Ecological combined constructed wetland system for rare earth mine tail water treatment

Abstract

An ecological combined constructed wetland system for rare earth mine tail water treatment is characterized in that a downward vertical flow wetland and an upward vertical flow wetland of a three-stage combined wetland system are communicated through a bottom communicating pipe, and the upward vertical flow wetland and a floating island wetland are communicated through an upper overflow weir; the tail water treated by the sewage adjusting tank sequentially flows through the downward vertical flow wetland, the upward vertical flow wetland and the floating island wetland; each of the downward vertical flow wetland and the upward vertical flow wetland comprises a filler layer with a three-layer structure, and the upper layer is a plant substrate layer and is composed of fine sand or sandy loam; the middle layer is a functional material layer and is composed of hematite, zeolite or activated carbon; the lower layer is a supporting layer and is composed of coarse sand or gravel; and the aquatic plants of the floating island wetland adsorb pollutants in the water body through root systems, and decompose residual pollutants by utilizing the metabolism of the plants. The tail water treatment device can efficiently remove particular pollutants such as ammonia nitrogen, nitrate nitrogen, heavy metals and rare earth elements in the tail water of the rare earth mine.

Description

TECHNICAL FIELD

[0001] The utility model relates to a tail water treatment's artificial wetland system, concretely is an ecological combined artificial wetland system for rare earth mine tail water treatment belongs to mine tail water treatment technical field. BACKGROUND

[0002] In recent years, with the increasing demand for rare earth resources worldwide, rare earth mining activities have become increasingly frequent. However, the tail water generated during the mining and processing of rare earth mines has become an environmental problem that needs to be addressed urgently. These tail waters often contain high concentrations of nitrogen, heavy metals, and rare earth elements, which can have a serious impact on the surrounding environment and ecosystem.

[0003] Traditional tail water treatment methods such as chemical precipitation, adsorption, and biological treatment can remove these pollutants to some extent, but there are still many limitations in terms of treatment efficiency, economy, and sustainability. SUMMARY

[0004] The utility model aims to provide an ecological combined artificial wetland system for rare earth mine tail water treatment, which can efficiently remove characteristic pollutants such as ammonia nitrogen, nitrate nitrogen, heavy metals, and rare earth elements in rare earth mine tail water, while improving the stability and environmental friendliness of the system.

[0005] To achieve the above-mentioned purpose, the utility model provides an ecological combined artificial wetland system for rare earth mine tail water treatment, which includes a sewage adjusting tank and a three-stage combined wetland system.

[0006] The three-stage combined wetland system includes a downward vertical flow wetland, an upward vertical flow wetland, and a floating island wetland. The downward vertical flow wetland is connected to the upward vertical flow wetland through a bottom communication pipe. The upward vertical flow wetland and the floating island wetland are connected through an upper overflow weir. The rare earth mine tail water treated by the sewage adjusting tank flows through the downward vertical flow wetland, the upward vertical flow wetland, and the floating island wetland in sequence.

[0007] The downward vertical flow wetland and the upward vertical flow wetland both contain three layers of filler layers,

[0008] The upper layer is a plant substrate layer composed of fine sand or sandy loam, which provides a growth substrate for aquatic plants and preliminarily removes suspended particulate matter.

[0009] The middle layer is a functional material layer composed of hematite, zeolite, or activated carbon, which is used to adsorb and filter ammonia nitrogen, nitrate nitrogen, heavy metals, and rare earth elements in wastewater.

[0010] The lower layer is a support layer composed of coarse sand or gravel, which is used to support the functional material layer and ensure smooth and uniform distribution of water flow in the wetland.

[0011] The aquatic plants of the floating island wetland adsorb the pollutants in the water body through the root system and decompose the residual pollutants by using the plant metabolism.

