US-12623940-B2 - MABR-based method for treating rare earth mine tailwater

US12623940B2US 12623940 B2US12623940 B2US 12623940B2US-12623940-B2

Abstract

The present disclosure provides an MABR-based method for treating rare earth mine tailwater, comprising: introducing rare earth mine tailwater into a sedimentation pond and simultaneously injecting pig farm breeding tailwater into the sedimentation pond, and fully mixing the two in the sedimentation pond for solid particulate sedimentation; performing pH adjustment, MABR enhancement treatment, percolation treatment with a percolation dam, and ecological purification with an ecological purification pond; and overflowing and discharging the rare earth mine tailwater purified by the ecological purification pond to a natural water body.

Inventors

Yuan Zhang
HONGHAO XIE
XINFEI ZHANG
Jianhui Zhan
Yuliang Wu
Zhifeng Yang

Assignees

GUANGDONG UNIVERSITY OF TECHNOLOGY

Dates

Publication Date: 20260512
Application Date: 20230703
Priority Date: 20221031

Claims (15)

1 . A membrane aeration bioreactor (MABR)-based method for treating rare earth mine tailwater, comprising: introducing a rare earth mine tailwater into a sedimentation pond and simultaneously injecting pig farm breeding tailwater into the sedimentation pond, wherein a volume ratio of the rare earth mine tailwater to the pig farm breeding tailwater is 5 to 30:1; and fully mixing the rare earth mine tailwater to the pig farm breeding tailwater in the sedimentation pond for solid particulate sedimentation; overflowing the rare earth mine tailwater after solid particulate sedimentation from the sedimentation pond to a conditioning tank, and adding a pH adjusting agent to the conditioning tank to adjust a pH of the rare earth mine tailwater after solid particulate sedimentation to 6.5 to 7.0; delivering the rare earth mine tailwater after pH adjustment to a membrane aeration bioreactor for MABR enhancement treatment; wherein the membrane aeration bioreactor comprises a rectangular pool body, an inner wall of the rectangular pool body is covered with a geomembrane impermeable layer, a membrane assembly is fixed in the rectangular pool body, and air is supplied to the membrane assembly through a main air delivery pipe, causing the membrane assembly to carry out microporous aeration and provide an attachment environment for microorganisms in the membrane aeration bioreactor; overflowing the rare earth mine tailwater after MABR enhancement treatment to a percolation dam for percolation treatment; overflowing the rare earth mine tailwater after percolation treatment to an ecological purification pond for ecological purification; wherein the ecological purification pond comprises a soil pond, an inner wall of the soil pond is covered with another geomembrane impermeable layer, the another geomembrane impermeable layer is covered with a common soil layer, and submerged plants and emergent plants are planted on the common soil layer; and overflowing and discharging the rare earth mine tailwater purified by the ecological purification pond to a natural water body.
2 . The method according to claim 1 , before the step of overflowing the rare earth mine tailwater after percolation treatment to the ecological purification pond, further comprising: overflowing the rare earth mine tailwater after percolation treatment to a vertical submerged wetland for purification treatment; wherein the vertical submerged wetland comprises a zeolite filler, water is distributed from a top to a bottom, and an aeration device is arranged at the bottom; the zeolite filler is planted with aquatic plants, and the aquatic plants are any combination of one or more of barracuda, reefer, tumbleweed, water onion, iris, and flower-leaved reed bamboo.
3 . The method according to claim 1 , wherein rare earth mine tailwater after MABR enhancement treatment is partially returned to the conditioning tank to participate in pH and concentration adjustment of the rare earth mine tailwater.
4 . The method according to claim 1 , wherein the pH adjusting agent comprises sodium carbonate.
5 . The method according to claim 1 , wherein the membrane assembly comprises a support frame and an air inlet pipe fixed on the support frame; a top of the air inlet pipe is connected to the main air delivery pipe through a branch air delivery pipe, and a bottom of the air inlet pipe is closed; a side wall of the air inlet pipe defines a plurality of membrane filament connecting holes, and the plurality of membrane filament connecting holes are each fixedly connected to an inlet end of a membrane filament; the membrane filament further comprises an outlet end, and the outlet end is fixedly connected to an air outlet pipe; the air outlet pipe is connected to an air collection pipe; the membrane filament is a hollow filamentary structure surrounded by modified polyvinylidene fluoride fiber membrane.
6 . The method according to claim 5 , wherein the plurality of membrane filament connecting holes are arranged in 6-12 groups along an axial direction and are radially symmetrical with the air inlet pipe, and an outlet end of each group of the membrane filaments is connected to a corresponding air outlet pipe that is vertically arranged.
7 . The method according to claim 6 , wherein the membrane filament is connected to an adjacent membrane filament in a horizontal direction by a nylon screen.
8 . The method according to claim 1 , wherein walls of the sedimentation pond are arranged with water retaining walls that are staggered and fixedly connected to the walls along a direction of water flow, and the water retaining walls form a zigzag waterway in the sedimentation pond.
9 . The method according to claim 1 , wherein the percolation dam comprises limestone as filler.
10 . The method according to claim 1 , wherein a water depth of the ecological purification pond is set to 1.0-1.8 m, and the emergent plants are any combination of one or more of plantain, water onion, reed, and vetiver; the submerged plants are one or two of foxtail algae and bitter grass.
11 . The method according to claim 7 , wherein the air outlet pipe is at an angle of 30-60 degrees from the horizontal direction, and each group of the membrane filaments is spiraled upward with the air inlet pipe as a center.
12 . The method according to claim 6 , wherein the membrane filament is connected to an adjacent membrane filament in a vertical direction by a nylon screen.
13 . The method according to claim 6 , wherein a top of the air inlet pipe is fixedly connected to the support frame through an upper bracket, and a bottom of the air inlet pipe is fixedly connected to the support frame through a lower bracket; the bottom of the air inlet pipe further comprises a flow stopper, and the rare earth mine tailwater after pH adjustment is delivered to the membrane aeration bioreactor through a water distribution pipe; the water distribution pipe is fixed to a bottom of the membrane aeration bioreactor through a water pipe bracket, and a water outlet of the water distribution pipe is arranged directly below the flow stopper.
14 . The method according to claim 13 , wherein the water distribution pipe defines a plurality of water outlets, the membrane aeration bioreactor comprises a plurality of membrane assemblies and each water outlet corresponds to a corresponding membrane assembly; each water outlet is connected to a water outlet valve.
15 . The method according to claim 6 , wherein the air collection pipe is connected to the ecological purification pond for aeration.

