Chapter 11 Flashcards
MCL
maximum contaminant levels
DBP
disinfection by-products
THMs
trihalomethanes
ie. chloroform
aeration zone
particles of soil are covered in a film of water
- unsaturated, air is present
saturated zone
water has displaced air in these pore spaces
- “groundwater”
aquifer
water contained in soil composed of porous rock or gravel and bounded on the bottom by impervious rock
nitrate sources
nitrogen fertilizers
soil cultivation
human sewage (septic tanks)
atmospheric deposition
blue-baby syndrome
caused by bacteria in milk bottles reducing nitrate into nitrite
nitrite oxidizes iron in hemoglobin (Fe2+ to 3+) and baby suffers respiratory failure
N-nitrosamines
carcinogenic molecules
- can form in human stomach from nitrates + amines
ie. NDMA
leachate
liquid containing dissolved matter that drains from a terrestrial source (landfill)
B-TEX compounds
benzene, C6H6, toluene, xylene
Primary sewage treatment
larger particles are removed by screens/settling basin
- liquid grease is skimmed off
- ~30% of BOD removed
Secondary sewage treatment
suspended organic matter is biologically oxidized
Tertiary sewage treatment
specific substances are removed (only used in a few municipalities)
- phosphate removal via microbes
- heavy-metal removal via hydroxide/sulfide ions
-iron removal via aeration
VOC
volatile organic compounds