[0012] As a further improvement of the utility model, a corridor flow guide structure is arranged in the sewage adjusting tank, and an alkaline adjusting agent is added in the sewage adjusting tank, the water flow path is prolonged by arranging the corridor flow guide structure, the homogenization effect of the tail water of the rare earth mine is enhanced, the pH value of the tail water of the rare earth mine is adjusted from 2-4 to 6.5-7.5 by adding the alkaline adjusting agent, and stable water inlet conditions are provided for the subsequent treatment unit, and a submersible pump is arranged at the end of the sewage adjusting tank, and the submersible pump is used for pumping the adjusted tail water to the downward vertical flow wetland.

[0013] As a further improvement of the utility model, the floating island wetland contains various aquatic plants, and the aquatic plants include but are not limited to reed, alocasia and welsh onion, and are used for adsorbing and degrading the pollutants in the water body through the root system, and further improving the water quality of effluent.

[0014] As a further improvement of the utility model, the alkaline adjusting agent is one of sodium hydroxide, sodium carbonate or slaked lime.

[0015] Compared with the prior art, the utility model includes a sewage adjusting tank and a three-stage combined wetland system, wherein the three-stage combined wetland is composed of a downward vertical flow wetland, an upward vertical flow wetland and a floating island wetland, and functional materials such as zeolite, hematite and activated carbon are laid in the tank bodies of the upward flow and downward flow wetlands to improve the removal efficiency of nitrogen and heavy metals. The tail water of the rare earth mine to be treated flows through the sewage adjusting tank, the downward vertical flow wetland, the upward vertical flow wetland and the floating island wetland in sequence, in the sewage adjusting tank, the water quantity and pH value of the wastewater are adjusted, in the downward vertical flow wetland, ammonia nitrogen, part of heavy metals and rare earth elements are mainly removed, in the upward vertical flow wetland, nitrate nitrogen, heavy metals and rare earth elements are further removed, and finally in the floating island wetland, the remaining pollutants are adsorbed and degraded by the root system of the aquatic plants, and finally discharged to the surface water body. The utility model combines the iron autotrophic denitrification technology, the iron-carbon micro-electrolysis technology and the strong adsorption effect of zeolite, so that it shows high removal efficiency in treating specific pollutants (such as ammonia nitrogen, heavy metals and rare earth elements) in the tail water of the rare earth mine area, meanwhile, the system is stable in operation, strong in impact resistance and capable of adapting to the fluctuation of the tail water quality, low in energy consumption, simple in operation, low in maintenance cost, high in economy and sustainability, improves the regional ecological environment through the ecological restoration effect of the plants, and has the functions of environmental governance and ecological beautification. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a structural schematic view of the utility model;

[0017] Figure 2A schematic view of a gallery flow guide structure inside a sewage adjusting tank.

[0018] In the figure: 1, sewage adjusting tank, 2, down-flow vertical flow wetland, 3, up-flow vertical flow wetland, 4, floating island wetland, 5, submersible pump, 6, support layer, 7, functional material layer, 8, plant substrate layer, 9, aquatic plant, 10, communication pipe, 11, overflow weir. DETAILED DESCRIPTION

[0019] The utility model will be further described below with reference to the drawings.

[0020] As shown in the figure, an ecological combined artificial wetland system for rare earth mine tail water treatment, comprising a sewage adjusting tank 1 and a three-stage combined wetland system; Figure 1 The three-stage combined wetland system comprises a down-flow vertical flow wetland 2, an up-flow vertical flow wetland 3 and a floating island wetland 4, the down-flow vertical flow wetland 2 is communicated with the up-flow vertical flow wetland 3 through a bottom communication pipe 10, the up-flow vertical flow wetland 3 and the floating island wetland 4 are communicated through an upper overflow weir 11, and the rare earth mine tail water treated by the sewage adjusting tank 1 flows through the down-flow vertical flow wetland 2, the up-flow vertical flow wetland 3 and the floating island wetland 4 in turn;

[0021] The down-flow vertical flow wetland 2 and the up-flow vertical flow wetland 3 both comprise a filler layer with three layers,

