Wastewater treatment methods

Abstract

This invention proposes a wastewater treatment method, which includes: passing wastewater into a treatment area planted with aquatic plants for settling to adsorb heavy metal ions; passing the settling wastewater into a treatment area containing activated sludge for activated treatment; wherein the activated sludge is cleaned periodically, with 60% of the total activated sludge removed each cycle, and the sludge is cleaned in a bottom-up order; and the wastewater after activated treatment is evaporated and concentrated. This invention sequentially treats heavy metal ions, organic pollutants, and salt ions in wastewater, effectively purifying wastewater quality, improving wastewater treatment capacity, and protecting the environment.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater treatment method. Background Technology

[0002] Wastewater refers to wastewater and waste liquid discharged during industrial processes. The main pollutants in wastewater can be categorized as follows: inorganic wastewater (primarily containing inorganic pollutants), organic wastewater (primarily containing organic pollutants), mixed wastewater (containing both organic and inorganic substances), heavy metal wastewater, wastewater containing radioactive substances, and cooling water that is only contaminated by heat. Wastewater containing industrial raw materials, intermediate products, by-products, and pollutants generated during production processes that are lost with the wastewater is a significant cause of environmental pollution, particularly water pollution. Summary of the Invention

[0003] This invention provides a wastewater treatment method to solve one or more technical problems in the prior art.

[0004] In a first aspect, embodiments of the present invention provide a wastewater treatment method, comprising:

[0005] Wastewater is introduced into a treatment area planted with aquatic plants and left to stand for heavy metal ion adsorption.

[0006] The settled wastewater is then passed through a system of activated sludge for activated treatment. The activated sludge is cleaned periodically, with 60% of the total activated sludge removed each period, and the sludge is cleaned from bottom to top.

[0007] The wastewater after activation treatment is evaporated and concentrated.

[0008] In a preferred embodiment, the step of introducing wastewater into a treatment area planted with aquatic plants for settling and heavy metal ion adsorption further includes:

[0009] The aquatic plants in the first treatment zone were crushed and mixed with the sludge in the first treatment zone.

[0010] Add a heavy metal chelating agent to the mixed sludge;

[0011] The sludge is filtered to obtain sludge containing heavy metals;

[0012] Dolomite and potassium feldspar are added to sludge containing heavy metals and then calcined at high temperature.

[0013] Bentonite was added to the calcined silt to create planting soil.

[0014] In a preferred embodiment, the sludge contains 15%–25% dolomite, 15%–20% potassium feldspar, and 10%–15% bentonite by mass.

[0015] In a preferred embodiment, the aquatic plants in the first treatment area are cultivated using a mixed planting method of water chestnuts, reeds, and water bamboo.

[0016] In a preferred embodiment, the step of periodically cleaning the activated sludge further includes:

[0017] The removed activated sludge is then filtered and dried.

[0018] The dried activated sludge is added to sludge containing heavy metals and then calcined together at high temperature.

[0019] In a preferred embodiment, the step of evaporating and concentrating the activated wastewater includes:

[0020] Quicklime is added to the wastewater after activation treatment until the wastewater becomes alkaline;

[0021] The wastewater is first concentrated by evaporation, during which carbon dioxide is introduced.

[0022] The concentrated wastewater after the first evaporation and concentration was filtered;

[0023] The filtered wastewater concentrate is then subjected to a second evaporation concentration; however, the concentration factor of the first evaporation is less than that of the second evaporation.

[0024] In a preferred embodiment, the step of adding quicklime to the activated wastewater is performed simultaneously with the step of first evaporating and concentrating the wastewater.

[0025] In a preferred embodiment, after the step of performing a second evaporation and concentration on the filtered wastewater concentrate, the method further includes:

[0026] The concentrated wastewater from the second evaporation was cooled to zero degrees Celsius.

[0027] The cooled wastewater flows slowly through the freezing channel; the freezing channel is inclined and the temperature of the freezing channel is between -10℃ and -5℃.

[0028] The concentrated wastewater flowing through the freezing channel is collected for the production of crystalline salt.

[0029] The technical solutions described above have the following advantages or beneficial effects: This invention sequentially treats heavy metal ions, organic pollutants, and salt ions in wastewater, effectively purifying wastewater quality, improving wastewater treatment capacity, and protecting the environment.

[0030] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0031] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in the invention and should not be construed as limiting the scope of the invention.

[0032] Figure 1 A flowchart illustrating a wastewater treatment method according to an embodiment of the present invention is shown.

