A functional microalgae-wood chip device for remediating manganese ore wastewater and its application

Abstract

This invention belongs to the fields of microbial technology and environmental remediation. It discloses a functional microalgae-wood chip device for remediating manganese ore wastewater, comprising a wastewater tank, a manganese oxidation precipitation tank, and a denitrification tank. The manganese oxidation precipitation tank contains the bio-manganese-oxidizing microalgae *Desmodesmus sp. WR1* (accession number: CCTCC M 2016461). The denitrification tank contains wood chips. The effluent end of the wastewater tank is connected to the manganese oxidation precipitation tank via a first pipe, and the effluent end of the manganese oxidation precipitation tank is connected to the denitrification tank via a second pipe. The effluent end of the denitrification tank has an external discharge pipe and a return pipe extending into the manganese oxidation precipitation tank. A return pump is installed on the return pipe. Control valves are installed on the first pipe, the second pipe, the external discharge pipe, and the return pipe. This invention can efficiently remove manganese ions from manganese ore wastewater, and denitrification removes nitrogenous nutrients from the wastewater. It is economical, efficient, produces no secondary pollution, and is simple to operate, making it significant for the treatment of manganese ore wastewater.

Description

Technical Field

[0001] This invention belongs to the fields of applied microbial technology and environmental remediation, and more specifically, relates to a functional microalgae-wood chip device and its application for remediating manganese ore wastewater. Background Technology

[0002] In recent years, the demand for manganese mining, manganese alloys, and electrolytic manganese production has been high. However, the resulting phenomenon of excessive manganese content in receiving water bodies is common. Manganese is an essential trace element for living organisms, but numerous studies have shown that long-term excessive exposure or intake of manganese can seriously impair the function of the nervous and immune systems. Furthermore, due to the complex mineral composition of manganese mines, which often contain abundant nitrogen, phosphorus, mercury, iron, lead, nickel, cadmium, and other elements, manganese mining and beneficiation wastewater, especially mine pit water, beneficiation wastewater, and surface runoff around mines, is often acidic, posing a significant challenge to water quality remediation in the surrounding mining areas.

[0003] Traditional methods for manganese pollution control mainly include physical and chemical methods, such as activated carbon adsorption, strong oxidant oxidation, air oxidation contact filtration, chemical precipitation, adsorption, chemical oxidation, and ion exchange. However, biological methods for manganese removal are more environmentally friendly and efficient compared to non-biological methods. Biological manganese removal utilizes microorganisms with manganese oxidation potential or their secreted highly efficient manganese oxidases to oxidize manganese into water-insoluble manganese oxide particles. These particles are then removed from the water through filtration and sedimentation, making it an environmentally friendly and efficient technology.

[0004] However, the use of functional bacteria to oxidize and remove manganese and produce bio-manganese oxide requires maintaining appropriate culture temperature and pH conditions, as well as continuous aeration and nutrient input. The adaptability of functional bacteria to the aquatic environment will limit their application in the remediation of manganese-contaminated water environments. In addition, the use of bio-enzyme oxidation will increase the costs of enzyme extraction and preservation processes.

[0005] Therefore, there is an urgent need for a new method that is low-cost and can effectively remove manganese ions, nitrogen, and phosphorus from manganese ore wastewater. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a functional microalgae-wood chip device for the remediation of manganese ore wastewater. This invention aims to solve the problems of high cost and low efficiency in existing manganese ore wastewater treatment methods.

[0007] To achieve the above objectives, this invention provides a functional microalgae-wood chip device for remediating manganese ore wastewater, comprising a wastewater tank, a manganese oxidation sedimentation tank, and a denitrification tank. The manganese oxidation sedimentation tank contains the bio-manganese oxidation generating microalgae *Desmodesmus sp. WR1*, whose preservation number is CCTCC M 2016461. The denitrification tank contains wood chips. The effluent end of the wastewater tank is connected to the manganese oxidation sedimentation tank via a first pipe. The effluent end of the manganese oxidation sedimentation tank is connected to the denitrification tank via a second pipe. The effluent end of the denitrification tank is equipped with an external discharge pipe and a return pipe extending into the manganese oxidation sedimentation tank. A return pump is installed on the return pipe. Control valves are installed on the first pipe, the second pipe, the external discharge pipe, and the return pipe.

