Efficient recycling of industrial wastewater has achieved remarkable results

Make positive progress --

The water consumption per 10,000 yuan of industrial added value in 2020 will be 39.6% lower than that in 2015

Where does industrial wastewater come from?

"Petrochemical, iron and steel, food, textile printing and dyeing, paper and other industries in the production process will produce industrial wastewater, accompanied by the loss of industrial production materials, intermediate products and pollutants." Ministry of Industry and Information Technology electronics five senior engineer Yang Benxiao introduced.

With the rapid development of industry, the types of industrial products are more diverse, and the composition of industrial wastewater is more complex. In addition to nitrogen, phosphorus, suspended matter, there are toxic and harmful substances such as heavy metals and oil pollution that are difficult to deal with. Yang Benxiao said: "Industrial waste water recycling means that the waste water generated by industry or cities is treated to meet the utilization standard, and then used in industrial production."

After years of efforts, China's industrial wastewater recycling has made positive progress on the whole, and industrial water-saving results are remarkable.

From the perspective of emission level, since the "Twelfth Five-Year Plan", China's industrial wastewater discharge has decreased from 2.37 million tons in 2010 to 1.34 million tons in 2019, a decrease of about 44%.

From the perspective of utilization efficiency, the reuse rate of industrial water above designated size increased from 89% in 2015 to 92.9% in 2021, and the water consumption of 10,000 yuan of industrial added value in 2020 decreased by 39.6% compared with 2015.

From the perspective of key industries, the reuse rate of industrial water above the scale of steel and petrochemical reached 97% and 95.2%. During the "13th Five-Year Plan" period, key large and medium-sized enterprises in the steel industry have reduced wastewater emissions by about 300 million cubic meters and saved about 2.1 billion cubic meters of new water.

"China's per capita water resources are relatively poor, but industrial production needs to consume a lot of water resources, water resources and industrial water consumption do not match." Yao Hong, professor of the Department of Municipal and Environmental Engineering, School of Civil Engineering, Beijing Jiaotong University, believes that the classification of industrial wastewater, recycling of useful substances, and recycling of industrial wastewater within or between enterprises are of great significance to alleviate China's water shortage, reduce the cost of water production for enterprises, and promote the realization of carbon peak carbon neutrality.

Form effective patterns --

Make up for technical shortcomings, improve the level of intelligence, and explore the integration of industry and city

Industrial wastewater treatment and recycling is the main way of recycling industrial wastewater at present. Focusing on the blocked points and difficulties in the whole process of recycling, through strengthening collaborative research, innovative and efficient recycling equipment technology and technology has become an effective practice plan.

In Zibo, Shandong Province, for the loom wastewater generated in the production process of water-jet loom, a company and universities cooperated to develop wastewater treatment and recycling technology, which not only realized the optimization and integration of industrial wastewater and domestic wastewater recycling, but also degraded the biochemical properties of wastewater and effectively and accurately controlled pollution. After the implementation of the project, the industrial water reuse rate of the enterprise increased by 6%, and the annual water saving cost was 2 million yuan.

To overcome technical priorities, we must also overcome management difficulties. Many enterprises actively use the new generation of information technology such as big data and cloud computing to improve the digital management and network collaboration level of wastewater recycling, so that intelligent management and control has become a powerful fulcrum to accelerate the recycling of industrial wastewater.

In Luzhou, Sichuan province, a chemical enterprise has basically realized automatic program control by installing monitoring systems for the production links of reclaimed water reuse, sewage treatment and circulating water. Whether the industrial wastewater is discharged according to the standard and whether the production equipment is operated safely can be seen at a glance on the large screen of the total dispatching room, which can not only timely warn the hidden dangers of the equipment, but also real-time monitor the recycling of industrial wastewater.

Explore the integration of industry and city, and expand the recycling space. "After urban sewage treatment, it can be used as circulating cooling water replenishment for enterprises, or treated as primary dehydrated water after reverse osmosis process, which can effectively reduce the amount of new water withdrawal and improve the reuse rate of water in a wider range." Yang Benxiao said.

In Tianjin, a steel company has completely replaced the conventional water resources of the enterprise by collecting and treating the municipal sewage of the local town and fully absorbing the water from the sewage treatment plant of the neighboring town, achieving zero discharge of wastewater and zero exploitation of groundwater. Some industrial parks in Beijing have also accelerated the pace of urban sewage utilization, and the high-quality recycled water produced after treatment is used as production water for enterprises in the park.

"In 2020, the national urban recycled water utilization rate is about 24%, from the utilization point of view, China's urban sewage treatment reuse amount is not high, the proportion of industrial space is still large." Yang Benxiao believes that increasing the use of urban recycled water will be the key direction of waste water recycling in industrial enterprises and parks.

Better excavation space --

Strengthen technological innovation and activate the impetus of enterprises

China has a complete range of industrial categories and many enterprises, but the scale, facilities and technical reserves are uneven, and the reuse rate of industrial water above the scale is still a gap compared with the international advanced level. What should we do to further explore the potential recycling space of industrial wastewater?

Technological innovation is the foundation. "Improving the reuse rate of industrial water depends on key core technologies." Liu Guohua, deputy dean of the School of Environment at Renmin University of China, said that the existing level of industrial wastewater treatment technology needs to be improved, and there is still room for improvement in industrialization and market recognition of localization technology. It is necessary to strengthen the research of advanced technology and equipment by strengthening the deployment of major special projects, so that the wastewater can meet the standards after treatment and truly be used for enterprise production.

According to the "Industrial Wastewater recycling Implementation Plan", through the national science and technology innovation plan and other funding channels, support the research and development of efficient and low-cost treatment and reuse technology and equipment of industrial wastewater in different industries, and actively promote the demonstration and promotion of application in relevant industries.

Activating motivation is key. "The current recycling technology of industrial wastewater is mostly based on the ability to change water, and the energy consumption and material consumption are generally high." Yang Benxiao introduced, for example, in northern water shortage areas such as Inner Mongolia and Ningxia, the implementation of enterprise wastewater zero discharge, the cost of enterprises using recycled water reached 6-10 yuan/ton, and the cost of high-salt wastewater treatment and reuse reached 30-60 yuan/ton, which is much higher than the average price of 3.1 yuan/ton of new water purchase, and it is necessary to increase tax incentives and other measures. Continuously enhance the power of enterprises to carry out waste water recycling.

In the next step, enterprises in typical industries that actively implement the recycling and transformation of industrial wastewater will be inclined in terms of tax policies and financial support, so as to encourage and guide enterprises in typical industries to take the initiative to implement water-saving transformation and wastewater recycling.