Urban Water Cycle and Humans

Question 1

Bad Microbes

Answer 1

• pathogens: make ppl ill
• design DWTPs to remove/inactivate these

Question 2

Good Microbes

Answer 2

Detrivores: break down waste
- design WWTPs so they flourish
- can become bad if too many

Question 3

Human Hydrologic Cycle Process

Answer 3

1. Natural Water Bodies
2. Transport
3. Water Treatment
4. DIstribution
5. USE - produces wastewater
6. Transport
7. WAstewater Treeatment
8. Natural Water Bodies

all processes require energy (use gravity where possible)

Question 4

Drinking water contaminants

Answer 4

• metals (lead, arsenic..)
• toxic organic compounds (eg pesticides)
• pharmaceuticals
• endocrine-disrupting compounds (mimic or block hormones in body)

Question 5

Drinking Water Treatment purpose and treatment process

Answer 5

Main Purpose: protect ppl from environment
- treatment processes include sedimentation, filtration, membranes and disinfection

Question 6

Wastewater Treatment purposes

Answer 6

Main purpose: protect environment from us
second purpose: protect downstream ppl from upstream ppl

Question 7

What do typical municipal wastewaters contain?

Answer 7

• biodegradable compounds
• nitrogen
• phosphorous
• human pathogens
• metals
• toxic organics
• endocrine disruptors
• pharamceuticals

Question 8

Why can biodegradation of wastes be bad?

Answer 8

• generally requires more oxygen than available (in aqueous systems)
• in-stream biodegradation of human wastes leads to oxygen deficits (may not continue to support aquatic life)

Question 9

How much oxygen is required for complete biodegradation?

Answer 9

need to do Biochemical Oxygen Demand (BOD) test
- take waste sample, add oxygen, allow biodegradation, re measure oxygen

Question 10

Is complete biodegradation necessary? Can the recieveing stream tolerate some in stream O2-demand?

Answer 10

need to do D.O (dissolved oxygen) Sag calculations