[0008] Furthermore, the wood chips are poplar wood chips.

[0009] This invention also discloses the application of a functional microalgae-wood chip device for remediating manganese ore wastewater. The application steps of the functional microalgae-wood chip device for remediating manganese ore wastewater are as follows:

[0010] S1. Preparation of microalgae suspension;

[0011] Microalgae were inoculated into BG-11 culture medium and cultured in a light incubator. When the microalgae in the culture medium reached the logarithmic phase, the microalgae cells were collected by filtration. The microalgae on the filter membrane were rinsed with sterile distilled water to obtain a microalgae suspension.

[0012] S2. Open the control valve of the first pipeline to discharge manganese ore wastewater into the manganese oxidation precipitation tank, and then add the microalgae suspension prepared in step S1 according to the amount of manganese ore wastewater in the manganese oxidation precipitation tank.

[0013] S3. The manganese ore wastewater containing microalgae in the manganese oxidation sedimentation tank is left to stand for 3 days. Then, the control valve of the second pipeline is opened to discharge the treated wastewater to the denitrification tank.

[0014] S4. Prepare sawdust mesh bags;

[0015] The sawdust is placed into a polyester fiber mesh bag, then soaked overnight and drained to obtain the sawdust mesh bag.

[0016] S5. Place the sawdust mesh bag into the denitrification tank, and denitrify the wastewater in the denitrification tank for 3 days;

[0017] S6. After the denitrification treatment of the wastewater in the denitrification tank is completed, open the control valve of the discharge pipe to discharge a portion of the denitrified wastewater, and open the control valve of the return pipe to return a portion of the denitrified wastewater to the manganese oxidation sedimentation tank.

[0018] Furthermore, in step S1, the culture conditions for microalgae are: temperature 22±1℃, cold white fluorescent lamp illumination 50±10μmol photons·m-2·s-1, and light-dark ratio 12h:12h.

[0019] Furthermore, in step S5, the sawdust mesh bag is placed into the denitrification and nitrogen removal tank at a ratio of 50 g / L of sawdust dry weight.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. The functional microalgae-wood chip device of the present invention has a simple structure, low cost and high processing efficiency.

[0022] 2. The functional microalgae-wood chip device of the present invention utilizes bio-oxidized manganese to generate microalgae Desmodesmus sp. As a native species in the aquatic environment driven by light energy, microalgae are highly adaptable to the aquatic environment. They are photosynthetically autotrophic and can utilize nitrogen and phosphorus nutrients in the water to grow and proliferate rapidly. Photosynthesis produces oxygen and fixes carbon dioxide, which can increase the dissolved oxygen concentration and pH of the aquatic environment. Without the need for aeration and nutrient input, it can continuously meet the physicochemical conditions required for manganese ion oxidation—high dissolved oxygen and alkaline environment. Compared with manganese-oxidizing bacteria for manganese removal, it has lower cost and stronger adaptability.

[0023] 3. The bio-manganese oxide generated by microalgae can further promote the remediation of complex water pollution and promote the formation of microalgae sedimentation. This is beneficial for the discharge of upper wastewater from the manganese oxidation sedimentation tank, the collection of sediment, and also allows most of the microalgae to be retained in the primary device for reuse.

[0024] 4. Denitrification tanks and wood chips can further remove nitrogenous nutrients from manganese ore wastewater. They are low-cost, highly efficient, and do not produce secondary pollution.

[0025] 5. The return pipe and return pump can discharge the well-grown functional microalgae in the denitrification tank back into the manganese oxidation precipitation tank, thereby increasing the concentration of functional microalgae in the manganese oxidation precipitation tank and allowing it to be reused.

[0026] 6. This device treats manganese ore wastewater. After treatment in the manganese oxidation precipitation tank, the removal rate of manganese ions in the manganese ore wastewater can reach 100%. After treatment in the denitrification denitrification tank, the removal rate of total nitrogen in the manganese ore wastewater can reach 86%, the removal rate of nitrate nitrogen can reach 92%, and the removal rate of ammonia nitrogen can reach 94%.

