Filler for unpowered sand bioreactor and application of filler

Abstract

The invention discloses a filler for an unpowered sand bioreactor and application of the filler. One cubic meter of the filler for the unpowered sand bioreactor comprises 100-300 g of a nitrifying bacterium agent, 90-200 g of a denitrifying bacterium agent and the balance of sand. The sand is composed of coarse sand and fine sand, and the volume ratio of the coarse sand to the fine sand is (17-21): 31; the filler is specially invented for the unpowered sand bioreactor for rural domestic miscellaneous drainage treatment and tail water upgrading and reconstruction of a sewage treatment plant, the unpowered sand bioreactor can be rapidly started after being built, the designed treatment effect can be achieved in a short time, specifically, the mode that nitrification and denitrification are conducted synchronously is adopted, and the effect of improving the treatment efficiency is achieved. By utilizing the synergistic effect of strains, especially through the optimized commercial microbial agent, a microbial film is rapidly formed on the surface of the sand, so that the sewage treatment equipment is rapidly started, and the problems of bad strains, more infectious microbes, slow starting and the like of naturally enriched microorganisms can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a filler for an unpowered sand bioreactor and application thereof. Background Art

[0002] The unpowered sand bioreactor is a very economical, applicable and effective equipment for treating rural domestic sewage and improving the tailwater of sewage treatment plants. It uses sand with a very large specific surface area to enrich and domesticate microbial flora and enzymes that are beneficial to denitrification and phosphorus removal and digestion of various substances in domestic wastewater, thereby decomposing and digesting various pollutants in domestic wastewater to achieve a good treatment effect. However, the microbial flora in the unpowered sand bioreactor is naturally enriched, and there are the following main problems:

[0003] First, the newly built sand bioreactor lacks microorganisms that can decompose and digest various pollutants in domestic wastewater. It takes a long time for the environment in the sand bioreactor to reach the level required for microorganisms to efficiently digest various pollutants in sewage through natural and slow enrichment. Usually, it takes 15-30 days in summer and more than a month or even longer in winter for a sand bioreactor to operate normally from construction. After the sand bioreactor is built and put into use, domestic wastewater is continuously discharged every day. Therefore, in the early stage of the construction of the sand bioreactor, due to the lack of the required microbial flora, the decomposition and digestion effect cannot be achieved;

[0004] Second, the composition of domestic wastewater is complex. The composition of kitchen wastewater and washing wastewater is different. Kitchen wastewater usually contains a lot of grease, food waste, food residues, kitchen wastewater, etc. Its main components are fat, carbohydrates, etc.; washing wastewater is composed of laundry wastewater and bathing wastewater, and various detergents contain high phosphorus. Domestic wastewater has different types in different occasions. The domestic wastewater in restaurants, farmhouses and other places is mainly kitchen wastewater, while the domestic wastewater in rural hotels and other places is mainly washing wastewater. In farmers' households, there are both kitchen wastewater and washing wastewater. Different microbial flora are required to treat domestic wastewater in different scenarios. Therefore, it is necessary to prepare it according to local conditions;

[0005] Third, naturally enriched microorganisms are not necessarily the most dominant flora, and cannot fully meet the needs of microbial flora for decomposing and digesting domestic wastewater;

[0006] Fourth, there is a shortage of technical personnel in rural areas, and the fillers of sand bioreactors are very arbitrary. In addition, the combination, enrichment and addition technology of complex microbial flora is difficult to popularize, and it is necessary to pre-prepare for different types of domestic wastewater;

[0007] Fifth, there is a lack of pre-prepared starter fillers for unpowered sand bioreactors suitable for rural areas. The patent application number 201310597290.8 of Li Jincheng, Shi Qin, Mo Deqing, Li Wenwen, and Shen Yuxiang of Guilin University of Technology studied a biologically active sand reactor, which has a complex structure and requires activated carbon as filler in addition to sand. It consumes electricity and is suitable for treating urban domestic sewage. It is difficult to promote in rural areas. At present, most of the domestic sewage treatment facilities in rural areas that consume electricity and have complex structures have been shut down.

