chapter 22.6-22.10 (wastewater)

BOD

organic matter

clarifiers

settling tank that lets gravity separate suspended solids from wastewater

sludge

solid or semi-solid byproduct produced during wastewater treatment

floc 

cluster of bacteria that form within wastewater 

distinguish between primary, secondary, and tertiary wastewater treatment

primary - physical process

secondary - biological processes

tertiary - nitrogen removal (2 steps)

primary treatment

• grates + screens

• separation of solids

• allowed to settle in tanks

• substantial BOD (organic matter)

secondary treatment

biological processes - removes dissolved + suspended organic matter from wastewater using microorganisms

tertiary treatment

nitrogen removal

1. ammonia to nitrate - nitrosomonas + nitrobactr convert ammonia to nitrate in aeration basins

2. nitrate to nitrogen gas - denitrification by bacteria, nitrogen bubbles out of wastewater

3. phosphorus removal - group of bacteria, PAO’s (phosphorus accumulating organisms) remove P; cycling between anaerobic + aerobic conditions

How are indicator organisms (coliforms) detected in water

by culture-based methods; membrane filtration + enzyme substate test, or modern molecular techniques like PCR + FSH 666