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The Different Stages of Purification in Water Screening

Marine ecosystems are a considerable part of our aquatic system. Covering over 70 percent of the earth's surface, these ecosystems provide us with food, income and support species that fertilize our crops, making them integral to sustaining life. Studies have also shown, however, that 50 percent of worldwide groundwater is unsuitable for drinking because of pollution. Preserving the planet's water supply is crucial to our survival. Purification in water screening helps clean polluted water through different stages.

  1. Preliminary

    • The preliminary treatment is the first stage in screening water for purification. Water at this stage is screened for particles and debris such as sticks, leaves and rocks. Chemicals are usually added at this stage to help prevent algae from developing.

    Coagulation

    • The coagulation stage gets rid of small silt, microbes and other suspended particles in the water. The chemical alum is added, which neutralizes and coagulates these particles by combining them into larger ones, causing them to settle out. This makes it easier to screen the particles and remove them from the holding tank. Some people have questioned the usefulness of alum because of its supposed large amounts of aluminum. However, there exists little evidence to back up this claim.

    Floccuation

    • The flocculation stage occurs when the coagulated suspended particles become dense and sink into the water. This stage is when the process slows down, as the particles can take some time to sink to the bottom of the holding tank. After all particles have submerged, the next stage can commence.

    Clarification

    • Clarification gets rid of any sludge or residue that accumulated at the bottom of the tank during the flocculation stage. These impurities are scraped from the water tank.

    Stabilization

    • During the stabilization process, water is checked for certain materials that could make it hard, such as calcium and magnesium. These minerals usually do not cause any harm when ingested, but they can damage copper pipes and decrease the effectiveness of detergents and soap while doing laundry or washing dishes. Stabilization removes these chemicals if the water has become too hard. If the water is too soft, the water can be treated by adding sodium bicarbonate, which increases the water's alkalinity and buffering capacity, neutralizing carbon dioxide. pH adjustment adds an appropriate chemical to the purification system, such as sodium hydroxide, freeing CO2 in the process. Oxygen is also reduced in some cases to make the water less corrosive.

    Filtration

    • Filtration is the final stage in the purification process. Microorganisms, mineral precipitates and remaining suspended materials are separated and removed from the water, effectively disinfecting it one more time.

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