Oil-removing, denitrifying and dephosphorizing agent for treating domestic sewage and preparation and use method thereof

Abstract

The present application relates to a kind of oil-removing denitrification phosphorus-removing agent for treating domestic sewage and its preparation, method for using, phosphorus-removing agent is prepared from the following weight parts of raw materials: 15-29 parts of dodecyl imidazoline, 18-35 parts of sodium alginate, 10-30 parts of coconut shell powder, 20-40 parts of potassium ferrate, 15-45 parts of microcrystalline cellulose.The composite phosphorus-removing agent can not only remove oil, denitrification and phosphorus, but also the consumption of reagent is only 1 / 4 of conventional phosphorus-removing agent, when using, a certain amount of iron-containing aluminate waste water is introduced into domestic sewage and mixed according to proportion, and the sedimentation tank process is changed into flotation process, then the composite phosphorus-removing agent is added, and the suspended substance in water is used to collect iron-aluminum phosphorus compound, after such modification, various harmful substances in water quality are removed, and the consumption of phosphorus-removing agent is also greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to an oil-removing, nitrogen-removing, and phosphorus-removing agent for treating domestic sewage, and its preparation and application methods. Background Technology

[0002] The main methods for nitrogen and phosphorus removal from domestic sewage include biological, physical, and chemical methods. Biological methods involve constructing biofilters to cultivate microorganisms and purify the water. Physical methods generally use filter media adsorption or membrane treatment. Chemical methods typically involve adding sodium hypochlorite and iron / aluminum salt polymeric coagulants. Steel plant sewage is generally smaller in volume and more complex in composition than urban sewage, containing not only high levels of nitrogen and phosphorus but also a significant amount of industrial grease, increasing the difficulty of treatment. Compared to other methods, biological and physical methods are relatively expensive. A more economical, practical, and convenient method is to add chemical agents. Currently, sodium hypochlorite and polyferric sulfate are used to treat sewage, but the treatment effect is generally limited.

[0003] Because existing phosphorus removal agents on the market have relatively limited effects and require large dosages, and it is difficult to achieve multiple uses for domestic sewage from steel plants, the treatment effect is also difficult to guarantee. In particular, when the water contains oil, the adsorption loss of the agent is large, and the waste of the agent seriously affects the effect of use. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an oil-removing, nitrogen-removing, and phosphorus-removing agent for treating domestic sewage, as well as its preparation and application methods. This composite phosphorus-removing agent can not only remove oil, nitrogen, and phosphorus, but also consumes only 1 / 4 of the amount of conventional phosphorus-removing agents. In this invention, a certain amount of iron-aluminate wastewater is introduced and mixed with domestic sewage in a certain proportion, and the sedimentation process is changed to a flotation process. Then, the composite phosphorus-removing agent is added, and the suspended matter in the water is used to capture iron-aluminate-phosphorus compounds. After this modification, various harmful substances in the water are removed, and the consumption of phosphorus-removing agent is greatly reduced.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] This degreasing, denitrifying, and phosphorus-removing agent is used to treat domestic sewage. The phosphorus removal agent is prepared from the following raw materials in parts by weight: 15-29 parts of dodecyl imidazoline, 18-35 parts of sodium alginate, 10-30 parts of coconut shell powder, 20-40 parts of potassium ferrate, and 15-45 parts of microcrystalline cellulose.

[0007] The domestic sewage mentioned is domestic sewage from the steel plant.

[0008] The water quality parameters are: total phosphorus 20-25 mg / L, ammonia nitrogen 10-15 mg / L, and oil 20-25 mg / L.

[0009] The preparation method of the degreasing, denitrifying, and phosphorus removal agent for treating domestic sewage includes the following methods:

[0010] In a sealed container, dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose are added and mixed using a gas mixing method. Dry nitrogen is then introduced and the mixture is stirred for 1 to 2 hours. The mixed material is then sieved through a 60 to 100 mesh screen and fed into a rotary tablet press to make tablets, thus obtaining the phosphorus removal agent.

[0011] The specific method for using the degreasing, denitrifying, and phosphorus-removing agent for treating domestic sewage is as follows:

[0012] The steel plant's ferroaluminate wastewater is mixed with domestic sewage in an equalization tank. Then, a basket is suspended at the inlet of the aeration tank and the prepared phosphorus removal tablets are placed inside. At the same time, aeration is turned on. A scraper is installed at the end of the aeration tank to remove floating harmful substances. The treated water is discharged through a baffle plate.

