Reuse of reclaimed water, that is, the recycling of sewage. The treated wastewater is reused as renewable resources to increase the reuse and recycling rate of water. After the wastewater is treated by the reclaimed water reuse system, on the one hand, it opens up a second source of water for water supply, which can greatly reduce the consumption of "water" (tap water), thereby reducing enterprise costs; on the other hand, it can solve the problem to a certain extent. "Sewage" (sewage) pollutes water sources, thereby protecting water sources and reducing new water consumption.
At present, environmental pollution has become an important bottleneck restricting industrial development. The characteristics of industrial wastewater are: large amount of wastewater discharge, high salt content, high concentration of organic matter, and difficulty in treatment.
China has a large population and low water consumption per capita. As the quality of water sources deteriorates, the water crisis has become increasingly severe. Therefore, the state issued the National Water Pollution Prevention and Control Action Plan (referred to as the "Water Ten Measures") to encourage advanced treatment and reuse of industrial wastewater to save water.Some local standards are also getting higher and higher. For example, DB37-3416.3-2018 "Comprehensive Discharge Standard for Water Pollution in the Basin-Xiaoqinghe" requires wastewater to be limited to 1600mg/L and COD less than 50mg/L.
For the reuse of reclaimed water, the first consideration is the place where the reuse is used.
The water use occasions of industrial enterprises include: circulating cooling water, boiler water, process water, flushing water, etc.
Municipal water mainly includes: drinking water, green water, landscape water, etc.
These water quality standards generally include two main and comprehensive indicators: turbidity/suspended solids (ss) and salt content (TDS).
Reclaimed water reuse and zero discharge technology has become one of the best ways to deal with this situation, because it not only saves water resources, but more importantly, it can extremely reduce pollution emissions and reduce water costs at the same time.Commonly used reclaimed water reuse and zero liquid discharge processes are integrated with technologies such as pretreatment, double membrane method, electrodialysis, evaporative crystallization/bipolar membrane, etc. The specific processes are shown in Figure 1 and Figure 2:
Fig1. Common reclaimed water reuse and zero liquid discharge process I
Fig2. Common reclaimed water reuse and zero liquid discharge process II
The wastewater is pretreated to reduce suspended solids, organic matter (COD), and hardness to ensure that the suspended solids are almost zero, COD is less than 40mg/L, and the hardness is less than 100mg/L, and then most of the water is reused by double-membrane process combination.
The concentration of double-membrane process is further concentrated by electrodialysis and evaporation crystallization, and finally brine separation is realized; or 2mol / L acid-base is prepared by electrodialysis bipolar membrane to realize resource utilization of wastewater and salt.
Fig 3. The picture of reclaimed water reuse project
Independent research and development
Realize full reuse of wastewater
Practice of a number of 10,000-ton demonstration projects
Realize the reuse of reclaimed water, the separation of salt and dry mud
The produced water quality is good, meeting the requirements of production reuse
In response to the deterioration of water quality and shortage of water resources, in recent years, JIUWU HI-TECH has relied on mature and complete membrane integration technology in papermaking wastewater, metallurgical wastewater, and printing and dyeing wastewater, and pursued the development concept of lucid waters and lush mountains are invaluable assets
and realized wastewater zero liquid discharge.
The zero discharge process of papermaking wastewater of JIUWU HI-TECH is a major technological breakthrough in the field of pulp and paper wastewater treatment in the world, realizing the full reuse of wastewater, and making new contributions to the formation of the pattern of "harmonious development between man and nature". Reuse of reclaimed water is of great significance to promoting the sustainable development of agriculture, industrial production and national economy, and has greatly alleviated the shortage of water resources. Many countries now regard the reuse of reclaimed water as the preferred solution to solve the water shortage problem