[0022] The upper layer is a plant substrate layer 8 composed of fine sand or sandy loam, which is used to provide the growth substrate of aquatic plants 9 and preliminarily remove suspended particulate matter;

[0023] The middle layer is a functional material layer 7 composed of hematite, zeolite or activated carbon, which is used to adsorb and filter ammonia nitrogen, nitrate nitrogen, heavy metals and rare earth elements in wastewater;

[0024] The lower layer is a support layer 6 composed of coarse sand or gravel, which is used to support the functional material layer and ensure the smooth flow and uniform distribution of the wetland;

[0025] The aquatic plants 9 of the floating island wetland 4 adsorb pollutants in the water body through root systems and decompose residual pollutants by plant metabolism.

[0026] The sewage adjusting tank 1 is internally provided with a gallery flow guide structure, and an alkaline adjusting agent is added inside the sewage adjusting tank 1, the water flow path is prolonged by arranging the gallery flow guide structure, the wastewater homogenization effect is enhanced, the pH value of the wastewater is adjusted from 2-4 to 6.5-7.5 by adding the alkaline adjusting agent, stable water inlet conditions are provided for the subsequent treatment unit, and a submersible pump 5 is arranged at the end of the sewage adjusting tank 1, which is used to pump the adjusted wastewater to the down-flow vertical flow wetland 2.

[0027]

[0028] ​The floating island wetland 4 contains a variety of aquatic plants 9, including but not limited to reeds, cattails and water onions, which are used to adsorb and degrade pollutants in the water through their roots, thereby further improving the quality of the effluent.

[0029] The alkalinity regulator is one of sodium hydroxide, sodium carbonate, or quicklime.

[0030] Working principle: The tailwater from the rare earth mine first enters the wastewater equalization tank 1. Wastewater equalization tank 1 is the first treatment unit of this system, mainly used to regulate the wastewater volume, pH value, and homogenize the water quality, providing stable influent conditions for the subsequent wetland unit. The internal structure of wastewater equalization tank 1 is as follows: Figure 2 The corridor-guided flow structure shown enhances the homogenization of rare earth mine tailwater by extending the internal flow path of the wastewater equalization tank 1, thus preventing short-circuiting. Based on the acidic nature of the tailwater, the pH value is monitored in real-time by online monitoring equipment, and alkaline regulators (such as sodium hydroxide, sodium carbonate, or quicklime) are automatically added to adjust the pH value of the wastewater from 2-4 to 6.5-7.5, meeting the treatment requirements of the subsequent wetland unit. Simultaneously, a submersible pump 5 located at the end of the wastewater equalization tank 1 pumps the adjusted tailwater to the downstream vertical flow wetland 2.

[0031] The core function of the downflow vertical flow wetland 2 is to remove ammonia nitrogen, some heavy metals, and rare earth elements from wastewater. The packing material of the downflow vertical flow wetland 2 consists of three layers, from top to bottom: the upper plant substrate layer 8, composed of fine sand or sandy loam, is used for planting aquatic plants (such as reeds) and for preliminary filtration of suspended particulate matter in the effluent; the middle functional material layer 7 is composed of hematite and zeolite. Hematite has excellent adsorption capacity, effectively removing heavy metals and rare earth elements from wastewater, while zeolite is mainly used to adsorb ammonia nitrogen, further reducing the nitrogen concentration in the effluent; the lower support layer 6 is composed of coarse sand or gravel, used to support the functional material layer and ensure uniform water flow. During operation, wastewater flows through the wetland from top to bottom. In the plant substrate layer 8, suspended particulate matter is adsorbed by plant roots. In the functional material layer 7, heavy metals, rare earth elements, and ammonia nitrogen are removed through adsorption. Finally, the wastewater is evenly distributed through the support layer 6.