[0013] The mixing ratio of ferroaluminate wastewater and domestic sewage is (4-6):(1-2) by mass.

[0014] The pharmaceutical raw materials in this invention function as follows:

[0015] Dodecyl imidazoline, also known as DCM, is an amphoteric surfactant with calcium soap dispersing ability and good water solubility. In oily wastewater, it can demulsify and foam. When used with sodium alginate, it can overcome the influence of water hardness and improve detergency.

[0016] Sodium alginate has gelling properties. In water, it can combine with calcium ions to form a gel. When oil is present in the water, it absorbs oil molecules and water molecules to form a uniform gel system, emulsifying the oil. When used with dodecyl imidazoline, it can enhance the removal of phosphates in water.

[0017] Coconut shell powder, produced by Xi'an An'ao Biotechnology Co., Ltd., has adsorption and oil removal functions. When used in wastewater, it can remove organic pollutants with an oil removal rate of 80%-95% and a COD removal rate of 53%. The dual properties of coconut shell powder make it highly effective in wastewater treatment and it has a wide range of applications.

[0018] Potassium ferrate is suitable for treating various types of wastewater. It has a significant effect on removing organic pollutants, metal ions, dehydration, and deodorization. The iron salts decomposed after denitrification also have a certain effect on phosphorus removal, saving some reagent consumption. Another function of sodium ferrate in water purification is disinfection and sterilization, which is effective in removing harmful pathogenic microorganisms in domestic sewage.

[0019] Microcrystalline cellulose is commonly used as an adsorbent, binder, and disintegrant. The addition of microcrystalline cellulose to the composite phosphorus removal agent of this invention can improve the disintegration rate of the phosphorus removal agent tablets, causing them to disintegrate into a mist within 1 minute, thus enabling the water treatment agent to take effect more quickly.

[0020] The present invention found in experiments that the combined use of dodecyl imidazoline and sodium alginate has a strong oil removal capacity in high-oil wastewater with less consumption and loss of reagents. Moreover, by adjusting the water volume in the steel plant, the dosage of the composite phosphorus removal agent can be reduced to 1 / 4 of that of ordinary phosphorus removal agent, which greatly reduces the cost of reagents and makes it suitable for widespread use. The combined use of coconut shell powder and potassium ferrate can not only remove organic pollutants, but also sterilize and purify water, improving the effluent water quality standards.

[0021] Before using the composite agent of this invention, the purpose of mixing the ferroaluminate-containing wastewater with domestic sewage in a certain proportion is to increase the ferroaluminate in the domestic sewage. This has two advantages: firstly, it saves on the consumption of phosphorus removal agents, as the ferroaluminate it provides helps remove phosphorus, so that the dosage of the composite phosphorus removal agent is only 1 / 4 of that of ordinary phosphorus removal agents; secondly, it enables the recycling and reuse of this part of the sewage, eliminating the need for additional treatment of this part of the wastewater.

[0022] Table 1 shows a comparison of water quality before and after wastewater treatment according to the present invention.

[0023] Table 1

[0024] Water quality parameters Total phosphorus (mg / L) Ammonia nitrogen (mg / L) Oil (mg / L) Before processing 20～25 10～15 20～25 After processing 0.38～0.5 2.8～3.0 2.23～2.7

[0025] Compared with existing technologies, the beneficial effects of this invention are:

[0026] 1. The dosage of the composite phosphorus removal agent of this invention is 1 / 4 that of ordinary phosphorus removal agents. It has the characteristics of low agent consumption and significant denitrification and phosphorus removal effect, and has great value for promotion and application.

[0027] 2. The composite phosphorus removal agent of this invention, composed of dodecyl imidazoline and sodium alginate, exhibits strong oil removal ability in high-oil wastewater with low agent loss, thus ensuring the effectiveness of the composite phosphorus removal agent.

[0028] 3. The composite phosphorus removal agent of this invention, composed of coconut shell powder and potassium ferrate, not only removes organic pollutants but also sterilizes and purifies water, improving the quality standards of the effluent.

[0029] 4. The composite phosphorus removal agent of the present invention dissolves quickly in water and can dissolve and take effect within 1 minute without affecting the flotation effect.

[0030] 5. Before using the composite phosphorus removal agent of this invention, the water quality conditions are changed by mixing the iron-aluminate wastewater from the steel plant with domestic sewage in a certain proportion, which not only adjusts the water quality but also saves the amount of agent.

