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Wastewater Management

Wastewater Management. Wastewater. Wastewater (or sewage) refers to any water that has been used by people in some way Includes water from showers, sinks, washing machines and dishwashers (anything with a drain!)

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Wastewater Management

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  1. Wastewater Management

  2. Wastewater • Wastewater (or sewage) refers to any water that has been used by people in some way • Includes water from showers, sinks, washing machines and dishwashers (anything with a drain!) • All drains converge to a single pipe underground leading to the outside of the building

  3. Septic Systems (20% of Canadians) • Rural areas (usually) • Wastewater runs to an underground septic tank • Inside the tank, solids and oils separate from the water (solids sink / oils and fats float)

  4. Lighter than water (oils/fats) Heavier than water (solids)

  5. Septic Systems (continued) • Water called effluent (or gray water) runs downhill to a drain field of perforated pipes which are laid in gravel-filled trenches. • Bacteria decompose organics in the wastewater • The purified water percolates (seeps) downwards into the soil

  6. Above the drain field – grass is often the greenest!

  7. Septic Systems (continued) • Periodically – usually every 1-3 years, the septic tank needs to be pumped out. • The material pumped out is called septage. • Septage is disposed of in a) landfillsb) incineratorsc) fieldsd) large lakes / oceans

  8. Sewer Systems (80% of Canadians) • All wastewater (and sometimes storm water entering storm sewers) goes to a central treatment facility

  9. Sewage Treatment Process • Primary Treatment - screens and settling tanks (or clarifiers) - physical trapping of or sinking of solids

  10. Secondary Treatment - biotechnology - bacterial populations – decompose organic matter - mixing of air with the water - stirring • Production of sewage sludge Activated Sludge = bacterial action (decomposers)

  11. The water that has been flowing through the system – effluent – is treated with chlorine and sometimes UV light or ozone to kill any remaining bacteria

  12. Tertiary Treatment (sometimes) - removal of nutrients - such as phosphorus - done by reacting nutrient with a metal - precipitate (solid powder) forms

  13. Effluentis then piped into rivers, lakes or the ocean

  14. What can be done with the sludge (also called biosolids)? • Dump it in lakes / oceans • Dump it into landfills • Incinerate it (possibly produce electricity) • Spread it on fields (cheap fertilizer) Advantages / Disadvantages of each?

  15. Large-Scale Sewage Treatment Advantages Disadvantages • Can treat large amounts of sewage quickly • Uses a fairly small area of land • The facility is expensive to build and maintain • Effluent may still contain pathogens and some chemicals (e.g. pharmaceuticals and medicines) • Requires water!

  16. Peel Region (Mississauga, Brampton and Caledon) • Two wastewater facilities on the shores of Lake Ontario (Lakeview and Clarkson) • Other small ones (e.g. Inglewood discharges effluent into the Credit River) • http://www.peelregion.ca/pw/water/sewage-trtmt/

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