Water Purification and Wastewater Treatment Flashcards
Removes objectionable tastes and odors
activated charcoal
a coagulant
Aluminum sulfate (“alum”)
Alum chemically reacts to form gelatinous particles
floc
Flocculated material settles out and is piped to wastewater treatment plant
Settling Basins
◦ Bacteria in sewage degrade organic matter
◦ Tank buried in ground to treat sewage from an individual home
◦ Wastewater flows into tank
Septic Tanks
used to minimize corrosiveness of polished water
Caustic soda
Solid material (“sludge”) settles to bottom of tank
Cleaner water flows out of tank into ground through subsurface drains
Septic Tanks
3-5’ deep
Sunlight, algae, oxygen interact to clean wastewater
Lagoons (Stabilization Ponds)
Types of sewers.
Carry stormwater and wastewater
Combined Sewers
Types of sewers.
◦ Sanitary Sewers
◦ Storm Sewers
Separated Sewers
Some wastewater may be diverted to receiving streams
High rainfall events
Its function is to speed up natural processes by which water purifies itself
Treatment
Essential key in Conventional Sewage Treatment
Dissolved Oxygen
Conventional Sewage Treatment.
Types of Primary Treatment.
◦ Screening
◦ Grinding
◦ Grit Chamber (heavy particles - “grit”)
◦ Sedimentation Tank (suspended solids - “sludge”)
◦ Chlorination of effluent
Conventional Sewage Treatment.
Mechanical Process
Primary Treatment
Conventional Sewage Treatment.
Types of Secondary Treatment.
◦ Trickling Filter
◦ Activated Sludge
Conventional Sewage Treatment.
Biological Process
Secondary Treatment
Conventional Sewage Treatment that uses bacteria to removed ODW and lower BOD
Biological Process
◦ Effluent leaves sedimentation tank and is pumped to an aeration tank
◦ Effluent is mixed with air and sludge loaded with bacteria (“activated sludge”)
◦ Sludge contacts with raw sewage, and bacteria in the sludge then decompose the raw sewage, lowering ODW and BOD
Secondary Treatment With Activated Sludge
◦ Effluent leaves sedimentation tank and flows through trickling filters
◦ Bed of stones 3-10’ deep through which sewage passes
◦ Bacteria gather on stones and multiply, consuming ODW
◦ Cleaner water trickles through pipes at bottom of filter for additional treatment
Secondary Treatment With Trickling Filters
Physical and chemical processes that specific pollutants left in wastewater after primary and
secondary treatment
Advanced (Tertiary) Wastewater Treatment
◦ Bleaching to remove coloration
◦ Disinfection to kill pathogens
◦ Coagulation-sedimentation with alum
◦ Adsorption using activated charcoal
◦ Electrodialysis for salt removal
Advanced (Tertiary) Wastewater Treatment
◦ Landfills
◦ Incineration
◦ Land application
◦ Anaerobic digestion
Sludge Disposal
An act to restore and/or maintain the chemical, physical, and biological integrity of the nation’s surface waters
Clean Water Act
