Domestic sewage treatment method

Abstract

The invention provides a domestic sewage treatment method, and belongs to the technical field of sewage treatment methods. According to the invention, the domestic sewage is subjected to grid filtration to remove floating impurities; putting a composite sewage treatment agent into the filtered domestic sewage, and performing ultrasonic treatment on the mixed sewage to obtain mixed sewage; discharging the mixed sewage into a settling pond, using settled sludge for producing biomass fertilizer, discharging supernatant clear water into a filtering pond, and directly discharging clear water filtered by an activated carbon layer and a quartz sand layer; the compound sewage treatment agent is prepared from modified melanospora powder, compound bacteria liquid, polyacrylamide, water and calcium oxide. According to the domestic sewage treatment method, the COD value, the ammonia nitrogen content and the heavy metal ion content in the water body can be effectively removed, and the removal efficiency reaches 99.6%, 99.9% and 97.3% respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment methods, and in particular to a method for treating domestic sewage. Background Art

[0002] Domestic sewage contains a large amount of organic matter, such as cellulose, starch, sugar, fat and protein, etc.; it also often contains pathogens, viruses and parasite eggs; inorganic salts such as chloride, sulfate, phosphate, bicarbonate and sodium, potassium, calcium, magnesium, etc.; heavy metal ions such as copper and lead. The general characteristics are high nitrogen, sulfur and phosphorus content, and under the action of anaerobic bacteria, it is easy to produce odorous substances. Traditional domestic sewage treatment methods include biological treatment, physical treatment and chemical treatment, but these methods have problems such as low efficiency and high cost.

[0003] Chinese patent application CN111995172A discloses a method for treating domestic sewage, in which the domestic sewage is filtered and then sent to a grit tank, an oxidation tank, a secondary sedimentation tank, a coagulation tank and a denitrification deep bed filter for treatment. This technical solution can effectively reduce the content of N and P in the sewage, but the process is complicated and does not consider the efficiency of treating organic matter and other heavy metal ions in the sewage. Chinese patent CN109851142B discloses a method for treating municipal domestic sewage, in which municipal domestic sewage is adsorbed, flocculated and heavy metal ions are removed, and a gradient magnetic field is applied to assist in adsorption. This technical solution uses chemical reagents, which are not efficient in removing ammonia nitrogen, and the ammonia nitrogen content (NH 3 -N) is often used as an important indicator of wastewater discharge.

[0004] Algae is a type of plant rich in chlorophyll and has a strong absorption capacity. Studies have found that some algae have a high adsorption capacity for harmful substances such as heavy metal ions, organic pollutants, and nutrients in wastewater. By adding algae to wastewater, the algae will adsorb and enrich harmful substances, thereby purifying the wastewater. Algae can also convert the adsorbed harmful substances into organic matter through photosynthesis, further reducing the pollution level of wastewater.

[0005] However, the use of algae in sewage treatment often requires the cultivation of algae. Therefore, how to effectively utilize the adsorption properties of algae to obtain a method for treating domestic sewage with a simple process and good treatment effect on organic pollutants such as heavy metals and ammonia nitrogen is a technical problem that needs to be solved at present. Summary of the invention

[0006] The object of the present invention is to provide a method for treating domestic sewage, which is used to solve the technical problem that the existing sewage treatment methods have low treatment efficiency of ammonia nitrogen and heavy metal ions.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for treating domestic sewage, comprising the following steps:

[0009] (1) Screen filter domestic sewage to remove floating impurities;

[0010] (2) adding a composite sewage treatment agent to the filtered domestic sewage, and subjecting the mixed sewage to ultrasonic treatment to obtain mixed sewage;

[0011] (3) The mixed sewage is discharged into a sedimentation tank, and the sludge after sedimentation is used to produce biomass fertilizer. The upper layer of clean water is discharged into a filtration tank, and the clean water after filtering through the activated carbon layer and the quartz sand layer can be directly discharged;

[0012] The composite sewage treatment agent comprises modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide.

