water treatment tank are arranged in sequence, and the black water pre-fermentation tank 1 is connected to the harmless treatment tank 2, and the harmless treatment tank 2 is connected to the liquid fertilizer storage tank 3.

[0037] Further, the black water treatment system can be set as a divisible structure, that is, the black water pre-fermentation tank 1, the harmless treatment tank 2, and the liquid fertilizer storage tank 3 are independently arranged and connected in series; or; the black water treatment system is set as an integrated structure, the black water pre-fermentation tank 1, the harmless treatment tank 2, and the liquid fertilizer storage tank 3 are arranged inside the integrated structure, and a perforated flower wall 8 structure can be set between adjacent treatment grids to achieve a barrier effect. In the three-grid black water treatment tank, the spherical biological filler 7 is added to the black water pre-fermentation tank 1 and the harmless treatment tank 2, wherein the accumulated volume of the spherical biological filler 7 in the first treatment grid accounts for 50%-80% of the volume of the first treatment grid; the accumulated volume of the spherical biological filler 7 in the second treatment grid accounts for 50%-80% of the volume of the second treatment grid, and the volume is preferably the effective volume. Among them, the water inlet pipe 5 of the black water treatment system, the connecting pipes between each treatment grid, and the pipe opening height positions of the overflow outlet pipe 6 should be staggered to avoid short-circuiting; and in order to facilitate the use of liquid fertilizer, the diameter of the inspection port 9 of the liquid fertilizer storage tank 3 of the three-grid black water treatment tank is set to 400mm-500mm.

[0038] When it is a three-compartment black water treatment pool, the method for treating black water is as follows: the black water passes through the first treatment compartment and undergoes a hydrolysis reaction under the action of a fermentation agent, with a residence time of not less than 10 days. The solid matter and large-molecule organic matter in the first treatment compartment are preliminarily decomposed into soluble matter and small-molecule organic matter, thereby realizing pre-fermentation of black water; the black water passes through the second treatment compartment and retains a time of not less than 5 days. The pathogenic microorganisms in the black water in the second treatment compartment are inactivated, thereby realizing harmless treatment of the black water; the black water passes through the third treatment compartment and retains a time of not less than 15 days. The treated black water becomes liquid fertilizer, which is stored in the third treatment compartment and applied to farmland for resource utilization.

[0039] In another embodiment, in combination Figure 2 As shown, the multi-format black water treatment tank structure is a four-format black water treatment tank; that is, it includes a first treatment grid, a second treatment grid, a third treatment grid and a fourth treatment grid, and the fourth treatment grid is a secondary fermentation tank 4; the secondary fermentation tank 4 is located between the black water pre-fermentation tank 1 and the harmless treatment tank 2, and the black water pre-fermentation tank 1 is connected to the secondary fermentation tank 4, the secondary fermentation tank 4 is connected to the harmless treatment tank 2, and the harmless treatment tank 2 is connected to the liquid fertilizer storage tank 3.

[0040] Further, the black water pre-fermentation tank 1, the secondary fermentation tank 4, the harmless treatment tank 2, and the liquid fertilizer storage tank 3 are independently arranged and connected in series; or; the black water treatment system is set as an integrated structure, and the black water pre-fermentation tank 1, the secondary fermentation tank 4, the harmless treatment tank 2, and the liquid fertilizer storage tank 3 are arranged inside the integrated structure. At this time, a perforated flower wall 8 structure can be set between adjacent treatment grids to achieve a barrier effect. In the four-grid black water treatment tank, spherical biological fillers 7 are added to the first treatment grid, the second treatment grid, and the third treatment grid, wherein the accumulated volume of the spherical biological fillers 7 in the first treatment grid accounts for 50%-80% of the volume of the first treatment grid; the accumulated volume of the spherical biological fillers 7 in the second treatment grid accounts for 50%-80% of the volume of the second treatment grid; the accumulated volume of the spherical biological fillers 7 in the third treatment grid accounts for 50%-80% of the volume of the third treatment grid, and the volume is preferably the effective volume.

