Oil, nitrogen and phosphorus removal agent for treating domestic sewage, preparation method therefor, and use method thereof

Abstract

The present invention relates to an oil, nitrogen and phosphorus removal agent for treating domestic sewage, a preparation method therefor, and a use method thereof. 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. The composite phosphorus removal agent can not only remove oils, nitrogen, and phosphorus but also have an agent consumption of only 1 / 4 of that of a conventional phosphorus removal agent. When the present invention is utilized, a certain amount of ferroaluminate-containing wastewater is introduced to be mixed with domestic sewage at a ratio; in addition, a sedimentation tank process is changed to a flotation process, and the composite phosphorus removal agent is then added, so that iron, aluminum, and phosphorus compounds are captured by suspended substances in water. After such transformation, various harmful substances in water are removed, and the consumption of the phosphorus removal agent is greatly reduced.

Description

Degreasing, denitrifying and dephosphorizing agent for treating domestic sewage and preparation and use method thereof Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a degreasing, denitrifying and dephosphorizing agent for treating domestic sewage, and a preparation method and a use method thereof. Background Art

[0002] There are three main methods for denitrification and phosphorus removal of domestic sewage: biological, physical and chemical. The biological method is to cultivate microorganisms by constructing a biological filter to purify water quality. The physical method generally uses filter adsorption or membrane treatment. The chemical method generally uses sodium hypochlorite and iron salt, aluminum salt and polymer coagulant treatment. The amount of domestic sewage from steel mills is generally small, and its composition is more complex than that of urban domestic sewage. In addition to the high nitrogen and phosphorus content, there are also many industrial oils and fats mixed in it, which increases the difficulty of treatment. Comparing the treatment methods, the treatment costs of biological and physical methods are relatively high. The more economical, practical and convenient method is to add chemical agents. At present, the sewage is treated by adding sodium hypochlorite and polyferric sulfate, and the water treatment effect is average.

[0003] Because the existing phosphorus removal agents on the market have relatively simple effects and require large dosages, it is difficult to achieve multiple uses with one dose for domestic wastewater from steel plants, and 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 use effect.

[0004] Summary of the Invention

[0005] The object of the present invention is to overcome the shortcomings of the existing technology and provide a degreasing, denitrifying and dephosphorizing agent for treating domestic sewage, as well as a preparation and use method thereof. The composite dephosphorizing agent can not only remove oil, denitrify and dephosphorize, but also consumes only 1 / 4 of the agent of a conventional dephosphorizing agent. When used, the present invention introduces a certain amount of iron-aluminate-containing wastewater and domestic sewage in proportion, and changes the sedimentation tank process to a flotation process. The composite dephosphorizing agent is then added, and suspended matter in the water is used to capture iron, aluminum and phosphorus compounds. After such a transformation, various harmful substances in the water are removed, and the consumption of the dephosphorizing agent is also greatly reduced.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions:

[0007] The invention discloses a degreasing, denitrifying and dephosphorizing agent for treating domestic sewage. The dephosphorizing agent is prepared from the following raw materials in parts by weight: 15 to 29 parts of dodecyl imidazoline, 18 to 35 parts of sodium alginate, 10 to 30 parts of coconut shell powder, 20 to 40 parts of potassium ferrate and 15 to 45 parts of microcrystalline cellulose.

[0008] The domestic sewage is domestic sewage from a steel plant.

[0009] The water quality parameters are total phosphorus 20-25 mg / L, ammonia nitrogen 10-15 mg / L, and oil 20-25 mg / L.

[0010] A method for preparing a degreasing, denitrifying and dephosphorizing agent for treating domestic sewage comprises the following steps:

[0011] In a closed container, a gas mixing method is adopted to add dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose and mix them. Then, dry nitrogen is introduced to carry out gas stirring and mixing for 1 to 2 hours. Then, the mixed material is sieved with 60 to 100 meshes and then sent to a rotary tablet press to be made into tablets to obtain a phosphorus removal agent.

[0012] The method of using the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage is as follows:

[0013] The iron-aluminate wastewater from the steel plant is mixed with domestic sewage in a regulating tank. Then, a hanging basket is hung at the water 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 the baffle.

[0014] The mixing ratio of ferroaluminate wastewater and domestic sewage is (4-6) to (1-2) by mass.

[0015] The pharmaceutical raw materials in the present invention function as follows:

[0016] Dodecyl imidazoline, also known as DCM, is an amphoteric surfactant with calcium soap dispersibility and good water solubility. It can play a role in demulsification and foaming in oily wastewater. When used together with sodium alginate, it can overcome the influence of water hardness and improve the detergency.

[0017] Sodium alginate has gelling properties and can combine with calcium ions in water to form a gel. When there is oil in the water, it will absorb oil molecules and water molecules to form a uniform gel system, emulsify the oil, and used together with dodecyl imidazoline, it can enhance the removal of phosphates in water.