[0013] Furthermore, the activated carbon layer and the quartz sand layer are both distributed at the bottom of the filter pool, and the activated carbon layer is distributed above the quartz sand layer; the particle size of the activated carbon in the activated carbon layer is 5 to 10 mm;

[0014] The quartz sand layer is divided into three layers, the particle size of the upper quartz sand is 1-5 cm, the particle size of the middle quartz sand is 5-10 mm, and the particle size of the lower quartz sand is 1-5 mm.

[0015] Furthermore, the usage ratio of the modified black spore algae powder, the composite bacterial solution, the polyacrylamide, the water and the calcium oxide is 2-8 g: 10-15 mL: 20-30 g: 50-80 g: 15-28 g.

[0016] Furthermore, the preparation method of the modified black spore algae powder is: after washing and drying the black spore algae, heat-treating it at 400-600° C. for 10-30 minutes, and then crushing it into powder to obtain the modified black spore algae powder.

[0017] Furthermore, the preparation method of the composite bacterial liquid is: after mixing the kitchen waste with beet molasses and water, fermenting at 25-30° C. for 15-20 days, and filtering the liquid obtained is the composite bacterial liquid.

[0018] Furthermore, the mass ratio of the kitchen waste, beet molasses and water is 1:0.1-0.3:6-8.

[0019] Furthermore, the frequency of the ultrasonic treatment is 100 to 200 Hz, and the time of the ultrasonic treatment is 50 to 100 minutes.

[0020] Furthermore, the dosage of the composite sewage treatment agent is 100-500 mg / L domestic sewage.

[0021] Furthermore, the thickness of the activated carbon layer is 1 to 5 cm, and the total thickness of the quartz sand layer is 10 to 20 cm.

[0022] Beneficial effects of the present invention:

[0023] The present invention effectively increases the surface area of ​​the black spore algae and improves the adsorption performance of the black spore algae by heat treatment modification. Studies have found that the modified black spore algae powder can effectively adsorb Cu in water. 2+ and Pb 2+ And through the filtration of the activated carbon layer and the quartz sand layer in the filter pool, all the black spore algae powder can be filtered out. It is easy to use and has better effects. It can be used without cultivating the algae.

[0024] The present invention mixes modified black spore algae powder, composite bacterial solution, flocculant and oxidant for use, which can realize the dual functional characteristics of physical adsorption and chemical degradation of organic pollutants and heavy metal ions in sewage, and accelerates the contact rate between organic pollutants and composite bacterial solution and degradation efficiency through ultrasound-assisted degradation. Polyacrylamide is used as a flocculant to flocculate the black spore algae powder colloidal particles adsorbed with organic pollutants and heavy metal ions in sewage, which is convenient for filtration and removal.

[0025] The present invention arranges an activated carbon layer and a quartz sand layer at the bottom of the filter pool. The clear water separated by precipitation first passes through the activated carbon layer to remove the yellowness of the water body, and then passes through the quartz sand layer with particle sizes ranging from large to small, which can effectively perform deep filtration on the tiny colloidal particles in the water body. By utilizing the multi-level particle size filtration layer of the quartz sand layer, a "backflow" phenomenon will occur between the tiny colloidal particles, so that the particles pass through the quartz sand layer back and forth and are adsorbed on the surface of the quartz sand, and are effectively removed.

[0026] The domestic sewage treatment method of the present invention can effectively remove the COD value, ammonia nitrogen content and heavy metal ion content in the water body, and the removal efficiency reaches 99.6%, 99.9% and 97.3% respectively. DETAILED DESCRIPTION

[0027] The present invention provides a method for treating domestic sewage, comprising the following steps:

[0028] (1) Screen filter domestic sewage to remove floating impurities;

[0029] (2) adding a composite sewage treatment agent to the filtered domestic sewage, and subjecting the mixed sewage to ultrasonic treatment to obtain mixed sewage;

[0030] (3) The mixed sewage is discharged into a sedimentation tank, and the sludge after sedimentation is used to produce biomass fertilizer. The upper layer of clean water is discharged into a filtration tank, and the clean water after filtering through the activated carbon layer and the quartz sand layer can be directly discharged;

[0031] The composite sewage treatment agent comprises modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide.

