Water Purification & Wastewater Treatment (Ch. 22.6–22.10)

Typhoid agent

Salmonella typhi

Cholera agent

Vibrio cholerae

Waterborne protozoa

Giardia, Cryptosporidium, Entamoeba (survive as cysts)

Point vs. non-point pollution

point: domestic and industrial. Non-point: parking lots, feed lots, farms, golf courses

BOD

biochemical oxygen demand. Oxygen needed to degrade organic matter

Drinking water steps

sedimentation, coagulation, filtration, chlorination, storage, distribution

Coagulation

forms floc that traps insoluble material and microbes

Primary wastewater treatment

physical: screens, settling, solids removal. BOD still high

Secondary wastewater treatment

aerobic activated sludge with microbial flocs

Bulking sludge

floc that does not settle properly

Tertiary N removal

nitrification (aerobic) then denitrification (anoxic)

PAOs

phosphorus accumulating organisms. Cycle between anaerobic and aerobic conditions

Chlorine drawback

forms carcinogenic THMs. Gaseous chlorine is dangerous

UV disinfection

damages DNA and prevents reproduction

MPN / standard coliform method

tubes scored positive for gas

Anaerobic digestion

high-BOD industrial waste. Less sludge. Produces methane