[0018] Coconut shell powder is produced by Xi'an Ao Biotechnology Co., Ltd. It has adsorption and oil removal functions. When used in sewage, it can remove organic pollution. The oil removal rate can reach 80%-95%, and the COD removal rate is 53%. The dual properties of coconut shell powder are effective in wastewater treatment and are widely used.

[0019] Potassium ferrate is suitable for treating various types of wastewater, and has significant effects 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 drug consumption. Another effect of sodium ferrate on water purification is disinfection and sterilization, and it is effective in removing harmful pathogenic microorganisms in domestic sewage.

[0020] Microcrystalline cellulose is commonly used as an adsorbent, adhesive, and disintegrant. The addition of microcrystalline cellulose to the composite phosphorus remover of the present invention can increase the disintegration speed of the phosphorus remover tablets, disintegrating into mist within 1 minute, thereby enabling the water treatment agent to take effect faster.

[0021] The present invention has found in experiments that the combined use of dodecyl imidazoline and sodium alginate has a strong degreasing ability in high-fat wastewater, with less loss of reagent consumption. Moreover, by adjusting the water volume of the steel plant, the dosage of the composite dephosphorization agent can be reduced to 1 / 4 of that of an ordinary dephosphorization agent, greatly reducing the cost of the reagent, and is suitable for promotion and use. The combined use of coconut shell powder and potassium ferrate can not only remove organic pollutants, but also sterilize and purify water, thereby improving the water quality standard of the effluent.

[0022] The purpose of mixing the ferroaluminate-containing wastewater and domestic sewage in proportion before use of the composite agent of the present invention is to add ferroaluminate to the domestic sewage. On the one hand, this saves the consumption of the dephosphorization agent. The ferroaluminate provided helps to remove phosphorus, so that the dosage of the composite dephosphorization agent is only 1 / 4 of that of the ordinary dephosphorization agent. On the other hand, this part of the sewage can be recycled and utilized without the need for additional treatment of this part of the wastewater.

[0023] The comparison of water quality before and after the sewage treatment of the present invention is shown in Table 1;

[0024] Table 1

[0025] Compared with the existing technology, the beneficial effects of the present invention are:

[0026] 1. The dosage of the composite dephosphorization agent of the present invention is 1 / 4 of that of the common dephosphorization agent, and it has the characteristics of low agent consumption and significant denitrification and dephosphorization effects, and has great promotion and application value.

[0027] 2. The combined use of dodecyl imidazoline and sodium alginate as the components of the composite dephosphorization agent of the present invention has a strong degreasing ability in high-fat wastewater, with low agent loss, thus ensuring the use effect of the composite dephosphorization agent.

[0028] 3. The composite phosphorus removal agent of the present invention, comprising coconut shell powder and potassium ferrate, can not only remove organic pollutants but also sterilize and purify water, thereby improving the effluent quality standard.

[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. The composite dephosphorization agent of the present invention changes the water quality conditions before use, and mixes the iron-aluminate wastewater from the steel plant with domestic sewage in proportion, which not only regulates the water quality but also saves the amount of medicine.

[0031] 6. The composite phosphorus removal agent of the present invention is a compressed tablet, which is convenient to store, has good stability, is easy to transport, and is highly safe compared to liquid medicine. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the embodiments. However, 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 dephosphorizing agent for treating domestic sewage is prepared from the following raw materials in parts by weight: 15 parts of dodecyl imidazoline, 35 parts of sodium alginate, 10 parts of coconut shell powder, 40 parts of potassium ferrate and 15 parts of microcrystalline cellulose.

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

[0036] In a closed container, a gas mixing method is used to sequentially add dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose and mix them. Dry nitrogen is then introduced to perform gas stirring and mixing for 1 hour. The mixed material is then sieved through 80 mesh and then fed into a rotary tablet press to be made into tablets to obtain the composite phosphorus remover of the present invention.

[0037] The method of using the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage is as follows:

[0038] The iron-aluminate wastewater from the steel plant is mixed with domestic sewage in a ratio of 4.5:1.5 in a regulating tank. Then, a hanging basket is hung at the water 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 the baffle.

[0039] Example 2:

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

[0041] The preparation method of the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage comprises the following steps: in a closed container, using a gas mixing method, sequentially adding dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose and mixing them, then introducing dry nitrogen gas and stirring and mixing for 1.5 hours, then sieving the mixed material through a 100-mesh sieve, and then feeding the mixed material into a rotary tablet press to prepare tablets to obtain the composite dephosphorizing agent of the present invention.

[0042] The method of using the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage is as follows:

[0043] The iron-aluminate wastewater from the steel plant is mixed with domestic sewage in a ratio of 4:2 in a regulating tank. Then, a hanging basket is hung at the water 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, and the treated water is discharged through the baffle.