[0008] Sixth, the Ministry of Ecology and Environment recently issued the "Guiding Opinions on Further Promoting Rural Domestic Wastewater Treatment", which requires that unreasonable technical processes (such as overly complex processes, high operating costs, and not in line with rural realities) should be optimized and adjusted in a timely manner. At present, many energy-consuming sewage treatment devices in rural areas are out of service. The main reason is that the process is too complicated, the electricity and maintenance costs are too high, and they are not in line with rural realities. In addition, new carbon emissions will be generated in the process of sewage treatment.

[0009] Therefore, the activated sand bioreactor pre-mixed with microbial agents is a practical technology with low carbon, low operating cost and sustainable operation.

[0010] In view of this, the present invention is proposed. Summary of the invention

[0011] The purpose of the present invention is to provide a filler for an unpowered sand bioreactor and an application thereof. The filler for an unpowered sand bioreactor of the present invention can enable the unpowered sand bioreactor to be quickly started after construction by introducing microbial agents, and achieve the designed treatment effect in a short time.

[0012] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0013] The first aspect of the present invention provides a filler for an unpowered sand bioreactor, wherein 1 cubic meter of the filler for an unpowered sand bioreactor comprises:

[0014] 100-300g of nitrifying bacteria agent, 90-200g of denitrifying bacteria agent, and the rest is sand;

[0015] The sand is composed of coarse sand and fine sand, and the volume ratio of the coarse sand to the fine sand is (17-21):31.

[0016] Preferably, 1 cubic meter of the filler for the unpowered sand bioreactor also includes 50 to 300 g of functional bacterial agent;

[0017] The functional bacterial agent is selected from at least one of a phosphorus removal bacterial agent, an oil removal bacterial agent and a high-salt bacterial agent.

[0018] Preferably, the coarse sand particle size is 3.46-4.75 mm; the fine sand particle size is 0.5-1 mm;

[0019] The sand is natural sand and / or machine-made sand, the loss on ignition of the sand is not more than 0.8%, and the density of the sand is less than 2g / cm 3 The light matter content is not more than 0.22%.

[0020] Preferably, the number of viable bacteria in the nitrifying bacteria agent is not less than 200 million cfu / g.

[0021] Preferably, the number of viable bacteria in the denitrifying bacteria agent is not less than 3 billion cfu / g.

[0022] Preferably, the number of live bacteria in the phosphorus removal bacterial agent is not less than 3 billion cfu / g; the number of live bacteria in the oil removal bacterial agent is not less than 3 billion cfu / g; the number of live bacteria in the high-salt bacterial agent is not less than 3 billion cfu / g.

[0023] The second aspect of the present invention provides an application of the filler for the unpowered sand bioreactor in sewage treatment.

[0024] Preferably, the sewage comprises domestic sewage and / or tail water from a sewage treatment plant.

[0025] Preferably, the type of functional bacterial agent is selected according to the type of sewage. For example, if the sewage contains phosphorus, the functional bacterial agent includes a phosphorus removal bacterial agent; if the sewage contains oil and salt, the functional bacterial agent includes an oil removal bacterial agent and a high-salt bacterial agent.

[0026] The third aspect of the present invention also provides a sewage treatment method, the sewage treatment method comprising the following steps:

[0027] (a) loading the filler for the unpowered sand bioreactor into a sand pool of the unpowered sand bioreactor and leaving it to stand for 20 to 30 hours;

[0028] (b) adjusting the pH value of the sewage to 7.0-8.0 and the carbon-nitrogen ratio to between (5-8):1, and then introducing the sewage into a non-powered sand bioreactor for treatment.

[0029] Preferably, the step of loading the filler for the unpowered sand bioreactor according to any one of claims 1 to 6 into the sand pool of the unpowered sand bioreactor specifically comprises:

[0030] Firstly, the denitrifying bacteria agent, the nitrifying bacteria agent and the functional bacteria agent are prepared into an aqueous solution and left for a period of time to obtain a microbial solution;

[0031] Then, 25% to 35% of the microbial solution is sprayed on the coarse sand and mixed to obtain coarse active sand; then, the remaining microbial solution is sprayed on the fine sand and mixed to obtain fine active sand;

[0032] Subsequently, if the unpowered sand bioreactor is fed with water from the middle or upper middle part, the coarse activated sand is loaded into the sand pool at the top and the fine activated sand is loaded at the bottom; if the unpowered sand bioreactor is fed with water from the bottom, the coarse activated sand is loaded into the sand pool at the bottom and the fine activated sand is loaded at the top.

