2. WASTEWATER
• Wastewater can be defined as any water that has been used for domestic,
commercial, industrial or agricultural purposes and has become contaminated
as result.
• It may contain a range of pollutants including human and animal waste,
chemicals, pathogens and other substances that can pose risk to human health
and the environment.
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4. WHAT NEEDS TO BE REMOVED?
• Wastewater may contain a variety of substances:
• trash and debris
• human waste
• food scraps
• oils
• grease
• soaps
• chemicals (cleaning, pesticides, industrial)
• pharmaceuticals and personal care products
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5. WASTEWATER TREATMENT
• It is the process of removing physical, chemical, and biological contaminants
from wastewater and household sewage.
• Goal is to separate wastewater into:
Environmentally-safe fluid waste stream.
Solid waste to be disposed or reused.
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6. PROCESS OF WATER TREATMENT
• Water which enters a water treatment facility undergoes a series of steps to
cleanse the water using physical, chemical, and biological processes
• Upon exiting the water treatment facility, the decontaminated water is
released into rivers or streams, entering again into the environment
• Sometimes used specifically for agriculture and irrigation
• Possible to purify into clean drinking water again
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7. STEPS OF THE WASTEWATER
TREATMENT PROCESS
1. Pretreatment
2. Physical or Primary Treatment
3. Biological or Secondary Treatment
4. Chemical or Tertiary Treatment
5. Sludge Processing
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9. TREATMENT PROCESS
STEP 1: PRETREATMENT
• Prepares waste water for entering the treatment plant
• Removal of larger debris by screening (shown right)
• Trash
• Tree limbs
• Removal of grit and gravel by screening and settling
• Gravel must be removed early as it can damage machinery
and equipment in the treatment plant
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10. TREATMENT PROCESS
STEP 2: PRIMARY TREATMENT
• In Primary Treatment, as much solid material is removed as possible by
relying on gravity
• Removes most of the sludge and scum
• Sludge: Organic and inorganic materials which will naturally settle
• removed by sedimentation
• Scum: Materials which will float (oil, grease, soap)
• removed by skimming
• This step successfully removes 50 to 70% of suspended solids and up to 65%
of oil and grease
• Colloidal and dissolved materials are not affected by this step 10
11. TREATMENT PROCESS STEP 3:
SECONDARY TREATMENT
• Secondary treatment is designed to remove residual organic materials
and suspended solids that were not removed during primary treatment
• Works to degrade the biological content of the sewage that comes from
human waste, food waste, soaps and detergent.
• Removal of biodegradable dissolved and colloidal organic matter using
aerobic biological treatment and flocculation
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12. TREATMENT PROCESS
STEP 4: TERTIARY TREATMENT
• Tertiary treatment (also known as advanced treatment) includes the
remaining processes necessary to remove the following from wastewater:
• Nitrogen
• Phosphorus
• additional suspended solids
• remaining organics
• heavy metals
• dissolved solids
• Disinfection: Diseases-causing organisms require one special operation again.
The wastewater must be disinfected for at least 20-25 minutes in tanks that
contain a mixture of chlorine and sodium hypochlorite for elimination to
protect the health of the animals and people. 12
13. TREATMENT PROCESS
STEP 5: SLUDGE TREATMENT
• Sludge consists of all the solid material removed from wastewater during the
water treatment process
• While the water in treatment is ready for release into streams and
groundwater, sludge requires further treatment before it can be disposed or
used
• Must reduce the amount of organic matter
• Must reduce the number of disease causing microbes
• Remove as much remaining liquid as possible
• Sludge treatment options include:
• Aerobic digestion
• Anaerobic digestion
• Composting
• Incineration
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14. LIMITATIONS TO TREATMENT PROCESSES
• Cost
• Infrastructure
• Maintenance of facilities and equipment
• By-products disposal
• Energy requirement
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15. CONCLUSION
The proper treatment of wastewater is crucial for preserving
the environment, especially with the rise of urbanization and
industrialization. Wastewater treatment methods such as
physical, chemical, and biological technologies (primary to
tertiary treatment) are being employed to ensure the long-term
viability of our ecosystem.
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