[0041] In this embodiment, the volume ratio of the first treatment compartment, the second treatment compartment, the third treatment compartment, and the fourth treatment compartment of the four-compartment black water treatment tank is 2:1:2:1. Among them, the height positions of the pipe openings of the water inlet pipe 5 of the black water treatment system, the connecting pipes between the treatment compartments, and the overflow outlet pipe 6 should be staggered to avoid short-circuiting; and in order to facilitate the use of liquid fertilizer, the diameter of the inspection port 9 of the liquid fertilizer storage tank 3 of the three-compartment black water treatment tank is set to 400mm-500mm.

[0042] When it is a four-grid black water treatment pool, the method for treating black water is as follows: the black water passes through the first treatment grid and undergoes a hydrolysis reaction under the action of a fermentation agent, with a residence time of not less than 10 days. In the first treatment grid, solid insoluble substances are preliminarily decomposed into soluble substances, thereby realizing pre-fermentation of black water; the black water passes through the fourth treatment grid and remains for not less than 5 days. In the fourth treatment grid, the macromolecular organic matter that has been preliminarily dissolved in the black water undergoes a hydrolysis reaction and is further decomposed into smaller molecular substances, thereby realizing secondary fermentation of black water; the black water passes through the second treatment grid and remains for not less than 5 days. In the second treatment grid, pathogenic microorganisms in the black water are inactivated, thereby realizing harmlessness of the black water; the black water passes through the third treatment grid and remains for not less than 10 days. The treated black water becomes liquid fertilizer, which is stored in the third treatment grid and applied to farmland for resource utilization; wherein the total residence time of the black water is not less than 30 days.

[0043] The following is a 10-day anaerobic fermentation experiment of black water in a 2L anaerobic fermentation bottle to explore the effects of different fermentation agent dosages on the anaerobic fermentation of black water, wherein no certain format structure is limited.

[0044] (1) Experimental preparation: A toilet was selected for the experiment with black water, and the flushing volume of the toilet was 5L each time. After sampling, the black water was mixed and dispensed into anaerobic fermentation bottles for anaerobic fermentation experiments. Among them, the black water pH was 9.2±0.3, TCOD was (2900±100) mg / L, SCOD was (300±20) mg / L, TS was (1950±150) mg / L, VS was (1200±100) mg / L, TN was (545±25) mg / L, TP was (125±15) mg / L, total potassium (TK) was (3.5±1.7) mg / L, fecal coliform count was (1.6±0.8)×1010 MPN / L, and the number of Ascaris eggs was (2650±350) MPN / L.

[0045] (2) Experimental device: A double-layer anaerobic reactor was used, with an effective volume of 2 L and a stirrer with a rotation speed of 30 r / min. A constant temperature water bath with a circulation pump was used to inject constant temperature water into the reactor interlayer to control the reaction temperature.

[0046] (3) Experimental process:

[0047] First, determine the appropriate dosage of anaerobic fermentation agents. Before the formal experiment, black water fermentation pre-experiments were carried out at two dosage gradients of 0, 0.2, 0.4, 0.6, 0.8, 1mL and 0, 2, 4, 6, 8, 10mL, respectively. The black water volume was 2L and the fermentation time was 20d. The preliminary experimental results showed that the anaerobic fermentation effect was poor at a dosage of less than 1mL, while the effect of anaerobic fermentation agents was not significantly different at a dosage of 2-10mL. Therefore, the dosage gradient of the agent was set to 0.5, 1.0, 1.5, 2.0 and 2.5mL. After 10d of fermentation, the indicators such as SCOD and VFA tended to be stable, so the fermentation time was determined to be 10d.