[0033] Compared with the prior art, the beneficial effects of the present invention include at least:

[0034] The filler for the unpowered sand bioreactor of the present invention is specially invented for the unpowered sand bioreactor used for the treatment of rural domestic wastewater and the upgrading of tail water from sewage treatment plants. The unpowered sand bioreactor can be quickly started after its construction and the designed treatment effect can be achieved in a short time. Specifically, the method of simultaneous nitrification and denitrification is adopted, and the synergistic effect between bacterial strains is utilized, especially through the preferred commercial bacterial agent, a microbial film is quickly formed on the surface of the sand, so that the sewage treatment equipment can be quickly started, which can effectively solve the problems of poor bacterial strains, many miscellaneous bacteria, slow startup, etc. of naturally enriched microorganisms.

[0035] In addition, the present invention aims at sewage of different characteristics. During the installation stage after the equipment is built, the construction personnel will load the fillers for the unpowered sand bioreactor into the unpowered sand bioreactor to achieve rapid startup and achieve the designed treatment effect in a short time. Since the microorganisms have the ability of self-reproduction, they do not need to be added again after the equipment is operating normally, which facilitates the user's management and reduces the user's management costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0037] Figure 1 This is a line graph of the effluent COD index in the experimental example of the present invention.

[0038] Figure 2 It is a line graph of the effluent SS index in the experimental example of the present invention;

[0039] Figure 3 It is a line graph of the total nitrogen index of the effluent in the experimental example of the present invention;

[0040] Figure 4 It is a line graph of the b index of the effluent vegetable oil in the experimental example of the present invention. DETAILED DESCRIPTION

[0041] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0042] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0043] The raw materials used in the following examples are as follows:

[0044] Nitrifying bacteria agent: The number of viable bacteria is not less than 200 million cfu / g, from BioFeng;

[0045] Denitrifying bacteria agent: The number of live bacteria is not less than 3 billion cfu / g, from BioFeng;

[0046] Phosphorus removal agent: The number of viable bacteria is not less than 3 billion cfu / g, from BioFeng;

[0047] Oil removal agent: The number of live bacteria is not less than 3 billion cfu / g, from BioFeng;

[0048] High-salt bacterial agent: The number of live bacteria is not less than 3 billion cfu / g, derived from BioFeng.

[0049] Example 1

[0050] This embodiment is a filler for an unpowered sand bioreactor. One cubic meter of the filler for an unpowered sand bioreactor includes:

[0051] 100g nitrifying bacteria agent, 200g denitrifying bacteria agent, and the balance is sand;

[0052] The sand is composed of coarse sand and fine sand, the volume ratio of the coarse sand to the fine sand is 17:31, wherein the particle size of the coarse sand is 3.46-4.75 mm; the particle size of the fine sand is 0.5-1 mm;

[0053] The sand is quartz sand, the loss on ignition is 0.6%, and the density in the sand is less than 2g / cm 3 The light matter content is 0.17%.

[0054] Example 2

[0055] This embodiment is a filler for an unpowered sand bioreactor. One cubic meter of the filler for an unpowered sand bioreactor includes:

[0056] 300g of nitrifying bacteria agent, 90g of denitrifying bacteria agent, and the balance is sand;

[0057] The sand is composed of coarse sand and fine sand, the volume ratio of the coarse sand to the fine sand is 21:31, wherein the particle size of the coarse sand is 3.46-4.75 mm; the particle size of the fine sand is 0.5-1 mm;

[0058] The sand is quartz sand, the loss on ignition is 0.6%, and the density in the sand is less than 2g / cm 3 The light matter content is 0.17%.