[0032] In the present invention, the activated carbon layer and the quartz sand layer are both distributed at the bottom of the filter pool, and the activated carbon layer is distributed above the quartz sand layer; the particle size of the activated carbon in the activated carbon layer is 5 to 10 mm, preferably 6 to 8 mm.

[0033] In the present invention, the quartz sand layer is divided into three layers, the particle size of the upper quartz sand is 1-5 cm, the particle size of the middle quartz sand is 5-10 mm, and the particle size of the lower quartz sand is 1-5 mm; preferably, the particle size of the upper quartz sand is 2-4 cm, the particle size of the middle quartz sand is 6-8 mm, and the particle size of the lower quartz sand is 2-4 mm.

[0034] In the present invention, the usage ratio of the modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide is 2-8g: 10-15mL: 20-30g: 50-80g: 15-28g, preferably 3-6g: 11-14mL: 22-28g: 55-75g: 20-26g, and further preferably 4-5g: 12-13mL: 25-28g: 60-70g: 20-24g.

[0035] In the present invention, the preparation method of the modified black spore algae powder is: after washing and drying the black spore algae, heat-treating it at 400-600°C for 10-30 minutes, and then crushing it into powder to obtain the modified black spore algae powder; preferably, heat-treating it at 450-550°C for 15-20 minutes.

[0036] In the present invention, the preparation method of the composite bacterial liquid is: after mixing kitchen waste with beet molasses and water, fermenting at 25-30°C for 15-20 days, and filtering the liquid obtained is the composite bacterial liquid; preferably, fermenting at 28°C for 15 days, and filtering the liquid obtained is the composite bacterial liquid.

[0037] In the present invention, the mass ratio of the kitchen waste, beet molasses and water is 1:0.1-0.3:6-8, preferably 1:0.2-0.3:7-8.

[0038] In the present invention, the frequency of the ultrasonic treatment is 100-200 Hz, preferably 120-180 Hz, and more preferably 150 Hz; the time of the ultrasonic treatment is 50-100 min, preferably 60-80 min, and more preferably 70 min.

[0039] In the present invention, the dosage of the composite sewage treatment agent is 100-500 mg / L domestic sewage, preferably 200-400 mg / L domestic sewage, and more preferably 300 mg / L domestic sewage.

[0040] In the present invention, the thickness of the activated carbon layer is 1-5 cm, preferably 2-4 cm; the total thickness of the quartz sand layer is 10-20 cm, preferably 15 cm, and the upper, middle and lower quartz sand layers are 5 cm each.

[0041] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0042] Example 1

[0043] A method for treating domestic sewage comprises the following steps:

[0044] (1) Screen filter domestic sewage to remove floating impurities;

[0045] (2) adding 400 mg / L of the composite sewage treatment agent to the filtered domestic sewage, stirring the sewage and applying 200 Hz ultrasonic vibration for 60 min to obtain mixed sewage;

[0046] (3) The mixed sewage is discharged into the sedimentation tank. After standing for 2 hours, the precipitated sludge is used to produce biomass waste, and the upper clean water is discharged into the filtration tank. The filter tank is provided with an activated carbon layer (particle size 5-8 mm, thickness 3 cm), an upper quartz sand layer (particle size 1-2 cm, thickness 5 cm), a middle quartz sand layer (particle size 5-8 mm, thickness 5 cm) and a lower quartz sand layer (2-4 mm, thickness 5 cm) from top to bottom. The filtered clean water can be discharged directly.

