In our last article, we gave a general overview of what desalination is and a brief history of the process. In part two of our series on desalination, we will talk about the different desalination process options.
Process of Desalination
There are multiple processes of desalination. Each process has its pros and cons. Whichever process you use, the concept is still the same which is basically boiling saltwater and then condensation of the freshwater vapor. The different processes are as follows:
- Solar Distillation
- Natural Evaporation
- Vacuum Distillation
- Multi-stage Flash Distillation
- Multiple-effect Distillation
- Vapor-compression Distillation
- Reverse Osmosis
- Electrodialysis Membrane
- Membrane Distillation
- Wave-powered Desalination
The process of solar distillation copies the water-cycle found in nature. Solar energy heats the saltwater, which speeds up the evaporation process. A cool chamber captures where the vapor then becomes freshwater.
Natural evaporation is when you heat the saltwater. Then, you transfer it into a greenhouse. The water vapor then condenses and forms rain, where it not only waters the plants in the greenhouse but also filters through the soil. Then, it collects in an artificial aqueduct.
Vacuum distillation is a process where the atmospheric pressure is lowered. Thus reducing the amount of energy and time you need to boil saltwater. This reduces the amount of energy needed to convert the saltwater to freshwater.
Multi-stage distillation is where you evaporate salt water through a series of hot flashes. The energy from each flash powers the next flash in the chain.
Multiple-effect distillation is where you spray saltwater onto heated pipes to create steam. The steam then keeps the pipes heated while more saltwater sprays. This all occurs while the water vapor collects and then cools into freshwater.
Vapor-compression distillation is a process where water vapor present above saltwater is compressed. The compression provides the heat needed to evaporate the water in saltwater. Then, the evaporation recollects into freshwater.
Reverse osmosis is a process where saltwater is run through a membrane that filters out the salt and minerals in the water. The remaining freshwater is then purified for human use.
Firstly, freeze-thaw starts with freezing saltwater into ice. Then, the thawing process removes the salt and freshwater remains.
The electrodialysis membrane is a process where electricity filters the salt from saltwater into a membrane, which then filters out freshwater.
Membrane distillation is a process in which varied temperatures are used in conjunction with a membrane to evaporate water from a brine byproduct solution and then made into freshwater.
Wave-powered distillation is a process in which submerged buoys desalinate saltwater as a wave passes through the buoy. The freshwater remains in the buoy until it can be collected.