Water shortage, water hunger and water pollution are events that puzzle modern people and are related to the survival of human beings, creatures and the earth. Water treatment, water purification, seawater desalination and seawater desalination have become inevitable and necessary.

There are many water treatment methods. Traditional methods and technologies increase secondary and tertiary pollution, increase energy consumption and aggravate the greenhouse effect. Innovative methods of energy saving and environmental protection are constantly being pursued. New methods, new ideas and new creations often appear.

Because social production and life are closely related to water, and water hunger, water shortage, water drought and water pollution are intertwined, it has a wide range of applications in the field of water treatment, which constitutes a huge industrial application.

Water treatment usually includes sewage treatment and drinking water treatment. Commonly used water treatment agents are: polyaluminum chloride, polyaluminum ferric chloride, basic aluminum chloride, polyacrylamide, activated carbon and various filter materials. Drinking water includes seawater desalination, seawater desalination and purification.

Simply put, "water treatment" is the process of removing some substances that are not needed for production and life in water by physical and chemical means. It is a process of water quality regulation such as sedimentation, filtration, coagulation, flocculation, corrosion inhibition and scale inhibition for a specific purpose.

The effect of water treatment can be measured by water quality standards. It is the new hope and future of new energy-saving and environmental protection water treatment to constantly try positive infiltration.

Forward osmosis-a new method of water purification and desalination

In the fields of seawater desalination, seawater desalination and water treatment, the word "osmosis" is long and complicated, also known as forward osmosis or forward osmosis, to express the differences, differences or corresponding relationships among reverse osmosis, reverse osmosis and reverse osmosis, and to emphasize that forward osmosis is a pair of methods that are opposite to reverse osmosis. As a potential new technology of water purification and seawater desalination, forward osmosis is being studied theoretically and practically from many angles in the world. Foreign 1976 has an original attempt of liquid-liquid system, and domestic 1992 invented the forward osmosis (pressureless) adsorption osmotic desalination of liquid-solid system (cn92110710.2). It was not until about 10 years later that we followed the international trend again and started the standard imitation and replication mode. In 2008, there was a summary report. Main application fields:

1. Living facilities: various hot water boilers, central air conditioners, heat exchange systems, household central air conditioners, wall-hung boilers, etc.

2. General industrial equipment: air compressor, refrigerator, heat exchanger, cooler, etc.

3. Special industry application: anti-scaling, descaling, magnetization, sterilization and algae removal of water equipment in food, pharmaceutical, alcohol and other industries, and the establishment of an environment-friendly hydropower building system. With the rapid development of science and technology, pressure-driven reverse osmosis membrane separation technology (RO) has made great innovations and improvements in membrane, membrane module, equipment and technology, but people are more and more aware of the limitations of RO technology in the field of energy conservation and environmental protection. As far as seawater desalination is concerned, RO technology can be considered to be close to the peak of development. Therefore, at present, foreign countries have carried out relevant research on "Forward Osmosis Membrane Separation Technology (FO)" and achieved certain results, and it has been applied in seawater desalination, sewage treatment, food processing, medicine and other fields, especially "Pressure Delayed Osmosis (FRO) seawater power generation", which is a promising clean and renewable energy development technology J. However, at present, there is little attention to FO in China, and there are no related researches and papers. Although, in the 1990s, China had a creative invention "seawater desalination by pressureless adsorption and infiltration" (CN92110710.2).

Forward osmosis separation technology has been applied for a long time. A long time ago, people used salt to store food for a long time, because in a high-salt environment, most bacteria, molds and pathogenic bacteria would be dehydrated to death or temporarily lose their activity. Nowadays, people have begun to use forward osmosis membrane separation technology to study seawater desalination, industrial wastewater treatment, landfill leachate treatment and so on. The food industry uses forward osmosis membrane separation to concentrate beverages in the laboratory; The life support system in emergency rescue uses forward osmosis membrane separation technology to produce fresh water. With the development of materials science, forward osmosis technology has been applied to the controlled release of drugs in human body.

Non-pressurized osmotic adsorption method (1990s)

Non-pressurized adsorption infiltration seawater desalination method, or "forward osmosis method", is to let water penetrate into a solution or solid with super absorbent or salt concentration even exceeding seawater through a porous membrane without external pressure, but the special salt extract in the solution is easy to evaporate without increasing too much heat (the energy ratio of thermal energy to reverse osmosis pressurization? )。 Divided into two directions: solid salt and liquid salt. Desorption of solid salt consumes less energy.

Seawater desalination technology: pressureless adsorption and infiltration seawater desalination method (CN 92110710.2)1992: invented by Deng Yu in 1990s and included in American Chemical Abstracts.

The other two methods are innovative and improved in membrane structure.

Carbon nanotube film

Protein membrane of living cells with pores is made of carbon nanotubes, and the pores of the membrane are made of protein, which is used to guide water molecules through the cell membrane of living cells.