[0059] Example 3

[0060] This embodiment is a filler for an unpowered sand bioreactor. One cubic meter of the filler for an unpowered sand bioreactor includes:

[0061] 240g of nitrifying bacteria agent, 200g of denitrifying bacteria agent, and the balance is sand;

[0062] The sand is composed of coarse sand and fine sand, the volume ratio of the coarse sand to the fine sand is 19:31, wherein the particle size of the coarse sand is 3.46-4.75 mm; the particle size of the fine sand is 0.5-1 mm;

[0063] The sand is quartz sand, the loss on ignition is 0.6%, and the density in the sand is less than 2g / cm 3 The light matter content is 0.17%.

[0064] Example 4

[0065] This embodiment is a filler for an unpowered sand bioreactor. One cubic meter of the filler for an unpowered sand bioreactor includes:

[0066] 120g nitrifying bacteria agent, 100g denitrifying bacteria agent, 250g functional bacteria agent, and the rest is sand;

[0067] The sand is composed of coarse sand and fine sand, the volume ratio of the coarse sand to the fine sand is 19:31, wherein the particle size of the coarse sand is 3.46-4.75 mm; the particle size of the fine sand is 0.5-1 mm;

[0068] The sand is quartz sand, the loss on ignition is 0.6%, and the density in the sand is less than 2g / cm 3 The light matter content is 0.17%;

[0069] The functional bacterial agents include 100g of phosphorus removal agent, 80g of oil removal agent and 70g of high-salt bacterial agent.

[0070] Example 5

[0071] This embodiment is a filler for an unpowered sand bioreactor. One cubic meter of the filler for an unpowered sand bioreactor includes:

[0072] 120g nitrifying bacteria agent, 100g denitrifying bacteria agent, 150g functional bacteria agent, and the rest is sand;

[0073] The sand is composed of coarse sand and fine sand, the volume ratio of the coarse sand to the fine sand is 19:31, wherein the particle size of the coarse sand is 3.46-4.75 mm; the particle size of the fine sand is 0.5-1 mm;

[0074] The sand is quartz sand, the loss on ignition is 0.6%, and the density in the sand is less than 2g / cm 3 The light matter content is 0.17%;

[0075] The functional bacterial agents include 80g of degreasing bacterial agent and 70g of high-salt bacterial agent.

[0076] Example 6

[0077] This embodiment is a filler for an unpowered sand bioreactor. One cubic meter of the filler for an unpowered sand bioreactor includes:

[0078] 120g nitrifying bacteria agent, 100g denitrifying bacteria agent, 100g functional bacteria agent, and the rest is sand;

[0079] The sand is composed of coarse sand and fine sand, the volume ratio of the coarse sand to the fine sand is 19:31, wherein the particle size of the coarse sand is 3.46-4.75 mm; the particle size of the fine sand is 0.5-1 mm;

[0080] The sand is quartz sand, the loss on ignition is 0.6%, and the density in the sand is less than 2g / cm 3 The light matter content is 0.17%;

[0081] The functional bacterial agent is 100g of phosphorus removal bacterial agent.

[0082] Example 7

[0083] This embodiment is a method for treating tail water from a sewage treatment station. Before the tail water is treated, the COD is 220 mg / L, the ammonia nitrogen is 30 mg / L, the carbon-nitrogen ratio is 7.33, and the pH value is 7.5. There is no need to adjust the carbon-nitrogen ratio and the pH value. The sewage treatment method comprises the following steps:

[0084] (a) The method of loading the filler for the unpowered sand bioreactor of Example 3 into the sand pool of the unpowered sand bioreactor specifically comprises:

[0085] First, the denitrifying bacteria agent and the nitrifying bacteria agent are prepared into an aqueous solution at a mass ratio of 1:20 and left for a period of time to obtain a microbial solution;

[0086] Then, 30% of the microbial solution is sprayed on the coarse sand and mixed to obtain coarse active sand; then, the remaining microbial solution is sprayed on the fine sand and mixed to obtain fine active sand;

[0087] The unpowered sand bioreactor is fed with water from the middle and upper part, and the coarse activated sand is placed on the top and the fine activated sand is placed on the bottom in the sand pool and left to stand for 20 to 30 hours;

[0088] (b) Introducing the sewage into an unpowered sand bioreactor for treatment.

