The disposal of high-salt wastewater is a worldwide problem. China produces more than 300 million cubic meters of such wastewater every year. According to the statistics of 2018, the amount of waste salt in China exceeds 20 million tons per year, accounting for about 15% of the hazardous wastes. China's legislation in the field of hazardous waste has not exceeded 10 years, and has been tightening in the last five years. In recent years, the judicial interpretation of the two high commissioners and the publication of the new environmental protection law have become an important catalyst for the accelerated development of the industry. At the same time, with the intensification of environmental protection, Shandong, Hebei and other provinces have promulgated strict wastewater salt limitation discharge standards and zero discharge byproduct salt provisional provisions for dangerous waste. The treatment and recycling of concentrated brine has also become a hot topic. With the increasing demand for environmental protection and the increasingly stringent management of hazardous wastes, the reduction, harmlessness and resource utilization of waste salt and concentrated brine are important problems to be solved in chemical production process.
At present, membrane technology is widely used in the fields of fine separation of pharmaceutical and food, process reengineering of chemical industry, environmental protection water treatment, industrial gas purification and so on. In the resourcefulness of waste salt and concentrated brine, nanofiltration membranes are mainly used to purify monovalent ions and polyvalent ions with different interception efficiency. The characteristics of nanofiltration membrane with small molecular weight interception are used to reduce organic matter, and bipolar membrane electrodialysis is used to produce acid and base. Membrane technology plays an important role in most production and life in the 21st century. It is a key common supporting technology for energy saving, emission reduction and green manufacturing. At present, the harmless, reduction and resource utilization of waste salt are mainly realized through the coupling of incineration technology, membrane technology, advanced oxidation technology and crystallization technology. That is organic matter reduction, salt purification and concentration and ultimately resource utilization.
Jiangsu Jiuwu Hi-tech Co., LTD started from the aspects of process optimization and the development of integrated membrane equipment, formed a variety of products, such as integrated technology of mixed salt and salt membrane, waste salt reduction technology and waste salt resource utilization technology. It solves the dilemma that waste salt can not be used. At the same time, in view of the stricter environmental protection management and the growing demand of the people for "blue sky and clean water", Jiuwu Hi-Tech successfully established its application in the utilization of waste salt resources, and realized the application and popularization of membrane integration technology in several enterprises in Lianyungang, Jiangsu and Nantong, Jiangsu, respectively.
On the one hand, the application of membrane integration technology in the resource treatment of waste salt and concentrated brine can solve the dilemma of land occupied by waste salt accumulation for a long time, eliminate the threat of waste salt accumulation to the environment, and realize green production in petrochemical industry. On the other hand, realizing the recycling of waste can produce acid and alkali by-products, turn waste into treasure and realize circular economy.
In recent years, the downward pressure of domestic economy has increased and the growth rate has slowed down, while the production of waste salt has increased year by year. With the tightening of policies and regulations, the low-cost and high-pollution development model of chemical enterprises has come to an end. "Membrane integration" technology of harmless, reducing and resource utilization of waste salt will become the inevitable choice for upgrading the waste salt industry and the key to the core competitiveness of chemical enterprises. It will be applied in the treatment and disposal of waste salt in an all-round way.