[0047] The composite sewage treatment agent comprises modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide in a dosage ratio of 8g:15mL:25g:80g:20g. The modified black spore algae powder is obtained by washing and drying the black spore algae, heat-treating it at 400°C for 30 minutes, and then crushing it into powder.

[0048] The preparation method of the composite bacterial liquid is as follows: after mixing the food waste with beet molasses and water, fermenting at 25°C for 15 days, and filtering the liquid obtained is the composite bacterial liquid, and the mass ratio of the food waste, beet molasses and water is 1:0.2:6.

[0049] Example 2

[0050] A method for treating domestic sewage comprises the following steps:

[0051] (1) Screen filter domestic sewage to remove floating impurities;

[0052] (2) adding 450 mg / L of a composite sewage treatment agent to the filtered domestic sewage, stirring the sewage and applying 200 Hz ultrasonic vibration for 60 min to obtain mixed sewage;

[0053] (3) The mixed sewage is discharged into the sedimentation tank. After standing for 2 hours, the precipitated sludge is used to produce biomass waste, and the upper clean water is discharged into the filtration tank. The filter tank is provided with an activated carbon layer (particle size 5-8 mm, thickness 3 cm), an upper quartz sand layer (particle size 1-2 cm, thickness 5 cm), a middle quartz sand layer (particle size 5-8 mm, thickness 5 cm) and a lower quartz sand layer (2-4 mm, thickness 5 cm) from top to bottom. The filtered clean water can be discharged directly.

[0054] The composite sewage treatment agent comprises modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide in a dosage ratio of 2g:10mL:25g:80g:20g. The modified black spore algae powder is obtained by washing and drying the black spore algae, heat-treating it at 450°C for 30 minutes, and then crushing it into powder.

[0055] The preparation method of the composite bacterial liquid is as follows: after mixing the food waste with beet molasses and water, fermenting at 25°C for 15 days, and filtering the liquid obtained is the composite bacterial liquid, and the mass ratio of the food waste, beet molasses and water is 1:0.2:6.

[0056] Example 3

[0057] A method for treating domestic sewage comprises the following steps:

[0058] (1) Screen filter domestic sewage to remove floating impurities;

[0059] (2) adding 500 mg / L of the composite sewage treatment agent to the filtered domestic sewage, stirring the sewage and applying 200 Hz ultrasonic vibration for 60 min to obtain mixed sewage;

[0060] (3) The mixed sewage is discharged into the sedimentation tank. After standing for 2 hours, the precipitated sludge is used to produce biomass waste, and the upper clean water is discharged into the filtration tank. The filter tank is provided with an activated carbon layer (particle size 5-8 mm, thickness 3 cm), an upper quartz sand layer (particle size 1-2 cm, thickness 5 cm), a middle quartz sand layer (particle size 5-8 mm, thickness 5 cm) and a lower quartz sand layer (2-4 mm, thickness 5 cm) from top to bottom. The filtered clean water can be discharged directly.

[0061] The composite sewage treatment agent comprises modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide in a dosage ratio of 4g:15mL:25g:80g:20g. The modified black spore algae powder is obtained by washing and drying the black spore algae, heat-treating it at 500°C for 30 minutes, and then crushing it into powder.

[0062] The preparation method of the composite bacterial liquid is as follows: after mixing the food waste with beet molasses and water, fermenting at 25°C for 15 days, and filtering the liquid obtained is the composite bacterial liquid, and the mass ratio of the food waste, beet molasses and water is 1:0.2:6.

