Date Posted: 1/24/2014 6:11:21 AM
Posted By: Karjosse Membership Level: Silver Total Points: 615
Pure water is colourless, but water in nature can often be coloured by foreign substances. Water whose colour is partly due to suspended solids is said to have apparent colour, and water colour contributed by dissolved substances is known as true colour.After contact of water with organic debris such as leaves, conifer needles, weeds or woods, water picks up tannins, humid acids, and humates and takes on yellowish brown hues. Iron oxides cause reddish water, and manganese oxides cause brown or blackish water. Industrial wastes from textile or dyeing operations, pulp and paper production, and mining, refining and slaughterhouse operations may add substantial colouration to water I receiving streams.Impacts of water colour:Coloured water is not aesthetically accepted to the general public. In fact, given a choice, consumers tend to choose clear, non coloured water otherwise poorer water treated potable water supplies with an objectionable colour. Highly coloured water is unsuitable for laundry, dyeing, paper making, beverage manufacturing, dairy production and other processing and textile and plastic production. Thus, the colour of water affects its marketability for both domestic and industrial use.While true colour is not usually considered unsanitary or unsafe, the organic compounds causing the water colour may exert the chlorine demand and thereby seriously reduce the effectiveness of chlorine as a disinfectant. Perhaps more important are the products formed by the combination of chlorine and the colour-producing substances. Phenolic compounds, common constituents of vegetative decay products, produce very objectionable taste and odor compounds of chlorine. Additionally, some compounds of naturally occurring organic acids and chlorine are either known to be are or are suspected to be carcinogenic (cancer-causing agents)Measurement of water colour:Although several methods of colour measurements are available, methods involving comparison with standardized coloured materials are most often used. Colour comparison tubes containing a series of standards may be used for direct comparison of water samples that have been filtered to remove the apparent colour. Results are expressed in true colour units (TCU) where one unit is equivalent to the colour produced by 1mg/L of platinum in the form of chloroplantine ions. For colours other than yellowish-brown hues, especially for coloured water originating from industrial waste effluents, special spectrometric techniques are usually employed.In the fieldwork, instruments employing coloured glass drinks that are calibrated to the colour standards are often used. Because biological and physical changes occurring during storage may affect colour, samples should be tested within 72 hours of collection.Water colour Use:Colour is not a parameter usually included in waste water analysis. In potable water analysis, the common practice is to measure only the true colour produced by organic acids resulting from decaying vegetation in the water. The resulting value can be taken as an indirect measurement of humic substances in the water.
Next: Some awesome and dangerous motorcycle adventures.Previous: How to avoid bad company in campus
Get premium membership