[0048] By changing the dosage of anaerobic fermentation agent, anaerobic fermentation experiment of black water was carried out in 6 anaerobic fermentation bottles with an effective volume of 2L (corresponding to F0-F5), and 0, 0.5, 1.0, 1.5, 2.0, and 2.5 ml of anaerobic fermentation agent were added to F0-F5 respectively. The fermentation cycle was 10 days, among which F0 was the control group and F1-F5 were the experimental groups. The anaerobic fermentation experiment was carried out at room temperature (20℃±1℃) for 10 days. Polyurethane sponge filler was added to the anaerobic fermentation bottle to promote microbial growth, and the dosage was 40% of the effective volume of the corresponding anaerobic fermentation bottle. The pH, TCOD, SCOD, total nitrogen, total phosphorus, ammonia nitrogen, VFA and other indicators of black water were monitored. The raw black water and fermented water samples after 0.45μm membrane filtration were stored at 4℃ and the determination was completed within 3 days. After sampling every day, nitrogen was passed through the anaerobic fermentation bottle for 5 minutes to ensure the anaerobic environment.

[0049] Secondly, determine the effect of temperature on the anaerobic fermentation of black water enhanced by anaerobic fermentation agents. 2.0 mL of anaerobic fermentation agent (the dosage was determined by the above experiment) was added to each of the three reactors containing 2 L of black water, the stirring speed was 30 r / min, the polyurethane filler filling volume ratio was 70%, and the anaerobic fermentation experiment was carried out for 10 days at three temperature gradients of 10, 20, and 30 ° C. The experiments were numbered T1, T2, and T3, and a control group T0 without adding anaerobic fermentation agents was set at 20 ° C. The raw black water and fermented water samples after 0.45 μm membrane filtration were stored at 4 ° C and the determination was completed within 3 days. After sampling every day, nitrogen was passed through the anaerobic fermentation bottle for 5 minutes to ensure an anaerobic environment.

[0050] Furthermore, the microbial community structure during the anaerobic fermentation of black water was analyzed. At room temperature, the anaerobic fermentation experiment was carried out in an anaerobic reactor with an effective volume of 2L, the dosage of anaerobic fermentation agent was 2.0mL, and the stirring rate was 30r·min -1 , the filling rate of polyurethane filler is 70%, recorded as M1. A control group without adding anaerobic fermentation agent is set as M0, and other conditions are the same. Take black water raw water and M0 and M1 fermentation broths with fermentation time of 1, 5, and 10d, and obtain precipitates after centrifugation at 12000r·min-1. The precipitates are subjected to high-throughput sequencing to analyze their microbial community structure. Other index analysis methods in this embodiment, such as pH value, TS, VS, TCOD, SCOD, ammonia nitrogen, TN, TP, etc., are determined in accordance with national standard methods; for example, pH is determined using a pH100A pH meter, etc. Other specific analysis methods are prior art and are not recorded in detail here.

[0051] (4) Experimental results and analysis: Figure 3-Figure 8 As shown in the figure, under the condition of normal temperature and without adding bacteria, the value of TCOD showed an overall trend of fluctuating and decreasing. Compared with F0, the concentration of TCOD decreased slowly in the anaerobic fermentation bottle with the addition of anaerobic fermentation bacteria. Among them, F5 added the largest dose of anaerobic fermentation bacteria, and its TCOD removal rate was 36%, which was lower than 43.3% of F4. F1, F2 and F3 had similar TCOD removal rates, all around 67%. This difference in TCOD changes may be due to the addition of bacteria, which caused the large particles in the black water that were easier to precipitate through physical sedimentation to be decomposed into smaller particles that were less likely to settle. It can also be seen from the apparent morphology of the black water: there are more flocs in the anaerobic fermentation bottle with the addition of bacteria, while most of the solid matter in the control group settled at the bottom.