[0031] 6. The composite phosphorus removal agent of this invention is a compressed tablet, which is more convenient to store, has better stability, is easier to transport, and is safer than liquid medicine. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the embodiments, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0033] Example 1:

[0034] The degreasing, denitrifying, and phosphorus-removing agent used for treating domestic sewage is prepared from the following raw materials in parts by weight: 15 parts dodecyl imidazoline, 35 parts sodium alginate, 10 parts coconut shell powder, 40 parts potassium ferrate, and 15 parts microcrystalline cellulose.

[0035] The preparation method of the degreasing, denitrifying, and phosphorus-removing agent for treating domestic sewage is as follows:

[0036] In a sealed container, dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose are added sequentially using a gas mixing method. Dry nitrogen is then introduced for gas stirring and mixing for 1 hour. The mixed material is then sieved through an 80-mesh sieve and fed into a rotary tablet press to make tablets, thus obtaining the composite phosphorus removal agent of this invention.

[0037] The specific steps for using the degreasing, denitrifying, and phosphorus-removing agent for treating domestic sewage are as follows:

[0038] The steel plant's ferroaluminate wastewater and domestic sewage are mixed in an equalization tank at a ratio of 4.5:1.5. Then, a basket is suspended at the inlet of the aeration tank and the prepared phosphorus removal agent tablets are placed into it. At the same time, aeration is turned on. A scraper is installed at the end of the aeration tank to remove the floating harmful substances. The treated water is discharged through a baffle plate.

[0039] Example 2:

[0040] The degreasing, denitrifying, and phosphorus-removing agent used for treating domestic sewage is prepared from the following raw materials in parts by weight: 29 parts dodecyl imidazoline, 18 parts sodium alginate, 30 parts coconut shell powder, 20 parts potassium ferrate, and 45 parts microcrystalline cellulose.

[0041] Preparation method of degreasing, denitrifying and phosphorus-removing agent for treating domestic sewage: In a closed container, dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose are added sequentially by gas mixing method and mixed. Dry nitrogen is then introduced for gas stirring and mixing for 1.5 hours. The mixed material is then sieved through a 100-mesh sieve and then fed into a rotary tablet press to make tablets, thus obtaining the composite phosphorus removal agent of the present invention.

[0042] The specific steps for using the degreasing, denitrifying, and phosphorus-removing agent for treating domestic sewage are as follows:

[0043] The steel plant's ferroaluminate wastewater and domestic sewage are mixed in a 4:2 ratio in an equalization tank. Then, a basket is suspended at the inlet of the aeration tank and the prepared phosphorus removal tablets are placed into it. At the same time, aeration is turned on. A scraper is installed at the end of the aeration tank to remove the floating harmful substances. The treated water is discharged through a baffle plate.

[0044] Example 3:

[0045] The degreasing, denitrifying, and phosphorus-removing agent used for treating domestic sewage is prepared from the following raw materials in parts by weight: 20 parts dodecyl imidazoline, 26 parts sodium alginate, 20 parts coconut shell powder, 30 parts potassium ferrate, and 30 parts microcrystalline cellulose.

[0046] Preparation method of degreasing, denitrifying and phosphorus removal agent for treating domestic sewage: In a closed container, dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose are added sequentially by gas mixing. Dry nitrogen is then introduced and the mixture is stirred for 2 hours. The mixed material is then sieved through a 60-mesh sieve and fed into a rotary tablet press to make tablets, thus obtaining the composite phosphorus removal agent of the present invention.

[0047] The specific steps for using the degreasing, denitrifying, and phosphorus-removing agent for treating domestic sewage are as follows:

[0048] The steel plant's ferroaluminate wastewater and domestic sewage are mixed in a 6:1 ratio in an equalization tank. Then, a basket is suspended at the inlet of the aeration tank and the prepared phosphorus removal tablets are placed into it. At the same time, aeration is turned on. A scraper is installed at the end of the aeration tank to remove the floating harmful substances. The treated water is discharged through a baffle plate.

[0049] Experimental Example 1:

[0050] The experiment was conducted on the domestic sewage system of a steel plant. The water quality parameters were total phosphorus 21.4 mg / L, ammonia nitrogen 11.5 mg / L, and oil 20 mg / L. The above three examples were compared with the water treated by polyferric sulfate and polyaluminum sulfate. A dosage gradient was set for the flotation experiment.