[0033] Figure 2 A flowchart of step S100 in a wastewater treatment method according to an embodiment of the present invention is shown.

[0034] Figure 3 A flowchart of step S200 in a wastewater treatment method according to an embodiment of the present invention is shown.

[0035] Figure 4 A flowchart of step S300 in a wastewater treatment method according to an embodiment of the present invention is shown. Detailed Implementation

[0036] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0037] Figure 1 A flowchart illustrating a wastewater treatment method according to an embodiment of the present invention is shown.

[0038] This invention provides a wastewater treatment method. See also... Figure 1 As shown, the method includes:

[0039] Step S100: The wastewater is passed into a treatment area planted with aquatic plants and left to stand for heavy metal ion adsorption. Using aquatic plants, which have the ability to accumulate heavy metals, can effectively adsorb and accumulate heavy metal ions.

[0040] Step S200: The settled wastewater is passed through a system of activated sludge for activated treatment. Activated treatment effectively reduces organic pollutants in the wastewater. The activated sludge is cleaned periodically, with 60% of the total activated sludge removed each cycle. The sludge is cleaned from bottom to top. Because the microorganisms in the activated sludge metabolize, removing the bottom layer of activated sludge promotes the proliferation of new microorganisms, accelerating the decomposition of organic pollutants.

[0041] Step S300: The activated wastewater is evaporated and concentrated. After the removal of heavy metal ions and organic pollutants, the wastewater contains a large amount of inorganic salt ions, requiring further treatment through evaporation and concentration to more completely purify the pollutants.

[0042] This embodiment sequentially treats heavy metal ions, organic pollutants, and salt ions in wastewater, effectively purifying the wastewater quality, improving wastewater treatment capacity, and protecting the environment.

[0043] In one specific embodiment, see Figure 2 As shown, step S100, which involves passing wastewater into a treatment area planted with aquatic plants for settling to allow for the adsorption of heavy metal ions, further includes:

[0044] Step S110: Crush the aquatic plants in the first treatment zone and mix them with the sludge in the first treatment zone. Aquatic plants absorb heavy metal ions and accumulate them within themselves; mixing the aquatic plants together with the sludge prevents the outflow of adsorbed heavy metal ions.

[0045] Step S120: Add a heavy metal chelating agent to the mixed sludge. This allows the heavy metal chelating agent to precipitate the heavy metal ions contained in the sludge, forming a precipitate.

[0046] Step S130: Filter the sludge to obtain sludge containing heavy metals.

[0047] Step S140: Add dolomite and potassium feldspar to the sludge containing heavy metals and calcine it at high temperature. This can passivate the heavy metal ions in the sludge and prevent plants from absorbing them.

[0048] Step S150: Bentonite is added to the calcined sludge to serve as planting soil. This addition of a heavy metal chelating agent, along with passivation by dolomite and potassium feldspar, ensures that all heavy metal ions in the sludge are converted into precipitates or passivated, preventing absorption by the plants. Bentonite also helps increase the water retention of the calcined sludge.

[0049] Furthermore, the sludge contains 15%–25% dolomite, 15%–20% potassium feldspar, and 10%–15% bentonite by mass. The added dolomite and potassium feldspar can act as soil passivating agents under high-temperature calcination conditions, passivating heavy metal ions in the soil.

[0050] In one specific embodiment, when the mass fraction of dolomite lime is 25%, the mass fraction of potassium feldspar is 20%, and the mass fraction of bentonite is 10%, the passivation of heavy metal ions in the silt is optimal, and the soil with added bentonite has good water retention.

[0051] Furthermore, the aquatic plants in the first treatment area are cultivated using a mixed planting method of water hyacinth, reeds and water chestnuts. The plants with multiple growth methods can more comprehensively adsorb heavy metal ions in the water.

[0052] In one specific implementation, see Figure 3 As shown, step S200, which involves periodically cleaning the activated sludge, further includes:

[0053] Step S210: The removed activated sludge is filtered and dried.

[0054] Step S220: The dried activated sludge is added to the sludge containing heavy metals and then calcined together at high temperature. In this way, the metal ions remaining in the activated sludge will also be passivated after being calcined together with the sludge containing heavy metals, preventing them from flowing out.

[0055] In one specific implementation, see Figure 4 As shown, step S300, which involves evaporating and concentrating the activated wastewater, includes:

[0056] Step S310: Add quicklime to the wastewater after activation treatment until the wastewater becomes alkaline. Adding quicklime not only adjusts the alkalinity, but also generates a lot of heat when quicklime reacts with water, thereby preheating the wastewater and reducing the evaporation and concentration time.

