Zero discharge of wastewater generally refers to the recovery and reuse of industrial wastewater after treatment, and finally there is no discharge of waste liquid. On the one hand, the utilization rate of resources is higher, on the other hand, the environmental pollution is reduced. In some industrial fields, large water consumption is an established fact. Therefore, promoting zero discharge of wastewater has naturally become an important environmental protection direction in these fields.

Several national policies have also made it clear to accelerate the comprehensive utilization of industrial resources and promote the recycling of industrial wastewater. The policy is clear that the repetition rate of industrial water above Designated Size in iron and steel, petrochemical and chemical industries, nonferrous metals and other industries should reach 94% or more. A new pattern of efficient recycling of wastewater from major water consuming industries will be basically formed in 2025.

The operation of the iron and steel industry is inseparable from the large consumption of water resources, and the volume of wastewater discharge is also large. The combination of zero wastewater discharge and the iron and steel industry is the inevitable trend of green development. It should be recognized that the zero discharge of wastewater and the iron and steel industry are now in the "running in period", and pay more attention to step by step. It's the same reason why you can't eat hot tofu in a hurry.

Some experts who have been deeply engaged in the field of wastewater recycling in the iron and steel industry for many years pointed out that at this stage, the iron and steel industry should focus on the treatment of concentrated brine at the end of the whole plant level water cycle, should not excessively pursue "zero discharge of wastewater", and should act according to its ability, depending on the situation.

In the gap between ideal and reality, zero discharge of wastewater can really achieve the perfect combination of pollution reduction and higher resource utilization. The difficulty exists and still needs to pass the test of time. At present, wastewater may become a resource product for secondary utilization after advanced treatment, but it may also produce a series of practical problems, such as unable to absorb some concentrated brine, high operation cost and difficult system maintenance.

At the end of December 2021, the implementation plan for industrial wastewater recycling issued by six departments proposed that by 2025, the reuse rate of industrial water in the iron and steel industry should be higher than 97%. Indeed, the policy has high requirements for the utilization rate of water resources in the iron and steel industry. However, it should also be noted that there are still many feasible schemes for the green transformation of the iron and steel industry, which can be connected to the track of zero discharge of wastewater.

Some insiders believe that the iron and steel industry should gradually develop from internal water circulation to regional water circulation system. Let the water of different units such as enterprises and communities circulate, open up the closed-loop recycling of water resources utilization, implement a wider range of water resources recycling, and help the iron and steel industry improve the utilization rate of water resources, so as to form a new pattern of water resources recycling in the industry.

The composition of wastewater from iron and steel industry is complex, which may cause various environmental pollution problems. Therefore, at present, it is necessary to distinguish the primary and secondary problems in the industrial wastewater, break them one by one, and gradually approach the road of zero discharge of wastewater.

However, it is certain that with the promotion of wastewater zero discharge technology, the discharge of water pollutants will continue to approach "zero", and there is still a long way to go to finally realize wastewater zero discharge.