[0063] Example 4

[0064] A method for treating domestic sewage comprises the following steps:

[0065] (1) Screen filter domestic sewage to remove floating impurities;

[0066] (2) adding 300 mg / L of the composite sewage treatment agent to the filtered domestic sewage, stirring the sewage and applying 200 Hz ultrasonic vibration for 60 min to obtain mixed sewage;

[0067] (3) The mixed sewage is discharged into the sedimentation tank. After standing for 2 hours, the precipitated sludge is used to produce biomass waste, and the upper clean water is discharged into the filtration tank. The filter tank is provided with an activated carbon layer (particle size 5-8 mm, thickness 3 cm), an upper quartz sand layer (particle size 1-2 cm, thickness 5 cm), a middle quartz sand layer (particle size 5-8 mm, thickness 5 cm) and a lower quartz sand layer (2-4 mm, thickness 5 cm) from top to bottom. The filtered clean water can be discharged directly.

[0068] The composite sewage treatment agent comprises modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide in a dosage ratio of 6g:15mL:25g:60g:15g. The modified black spore algae powder is obtained by washing and drying the black spore algae, heat treating it at 550°C for 30 minutes, and then crushing it into powder.

[0069] The preparation method of the composite bacterial liquid is as follows: after mixing the food waste with beet molasses and water, fermenting at 25°C for 15 days, and filtering the liquid obtained is the composite bacterial liquid, and the mass ratio of the food waste, beet molasses and water is 1:0.2:6.

[0070] Example 5

[0071] A method for treating domestic sewage comprises the following steps:

[0072] (1) Screen filter domestic sewage to remove floating impurities;

[0073] (2) adding 100 mg / L of the composite sewage treatment agent to the filtered domestic sewage, stirring the sewage and applying 200 Hz ultrasonic vibration for 60 min to obtain mixed sewage;

[0074] (3) The mixed sewage is discharged into the sedimentation tank. After standing for 2 hours, the precipitated sludge is used to produce biomass waste, and the upper clean water is discharged into the filtration tank. The filter tank is provided with an activated carbon layer (particle size 5-8 mm, thickness 3 cm), an upper quartz sand layer (particle size 1-2 cm, thickness 5 cm), a middle quartz sand layer (particle size 5-8 mm, thickness 5 cm) and a lower quartz sand layer (2-4 mm, thickness 5 cm) from top to bottom. The filtered clean water can be discharged directly.

[0075] The composite sewage treatment agent comprises modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide in a dosage ratio of 8g:15mL:25g:80g:20g. The modified black spore algae powder is obtained by washing and drying the black spore algae, heat treating it at 600°C for 30 minutes, and then crushing it into powder.

[0076] The preparation method of the composite bacterial liquid is as follows: after mixing the food waste with beet molasses and water, fermenting at 25°C for 15 days, and filtering the liquid obtained is the composite bacterial liquid, and the mass ratio of the food waste, beet molasses and water is 1:0.2:6.

[0077] Comparative Example 1

[0078] The technical solution is the same as that of Example 1, except that the composite sewage treatment agent does not contain modified black spore algae powder.

[0079] Comparative Example 2

[0080] The technical solution is the same as that of Example 2, except that the heat treatment temperature of the modified black spore algae powder is 900°C.

[0081] Comparative Example 3

[0082] The technical solution is the same as that of Example 3, except that only an activated carbon layer and a single layer of quartz sand (particle size 1-2 cm, thickness 5 cm) are provided in the filtration tank.

[0083] Comparative Example 4

[0084] The technical solution is the same as that of Example 3, except that only an activated carbon layer is provided in the filtration tank.

[0085] Comparative Example 5

[0086] The technical solution is the same as that of Example 5, except that the composite sewage treatment agent does not contain the composite bacterial liquid.

[0087] Experimental example

[0088] Taking the domestic sewage of a certain town as an example, the water quality of the domestic sewage was tested, and the results are shown in Table 1.

[0089] Table 1 Detection results of domestic sewage in a certain town

[0090]

[0091] The water quality treated by Examples 1 to 5 and Comparative Examples 1 to 5 was tested, and the results are shown in Table 2 below.