[0057] Step S320: The wastewater is concentrated through initial evaporation, during which carbon dioxide is introduced. This causes limewater, produced by adding quicklime, to precipitate upon contact with carbon dioxide, reducing the number of cations in the wastewater.

[0058] Step S330: Filter the wastewater concentrate after the first evaporation and concentration. Filtration after evaporation and concentration effectively reduces the sediment and impurities in the concentrate.

[0059] Step S340: The filtered wastewater concentrate is subjected to a second evaporation concentration; wherein, the first evaporation concentration ratio is less than the second evaporation concentration ratio. The first evaporation concentration is a preliminary evaporation concentration, which concentrates the wastewater first, while the second evaporation concentration is a deep evaporation concentration. Therefore, the amount of water concentrated in the second evaporation concentration is much greater than that in the first evaporation concentration. The two evaporation concentrations can not only reduce the maximum evaporation load, but also have higher efficiency.

[0060] Furthermore, the step of adding quicklime to the wastewater after activation treatment is carried out simultaneously with the step of evaporating and concentrating the wastewater for the first time, which can reduce the heat loss when adjusting to alkalinity.

[0061] Further, see Figure 4 As shown, after step S340, which involves a second evaporation and concentration of the filtered wastewater concentrate, the method further includes:

[0062] Step S350: Cool the concentrated wastewater solution from the second evaporation to zero degrees Celsius.

[0063] Step S360: The cooled wastewater flows slowly through the freezing channel; wherein, the freezing channel is set at an angle and the temperature of the freezing channel is between -10℃ and -5℃, so that when the concentrate flows through the freezing channel, some of the water contained therein will freeze and separate, further purifying the concentrate.

[0064] Step S370: The wastewater concentrate flowing through the freezing channel is collected for the production of crystalline salt. The remaining wastewater concentrate has a high content of salt ions, and high-purity crystalline salt can be obtained by high-temperature processing.

[0065] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A wastewater treatment method, characterized in that, Includes the following steps: Wastewater is introduced into the first treatment zone, which is planted with aquatic plants, and left to stand for heavy metal ion adsorption. The settled wastewater is then passed through a system of activated sludge for activated treatment. The activated sludge is cleaned periodically, with 60% of the total amount of activated sludge removed each period, and the cleaning is carried out from bottom to top. The wastewater after activation treatment is evaporated and concentrated. The step of passing the wastewater into a first treatment zone planted with aquatic plants for settling and heavy metal ion adsorption further includes: The aquatic plants in the first treatment zone were crushed and mixed with the sludge in the first treatment zone. Add heavy metal chelating agents to the mixed sludge; The sludge is filtered to obtain sludge containing heavy metals; Dolomite and potassium feldspar are added to sludge containing heavy metals and then calcined at high temperature. Bentonite was added to the calcined sludge to serve as planting soil; The step of evaporating and concentrating the activated wastewater includes: Quicklime is added to the wastewater after activation treatment until the wastewater becomes alkaline; The wastewater is first concentrated by evaporation, during which carbon dioxide is introduced. The concentrated wastewater after the first evaporation and concentration was filtered; The filtered wastewater concentrate is then subjected to a second evaporation concentration; however, the concentration factor of the first evaporation is less than that of the second evaporation. The step of adding quicklime to the wastewater after activation treatment is performed simultaneously with the step of evaporating and concentrating the wastewater for the first time. Following the step of performing a second evaporation and concentration on the filtered wastewater concentrate, the following is also included: The concentrated wastewater from the second evaporation was cooled to zero degrees Celsius. The cooled wastewater concentrate flows slowly through the freezing channel; the freezing channel is inclined and the temperature of the freezing channel is between -10℃ and -5℃. The concentrated wastewater flowing through the freezing channel is collected for the production of crystalline salt.

2. The wastewater treatment method as described in claim 1, characterized in that, The added dolomite lime has a mass fraction of 15%–25%, potassium feldspar has a mass fraction of 15%–20%, and bentonite has a mass fraction of 10%–15%.

3. The wastewater treatment method as described in claim 1, characterized in that, The aquatic plants in the first treatment area are cultivated using a mixed planting method of water chestnuts, reeds, and water bamboo.

4. The wastewater treatment method as described in claim 1, characterized in that, The process of periodically cleaning the activated sludge also includes: The removed activated sludge is then filtered and dried. The dried activated sludge is added to sludge containing heavy metals and then calcined together at high temperature.

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