Why Filter? Six Basic Contaminants in Fluid

Who wants contaminated water? Testing water and fluids for contaminants is important because there are six basic types of material that can make it murky (or simply mysterious).

Thermo Scientific Nalgene Analytical Filter Units

1. Suspended Particles

• Sand, silt, leaves, etc. Measure these with a turbidity meter. Remove them with filters with pore sizes of 1 to 20 microns
• Colloidal particles (What? These are small particles 0.01 to 1.0 micron so fine they do not settle without prior coagulation). Remove them with anion exchange resin (DI), ultrafiltration, reverse osmosis, and distillation

2. Dissolved Inorganics like silicates, chlorides, fluorides, bicarbonates, sulfates, phosphates, nitrates, and ferrous compounds. Measure these with a conductivity meter. Remove them with deionization and reduce them by reverse osmosis and distillation

3. Dissolved Organics include proteins, alcohols, chloramines, and residues of pesticides, herbicides, and detergents. A Total Organic Carbon Analyzer (TOC) can measure them. Remove them with activated carbon, exchange resins, reverse osmosis, ultrafiltration, and ultraviolet radiation (UV)

4. Dissolved Gases such as carbon dioxide and oxygen. Measure oxygen levels with a dissolved oxygen (DO) meter. Remove them with anion exchange resins. Measure carbon dioxide levels with a conductivity meter; remove them with mixed bed exchange resins

5. Microorganisms/Pyrogens and Viruses

• Most surface waters contain microorganisms such as bacterium, amoebae and algae. City water treatment facilities add chlorine to kill these. Generally, chlorine is removed in the first step of water purification allowing microorganisms to multiply. Remove them by distillation, reverse osmosis,andUV radiation.
• Pyrogens or bacterial endotoxins are fragments of cell walls. Viruses are considered to be non-living nucleic acids. Remove these by distillation, ultrafiltration, reverse osmosis, and carbon adsorption

6. Nucleases & DNA: RNase and DNase enzymes naturally occur in the body. However, in water they can inhibit RNA and DNA amplification. Remove them with a combination of adsorption, ultrafiltration, and UV radiation.

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