On-Site Sewage Treatment Basics and Design
What are the 3 approaches to wastewater 1) Centralized
treatment? -collection network for many homes with central treatment facility
-surface discharge (PCA permit)
2)Decentralized
-individual/small groups of homes with onsite treatment
-soil based dispersal/subsurface discharge (PCA permit)
3) Combination of the two
What four components make up an onsite 1) Wastewater source
wastewater treatment system? 2)Collection and storage
3)Pretreatment compounds
4) Final treatment and dispersal components (->groundwater->well-
>source)
What methods are used in primary treatment of -stabilization ponds
wastewater (minimum)? -septic tank
What methods are used in secondary treatment -activated sludge
of wastewater? -trickling filter
-standard soil treatment area
What methods are used in disinfection of -chlorination
wastewater? -dechlorination
-UV
-ozone
What methods are used in advance wastewater -N removal
treatment? -P removal
-filtration
, Where does Minneapolis's drinking water come Mississippi River
from?
How many times has the water in the Mississippi 8 times
River been digested once it reaches New Orleans?
What is the current goal for wastewater treatment? Dispersal
What was the past goal for wastewater treatment? Disposal
What is the limiting factor for tech Cost
advancements allowing removal of pathogens,
solids, nutrients?
List advantages of decentralized systems in -cost effective
wastewater treatment. -easier maintenance
-lower O&M requirements
-lower energy requirements
-flexible design
-enhancement for reuse
-green development
-sewer extent limited
-multiple, small discharges = enhanced assimilation
-conserves water w/in wtsd: groundwater recharge
-avoid large mass loading at outfalls
-malfunction risks smaller and more manageable
-
How many septic tanks are in MN? 600,000
How many people use decentralized systems for 25%
wastewater treatment in the US?
How many of the decentralized systems in the US >50%
are in suburbs or cities?
How many gallons of water do typical toilets use 5 gallons
for flushing?
How many gallons of water do newer toilets use 1.6 gallons
for flushing?
Why are septic systems used? -to treat/disperse of wastewater where sewers aren't available, desirable,
or affordable (biggest issue!)
What are the 3 approaches to wastewater 1) Centralized
treatment? -collection network for many homes with central treatment facility
-surface discharge (PCA permit)
2)Decentralized
-individual/small groups of homes with onsite treatment
-soil based dispersal/subsurface discharge (PCA permit)
3) Combination of the two
What four components make up an onsite 1) Wastewater source
wastewater treatment system? 2)Collection and storage
3)Pretreatment compounds
4) Final treatment and dispersal components (->groundwater->well-
>source)
What methods are used in primary treatment of -stabilization ponds
wastewater (minimum)? -septic tank
What methods are used in secondary treatment -activated sludge
of wastewater? -trickling filter
-standard soil treatment area
What methods are used in disinfection of -chlorination
wastewater? -dechlorination
-UV
-ozone
What methods are used in advance wastewater -N removal
treatment? -P removal
-filtration
, Where does Minneapolis's drinking water come Mississippi River
from?
How many times has the water in the Mississippi 8 times
River been digested once it reaches New Orleans?
What is the current goal for wastewater treatment? Dispersal
What was the past goal for wastewater treatment? Disposal
What is the limiting factor for tech Cost
advancements allowing removal of pathogens,
solids, nutrients?
List advantages of decentralized systems in -cost effective
wastewater treatment. -easier maintenance
-lower O&M requirements
-lower energy requirements
-flexible design
-enhancement for reuse
-green development
-sewer extent limited
-multiple, small discharges = enhanced assimilation
-conserves water w/in wtsd: groundwater recharge
-avoid large mass loading at outfalls
-malfunction risks smaller and more manageable
-
How many septic tanks are in MN? 600,000
How many people use decentralized systems for 25%
wastewater treatment in the US?
How many of the decentralized systems in the US >50%
are in suburbs or cities?
How many gallons of water do typical toilets use 5 gallons
for flushing?
How many gallons of water do newer toilets use 1.6 gallons
for flushing?
Why are septic systems used? -to treat/disperse of wastewater where sewers aren't available, desirable,
or affordable (biggest issue!)
