Final Exam Flashcards
1
Q
water treatment purpose
A
- drinking
- recreation
- irrigation
- cooling
- habitat
2
Q
Pollutant
A
something that effects our desired uses of water
- Organic matter - increases BOD
- Infectious agents
- nutrients - N and P
- Toxics - pesticides, industrial, PCPP, metals
3
Q
Actual vs Goals
A
- BOD 250 mg/L vs 15 mg/L
- Suspended solids 220 mg/L
- P 8 mg/L <1 mg/L static <0.05 mg/L moving <0.1 mg/L
- N 40 mg/L <0.1 - 10 mg/L <1 mg/L
Accounts for dilution when teh WWTP discharges into the receiving water
Use base flow to make calculations - based on 7Q10 (lowest 7 day discharge over a 10 year period)
Stream discharge + WWTP discharge / WWTP discharge
4
Q
Primary treatment
A
- physical removal of solids
- decrease BOD, N and P via sorption and lowering OM
- screening
- clarifer - settling tank
- decrease velocity
- more particulate settles
- things float
- arms sweep off the oil and grease from the surface
5
Q
Combined Sewer
A
- domestic wastewater and stormwater
- combined sewer overflows
- allows for overflow and prevents backups into homes
- Increase the flow rate then decrease the residence time
- less effective
- volume/flow = time
6
Q
secondary treatment
A
- decrease BOD
- biological process that uses microbes to consome BOD
- carb + O2 = CO2 + H2O
- activated sludge - rich in microbes
- airate to mix and provide O2
- also decrease N and P due to microbial uptake
- sediement tanks
7
Q
Sediment tanks
A
- secondary treatment
- add chemicals to coagulate and induce settling
- settling velocity increases as size increases (aggregation)
- Stokes law - terminal settling velocity
- increase diameter of the particle increases the terminal settling velocity
- also accounts for denisty of the particle, density of water, gravity (effect using centrifuge), visocity of water
8
Q
Coagulates
A
Aluminum sulfate
iron chloride
calcium hydroxide
Form metal hydrates
acidic because metal pulls electron density of oxygen in water and loss a proton
9
Q
Tertiary treatment
A
- nutrient removal
- wastewater increases OM in water by directly adding OM and by promoting plant synthesis via extra nutrients
- uptake in biomass via bacteria
- Metal ions bind phosphate but does not help nitrate
- use phosphorous hyperaccumulating bacteria
- uptake more P than they need
- luxury uptake
- Acinetobacter
- Denitrification - nitrification
10
Q
Denitrification - nitrification
A
- nitrification - organic N to ammonium (decomp) and ammonium to nitrate
- requires O2
- denitrification - nitrate to nitrogen gas
- anaerobic
- in an open pool
- O2 on surface is used immediately and anaerobic conditions are found in the rest of the tube
- supply methanol for food
- Nitrification and denitrification must be seperated
11
Q
disinfect
A
NaOCl then discharge
12
Q
Biosolids
A
- metals - on surfaces
- nonpolar organics - floating organic grease, organic rich layer at the bottom with bacteria, run water through carbon filter
- biosolids - organic C, N, P, metals, nonpolar organics, water (only 0.1% solid)
- highly concentrated
- land applied as fertilizer
13
Q
Dewatering
A
- pressing
- centrifuge
14
Q
Digesters
A
- organic C to CO2 and methane
- anaerobic
- methanogenic
- 35C temp
- collect methane to generate heat
- burn methane to make CO2
15
Q
Greenhouse effect
A
- UV (short wavelength and high energy) into greenhouse
- re-emitted as IR which is long wave
- glass not transparent to IR and it absorbs IR via an increase in vibrational energy
- glass reflects IR in inside and outside
- net gain of energy inside