[0089] Example 8

[0090] This embodiment is a method for treating domestic sewage. In addition to high ammonia nitrogen content, the domestic sewage also contains high grease, salt and phosphorus. The sewage treatment method comprises the following steps:

[0091] (a) The method of loading the filler for the unpowered sand bioreactor of Example 4 into the sand pool of the unpowered sand bioreactor specifically comprises:

[0092] First, the denitrifying bacteria agent, the nitrifying bacteria agent and the functional bacteria agent are prepared into an aqueous solution according to a mass ratio of 1:20 and left for a period of time to obtain a microbial solution;

[0093] Then, 30% of the microbial solution is sprayed on the coarse sand and mixed to obtain coarse active sand; then, the remaining microbial solution is sprayed on the fine sand and mixed to obtain fine active sand;

[0094] The unpowered sand bioreactor is fed with water from the bottom, and the coarse activated sand is placed at the bottom and the fine activated sand is placed at the top in the sand pool and left to stand for 24 hours;

[0095] (b) Introducing sewage into an unpowered sand bioreactor for treatment.

[0096] Experimental example

[0097] This experimental example is a comparative study of different microbial agent addition methods under the same conditions:

[0098] Under the same conditions, three different ways of adding microbial agents were compared and the test results are as follows:

[0099] 1. Same test conditions

[0100] 1. Use a fiberglass sand filter tank with the same shape and volume, with a tank volume of 2.5 cubic meters.

[0101] 2. The unified filling material is 2.0 cubic meters, including 0.764 cubic meters of coarse sand with a diameter of 3.46-4.75 mm and 1.236 cubic meters of fine sand with a diameter of 0.5-1.0 mm. The coarse sand is at the bottom and the fine sand is at the top. Water enters from the bottom and exits from the top.

[0102] 3. Unified water source. For rural domestic sewage from the same village, the amount and time of adding water to the sand filter tank are consistent. On the first day, 1.0 cubic meters of domestic sewage was uniformly added to the sand filter tank, and 0.25 cubic meters of domestic sewage was added every day thereafter. The original water quality is shown in Table 1:

[0103] Table 1

[0104] index original COD(mg / L) 198.5 SS(mg / L) 86.3 Total nitrogen (N) 49.5 Total vegetable oilsb 19.2

[0105] 4. The uniform water temperature is 26℃-30℃.

[0106] 5. The test period is 10 days.

[0107] 6. Water quality test cycle: test once every other day and take samples from the water outlet of the equipment.

[0108] 2. Different control factors

[0109] 1. Sand filter tank A is a pre-prepared microbial agent test group. The pre-preparation method is strictly carried out according to the preparation method in Example 8 of the present invention. The microbial agent and the filler are pre-prepared in advance and put into rural domestic sewage at the same time as the other two control groups. The types and quantities of the added microbial agents are as follows:

[0110] (1) 215 g of commercial nitrifying bacteria agent, the effective viable bacterial count (CFU) of the agent was tested to be ≥ 2 billion / g;

[0111] (2) 185 g of commercial denitrifying bacterial agent, the effective viable bacterial count (CFU) of the agent was tested to be ≥ 3 billion / g;

[0112] (3) 115 g of commercial degreasing bacterial agent, the effective viable bacterial count (CFU) of the bacterial agent was tested to be ≥ 3 billion / g;

[0113] 2. Sand filter tank B is the control tank with post-addition of bacterial agent

[0114] First, fill the sewage according to the uniform standard, and then add the same type and quantity of microbial agents as those added to the sand filter tank A, add water and pour it into the sand filter tank.

[0115] 3. Sand filter tank C is the control group without adding microbial agents.

[0116] 4. Except for the different methods of adding microorganisms, all other conditions in the three test tanks were the same.