[0051] The experimental method is as follows: First, the ferroaluminate wastewater and domestic sewage were mixed in the equalization tank according to the ratio of Examples 1-3. 1L of the mixed water sample was taken and stirred at 200r / min for 30s. Then, the mixture was stirred at 60r / min for 1min. The reagent was added according to the raw material ratio and preparation method of Examples 1-3. The air flotation was turned on for 40s. After the scum floated to the surface, the water quality parameters of the intermediate liquid were measured and compared with those of domestic sewage treated with polyferric sulfate and polyaluminum sulfate. The measured data are shown in Tables 2-4.

[0052] Table 2. Changes in total phosphorus at different concentrations (mg / L):

[0053]

[0054] Table 3. Changes in ammonia nitrogen at different concentrations (mg / L):

[0055]

[0056] Table 4. Changes in oil concentration (mg / L):

[0057]

[0058] The data above shows that the composite phosphorus removal agent of this invention has excellent effects. The total phosphorus, ammonia nitrogen and oil all meet the discharge standards for water pollutants in the iron and steel industry (GB 13456-2012). In comparison, the effects of polyferric sulfate and polyaluminum sulfate are relatively poor and cannot meet the production needs.

[0059] Experimental Example 2:

[0060] Experimental results on the oil removal capacity of dodecyl imidazoline and sodium alginate in the composite phosphorus removal agent of this invention in high-oil wastewater:

[0061] The experiment was conducted on the domestic wastewater system of a steel plant. The oil content in the water was 24.8 mg / L. Three compound phosphorus removal agents were selected, including dodecyl imidazoline and sodium alginate used alone and in combination. Comparative analysis was performed. For the three phosphorus removal agents, the dosage of dodecyl imidazoline alone was 50 parts; the dosage of sodium alginate alone was also 50 parts; the dosage of the combination of dodecyl imidazoline and sodium alginate was 25 parts, with a total addition of 50 parts. The weight proportions of the other agents were the same: 25 parts coconut shell powder, 30 parts potassium ferrate, and 25 parts microcrystalline cellulose. The preparation method was the same as in Example 3.

[0062] During the experiment, ferroaluminate wastewater and domestic sewage were mixed in an equalization tank at a ratio of 6:1. A 1L sample of the mixed water was taken for the experiment. The mixture was stirred at 200r / min for 30s, then slowed to 60r / min for 1min. The above-mentioned experimental reagent was added to the mixed water sample, and the air flotation was turned on for 40s. The results are shown in Table 5 below.

[0063] Table 5

[0064]

[0065] Table 5 shows that the combined use of dodecyl imidazoline and sodium alginate is more effective than the use of either single agent. The combination of dodecyl imidazoline and sodium alginate has a synergistic effect.

Claims

1. An oil-removing, nitrogen-removing, and phosphorus-removing agent for treating domestic sewage, characterized in that, The phosphorus removal agent is prepared from the following raw materials in parts by weight: 15-29 parts dodecyl imidazoline, 18-35 parts sodium alginate, 10-30 parts coconut shell powder, 20-40 parts potassium ferrate, and 15-45 parts microcrystalline cellulose. The specific method for using the degreasing, denitrifying, and phosphorus-removing agent for treating domestic sewage is as follows: The steel plant's iron-aluminate wastewater is mixed with domestic sewage in an equalization tank. Then, a basket is suspended at the inlet of the aeration tank and the prepared phosphorus removal agent tablets are placed into it. At the same time, aeration is turned on. A scraper is installed at the end of the aeration tank to remove the floating harmful substances. The treated water is discharged through a baffle plate. The mixing ratio of ferroaluminate wastewater and domestic sewage is (4-6):(1-2) by mass.

2. The degreasing, denitrifying, and phosphorus-removing agent for treating domestic sewage according to claim 1, characterized in that, The domestic sewage mentioned is domestic sewage from the steel plant.

3. The preparation method of the degreasing, denitrifying, and phosphorus-removing agent for treating domestic sewage as described in claim 1 or 2, characterized in that, Including the following methods: In a sealed container, dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose are added and mixed using a gas mixing method. Dry nitrogen is then introduced and the mixture is stirred for 1 to 2 hours. The mixed material is then sieved through a 60 to 100 mesh screen and fed into a rotary tablet press to make tablets, thus obtaining the phosphorus removal agent.

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