Research Progress of Reclaimed Water Reuse Technology in Water Supply Plant

Absrtact: Water supply plants can meet the needs of production and domestic water use. In order to improve the utilization rate, it is necessary to study the technology of reclaimed water reuse. Wastewater will be produced in the process, and direct discharge will cause environmental pollution, so scientific treatment is needed. The article discusses from different aspects and introduces several advanced technologies, which are of great significance for reclaimed water reuse.

Introduction：

With the development of society, the shortage of water resources has become an issue of concern to people. We should adhere to the concept of sustainable development. For water supply plants, attention should be paid to the reuse of reclaimed water, and technology should be introduced to optimize the allocation of resources. Combining with the actual situation, we formulate a set of perfect strategies to implement the specific effects and provide people with clean water.

I. Reclaimed water reuse

The concept of reclaimed water originated in Japan. It refers to the use of domestic and industrial water after advanced technology treatment for agricultural irrigation, municipal landscaping, vehicle washing and other aspects which do not require high water quality. The simplest understanding is that it is between tap water and sewage, which greatly improves the utilization rate of water resources, promotes the construction of ecologically civilized cities, and realizes the harmonious coexistence between man and nature. In the rapid development of modern society, the demand for water resources continues to increase. In order to better meet the demand, we should realize the importance of reclaimed water reuse and focus on the perspective of long-term development. Actively learning advanced concepts and introducing them into the production system of waterworks can optimize the supply and demand structure and play a greater role. Reclaimed water reuse technology has been under study, and continuous innovation is needed to meet the actual situation and improve the effect. At the same time, it is necessary to carefully analyze the characteristics of water supply plants and reflect the pertinence in their application so as to realize the purpose of reclaimed water reuse in a real sense and alleviate the resource shortage.

II. Reclaimed Water Reuse Technology in Water Supply Plant

(1) Technology of direct reuse of wastewater from production

Foreign scholars have made in-depth research on this technology and achieved remarkable results, which has a correct guiding role for the development of practical work. Experiments on backwashing wastewater show that particulate matter can increase the precipitation of dissolved organic matter in raw water and reduce the content of other substances. Wastewater from waterworks is harmful to some extent. The main reason is that there are harmful substances in the water. Direct discharge will cause soil pollution, plant death and so on. Therefore, effective treatment should be carried out. Western developed countries have clearly stipulated that backwash wastewater can be reused only through membrane filtration. There are some shortcomings in the research of wastewater reuse technology in our country. We pay attention to simple technology and economic benefits. Although good results can be achieved in a short time, this method is not advisable in the long run. In order to be better applied in the reuse of wastewater, it is necessary to strengthen the research and realize the optimization and upgrading of technology.

(2) Wastewater treatment and reuse technology

Sedimentation technology is the most widely used backwashing wastewater treatment technology. The technology has been very mature. Usually, it is combined with coagulation pretreatment to ensure that the water quality meets the prescribed requirements and can be effectively utilized. The main advantages of sedimentation technology are: the overall cost is relatively low, but due to the imperfect infrastructure, it is difficult to achieve the desired results. Simple technology can not meet the treatment requirements, so it is necessary to increase sand filtration technology to improve the level and reduce harmful substances in water quality. Because of the great change of water quality, it is difficult to accurately control the amount of coagulant input, which is the main reason for the poor precipitation effect. In addition, sedimentation technology can increase the number of microorganisms in wastewater, which has a negative impact on direct application. This shows that the technology still has shortcomings and needs continuous improvement in order to achieve better results. Summarizing the experience from the problems, as the guidance of technical research, is of great help to enhance the reuse of reclaimed water.

Micro-sand assisted precipitation process improves the clarification effect by adding micro-sand and a coagulant to meet the requirements of water quality. The most remarkable advantage is its strong applicability, which can be used in low temperature, turbid water, and the actual effect is very good, and will not be affected by water quality conditions. In the treatment process, through comprehensive and in-depth research, it is shown that the use of micro-sand assisted sedimentation process to treat production wastewater can reduce the discharge of sludge water, has broad market prospects, and the application scope will continue to expand in the future. However, technology also has some drawbacks, which are mainly manifested in the complexity of the process, the difficulty of operation and the vulnerability to other factors. Cost is relatively high, many enterprises are in the consideration of economic benefits. Generally, micro-sand assisted precipitation process will not be used, but traditional technology will still be used.

In order to better popularize the application and realize the treatment of industrial wastewater, it is necessary to constantly innovate technology and develop in a more advanced direction.