[0052] Unlike TCOD, SCOD and ammonia nitrogen show opposite trends. As the number of reaction days increases, SCOD as a whole shows an increase first, then a decrease, and then a stable state. There are two reactions inside the anaerobic fermentation bottle at the same time. One is that the insoluble particles with larger particle size are gradually converted into insoluble particles with larger particle size under the action of microorganisms, and further converted into soluble substances, which will lead to an increase in SCOD. At the same time, the organic matter dissolved in the water will be used by microorganisms through the assimilation of microorganisms, which will lead to a decrease in SCOD. In the first three days of the reaction, the main reaction process in the anaerobic fermentation bottle is the conversion of insoluble substances into soluble organic matter. Therefore, the SCOD value accumulates rapidly in the first three days and shows an upward trend. In the next two days, the increase in the content of soluble organic matter in black water leads to a large growth of microorganisms, and assimilation begins to occupy a dominant position. At this time, the assimilation rate is greater than the dissolution rate, and SCOD shows a downward trend. After that, the two reactions gradually reach equilibrium, so the SCOD value also remains balanced. In the 6 anaerobic fermentation bottles, the SCOD concentration reached a peak on the third day and then began to decline. Among them, the SCOD peak value in the anaerobic fermentation bottle corresponding to F5 was the highest, at 1800 mg / L, while the peak value of the control group without adding bacterial agents was the lowest. During the entire reaction period, the SCOD value of the control group without adding bacterial agents was at the lowest position among the six anaerobic fermentation bottles. This shows that the addition of anaerobic fermentation agents can effectively promote the conversion of insoluble substances in black water into soluble organic matter, which may be beneficial to the growth of microorganisms in black water. Ammonia nitrogen accumulates continuously with the progress of anaerobic fermentation, and with the increase in the amount of bacterial agent added, the accumulation rate and amount of ammonia nitrogen increase. The ammonia nitrogen concentration of the F5 anaerobic fermentation bottle reached 328 mg / L after 10 days of reaction, which was significantly higher than the 264 mg / L of the control group. This shows that the anaerobic fermentation agent used can significantly promote the hydrolysis process of protein and make a great contribution to increasing the nutrient concentration in black water.

[0053] The effect of anaerobic fermentation agent dosage on ammonia nitrogen was analyzed. Ammonia nitrogen increased from the initial 147 mg·L -1 It began to accumulate rapidly, reaching a maximum of 342 mg·L -1 Since black water contains a lot of protein, microorganisms decompose the protein to form high-quality ammonia nitrogen. Studies have shown that the ammonia nitrogen concentration in the anaerobic fermentation process should be maintained at 200 mg·L -1 The following is to avoid high mass concentration of ammonia nitrogen inhibiting the activity of methanogens. However, the anaerobic fermentation agent used in this embodiment is intended to promote the anaerobic acid production process, that is, the first stage of anaerobic fermentation. Through this stage, a fermentation liquid rich in organic matter and nitrogen and phosphorus nutrients is produced, thereby realizing the resource utilization of black water. The accumulation of ammonia nitrogen can increase the content of nutrients in the fermentation liquid, which is beneficial to the resource utilization efficiency of black water. The amount of ammonia accumulation in the anaerobic fermentation bottle with the addition of anaerobic fermentation agent was significantly higher than that of the control group. After 10 days of reaction, the ammonia nitrogen mass concentration of F5 reached 342 mg·L-1 , which was significantly higher than the control group's 198 mg·L -1 Therefore, the addition of anaerobic fermentation agents can significantly promote the hydrolysis process of protein and urea, which is beneficial to increase the mass concentration of nutrients in black water. This is similar to SCOD. The addition of only 0.5 mL of anaerobic fermentation agents can increase the mass concentration of ammonia nitrogen in black water by 27%, while the mass concentration accumulation of ammonia nitrogen in F5 is only increased by 2% compared with F4. Therefore, after increasing the dosage of anaerobic fermentation bacteria to 2.0 mL, increasing the amount of agents used cannot significantly improve the accumulation efficiency of ammonia nitrogen.

[0054] The effect of the dosage of anaerobic fermentation agent on the generation of VFA was analyzed. The macromolecular organic matter in black water can be converted into small molecular organic matter that can be used by microorganisms and plants through anaerobic fermentation. The anaerobic fermentation agent used in this embodiment strengthens the process of anaerobic acid production and promotes the accumulation of VFA in black water. The VFA accumulation in the control group was the lowest, and after 10 days of reaction, it only increased from the initial 62.16 mg / L to 116.84 mg / L. In the anaerobic fermentation bottle to which the anaerobic fermentation agent was added, the accumulation of VFA was significantly higher than that of the control group, indicating that the anaerobic fermentation agent has a positive promoting effect on the acid production stage of anaerobic fermentation of black water. Increasing the dosage of the fermentation agent can increase the yield of VFA, but when the dosage is increased from 2 mL of F4 to 2.5 mL of F5, the VFA yield and accumulation rate are similar.

