CN-121974441-A - Pervaporation-membrane distillation coupling separation method for recycling deep water of urine

Abstract

A pervaporation-membrane distillation coupling separation method for recycling deep water of urine belongs to the technical field of water treatment. The method comprises the steps of immersing a microporous hydrophobic membrane in a strong alkali solution, treating the solution for 4-6 hours at 60-80 ℃, preparing a gel precursor solution by using a gel monomer and a cross-linking agent, coating the gel precursor solution on one side surface of the hydrophobic microporous membrane, stabilizing human urine, placing a coupling separation membrane with a pervaporation functional layer and a hydrophobic substrate in a membrane pool with an effective working area of 10 cm 2 , respectively circulating urine and pure water on two sides of the separation membrane, heating one side of a urine feed liquid to 60 ℃ by using a water bath pot, using 300-500 milliliters of pure water as condensate, and after the urine is treated to about 90% of water is recovered, replacing the feed liquid with the pure water to flush the separation membrane. The invention solves the problems of low water recovery rate and reuse water quality of the traditional distillation membrane in the urine treatment process, greatly improves the reuse rate of urine water, prevents the separation membrane from wetting, and greatly reduces the conductivity of effluent.

Inventors

• WANG WEI
• CHENG JIAWEI
• WANG PEIZHI
• LUO XUEQING
• YAO JINXIN

Assignees

• 哈尔滨工业大学

Dates

Publication Date

20260505

Application Date

20260319

Claims (4)

1. 1. A pervaporation-membrane distillation coupling separation method for recycling deep water of urine is characterized in that the method comprises the following steps: immersing a microporous hydrophobic membrane in a strong alkali solution with the concentration of 4-10M, and treating for 4-6 hours at the temperature of 60-80 ℃; preparing a gel precursor solution by mixing a gel monomer and a cross-linking agent, coating the gel precursor solution on one side surface of a hydrophobic microporous membrane, and controlling the quantity of the gel precursor solution to enable the thickness of a surface pervaporation functional layer to be 1-2 mu m; Step three, stabilizing the urine of the human to be treated, wherein sulfuric acid is selected as a stabilizer; Step four, treating urine by using a cross-flow liquid inlet device, and placing the coupling separation membrane with the pervaporation function layer and the hydrophobic substrate prepared in the step two in a membrane pool with an effective working area of 10 cm 2 , wherein urine (feed liquid) and pure water (condensate) are respectively circulated at two sides of the separation membrane, one side of the urine feed liquid is heated to 60 ℃ by using a water bath pot, and the temperature of the urine feed liquid is controlled to 20 ℃ by using 300-500 milliliters of pure water as condensate and using a condenser; And fifthly, after the urine is treated to about 90% of water is recovered, the feed liquid is replaced by pure water to flush the separation membrane, and after flushing, the new acid-stable urine feed liquid can be replaced for recycling treatment.
2. 2. The pervaporation-membrane distillation coupling separation method for recycling deep water of urine according to claim 1, wherein in the first step, the microporous hydrophobic membrane is made of PVDF or PTFE material, the pore diameter is 0.22-0.45 microns, and the thickness is 50-150 microns.
3. 3. The pervaporation-membrane distillation coupling separation method for recycling deep water of urine according to claim 1, wherein in the second step, the gel monomer is one or more of polyvinyl alcohol, acrylic acid, acrylamide, chitosan and cellulose, the cross-linking agent is one or more of glutaraldehyde, N' -methylene bisacrylamide and ethylene glycol dimethacrylate, and the mass ratio of the gel monomer to the cross-linking agent is 5-50:1.
4. 4. The pervaporation-membrane distillation coupling separation method for recycling deep water of urine, which is characterized in that in the third step, inorganic acid is added into urine for acidification a small amount of times while monitoring the pH value of the urine by using a pH meter until the pH value of the urine is adjusted to 2-3.

