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Wastewater Treatment

Wastewater Treatment. By Shantanu Mane Vaidehi Dharkar Viral Shah. What is Wastewater?. Water is used for many purposes. Water that has been used and contains domestic, industrial, institutional and commercial waste products is called wastewater. Where does wastewater come from?.

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Wastewater Treatment

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  1. Wastewater Treatment By Shantanu Mane Vaidehi Dharkar Viral Shah

  2. What is Wastewater? • Water is used for many purposes. • Water that has beenused and contains domestic, industrial, institutional andcommercial waste products is called wastewater.

  3. Where does wastewater come from? • Residences (kitchen, bathroom) • Commercial Institution • Industrial Institution (usually requires specialized treatment process)

  4. What is wastewater treatment? • Usually refers to sewage treatment or domestic wastewater treatment. • Process of removing contaminants from wastewater, both run-off and domestic.

  5. Goals • To produce a waste stream. • To produce solid waste (sludge). • Then discharge or reuse them back into the environment.

  6. Why do we need to treat wastewater? • Wastewater treatment is important to remove constituents or contaminants that could harm people or the environment. • Common constituents in domestic wastewater are: -Organic Solids -Nutrients -Pathogens

  7. Where is wastewater treated? • All sources of wastewater in a Sewage Service Area are connected to sewers, which join together to form a network called a collection system. • The collection system leads to a Water Pollution Control Plant (WPCP).

  8. How does it get there? • Water flows downhill because of gravity, so the WPCP is usually located at a low point in the service area. • If the force of gravity isn’t enough, pumping stations are used to boost wastewater through forcemains (pressurized sewers) to the WPCP.

  9. Stages of wastewater treatment:

  10. Preliminary Treatment: • Mechanical screens remove materials like rags,sticks, etc. • Grit removal processes remove grit, sand andgranular materials.

  11. Primary Treatment: Typical materials that are used during primary treatment include -fats, oils and greases (a.k.a FOG) -sand, gravel and rocks -larger settle-able solids including human waste -floating materials

  12. Primary sedimentation Methods used in primary treatment: Sand catcher

  13. Secondary Treatment: Biodegradable organic matter is removed by microorganisms (biomass). This is considered the second stage of wastewater treatment.

  14. Methods/Approaches of Secondary Treatment: Secondary treatment is usually accomplished by a process called suspended growth biological treatment. The term “suspended” is used because the biomass floats freely in the liquid. Other approaches are: -Fixed Film System -Lagoon System

  15. Tertiary Treatment: UV light radiation UV light radiation Chlorination Chlorination Ozonation Ozonation Removal of disease causing organisms from wastewater. 3 different disinfection processes:

  16. Advanced Treatment: Quaternary and sometimes tertiary treatment are classed as advanced treatment. Advanced treatment is not always required. Technologies include membrane filtration and reverse osmosis.

  17. Sludge

  18. What is sludge? • Sludge is solid material removed from primary sedimentation tanks and secondary clarifiers. • Other sludge components may include chemical precipitates and backwash solids from tertiary filters or other processes.

  19. Sludge Processing - Thickening • Raw sludge is usually more than 95% water! • Thickening the sludge reduces water and increases sludge solids concentration from 3% to 8%.

  20. Sludge Processing - Stabilization • Stabilization is a process that reduces pathogens and sludge odours. • Bio-solids are stabilized. • Biological stabilization is called digestion. • Aerobic digestion is a suspended growth process with oxygen present for stabilization. • Anaerobic digestion involves the decomposition of organic and inorganic matter in the absence of oxygen.

  21. Sludge Processing - Dewatering • Dewatering reduces the water content of bio-solids to the 20% to 30% range. • At this dryness level it is often called sludge cake.

  22. Sludge Processing – Bio-solids • Bio-solids are incorporated into the soil. Available nutrients are taken up by plants for growth. • If land application is not possible, bio-solids may be disposed of in a landfill, composted or incinerated. • Further processes exist to convert bio-solids to a marketable fertilizer.

  23. What can effluent be used for? Discharged into a stream, river, bay, lagoon or wetland. Used for the irrigation of a golf course, green way or park. If it's sufficiently clean it can be used for groundwater recharge.

  24. Conclusion Wastewater treatment is a great technique to make optimum use of water. Water which would simply be thrown away is put to good use. Reduces contamination of clean water sources.

  25. Thank you!

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