Air flotation means that suspended matter is attached to bubbles and rises to the water surface under the action of aeration, so as to achieve the separation effect of suspended matter and liquid. What we often say about air flotation is basically pressure dissolved air flotation. For the removal of low-density particles, air flotation is an effective method to remove organic matter, even some harmful substances, and improve the quality of water. The disadvantage of air flotation technology is that there are many parameters in operation, complex equipment, high cost of daily maintenance and difficult operation. Under special circumstances, it will also lead to the increase of pathogenic microorganisms in the effluent of water supply plants, and there are potential safety hazards in its application. In order to improve the application of technology, we should strengthen independent innovation, achieve breakthroughs at the existing level, truly achieve the treatment of industrial wastewater, and improve the efficiency of reclaimed water reuse. The purpose of finding problems is to facilitate improvement, to improve the application effect, and to provide advanced technical support.

(3) Biological Technology

It refers to the artificial microbial environment for sewage treatment. Aerobic treatment technology, including activated sludge method and biofilm method, is mainly used in sewage containing a large number of organic substances. The treatment scale is relatively large and the speed is very fast. It is applied in the terminal treatment of municipal secondary sewage treatment plants and industrial wastewater. Anaerobic treatment decomposes macromolecule organic matter into small molecule organic matter, aerobic treatment decomposes organic matter into water and carbon dioxide. According to the actual effect, it is found that the impurities in sewage can be effectively removed by biological method, which meets the water quality requirements of reclaimed water and is used in other fields, thus greatly improving the utilization rate of water resources. This technology has the advantages of strong operability and obvious treatment effect, and has become the choice of many water supply plants. Of course, technology is in the process of continuous development, so we should look at the problem from the perspective of development, in order to improve the technical level and provide a strong guarantee for water reuse.。

(4) Physicochemical Technology

It refers to the use of physical and chemical functions to purify wastewater. In addition to being used in reclaimed water reuse, it can also play an effective role in wastewater treatment. Flocculation and sedimentation, sand to remove suspended solids and colloids in wastewater, activated carbon mainly adsorbs some pigments, evaporation and concentration to remove a large amount of salt in water, using these methods to treat, can meet the water quality standards. The situation of water supply plants is relatively complex and will be affected by objective conditions. Therefore, in practical application, we should adhere to the principle of adapting measures to local conditions, make appropriate adjustments and changes to technology, and accord with specific conditions, so as to play a greater role. Physicochemical method requires people to master the principle of wastewater treatment and understand the operation process. At the same time, it can make up for the shortcomings of the technology itself and improve the level in the optimization, so the treatment effect will be better. Personnel should innovate technology and combine it with the actual situation organically, constantly strengthen the application level, and promote the development of reclaimed water reuse.

(5) Membrane Separation Technology

MBR membrane bioreactor is used for reclaimed water reuse. Membrane bioreactor is composed of membrane module and bioreactor. It is a combined process of activated sludge and membrane separation in biological treatment technology. Compared with the traditional treatment technology, the advanced technology has the characteristics of small size, modularization, high automation and good water quality. It can be used directly after the treatment is completed. It is very convenient and fast, reduces unnecessary procedures, and realizes the optimization and upgrading of the structure. Because of its remarkable advantages, it has been widely used in reclaimed water reuse treatment in the process of development. In addition to domestic water supply plants, many foreign countries have actively cited it. The treated wastewater can be used as industrial, agricultural and municipal water to reduce unnecessary waste of resources, realize water recycling and reuse, and take the road of sustainable development. In the future, advanced technology will be widely used to optimize the use structure of water resources for the benefit of human development.

Integrated membrane technology is a combination of several membrane separation technologies. It is necessary to adopt a combination method in wastewater treatment, and the effect will be better. Membrane reactor is used to remove a large number of organic substances from wastewater. Reverse osmosis is used to treat the effluent of membrane bioreactor, mainly by virtue of the role of organic substances and salts, to achieve the effect of purification and softening. The effluent quality meets the relevant standards. In addition, UF+RO and MF+RO processes are used in the reclaimed water reuse of municipal secondary sewage treatment plants. Both microfiltration and ultrafiltration are used as pretreatment of reverse osmosis, and reverse osmosis membranes play an important role. Continuous improvement of independent innovation capability, better application of technology in reclaimed water reuse, make contributions to multiple utilization of water resources, change the actual situation of water use.

Conclusion:

In summary, the research progress of reclaimed water reuse technology in water supply plants is of great significance and can play an effective role. Looking at the problem from the perspective of development, constantly introducing advanced technology to promote the development of reclaimed water reuse, so as to optimize the water use structure.