Direct contact membrane distillation (DCMD). Applicable to desalination. Heated seawater is passed along the surface of a hydrophobic polymer membrane. Evaporated water passes from the hot side through pores in the membrane into a stream of cold pure water on the other side. The difference in vapour pressure between the hot and cold side helps to push water molecules through.
Ion exchange:[11] Ion exchange systems use ion exchange resin- or zeolite-packed columns to replace unwanted ions. The most common case is water softening consisting of removal of Ca2+ and Mg2+ ions replacing them with benign (soap friendly) Na+ or K+ ions. Ion exchange resins are also used to remove toxic ions such as nitrite, lead, mercury, arsenic and many others.

Because the the semi-permeable membrane filters particles at the molecular level, reverse osmosis is extremely effective at removing bacteria, viruses, parasite cysts such as Giardia and Cryptosporidium, heavy metals such as lead and mercury, hard water minerals such as calcium and magnesium, and even fluoride and arsenic. It will not, however, remove certain pesticides and solvents small enough to pass through the membrane.
There are five types of contaminants that are found in water: particulates, bacteria, minerals, chemicals, and pharmaceuticals. Methods to remove these elements range from simple and inexpensive to elaborate and costly. Often to achieve purely potable water, several technologies must be combined in a particular sequence. Listed here are general brief descriptions of the twenty-five methods to purify water.
The first step calls for the installation of 2 push fit elbows. Note these were the only two elbows that leaked on me, despite use of thread tape and applying what I felt was the right torque. You really need to seat elbows well with the top of the male tread well below the plane of the housing. The push fits are of the type that once you push the poly tube in, that's it. So, being they are elbows, there is no coming back to easily address leak at the body joint. (I had NO push fit leaks in the system)... DONT Panic if it leaks at the body. Very careful removal of the inline filter and the RO membrane ... full review
Disinfection is accomplished both by filtering out harmful micro-organisms and by adding disinfectant chemicals. Water is disinfected to kill any pathogens which pass through the filters and to provide a residual dose of disinfectant to kill or inactivate potentially harmful micro-organisms in the storage and distribution systems. Possible pathogens include viruses, bacteria, including Salmonella, Cholera, Campylobacter and Shigella, and protozoa, including Giardia lamblia and other cryptosporidia. After the introduction of any chemical disinfecting agent, the water is usually held in temporary storage – often called a contact tank or clear well – to allow the disinfecting action to complete.
Ultraviolet light (UV) is very effective at inactivating cysts, in low turbidity water. UV light's disinfection effectiveness decreases as turbidity increases, a result of the absorption, scattering, and shadowing caused by the suspended solids. The main disadvantage to the use of UV radiation is that, like ozone treatment, it leaves no residual disinfectant in the water; therefore, it is sometimes necessary to add a residual disinfectant after the primary disinfection process. This is often done through the addition of chloramines, discussed above as a primary disinfectant. When used in this manner, chloramines provide an effective residual disinfectant with very few of the negative effects of chlorination.
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