[0032] The upflow vertical flow wetland 3 further removes nitrate nitrogen, heavy metals and rare earth elements in the tail water, and improves the overall purification depth. The filler of the upflow vertical flow wetland 3 is divided into three layers, similar to the downflow vertical flow wetland 2, but the middle functional material layer 7 is different: the lower support layer 6 is consistent with the downflow wetland, used to support the functional material layer and ensure uniform distribution of water flow; the middle functional material layer 7 is composed of hematite and activated carbon, in which hematite is used to adsorb heavy metals and rare earth elements in wastewater, activated carbon is used to remove organic pollutants and part of nitrogen compounds, at the same time, the primary cell reaction of iron-carbon micro-electrolysis material releases Fe²⁺, promotes the reduction and conversion of nitrate nitrogen, and enhances the precipitation and removal effect of heavy metals; the upper plant substrate layer 8 provides the growth substrate for aquatic plants, further adsorbing particulate matter and residual pollutants in wastewater. During operation, the tail water flows from the downflow vertical flow wetland 2 through the bottom communication pipe 10 from bottom to top through the support layer 6, functional material layer 7 and plant substrate layer 8 of the upflow vertical flow wetland 3, and through multiple effects such as adsorption, reduction and metabolism, further purifies the pollutants.

[0033] The floating island wetland 4 removes residual pollutants through the ecological restoration of aquatic plants 9. The floating island adopts a floating structure, and the plant roots are completely immersed in water. The aquatic plants 9 planted include reed, cattail and water onion. During operation, the tail water flows from the upper overflow weir 11 of the upflow wetland into the floating island wetland 4, and the plant roots adsorb residual nitrogen, phosphorus and trace heavy metals in the water body; the plants decompose organic pollutants in the metabolic process, and convert nitrogen, phosphorus and other nutrients into nutritional ingredients in the plant body, further purifying the wastewater. At the same time, the growth of plants can restore and improve the regional ecological environment to a certain extent.

[0034] During system operation, the pH value, flow rate and pollutant concentration are monitored in real time by online monitoring equipment, and the operating parameters are dynamically adjusted to ensure stable system treatment effect.

Claims

1. An ecological combined constructed wetland system for treating tailings water from rare earth mines, comprising a wastewater regulating pond (1) and a three-stage combined wetland system; characterized in that, The three-level combined wetland system includes a downflow vertical flow wetland (2), an upflow vertical flow wetland (3), and a floating island wetland (4). The downflow vertical flow wetland (2) and the upflow vertical flow wetland (3) are connected by a bottom connecting pipe (10), and the upflow vertical flow wetland (3) and the floating island wetland (4) are connected by an upper overflow weir (11). The tailwater from the rare earth mine, after being treated by the sewage regulating pond (1), flows through the downflow vertical flow wetland (2), the upflow vertical flow wetland (3), and the floating island wetland (4) in sequence. Both the downflow vertical flow wetland (2) and the upflow vertical flow wetland (3) contain a three-layer packing layer. The upper layer is the plant substrate layer (8), which is composed of fine sand or sandy loam. The intermediate layer is a functional material layer (7), which is composed of hematite, zeolite or activated carbon; The lower layer is a support layer (6), which is composed of coarse sand or gravel; The aquatic plants (9) in the floating island wetland (4) adsorb pollutants in the water through their roots and decompose residual pollutants through plant metabolism.

2. The ecological combined constructed wetland system for rare earth mine tailings treatment according to claim 1, characterized in that, The sewage equalization tank (1) is equipped with a corridor flow guiding structure and an alkaline regulator is added inside the sewage equalization tank (1). At the same time, a submersible pump (5) is installed at the end of the sewage equalization tank (1) to pump the regulated wastewater to the downflow vertical flow wetland (2).

3. The ecological combined constructed wetland system for rare earth mine tailings treatment according to claim 2, characterized in that, The floating island wetland (4) contains a variety of aquatic plants (9), including reeds, calamus and water onions.

4. An ecological combined constructed wetland system for rare earth mine tailings treatment according to claim 2 or 3, characterized in that, The alkalinity regulator is one of sodium hydroxide, sodium carbonate, or quicklime.

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