[cs_content][cs_section parallax=”false” separator_top_type=”none” separator_top_height=”50px” separator_top_angle_point=”50″ separator_bottom_type=”none” separator_bottom_height=”50px” separator_bottom_angle_point=”50″ style=”margin: 0px;padding: 45px 0px;”][cs_row inner_container=”true” marginless_columns=”false” style=”margin: 0px auto;padding: 0px;”][cs_column fade=”false” fade_animation=”in” fade_animation_offset=”45px” fade_duration=”750″ type=”1/1″ style=”padding: 0px;”][cs_text]Monitoring and Management > 5. Water >
Describe the design and composition of microscopic membrane filters and explain how they purify contaminated water[/cs_text][/cs_column][/cs_row][/cs_section][cs_section parallax=”false” separator_top_type=”none” separator_top_height=”50px” separator_top_angle_point=”50″ separator_bottom_type=”none” separator_bottom_height=”50px” separator_bottom_angle_point=”50″ style=”margin: 0px;padding: 45px 0px;”][cs_row inner_container=”true” marginless_columns=”false” style=”margin: 0px auto;padding: 0px;”][cs_column fade=”false” fade_animation=”in” fade_animation_offset=”45px” fade_duration=”750″ type=”1/1″ style=”padding: 0px;”][cs_text]
- Membrane Filter: A thin film of synthetic polymer through which there are pores of reasonably uniform size.
- Membrane filters are commonly made of:
- Polypropylene.
- Polyvinylchloride (PVC).
- Polycarbonate.
- Polyester.
- Polysulfone.
- Polytetrafluoroethylene.
- There are two main types of membrane filters:
- A sheet of porous material folded around a central rigid porous core.
- Particles are trapped on the outside, while clean water flows through.
- Forms a cartridge that can be placed in a suitable housing mounted in a water pipe.
- Porous material formed into hollow capillaries.
- Particles are trapped on the outside, while clean water flows through.
- Large numbers of capillaries are bundled together to form a filtering unit with a large surface area.
- A sheet of porous material folded around a central rigid porous core.
- Membrane filters are classified according to the size of their pores:
- Nanometre (nm): One billionth of a metre.
- Microfiltration (MF) membranes remove particles of 200-500 nm, such as microscopic parasites, viruses, and fine colloidal particles.
- Ultrafiltration (UF) membrandes remove particles of 2-100 nm, such as paint particles and large organic molecules.
- Nanofiltration (NF) membranes remove particles of less than 1 nm, such as metal ions and small molecules.
- Many membrane filters can be cleaned by blowing air from the clean side to dislodge trapped particle on the other side, and can therefore be reused.
- Membrane filters can be used for:
- Filtering drinking water.
- Treating waste-water.
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