[0092] Table 2 Test results of examples and comparative examples

[0093]

[0094] From the above examples, it can be seen that the present invention provides a method for treating domestic sewage. From the above examples 1 to 5, it can be seen that increasing the concentration of the composite sewage treatment agent in sewage can effectively improve the removal efficiency of organic pollutants, heavy metal ions and total phosphorus in sewage; from comparative example 1, it can be seen that the modified black spore algae powder has a significant effect on the removal of Cu 2+ and Pb 2+ The removal effect is obvious; from Comparative Example 2, it can be seen that high temperature heat treatment of black spore algae is not conducive to increasing the surface area of ​​black spore algae. This is because as the temperature rises, the micropores on the surface of the black spore algae biomass collapse, reducing the surface area of ​​the black spore algae powder, and the adsorption performance decreases instead; from Comparative Examples 3 and 4, it can be seen that the multi-stage particle size setting in the filter pool of the present invention can effectively reduce the chromaticity of the water body and at the same time reduce the content of microcolloid particles in the water body; from Comparative Example 5, it can be seen that the composite bacterial liquid also plays an important role in the composite sewage treatment agent. It can cooperate with the modified black spore algae powder to produce a dual-effect adsorption-degradation characteristic, which plays a key role in the degradation of organic pollutants in sewage.

[0095] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for treating domestic sewage, characterized in that: The following steps are involved: (1) Screen filter domestic sewage to remove floating impurities; (2) adding a composite sewage treatment agent to the filtered domestic sewage, and subjecting the mixed sewage to ultrasonic treatment to obtain mixed sewage; (3) The mixed sewage is discharged into a sedimentation tank, and the sludge after sedimentation is used to produce biomass fertilizer. The upper layer of clean water is discharged into a filtration tank, and the clean water after filtering through the activated carbon layer and the quartz sand layer can be directly discharged; The composite sewage treatment agent comprises modified black spore algae powder, composite bacterial liquid, polyacrylamide, water and calcium oxide.

2. The method for treating domestic sewage according to claim 1, characterized in that: The activated carbon layer and the quartz sand layer are both distributed at the bottom of the filter pool, and the activated carbon layer is distributed above the quartz sand layer; the particle size of the activated carbon in the activated carbon layer is 5 to 10 mm; The quartz sand layer is divided into three layers, the particle size of the upper quartz sand is 1-5 cm, the particle size of the middle quartz sand is 5-10 mm, and the particle size of the lower quartz sand is 1-5 mm.

3. The method for treating domestic sewage according to claim 2, characterized in that: The usage ratio of the modified black spore algae powder, the composite bacterial liquid, the polyacrylamide, the water and the calcium oxide is 2-8 g: 10-15 mL: 20-30 g: 50-80 g: 15-28 g.

4. The method for treating domestic sewage according to claim 1 or 3, characterized in that: The preparation method of the modified black spore algae powder is as follows: after washing and drying the black spore algae, heat-treating the black spore algae at 400-600° C. for 10-30 minutes, and then crushing the black spore algae into powder to obtain the modified black spore algae powder.

5. The method for treating domestic sewage according to any one of claims 1 to 3, characterized in that: The preparation method of the composite bacterial liquid is as follows: after mixing the kitchen waste with beet molasses and water, fermenting at 25-30° C. for 15-20 days, and filtering the liquid obtained is the composite bacterial liquid.

6. The method for treating domestic sewage according to claim 5, characterized in that: The mass ratio of the kitchen waste, beet molasses and water is 1:0.1-0.3:6-8.

7. The method for treating domestic sewage according to claim 1, 2 or 6, characterized in that: The frequency of the ultrasonic treatment is 100-200 Hz, and the time of the ultrasonic treatment is 50-100 min.

8. The method for treating domestic sewage according to claim 7, characterized in that: The dosage of the composite sewage treatment agent is 100-500 mg / L domestic sewage.

9. The method for treating domestic sewage according to claim 1 or 2, characterized in that: The thickness of the activated carbon layer is 1 to 5 cm, and the total thickness of the quartz sand layer is 10 to 20 cm.

Images