6 Flashcards
Describe the techniques used in the purification of drinking water from surface water.
Main common ones:
- Coagulation -> Flocculation -> Sedimentation
- Filtration
- Taste and odor control
- Disinfection
Describe the techniques used in the purification of drinking water from groundwater.
Main common ones:
- Iron and manganese removal
- Softening
- Arsenic and nitrate removal
- Disinfection
What is Coagulation?
Process adding and mixing chemical reagents to water to destabilize colloidal and fine solids suspended in water
Fix turbidity
What is flocculation?
Slow stirring promotes agglomeration (clustering) of destabilized particles formed during coagulation.
What is filtration?
Filtering water using fine sand, gravel, and anthracite to remove non-settleable flocs that stayed after coagulation/flocculation/sedimentation.
what is a way to remove odor from water samples
using an activated carbon filter, like charcoal to remove remaining organic contaminants
how can we soften water
by precipitating Ca and Mg out of the water via the addition of phosphate or lime stone
What are the disinfection methods for water?
-Membrane technology
- UV radiation
- Chemical methods: Ozonation or Chlorination
What are the advantages and disadvantages of membrane technology for disinfection methods?
Takes long time but is pretty efficient
What are the advantages and disadvantages of UV light for disinfection methods?
Pros:
- Good against microorganisms
- No need for chemicals
- No residue
- User friendly
- Less space
Cons:
- Low doses might nit work against all microorganisms
- High preventive maintenance (Fouling of tubes)
- Turbidity and total suspended solids block light so it can make this less effective (must be filtered to ensure it will work)
- Not cost effective
What are the advantages and disadvantages of Ozonation for disinfection methods?
Pros:
- O3 generated onsite (convenience)
- Generates radicals in water which can kill bacteria
- Only 10 min of concentrated O3 destroys bacterias and viruses
Cons:
- Energy intensive
- Short-half life and no residual preventive protection
What are the advantages and disadvantages of Chlorination for disinfection methods?
Cl2 in water leads to HOCl which goes into cell walls and oxidizes vital stuff for micro orgs
- Chlorine residual left over
Cons:
- Formation of byproducts like haloacetic acids and haloacetonitriles. Also, chlorinated phenols and halomethanes
which is the best disinfection method
UV, is the best for all things except for cost.
What’s the difference between municipal water and wastewater treatment?
wqater treatment: treating water from natural sources like surface and groundwater
Wastewater treatment: treating water from human waste (water humans have used)
What are the objectives of wastewater treatment?
Remove:
- Dissolved biodegradable organics (BOD)
- Suspended solids
- Pathogenic microorganisms
- N and P if eutrophication is a concern
what is screening
a pre treatment
to remove large object inorder to protect down stream equipment
what is grit removal
a pre-treatment
to remove dirt, sand and stones with other inrog particles
prevent clogging pipes
what is floatation
pre-treatment
to remove fast oils and grease (FOG) via air
what are the three pre-treatments used
screening
grit removal
floatation
what is the objective of the primary treatment of wastewater
to separate solids from wastewater.
they use a sedimentation tank to remove and settable or floatable solids not extracted during pre-treatment
soluble pollutants will remain
how much BOD is removed from primary treatment
30%
what is the purpose of secondary treatment
remove any remaining BOD and COD and TTS (which can be organic or not)
it may also remove some N and P or heavy mental (though this usually needed advanced methods)
how is secondary treatment preformed
via the use of living micro orgs
either aerobic or anerobic
what is the result form using aerobic orgs in secondary treat
they will produce CO@ and energy whike increasing thier bio mass in the tanks