[0027] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0028] Figure 1 A schematic diagram of a functional microalgae-wood chip device for remediating manganese ore wastewater;

[0029] Figure 2 Microscopic images of the microalga Desmodesmus sp.WR1, which generates biogenic manganese oxide, and the biogenic manganese oxide it produces;

[0030] Figure 3 This study investigates the removal of manganese ions from manganese ore wastewater by functional microalgae and the generation of bio-oxidized manganese.

[0031] Figure 4 The content of chlorophyll a in the primary and secondary devices;

[0032] Figure 5 The removal of ammonia nitrogen, nitrate nitrogen, total nitrogen, and total phosphorus from manganese ore wastewater by the primary and secondary units;

[0033] Figure 6 The changes in conductivity, dissolved oxygen, and pH of manganese ore wastewater during the treatment of manganese ore wastewater by the primary and secondary units;

[0034] Figure 7 The abundance of some denitrification genes in the water body when the secondary unit treats manganese ore wastewater;

[0035] Figure 8 Analysis of the sediment at the bottom of the manganese ore wastewater after the primary unit has finished treating it;

[0036] The attached diagram is labeled as follows: Wastewater tank 1, manganese oxidation sedimentation tank 2, denitrification and nitrogen removal tank 3. Detailed Implementation

[0037] To make the technical solutions, advantages, and objectives of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the protection scope of this application.

[0038] like Figure 1As shown, this invention discloses a functional microalgae-wood chip device for remediating manganese ore wastewater, comprising a wastewater tank 1, a manganese oxidation sedimentation tank 2, and a denitrification tank 3. The manganese oxidation sedimentation tank 2 contains Desmodesmus sp. WR1, a microalgae that generates manganese oxidation. The preservation number of Desmodesmus sp. WR1 is CCTCC M2016461. The denitrification tank 3 contains wood chips, specifically poplar wood chips. The effluent end of the wastewater tank 1 is connected to the manganese oxidation sedimentation tank 2 via a first pipe. The effluent end of the manganese oxidation sedimentation tank 2 is connected to the denitrification tank 3 via a second pipe. The effluent end of the denitrification tank 3 is equipped with an external discharge pipe and a return pipe extending into the manganese oxidation sedimentation tank 2. A return pump is installed on the return pipe. Control valves are installed on the first pipe, the second pipe, the external discharge pipe, and the return pipe.

[0039] The microalga *Desmodesmus* sp. WR1, belonging to the genus *Desmodesmus*, is a biogenic microalga that produces manganese oxides. Its cells typically form colonies of 4 or 2 cells, with spiny protrusions on the cell surface, and a cell size of approximately 6–10 μm. For example... Figure 2 As shown, this microalgae can oxidize and precipitate manganese ions in wastewater into bio-manganese oxide.

[0040] This invention also discloses the application of a functional microalgae-wood chip device, which is used to remediate manganese ore wastewater. The application steps are as follows:

[0041] S1. Preparation of microalgae suspension;

[0042] Microalgae were inoculated into BG-11 culture medium and cultured in a light incubator. When the microalgae in the culture medium reached the logarithmic phase, the microalgae cells were collected by filtration. The microalgae on the filter membrane were rinsed with sterile distilled water to obtain a microalgae suspension.

[0043] The culture conditions for microalgae were: temperature 22±1℃, cold white fluorescent lamp illumination 50±10μmol photons·m-2·s-1, light-dark ratio 12h:12h;

[0044] S2. Open the control valve of the first pipeline to discharge manganese ore wastewater into the manganese oxidation precipitation tank, and then add the microalgae suspension prepared in step S1 according to the amount of manganese ore wastewater in the manganese oxidation precipitation tank.

[0045] S3. The manganese ore wastewater containing microalgae in the manganese oxidation sedimentation tank is left to stand for 3 days. Then, the control valve of the second pipeline is opened to discharge the treated wastewater to the denitrification tank.

