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Water pollution and water treatment (Water pollution (Types of pollutants,…

- - - - The bacteria's oxidize the organic material and in the process they consume oxygen dissolved in water; the consequences of this are that the water flow became anaerobic killing animals and plants, the process of water purification is much more slower because of the scarcity of oxygen and this causes bad odors and the creation of toxic materials in the water. The consume of the oxygen by the bacteria is what we called BOD.
    - - An evaluation use to measure the levels by organic matter of the water contamination.
        
        The organic matter is oxidized by potassium dichromate. Is more used than the BOD because most of the organics materials are resistant to the microbial oxidization.
    - - The enrichment of the water with algal nutrients are contributed by the sewage and is a serious economical problem due the increasing of the BOD causing a deterioration of the water quality.
    - - After water contamination, the water needs to start a process of purification and when this occurs without man involving is called self-purification and is caused by physical, chemical and microbiological changes.
    - - This indicators provides a way to monitored natural water, searching for sewage pollution. There are two types of indicators:
        Coliform group: Any gram-negative, rod-shaped, facultative anaerobic bacterium.
        Fecal coliforms: Are coliforms that can grow in a temperature of 44.5°C.
- - - - The raw water is pumped into lagoons so silt and other materials sink. Certain flocculating chemicals are added to precipitate with water, and absorb finer particles.
    - - Water is pumped into tanks equipped with sand filters. The water is purified from bacterias and other microorganisms.
    - - Chlorine gas or certain chlorine compounds are added to water to complete the purification.
      - Extreme case: the water has a lot of calcium, magnesium or iron salts. Water must go through special chemical procedures to “soften”.
      - Flourides are added to reduce the incidence of dental caries.
    - - If the water has quantities of organic materials, it can be sprayed into air or flow to shallow waterfalls. This is to increase the availability of oxygen to microorganisms capable of oxidizing organic compounds.