L23 Urban Water Cycle and Humans Flashcards
Human Hydrologic Cycle Process
- Natural Water Bodies
- Transport
- Water Treatment
- DIstribution
- USE - produces wastewater
- Transport
- WAstewater Treeatment
- Natural Water Bodies
all processes require energy (use gravity where possible)
Hydrology
- Moves water around
- Takes whatever is dissolved
with it (nutrients, wastes,
microbes)
- Cleans parts of the
environment
- Deposits contaminants in
other parts
Bad Microbes
- pathogens: make ppl ill
- design DWTPs to remove/inactivate these
Good Microbes
Detrivores: break down waste
- design WWTPs so they flourish
- can become bad if too many
Drinking water contaminants
- bacteria
- viruses
- protozoa
- metals (lead, arsenic..)
- toxic organic compounds (eg pesticides)
- pharmaceuticals
- endocrine-disrupting compounds (mimic or block hormones in body)
Drinking Water Treatment purpose and treatment process
Main Purpose: protect ppl from environment
Treatment processes include sedimentation, filtration, membranes and disinfection
Wastewater Treatment purposes
Main purpose: protect environment from us
Second purpose: protect downstream people from upstream people
What do typical municipal wastewaters contain?
- biodegradable compounds (not always good)
- nitrogen
- phosphorous
- human pathogens
- metals
- toxic organics
- endocrine disruptors
- pharamceuticals
Why can biodegradation of waste be bad?
- generally requires more oxygen than is available (in aqueous systems)
- In-stream biodegradation of human wastes leads to oxygen deficits (may not continue to support aquatic life)
How much oxygen is required for complete biodegradation?
need to do a Biochemical Oxygen Demand (BOD) test
(Take a waste sample, add oxygen, allow biodegradation, and re-measure oxygen.)
Is complete biodegradation necessary? Can the receiving stream tolerate some in stream O2-demand?
need to do D.O (dissolved oxygen) calculations