Description

CROSS REFERENCE The present disclosure claims priority of Chinese Patent Application No. 202211366315.9, filed on Oct. 31, 2022, the entire contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD The present disclosure relates to the field of rare earth mine tailwater purification technology, and in particular to a MABR-based method for treating rare earth mine tailwater. BACKGROUND Rare earth resources are one of the important mineral resources in China. Due to the natural advantages of China's rare earth resources and the advanced rare earth key separation technology, China has become the world's leading rare earth producer. With the continuous development of new material industries such as rare earth permanent magnet materials and rare earth hydrogen storage materials in recent years, the demand for rare earths in China's market is also increasing, and the production of rare earths in China is also increasing year by year. However, the process of mining and smelting of rare earth mines may be a big ecological problem. Taking ion adsorption rare earth ore in the south of China as an example, the main mining process is usually soaking the soil with ammonium sulfate, replacing rare earth elements in the ionic state into solution, and then precipitation with oxalic acid or ammonium carbon to obtain rare earth concentrate of more than 92% grade; this mining in the specific operation is divided into heap leaching, pool leaching and, in situ leaching, of which, the first two methods have been banned, while in the process of the in situ leaching, a considerable amount of rare earth mine tailwater will be formed. The tailwater has the characteristics of high ammonia nitrogen, low COD, high salinity, high turbidity, and large changes in water quality and quantity, etc., which will have a great impact on the water cycle of the natural environment if not treated properly. The traditional treatment method of rare earth mine tailing water is to treat the tailwater by percolation through ecological ditch. However, the characteristics of rare earth mine tailwater such as high acidity (pH 3-5), high nitrogen content (50-300 mg/L), and low carbon content (CODCr≤20 mg/L) seriously affect the treatment effect of the ecological ditch. Therefore, the industry developed biochemical treatment method, of which the main principle is through nitrification and denitrification, short-course nitrification denitrification or anaerobic ammonia oxidation. The process parameters of short-course nitrification denitrification are strictly controlled, and anaerobic ammonia oxidation has high requirements for water temperature and more stringent control for process parameters; therefore, the above two are difficult to be practically applied in the treatment of rare earth tailwater from surface source pollution. Nitrification and denitrification are the main biochemical treatment processes for rare earth tailwater. For example, nitrification and denitrification biochemical process of activated sludge method and nitrification and denitrification process of contact oxidation method are applied in actual rare earth mine tailwater treatment projects. Nitrification is to transform ammonia nitrogen into nitrate nitrogen by nitrifying bacteria, and the main biochemical reaction conditions are water temperature, dissolved oxygen, and alkalinity. Denitrification is to transform nitrate nitrogen into nitrogen gas by denitrifying bacteria, and the main biochemical reaction conditions are water temperature and carbon source. These processes may use activated sludge (SBR), membrane bioreactor (MBR), and aeration biofilter (BAF), which have high requirements for operating temperature, carbon source demand, and oxygen supply, etc. Carbon source supply and oxygen supply require huge energy consumption, and the disadvantage of high energy consumption limits the use of these processes on a large scale. Therefore, there is an urgent need to develop a method that consumes less energy and at the same time can efficiently treat the rare earth mine tailwater. SUMMARY OF THE DISCLOSURE The main purpose of the present disclosure is to propose a rare earth mine tailwater ecological treatment method, which aims to solve the technical problems of traditional rare earth mine tailwater treatment methods, such as high energy consumption, high operating costs, and low treatment efficiency. To achieve the above purpose, a technical solution adopted by the present disclosure is to provide a membrane aeration bioreactor (MABR)-based method for treating rare earth mine tailwater, comprising: S1: introducing rare earth mine tailwater into a sedimentation pond and simultaneously injecting pig farm breeding tailwater into the sedimentation pond, wherein a volume ratio of the rare earth mine tailwater to the pig farm breeding tailwater is 5 to 30:1; and fully mixing the rare earth mine tailwater to the pig farm breeding tailwater in the sedimentati