[0055] The fecal coliform value is an important indicator for evaluating the harmlessness of black water. In this example, the fecal coliform value of raw black water and black water after 10 days of fermentation was monitored, and the results are shown in Table 2.

[0056] Table 2 Changes in fecal coliform values ​​in black water

[0057] Fermentation time (d) F0 F1 F2 F3 F4 F5 0 <![CDATA[4.0×10 -6 ]]> <![CDATA[4.0×10 -6 ]]> <![CDATA[4.0×10 -6 ]]> <![CDATA[4.0×10 -6 ]]> <![CDATA[4.0×10 -6 ]]> <![CDATA[4.0×10 -6 ]]> 10 <![CDATA[4.0×10 -5 ]]> 0.4 0.6 3.6 4.3 4.3

[0058] As can be seen from Table 2, after 10 days of anaerobic fermentation, the fecal coliform bacteria value in the black water has increased. The higher the fecal coliform bacteria value, the higher the dilution factor required to detect the presence of fecal coliform bacteria, and the fewer the number of fecal coliform bacteria that may be contained in the system. It can be clearly seen that the fecal coliform bacteria value in the anaerobic fermentation bottle with the addition of anaerobic fermentation bacteria is higher than that of the control group, indicating that anaerobic fermentation bacteria can promote the harmlessness of black water and play a positive role in reducing diseases.

[0059] The accumulation of SCOD, ammonia nitrogen and VFA in black water after 10 days of anaerobic fermentation at different anaerobic fermentation agent dosages is shown in Figure 2. Figure 8As shown in the figure, the final accumulated mass concentration of each index is positively correlated with the dosage of anaerobic fermentation agent, indicating that anaerobic fermentation agent can promote the hydrolysis of solid and macromolecular organic matter, the production of VFA and the removal of pathogenic bacteria in black water during anaerobic fermentation. The promotion effect is significant when the dosage increases from 0 to 2mL, and when the dosage of the agent increases from 2mL to 2.5mL, the SCOD value, VFA value and ammonia nitrogen mass concentration do not change significantly. Therefore, the appropriate dosage of anaerobic fermentation agent is 1.0mL / L black water, which is 1% of the amount of black water.

[0060] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A rural blackwater harmless and resourceful system based on microbial enhancement, characterized by: A multi-format black water treatment tank structure is adopted, and the multi-format black water treatment tank structure includes at least a first treatment grid, a second treatment grid and a third treatment grid, wherein the first treatment grid is a black water pre-fermentation tank, the second treatment grid is a harmless treatment tank, and the third treatment grid is a liquid fertilizer storage tank; the harmless treatment tank is connected to the liquid fertilizer storage tank; Add fermentation bacteria into the black water pre-fermentation tank; add spherical biological fillers into the black water pre-fermentation tank and the harmless treatment tank; the black water will be treated by the black water pre-fermentation tank, the harmless treatment tank, and the liquid fertilizer storage tank; The fermentation agent contains at least Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Cyanobacteria, and the abundance of Firmicutes exceeds 50%.

2. A rural blackwater harmlessness and resource utilization system based on microbial enhancement according to claim 1, characterized in that: The multi-format black water treatment tank structure is a three-format black water treatment tank; the black water pre-fermentation tank, the harmless treatment tank, and the liquid fertilizer storage tank in the three-format black water treatment tank are arranged in sequence, and the black water pre-fermentation tank and the harmless treatment tank are connected.

3. A rural blackwater harmlessness and resource utilization system based on microbial enhancement according to claim 2, characterized in that: The black water pre-fermentation tank, the harmless treatment tank, and the liquid fertilizer storage tank are independently arranged and connected in series in sequence.

4. The rural blackwater harmlessness and resource utilization system based on microbial enhancement according to claim 2 is characterized by: In the three-compartment black water treatment pool, the accumulated volume of the spherical biological filler in the first treatment compartment accounts for 50%-80% of the volume of the first treatment compartment; the accumulated volume of the spherical biological filler in the second treatment compartment accounts for 50%-80% of the volume of the second treatment compartment.

