Domestic Waste water is made up of 40% from toilet flushing, 30% from bathing, 15% from laundry, 10% from kitchen, and 5% from others. Waste water is made up of a lot of ingredients. One of the ingredients is water that is flushed from the toilet and other household activities. Other ingredients in waste water are:
- Bacteria, parasitic worms, and other pathogens
- Hair, vomit, feces
- Fruit sugar, drugs, and medicines
- Sand, metal particles, and ceramics
- Animals such as small fish
- Macro-solids such as children’s toys
- Gases such as carbon-dioxide
- Emulsions such as mayonnaise and paints
- Toxins such as poisons
- Pharmaceuticals
Waste water can come from a variety of sources such as:
- Leakage from Septic Tank or Cesspit
- Rainfall on the roof of buildings
- Cleaning liquids and paints from domestic sources
- Seawater coming into land
- Waste from acid or alkali manufacture
- Draining of storm water
- Wastes from pesticide manufacture
- Drainage from agricultural activities
Why must you treat waste water? Waste water must be treated to remove the pollutants in the waste water, to improve health and public hygiene, to preserve organisms in waterways, wildlife, and to improve quality of life.
The waste water treatment procedure consists of a series of steps.
First Step: Primary Treatment of Waste water: The primary treatment of waste water involves the removal of large objects from sewage. This involves removal of rags, grease, sticks, and floating objects. Preliminary treatment makes use of units such as screening, grit chamber, floatation units, skimming tanks, pumps, and pre-aeration units. Screening is used for removing floating matter. Grit chamber is used for removing sand and grits. Floatation unit is used for removal of oil and grease. Advanced primary treatment is done by methods such as coagulation and flocculation. Primary treatment involves the following processes – flocculation, sedimentation, and also coagulation. Sedimentation is used to settle heavy solids under the influence of gravity. The Fundamentals of Engineering helps in knowing the primary treatment of waste water.
Second Step: Secondary Treatment of Waste water: Secondary treatment of waste water includes biological treatment of water. This biological treatment removes the organic waste from the water. Microorganisms are used to convert solids that will not settle into solids that will settle. Secondary Treatment is used for waste water applications. The various systems for secondary water treatment are aeration systems, biological treatment systems, sludge and bio-solids processing system. Secondary treatment consists of the processes of activated sludge process, oxidation ponds and lagoons, and trickling filters. The Fundamentals of Engineering Exam include the secondary treatment of waste water.
While treating waste water, the sewage in the water can be considered as a resource or it can be considered as a pollutant. There are waste water treatment plants that purify the water using physical, chemical, or biological methods. Fixed film systems, trickling filters, sand filters, suspended film systems, activated sludge systems, and lagoon systems are also used in the secondary treatment stage.
Third Step: Tertiary Treatment of Waste water: Tertiary treatment involves the removal of disease causing germs. This tertiary treatment is done through chlorination, Ozone rays, Ultraviolet light, and hydrogen peroxide. Tertiary Treatment includes the following units and processes. They are membrane filtration and separation, de-chlorination, and disinfectant systems, reverse osmosis systems, Ion exchange, activated carbon absorption, and physical/chemical treatment.
Final Step: Circulation of Treated Water: These reclaimed waste waters help people to overcome shortage of water and provide a global solution of the various water related problems. The reclaimed waste water provides solution to the community in the following ways:
- Safeguarding drinking water in the region
- Reducing Pollution of City's permanent water resources
- Recycling water for Irrigation and industrial purposes.
The Fundamentals of Engineering Exam Prep cover all types of waste water treatment.
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