Design of Sewage Treatment Device Based on Cell Membrane Principle

Yudie CAO Di WANG Yilong HOU

Abstract   Based on the principle of selective permeability of cell membrane， a new urban sewage treatment device and urban sewage recycling system are designed. The new urban sewage treatment device consists of 10 parts， namely： inlet pipe， secondary filter screen， tertiary rectifier， gravity separation chamber， floating material collection chamber， sewage shunt pipes， cell membrane filtration chamber， cell membrane purification device， sediment collection chamber and purified water collection chamber. The urban sewage recycling system consists of 6 parts， namely： urban sewage collection device， filtration and sedimentation separation device， floating matter collection device， cell membrane sewage purification device， sediment collection device and urban water pool.

Key words   Cell membrane; Sewage treatment; Low energy consumption

Urban sewage is all the drainage collected through sewers， and it is the mixed water of various domestic sewage， industrial wastewater and urban rainfall runoff discharged into the sewer system  [1] . Domestic sewage is the water discharged from people’s daily life. Industrial wastewater is the wastewater discharged from the production process. Rainfall runoff is formed by precipitation or melting of snow and ice. The main methods of sewage treatment include physical， chemical， physical-chemical and biological methods. The current urban sewage treatment in China is mainly based on biological methods  [2] . Biological methods mainly include the bioremediation technology， the microbial adsorption technology， the microbial flocculation technology， the immobilized microbial technology， the biofilm （membrane bioreactor） treatment technology， and the biological enhanced treatment technology  [3] .

In this paper， a new type of urban sewage purification device was designed， which purifies sewage based on the principle of selective permeability of cell membrane. This method can be called "cell membrane water purification method". It has the characteristics of environmental friendliness， low energy consumption and strong adaptability. Once it is applied in the future， it will bring revolutionary changes to sewage treatment.

Principle of Cell Membrane Water Purification

The urban sewage recycling system is mainly based on the principle of selective permeability of cell membranes  [4] ， that is， the urban sewage is purified under the action of selective permeability of cell membranes. Water molecules can pass through the cell membranes， but other urban sewage pollutants cannot pass through， and the substances that cannot pass through the cell membranes are transported to corresponding processing departments through the collection process for further processing.

Composition of Urban Sewage Recycling System

It mainly includes 6 parts （Fig. 1）. ① Urban sewage collection device： It is used to collect urban sewage mixed with a large number of easily decomposable organic matter， refractory organic matter and domestic garbage generated in daily life. ② Filtration and sedimentation separation device： It realizes the preliminary separation of large-volume pollutants， easy-to-float pollutants and easy-to-precipitate pollutants in urban sewage. ③ Floating matter collection device： It collects and treats the initially separated floating pollutants， and play a storage role for the next treatment. ④ Cell membrane sewage purification device： It realizes the purification and treatment of urban sewage and is a key component of the entire urban water circulation system. ⑤ Sediment collection device： It collects and stores the preliminarily separated easy-to-precipitate pollutants and the pollutants left by the purification treatment by the cell membrane purification device. ⑥ Urban water pool： The urban sewage is purified and treated to meet the national water standard for urban residents and then enters the urban water pool for daily use by urban residents.

Structure of Cell Membrane Sewage Purification Device

The cell membrane sewage purification device is the core device of the entire urban water circulation system. We designed the structure of the sewage purification device， and the design structure is shown in Fig. 2. The overall size of the purification device is 50 cm×50 cm×50 cm， and the device includes 10 structures. ① Inlet pipe： The urban sewage enters from here. ②Secondary filter screen： It performs preliminary separation of large-volume pollutants in urban sewage.  ③ Ternary rectifier： It rectifies and smooths the high-pressure sewage from the inlet pipe， which is the premise of subsequent sewage purification treatment. ④ Gravity separation chamber： The pollutants that are easy to float and settle are separated from water under the action of gravity.  ⑤ Floating material collection chamber： It collects and treats the pollutants floating on the water surface under the action of buoyancy. ⑥ Sewage shunt pipes： First， the sewage from the gravity separation chamber is transported to the cell membrane purification chamber. Secondly， the sewage is divided and slow-flow treatment is carried out to prevent the excessive and rapid water flow from damaging to the cell membrane purification device. ⑦ Cell membrane filter chamber： Sewage enters the filter chamber through a shunt pipe to prepare for the cell membrane purification process. ⑧ Cell membrane purification device： The selective permeability of the cell membranes is used to treat the sewage. The purified water can enter the purified water collection chamber through the cell membranes， and other sundries stay on the surface of the cell membrane purification device. ⑨ Sediment collection chamber： It collects the waste generated after cell membrane purification. ⑩ Purified water collection chamber： It is used to collect purified water resources and provide a testing platform for quality inspectors to test the quality of purified water.

Process Flow of Urban Sewage Recycling System

According to the design of the urban sewage recycling system， the sewage enters the sewage purification device after being collected in the urban sewage collection tank. In the sewage purification device， it first enters the secondary filter chamber， and is treated by filtering large-volume pollutants. Then， it enters the gravity separation chamber， and the floating material separated by the sewage is collected into the floating material collection chamber under the action of gravity. The separated sewage is relaxed into the cell membrane filtration chamber through the shunt pipes. Under the action of the selective permeability of the cell membranes， the final purification treatment of the sewage is carried out. The sewage enters the clean water collection chamber through the cell membrane purification device， and the inspectors determine whether to flow into the urban reservoir by testing the water quality. The pollutants generated by the cell membrane purification device are collected into the sediment collection chamber， and the material in the collection chamber will be sent to corresponding processing device for further processing. The system is shown in Fig. 2.

Conclusions

The sewage treatment device is designed based on the selective permeability of cell membrane. This new method has the characteristics of environmental friendliness， low energy consumption， strong adaptability and good treatment effect. In this paper， a new type of urban sewage treatment device and urban sewage recycling system are designed. Once the application is realized in the future， it will bring revolutionary changes to sewage treatment.

References

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[4] SANTANA HEUNG JIN ALVES， CASELI LUCIANO. A bactericide peptide changing the static and dilatational surface elasticity properties of zwitterionic lipids at the air-water interface： Relationship with the thermodynamic， structural and morphological properties[J]. Biophysical Chemistry. 2021： 277.

 Editor： Yingzhi GUANG   Proofreader： Xinxiu ZHU