Description

Pervaporation-membrane distillation coupling separation method for recycling deep water of urine Technical Field The invention belongs to the technical field of water treatment, and particularly relates to a pervaporation-membrane distillation coupling separation method for recycling deep water of urine. Background With the continuous expansion of space exploration activities and the continuous development of the commercial aerospace industry, the sustainable water supply technology for space stations becomes more and more critical. The transport of water from earth by spacecraft is not only costly, but also limits the radius of space exploration. Since human urine is about 95% water, urine handling and recovery is the optimal strategy for space station water replenishment. An ideal urine treatment system would minimize the equipment volume while maximizing water recovery and contaminant removal. Unfortunately, complex endogenous substances in urine (such as salts, organics, and ammonia) can pose serious risk of fouling and leakage to the treatment device, thereby compromising the stability and recovery efficiency of urine treatment. For example, urine disposal devices (UPA) of the International Space Station (ISS) face problems of low recovery and poor distilled water quality. Existing urine treatment technologies, including Forward Osmosis (FO) and Reverse Osmosis (RO), suffer from multiple limitations (such as significant salinity dependence, low micropollutant rejection and severe membrane fouling), which limit their use in space stations. Membrane Distillation (MD) is a thermal membrane coupling technique that utilizes a hydrophobic membrane as the separation medium to achieve near complete entrapment of non-volatile materials. The technology is particularly suitable for urine treatment in a narrow space station environment due to the characteristics of small occupied area, insensitivity to salinity and capability of utilizing low-grade heat sources (such as solar energy and waste heat). In recent years, the international space station has developed an MD-based saline solution treatment device to compensate for the problem of insufficient treatment capacity of a urine treatment device (UPA). However, organic/inorganic components in urine can cause complex synergistic fouling on MD membranes, leading to membrane wetting and process failure. In addition, conventional distillation membranes have limited volatile component entrapment. Particularly, urea in urine is hydrolyzed under the catalysis of urease, and a large amount of ammonia gas is released to diffuse through a hydrophobic membrane, so that water pollution is caused. Therefore, the existing membrane distillation urine treatment technology is difficult to meet the stable water supply requirement of a space station. Disclosure of Invention The invention aims to solve the problems of pollution and failure of a distillation membrane in urine treatment, low ammonia nitrogen interception, low volatile organic matter interception and the like, and provides a pervaporation-membrane distillation coupling separation method for recycling deep water of urine. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: a pervaporation-membrane distillation coupling separation method for recycling deep water of urine comprises the following steps: immersing the microporous hydrophobic membrane in a strong alkali solution with the concentration of 4-10M, treating for 4-6 hours at the temperature of 60-80 ℃, and enabling hydroxyl groups to grow on the surface of the microporous hydrophobic membrane so as to enhance the surface hydrophilicity. Fixing the microporous hydrophobic membrane subjected to alkali treatment in a plate frame to ensure that only one surface of the microporous hydrophobic membrane is covered with the pervaporation functional layer (polyvinyl alcohol, chitosan or polyimide and the like), wherein the pervaporation functional layer is a compact hydrophilic gel layer, preparing gel precursor solution by mixing gel monomers and cross-linking agents, coating the gel precursor solution on the surface of the hydrophobic microporous membrane in the plate frame, and controlling the quantity of the gel precursor solution to ensure that the thickness of the surface pervaporation functional layer is 1-2 mu m; Step three, stabilizing the urine of the human to be treated, wherein sulfuric acid is selected as a stabilizer; And fourthly, treating urine by using a cross-flow liquid inlet device, placing the coupling separation membrane with the pervaporation function layer and the hydrophobic substrate prepared in the second step in a membrane pool with an effective working area of 10 cm 2, respectively circulating urine (feed liquid) and pure water (condensate) by using gear pumps at two sides of the separation membrane, heating one side of the urine feed liquid to 60 ℃ by using a water bath pot, controlling the temp