[0046] S4. Prepare sawdust mesh bags;

[0047] Pack the purchased poplar wood chips into a 9×11cm polyester fiber mesh bag at a rate of 25g / bag, then soak overnight and drain the water to obtain the wood chip mesh bag.

[0048] S5. Based on the wastewater volume in the denitrification tank, place the sawdust mesh bag into the denitrification tank at a ratio of 50g / L of sawdust dry weight, and denitrify the wastewater in the denitrification tank for 3 days.

[0049] S6. After the denitrification treatment of the wastewater in the denitrification tank is completed, open the control valve of the discharge pipe to discharge a portion of the denitrified wastewater, and open the control valve of the return pipe to return a portion of the denitrified wastewater to the manganese oxidation sedimentation tank.

[0050] Comparative analysis

[0051] A square acrylic transparent incubator with a volume of 7L, a length of 23cm, a width of 18cm, a height of 18cm, and an outlet distance of 2.5cm from the bottom was used to prepare a manganese oxidation sedimentation tank and a denitrification nitrogen removal tank. The manganese oxidation sedimentation tank was the primary device, and the denitrification nitrogen removal tank was the secondary device, and finally a functional microalgae-wood chip device for indoor experiments was obtained.

[0052] Functional microalgae suspensions were prepared, and three microalgae suspensions with different initial algal densities were prepared: a cell density of 5.5 × 10⁻⁶ cells / mL. 5 8.8×10 5 1.1×10 6 cells / mL. Three microalgae suspensions with different initial algal densities were used to treat manganese mine wastewater, and comparative analysis was conducted. Manganese mine wastewater without added functional algae was set as a control. Four batches of wastewater were used as influent.

[0053] 5 L of manganese-contaminated water sample collected in the field was injected into the primary device. All experiments were conducted under controlled indoor conditions of 22±2℃, illuminated by a cool white fluorescent lamp (50±10 μmol photons·m⁻²·s⁻¹) with a light-dark ratio of 12 h:12 h.

[0054] Samples were collected at 0h, 24h, 48h, and 72h during the treatment process for routine water quality analysis. The results are as follows: Figure 6 .

[0055] Microalgal biomass was represented by detecting chlorophyll a concentration. After overnight extraction with 80% acetone, absorbance was measured using a spectrophotometer at wavelengths of 663 nm and 646 nm. The results are as follows: Figure 4 .

[0056] In addition, the concentration of biogenerated manganese oxide in the culture system was detected by the leucoberbelin blue (LBB) method, and the concentration of residual manganese ions was detected by atomic absorption spectrophotometry. The detection results are as follows: Figure 3The removal rate of manganese ions in wastewater can reach 100%.

[0057] After the manganese ore wastewater has been treated in the primary unit for 3 days and allowed to settle completely, the control valve of the first pipeline is opened to allow the wastewater to flow into the secondary unit. Simultaneously, 4L of manganese ore wastewater is added to the primary unit to begin a new batch of wastewater treatment. Then, the control valve of the second pipeline is opened to discharge the wastewater from the primary unit into the secondary unit. Afterwards, sawdust mesh bags are placed in the secondary unit at a ratio of 50g / L dry weight of sawdust. Nitrogen is removed by denitrification, utilizing certain microorganisms in the sawdust. The abundance of some denitrification genes in the water is as follows: Figure 7 As shown. The total nitrogen, ammonia nitrogen, nitrate nitrogen, and total phosphorus content in the solution were tested regularly, and the test results are as follows. Figure 5 After treatment, the total nitrogen removal rate in the wastewater reaches 86%, the nitrate nitrogen removal rate reaches 92%, and the ammonia nitrogen removal rate reaches 94%. After the first and second stage units react simultaneously for 3 days, the treated wastewater from the second stage unit is discharged first, and then the upper wastewater from the first stage unit is discharged into the second stage unit. The first stage unit is replenished with new manganese ore wastewater, and the next batch of wastewater treatment begins. The functional microalgae grow well in the second stage unit. When the content of functional microalgae in the first stage unit is insufficient, an appropriate amount of wastewater treated in the second stage unit can be added to the first stage unit through a reflux pump.

