1what is the treatment process for a sequencing batch reactor?
1. Idle
2. Fill
3. React
4. Settle
5. Decant
2what is the adsorption capacity?
amount of adsorbate taken up by the adsorbent per unit mass of the adsorbent
3what is the equation for dosing given equilibrium adsorption capacity (qe)?
dose = C0-Ce / qe
4what are the 5 main steps of surface water treatment for drinking water?
1. Rapid Mix
2. Flocculation
3. Sedimentation
4. Filtration
5. Disinfection
5which type of hardness is typically removed first by increasing the pH & adding lime?
calcium carbonate hardness
6what is the specific role of adding lime to remove carbonate hardness?
precipitate out calcium carbonate and magnesium carbonate
7what type of hardness removal requires lime and soda ash?
non-carbonate hardness (calcium and magnesium)
8carbonate hardness is the minimum of what two values?
total hardness and alkalinity
9non-carbonate hardness is equal to what?
total hardness - carbonate hardness
10in activated sludge processes, Xw is equal to what other concentration?
Xr - recycled concentration
11dissolved oxygen is lowest at what point in the day?
night (photosynthesis occurs in the morning and respiration occurs at night which removes O2)
12why is dissolved oxygen important for aquatic life?
fish breathe it
13what happens to the dissolved oxygen when the turbidity increases?
it decreases
14does colder water contain more or less dissolved oxygen than warm water?
more
15what effect does eutrophication have on dissolved oxygen?
it leads to lower dissolved oxygen due to microorganisms decomposing & excess algae
16if salt concentration increases, what happens to dissolved oxygen levels?
if salt increases, then turbidity increases, which leads to lower dissolved oxygen levels
17what does a typical wastewater treatment process look like?
toilet -> grit chamber -> primary clarifier -> aeration tank -> secondary clarifier (can be wasted or recycled before next step) -> disinfection -> distribution
18what does biochemical oxygen demand (BOD) measure?
amount of oxygen required by aerobic microorganisms to break down organic matter in water over a specified period
19what do high BOD levels indicate?
high concentration of organic matter, meaning more oxygen is required by microorganisms to decompose these substances which can strain available DO
20why is lowering BOD essential?
to preserve oxygen levels for aquatic ecosystems and ensure water quality
21when do you use destruction of excess alkalinity?
when alkalinity is greater than total hardness
22equivalent weight is equal to what?
molecular weight/number of moles
23what does normality represent?
number of equivalent weight per liter of the solution
24normality is equal to what?
molarity*number of hydrogen ions transferred
25what treatment can effectively remove salts?
reverse osmosis
26what treatment can remove hardness?
ion exchange softening
27low pH can cause what?
corrosion
28what is dose equal to for chlorine?
demand + desired residual
29does a higher pH increase or decrease DBPs?
increase
30what happens to SRT when cutting wasting?
increases
31at what step in the wastewater treatment process, should PAC be added?
before coagulation