5. The rural blackwater harmlessness and resource utilization system based on microbial enhancement according to claim 1 is characterized by: The multi-format black water treatment tank structure is a four-format black water treatment tank; the four-format black water treatment tank is also provided with a fourth treatment compartment, which is a secondary fermentation tank; the secondary fermentation tank is located between the black water pre-fermentation tank and the harmless treatment tank, and the black water pre-fermentation tank is connected to the secondary fermentation tank, and the secondary fermentation tank is connected to the harmless treatment tank.

6. The rural blackwater harmlessness and resource utilization system based on microbial enhancement according to claim 5 is characterized by: The black water pre-fermentation tank, the secondary fermentation tank, the harmless treatment tank, and the liquid fertilizer storage tank are independently arranged and connected in series in sequence.

7. The rural blackwater harmlessness and resource utilization system based on microbial enhancement according to claim 5 is characterized by: In a four-grid black water treatment pool, spherical biological fillers are added to the first treatment grid, the second treatment grid and the third treatment grid, wherein the accumulated volume of the spherical biological fillers in the first treatment grid accounts for 50%-80% of the volume of the first treatment grid; the accumulated volume of the spherical biological fillers in the second treatment grid accounts for 50%-80% of the volume of the second treatment grid; and the accumulated volume of the spherical biological fillers in the third treatment grid accounts for 50%-80% of the volume of the third treatment grid.

8. The rural blackwater harmlessness and resource utilization system based on microbial enhancement according to claim 5 is characterized by: The volume ratio of the first treatment compartment, the second treatment compartment, the third treatment compartment and the fourth treatment compartment of the four-compartment black water treatment pool is 2:1:2:

1.

9. A method for harmless and resourceful treatment of rural black water based on microbial enhancement, characterized in that: A rural blackwater harmless treatment and resource utilization system based on microbial enhancement as described in any one of claims 2-4 is adopted. In a three-compartment blackwater treatment pool, the black water passes through the first treatment compartment and undergoes a hydrolysis reaction under the action of a fermentation agent, with a residence time of not less than 10 days. The solid matter and macromolecular organic matter in the first treatment compartment are preliminarily decomposed into soluble matter and small molecular organic matter, thereby realizing blackwater pre-fermentation; the black water passes through the second treatment compartment and retains a time of not less than 5 days. The pathogenic microorganisms in the black water in the second treatment compartment are inactivated, thereby realizing harmless treatment of the black water; the black water passes through the third treatment compartment and retains a time of not less than 15 days. The treated black water becomes liquid fertilizer, which is stored in the third treatment compartment and applied to farmland for resource utilization.

10. A method for harmless and resourceful treatment of rural black water based on microbial enhancement, characterized in that: A rural blackwater harmless treatment and resource utilization system based on microbial enhancement as described in any one of claims 5 to 8 is adopted. In a four-compartment blackwater treatment pool, the blackwater passes through the first treatment compartment and undergoes a hydrolysis reaction under the action of a fermentation agent, with a residence time of not less than 10 days. In the first treatment compartment, solid insoluble substances are preliminarily decomposed into soluble substances, thereby realizing pre-fermentation of blackwater; the blackwater passes through the fourth treatment compartment and resides for not less than 5 days. In the fourth treatment compartment, the macromolecular organic matter that has been preliminarily dissolved in the blackwater undergoes a hydrolysis reaction and is further decomposed into small molecular substances, thereby realizing secondary fermentation of blackwater; the blackwater passes through the second treatment compartment and resides for not less than 5 days. In the second treatment compartment, pathogenic microorganisms in the blackwater are inactivated, thereby realizing harmlessness of the blackwater; the blackwater passes through the third treatment compartment and resides for not less than 10 days. The treated blackwater becomes liquid fertilizer, which is stored in the third treatment compartment and applied to farmland for resource utilization; wherein the total residence time of the blackwater is not less than 30 days.

Images