[0044] Example 3:

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

[0046] The preparation method of the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage comprises the following steps: in a closed container, using a gas mixing method, adding dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose in sequence and mixing them, then introducing dry nitrogen gas and stirring and mixing for 2 hours, then sieving the mixed material through a 60-mesh sieve, and then feeding the mixed material into a rotary tablet press to prepare tablets to obtain the composite dephosphorizing agent of the present invention.

[0047] The method of using the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage is as follows:

[0048] The iron-aluminate wastewater from the steel plant is mixed with domestic sewage in a ratio of 6:1 in a regulating tank. Then, a hanging basket is hung at the water 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, and the treated water is discharged through the baffle.

[0049] Experimental Example 1:

[0050] The test was conducted in a domestic sewage system within a steel plant. The water quality parameters were 21.4 mg / L total phosphorus, 11.5 mg / L ammonia nitrogen, and 20 mg / L oil. The three examples above were used for comparison with water treated with polyferric sulfate and polyaluminum sulfate, and a dosage gradient was set for flotation experiments.

[0051] The experimental method is as follows: first, the iron-aluminate wastewater and domestic sewage are mixed in the regulating tank according to the ratio of Examples 1-3, 1 L of the mixed water sample is taken, stirred at 200 r / min for 30 seconds, then switched to slow stirring at 60 r / min and stirred for 1 minute, and then the reagents are added according to the raw material ratio and preparation method of Examples 1-3, and flotation is turned on for 40 seconds. After the slag floats, the water quality parameters of the intermediate liquid are measured and compared with those of domestic sewage treated with polyferric sulfate and polyaluminum sulfate. The measurement data are shown in Tables 2 to 4.

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

[0053] Table 3 Changes in ammonia nitrogen at different concentrations (mg / L):

[0054] Table 4 Changes in oil at different concentrations (mg / L):

[0055] From the above data, it can be seen that the composite phosphorus removal agent of the present invention has excellent effect. The total phosphorus, ammonia nitrogen and oil all meet the water pollutant discharge standard of the steel industry (GB 13456-2012). Compared with polyferric sulfate and polyaluminum sulfate, the effect is relatively poor and cannot meet production needs.

[0056] Experimental Example 2:

[0057] Experiment on the degreasing ability of dodecyl imidazoline and sodium alginate in the composite phosphorus removal agent of the present invention in high-fat wastewater:

[0058] The test was conducted on a domestic sewage system within a steel plant with an oil content of 24.8 mg / L. Three composite dephosphorylators were selected. Dodecyl imidazoline and sodium alginate were used alone or in combination. A comparative analysis was performed. The three dephosphorylators were: 50 parts of dodecyl imidazoline alone; 50 parts of sodium alginate alone; and 25 parts of dodecyl imidazoline and 25 parts of sodium alginate combined, with a total addition ratio of 50 parts. The remaining agents were the same in weight: 25 parts coconut shell powder, 30 parts potassium ferrate, and 25 parts microcrystalline cellulose. The preparation method was the same as in Example 3.

[0059] During the experiment, the ferroaluminate wastewater and domestic sewage were mixed in a regulating tank at a ratio of 6:1. 1 L of the mixed water sample was taken for the experiment. It was stirred at 200 r / min for 30 seconds, and then switched to slow stirring at 60 r / min for 1 minute. The above-mentioned experimental reagents were added to the mixed water sample, and flotation was turned on for 40 seconds. The measurement results are shown in Table 5 below.

[0060] Table 5

[0061] From Table 5, it can be seen that the combined use of dodecyl imidazoline and sodium alginate is better than that of a single agent alone. The combined use of dodecyl imidazoline and sodium alginate has a synergistic effect.

Claims

1. A degreasing, denitrifying and dephosphorizing 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 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.

2. The degreasing, denitrifying and dephosphorizing agent for treating domestic sewage according to claim 1, characterized in that: The domestic sewage is domestic sewage from a steel plant.

3. The method for preparing the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage according to claim 1 or 2, characterized in that: The following methods are included: In a closed container, dodecyl imidazoline, sodium alginate, coconut shell powder, potassium ferrate and microcrystalline cellulose are added and mixed by gas mixing method, and then dry nitrogen is introduced for gas stirring and mixing for 1 to 2 hours, and then the mixed material is sieved through 60 to 100 meshes, and then sent to a rotary tablet press to be made into tablets to obtain a dephosphorus agent.

4. The method for using the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage according to claim 1 or 2, characterized in that: The specific method is as follows: The iron-aluminate wastewater from the steel plant is mixed with domestic sewage in a regulating tank, and then a hanging basket is hung at the water inlet of the aeration tank to put the prepared phosphorus removal tablets into it. At the same time, aeration is turned on, and a scraper is installed at the end of the aeration tank to remove the floating harmful substances. The treated water is discharged through the baffle.

5. The method for using the degreasing, denitrifying and dephosphorizing agent for treating domestic sewage according to claim 4, characterized in that: The mixing ratio of ferroaluminate wastewater and domestic sewage is (4-6):(1-2) by mass.

Images