[0058] After four consecutive batches of manganese ore wastewater were treated, the precipitate from the first-stage unit was collected for XPS, XRD, and EDS analysis. The analysis results are as follows: Figure 8 As shown, the precipitate is mainly composed of the functional microalgae and the generated biogenic manganese oxide, calcium carbonate and other precipitates, of which the biogenic manganese oxide accounts for an average of 5.32% in the precipitate; analysis shows that the manganese oxide is mainly composed of manganese elements with +4 and +3 valences, with +4 manganese accounting for 63.29% and +3 manganese accounting for 36.71%.

[0059] In summary, the present invention provides a functional microalgae-wood chip device for the remediation of manganese mine wastewater. This device can efficiently remove manganese ions from manganese mine wastewater, and denitrification removes nitrogen-containing nutrients from the wastewater. It is economical, efficient, produces no secondary pollution, and is simple to operate, making it of great significance for the treatment of manganese mine wastewater.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A functional microalgae-wood chip device for remediating manganese ore wastewater, characterized in that: The system includes a wastewater tank, a manganese oxidation sedimentation tank, and a denitrification tank. The manganese oxidation sedimentation tank contains Desmodesmus sp. WR1, a microalgae that generates manganese oxidation. The preservation number of Desmodesmus sp. WR1 is CCTCC M 2016461. The denitrification tank contains sawdust. The effluent end of the wastewater tank is connected to the manganese oxidation sedimentation tank via a first pipe. The effluent end of the manganese oxidation sedimentation tank is connected to the denitrification tank via a second pipe. The effluent end of the denitrification tank is equipped with an external discharge pipe and a return pipe extending into the manganese oxidation sedimentation tank. A return pump is installed on the return pipe. Control valves are installed on the first pipe, the second pipe, the external discharge pipe, and the return pipe.

2. The functional microalgae-wood chip device for remediating manganese ore wastewater according to claim 1, characterized in that: The wood chips are poplar wood chips.

3. The application of a functional microalgae-wood chip device for remediating manganese ore wastewater as described in any one of claims 1 to 2, wherein the functional microalgae-wood chip device is applied to remediate manganese ore wastewater, and the application steps are as follows: S1. Preparation of microalgae suspension; Microalgae were inoculated into BG-11 culture medium and cultured in a light incubator. When the microalgae in the culture medium reached the logarithmic phase, the microalgae cells were collected by filtration. The microalgae on the filter membrane were rinsed with sterile distilled water to obtain a microalgae suspension. S2. Open the control valve of the first pipeline to discharge manganese ore wastewater into the manganese oxidation precipitation tank, and then add the microalgae suspension prepared in step S1 according to the amount of manganese ore wastewater in the manganese oxidation precipitation tank. S3. The manganese ore wastewater containing microalgae in the manganese oxidation sedimentation tank is left to stand for 3 days. Then, the control valve of the second pipeline is opened to discharge the treated wastewater to the denitrification tank. S4. Prepare sawdust mesh bags; The sawdust is placed into a polyester fiber mesh bag, then soaked overnight and drained to obtain the sawdust mesh bag. S5. Place the sawdust mesh bag into the denitrification tank, and denitrify the wastewater in the denitrification tank for 3 days; S6. After the denitrification treatment of the wastewater in the denitrification tank is completed, open the control valve of the discharge pipe to discharge a portion of the denitrified wastewater, and open the control valve of the return pipe to return a portion of the denitrified wastewater to the manganese oxidation sedimentation tank.

4. The application of the functional microalgae-wood chip device for remediating manganese ore wastewater according to claim 3, characterized in that: In step S1, the microalgae culture conditions are: temperature 22±1℃, cold white fluorescent lamp illumination 50±10μmolphotons·m-2·s-1, light-dark ratio 12h:12h.

5. The application of the functional microalgae-wood chip device for remediating manganese ore wastewater according to claim 3, characterized in that: In step S5, the sawdust mesh bag is placed into the denitrification and nitrogen removal tank at a ratio of 50 g / L of sawdust dry weight.

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