[0117] 3. The test results are divided into four line graphs

[0118] The corresponding line graphs of effluent COD, SS, total nitrogen, and vegetable oil b at different treatment days are shown in the figure below. Figures 1 to 4 As shown, Figure 1 It is the line chart of effluent COD index. Figure 2 It is the line chart of water output ss index. Figure 3 This is the line chart of the total nitrogen index in the effluent. Figure 4 It is the line chart of the indicator b of the effluent vegetable oil;

[0119] according to Figure 1 to Figure 4 The experimental results and GB18918-2002 "Pollutant Discharge Standards for Urban Wastewater Treatment Plants" show the time table analysis of each control group reaching the first-level standard, second-level standard and third-level standard as shown in Table 2:

[0120] Table 2

[0121]

[0122] As can be seen from Table 2, all indicators of the pre-mixed microbial agent group are significantly better than those of the post-added microbial agent group and the group without microbial agent. Not only are all indicators of the post-added microbial agent group and the group without microbial agent lagging behind the pre-mixed microbial agent group, but more importantly, the water quality of the post-added microbial agent group and the group without microbial agent is far from the discharge standard at the initial stage of water addition, which is a pollution to the water body.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A filler for an unpowered sand bioreactor, characterized in that: 1 cubic meter of the unpowered sand bioreactor filler includes: 100-300g of nitrifying bacteria agent, 90-200g of denitrifying bacteria agent, and the rest is sand; The sand is composed of coarse sand and fine sand, and the volume ratio of the coarse sand to the fine sand is (17-21):

31.

2. The filler for the unpowered sand bioreactor according to claim 1, characterized in that: 1 cubic meter of the filler for the unpowered sand bioreactor also includes 50 to 300 g of functional bacterial agent; The functional bacterial agent is selected from at least one of a phosphorus removal bacterial agent, an oil removal bacterial agent and a high-salt bacterial agent.

3. The filler for the unpowered sand bioreactor according to claim 1, characterized in that: The coarse sand particle size is 3.46-4.75 mm; the fine sand particle size is 0.5-1 mm; The sand is natural sand and / or machine-made sand, the loss on ignition of the sand is not more than 0.8%, and the density of the sand is less than 2g / cm 3 The light matter content is not more than 0.22%.

4. The filler for the unpowered sand bioreactor according to claim 1, characterized in that: The number of live bacteria in the nitrifying bacteria agent is not less than 200 million cfu / g.

5. The filler for the unpowered sand bioreactor according to claim 1, characterized in that: The number of live bacteria in the denitrifying bacteria agent is not less than 3 billion cfu / g.

6. The filler for the unpowered sand bioreactor according to claim 2, characterized in that: The number of live bacteria in the phosphorus removal bacterial agent is not less than 3 billion cfu / g; the number of live bacteria in the oil removal bacterial agent is not less than 3 billion cfu / g; the number of live bacteria in the high-salt bacterial agent is not less than 3 billion cfu / g.

7. Use of the filler for the unpowered sand bioreactor according to any one of claims 1 to 6 in sewage treatment.

8. The use according to claim 7, characterized in that: The sewage includes domestic sewage and / or tail water from a sewage treatment plant.

9. A method for treating sewage, characterized in that: The steps include: (a) placing the filler for the unpowered sand bioreactor according to any one of claims 1 to 6 into a sand pool of the unpowered sand bioreactor and leaving it to stand for 20 to 30 hours; (b) adjusting the pH value of the sewage to 7.0-8.0 and the carbon-nitrogen ratio to between (5-8):1, and then introducing the sewage into a non-powered sand bioreactor for treatment.

10. The sewage treatment method according to claim 9, characterized in that: The step of loading the filler for the unpowered sand bioreactor according to any one of claims 1 to 6 into the sand pool of the unpowered sand bioreactor specifically comprises: Firstly, the denitrifying bacteria agent, the nitrifying bacteria agent and the functional bacteria agent are prepared into an aqueous solution and left for a period of time to obtain a microbial solution; Then, 25% to 35% of the microbial solution is sprayed on the coarse sand and mixed to obtain coarse active sand; then, the remaining microbial solution is sprayed on the fine sand and mixed to obtain fine active sand; Subsequently, if the unpowered sand bioreactor is fed with water from the middle or upper middle part, the coarse activated sand is loaded into the sand pool at the top and the fine activated sand is loaded at the bottom; if the unpowered sand bioreactor is fed with water from the bottom, the coarse activated sand is loaded into the sand pool at the bottom and the fine activated sand is loaded at the top.

Images