Water treatment-WATER TREATMENT PROCESS-OZONISATION AND UV APPLICATION
Water Treatment
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Transcript of Water Treatment
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Water Treatment
Chapter 11
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Sewage Treatment• Rationale• More than 500 pathogenic bacteria, viruses, and
parasites can travel from human or animal excrement through water.
• Natural Processes• In many areas, outdoor urination and defecation is
the norm.• When population densities are low, natural processes can
quickly eliminate waste.
• Artificial Wetlands Are a Low Cost Method • Natural water purification
• Effluent can be used to irrigate crops or raise fish for human consumption.
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Lincoln Wastewater FacilitiesUnderneath and throughout Lincoln are over 1,000 miles of sanitary sewer lines and 16 pumping stations114 employees at solid waste and wastewater facilities
Theresa Street Facility27th & Cornhusker20 million gallons of water daily
Northeast Facility5 million gallons of water daily
Combined this would fill Holmes Lake in 3.5 days
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Lincoln Northeast Treatment Facility
3. aeration basin
1. screening and grit basin
2. primary clarifiers
4. secondary clarifiers
5. disinfection
6. solids digestion7. solids dewatering
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Municipal Sewage Treatment
1. Primary Treatment - Physical separation of large solids from the waste stream
• screening, pumping, grit removal• get the big stuff out• material collected hauled to
landfill• primary clarification
• removes settleable solids• removes floatable
materials like grease• 2-4 hrs
primary clarifier
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2. Secondary Treatment - Biological degradation of dissolved organic compounds
• Biological Treatment• Aeration basin• removes pollutants with
bacteria and protozoans• must be aerated• 8 hrs
• Secondary clarification• separates treated
wastewater from microorganism (from aeration basin)
• Disinfection• chlorination or UV light
Municipal Sewage Treatment
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2. Solids processing - Biological degradation of dissolved organic compounds
• solids digestion• anaerobic digesters to
stabilize organic solids• produce methane gas
(CH4) which can power turbine to generate electricity
• 18-20 days• solids dewatering
• removes excess water• solids (organ rich
material)
Municipal Sewage Treatment
Belt Filter Press Dewatering
Anaerobic Digesters
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2. Solids processing - Biological degradation of dissolved organic compounds
• land application• soil amendment and
fertilizer• alternatively dewatering is
replaced by collecting liquid and using it as fertilizer on city owned land
Municipal Sewage Treatment Subsurface Biosolids Injection
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Municipal Sewage Treatment3. Tertiary Treatment - Removal of plant nutrients (nitrates and phosphates) from secondary effluent.
• Chemicals, or natural wetlands
• Lincoln does not have tertiary treatment
• In many US cities, sanitary sewers are connected to storm sewers.• Heavy storms can overload
the system, causing by-pass dumping of raw sewage and toxic runoff directly into watercourses
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Unusual Pollutants are Now Being Detected in Surface Waters