Technical help: How to handle the concentrated water from seawater desalination?

Salt pans are everywhere! Dry it to make salt! :lol

This post was last edited by cdpulin on 2010-3-30 at 16:47. Personally, I think if salt is to be used, it needs to be processed first, as the scale inhibitors and other such substances contained in it must be removed.

It can be considered for delivery to the salt factory, but the salinity of the concentrated water must meet the factory’s standards; moreover, as mentioned on the 3rd floor, it needs to be further processed

It is more appropriate to discharge the concentrated water back into the sea. If it is sent to salt pans, the pollution of water quality caused by the pre-treatment processes for reverse osmosis will have a significant impact on the safety of the salt; after all, safety is the top priority! ! ! !

What a good sodium chloride solution; one could even set up another soda-making factory

It can be used to produce salt; this is done at the Beijiang Power Plant in Tianjin

This post was last edited by cdpulin on 2012-11-28 at 17:04. Several main processes for seawater desalination Editor: Dai Fulin Seawater desalination (also known as seawater desalting) is the process of separating salts from water in seawater. Removing water from seawater or eliminating the salt in seawater can both achieve the purpose of desalination. The methods of seawater desalination are also basically divided into these two major categories. 　　Among them, reverse osmosis, electrodialysis, and distillation are those that have been widely used in commercial applications. ①Reverse osmosis (RO): Under pressure, the fresh water in seawater passes through a semipermeable membrane to the low-pressure side of the membrane, while other components in seawater (such as salts) are retained on the high-pressure side of the membrane and are discharged along with the concentrated seawater, thereby achieving effective separation. In seawater desalination, an external pressure greater than the osmotic pressure of seawater is applied to the seawater side, causing the pure water in the seawater to reverse-osmosis into fresh water; this is the principle behind reverse-osmosis seawater desalination (Figure 1). To achieve the necessary desalination rate, the operating pressure is greater than 5.5 MPa. Figure 1: Reverse osmosis desalination process. ② Electrodialysis: Under the influence of a direct current electric field, ions migrate through selective ion exchange membranes, thereby allowing the electrolyte ions to be partially separated from the solution; this process is known as electrodialysis (Figure 2). Figure 2 Electroosmotic desalination process ③ Distillation method. The principle of seawater desalination by distillation is simple: seawater is heated, and fresh water is obtained after the water vapor condenses. Depending on the energy source, equipment, and process used, distillation methods are divided into Multi-stage flash distillation (MSF), Multiple-effect distillation (MED), and Vapor compression distillation (VC), among others. Among them, low-temperature multi-effect evaporation operates at temperatures below 70°C, which is much lower than the steam temperature of around 110°C in multi-stage flash evaporation; this approach effectively prevents the formation of scale due to inorganic salts, making it one of the most suitable evaporation techniques available today. At the same time, it can utilize various forms of low-grade heat sources; for example, by integrating with thermal or nuclear power plants, it can use the back pressure of 0.02–0.04 MPa (absolute pressure) from steam turbines to extract vapor for water production, thereby reducing power generation losses and improving the efficiency of the generator set (Figure 3). Figure 3 MED process flow using the backpressure steam of a steam turbine

After thorough consideration, the direct discharge approach is still to be adopted; however, as the production capacity for desalinated water increases, will this not lead to seawater becoming saltier worldwide? :D? ? At least processes such as salt drying and chlor-alkali production were eliminated, as they are after-all side businesses and would lead to an overly long industrial chain.

This post was last edited by cdpulin on 2012-11-28 at 17:07. There are currently no emission standards or regulatory measures in this regard; moreover, the amount of water in question is not even a fraction of what enters the ocean.

After all, direct discharge will still pollute the oceans, right?