GEO 106 Study Guide - Spring 2018, Comprehensive Midterm Notes - City, Time, Gravity
12 Oct 2018
School
Department
Course
Professor
GEO 106
MIDTERM EXAM
STUDY GUIDE
Fall 2018
CGEO702 DESALINATION RACHEL AU (500684608)
PROCESS
1. RAW WATER
- aka feed water
- factors to consider:
- water quality
- safe yield
- seawater intrusion impacts (affects on living organisms)
2. INTAKE
- consist of entrance structure
- pipe connecting it system
- potential pumps
- 2 types: surface intake + subsurface intake
- impingement: sufficiently large organisms caught in intake screen due to flow of
water (e.g. crabs, fish)
- entrainment: aquatic organisms enter intake
- req. on-going maintenance, excavation, dredging, embedment, pipe laying +
anchoring
→ non-reversible
→ minimize by sharing intakes w/ other facilities (e.g. power plants)
3. PRE-TREATMENT
- prevent debris, weed, algae, fish, shells, aquatic life, etc…
- req. water that prevents erosion, membrane fouling (clogging)/excessive
maintenance
4. BLENDING
- before/after treatment
- purpose: improve operation/aesthetics (customers)
- blend w/ other water for dilution, add chemicals, etc…
5. DESALINATION
- pumps to force water through RO membrane + energy recovery devices
- high pressure = most energy used
→ high pressure = most energy used
→ more energy used when high salinity
6. POST-TREATMENT
- can be acidic/have minerals → corrosive or unnatural taste
- add chemicals to make it acceptable to customers
- blending to adjust water quality
7. FINISHED WATER
- safe + reliable, distributed
8. DISTRIBUTION
- pipelines, pumps, storage tanks
- when new plant = must connect to pipeline system
→ if far = conveyance/transmission system
REVERSE OSMOSIS (RO)
- applying pressure on high-salinity side to remove salts
- uses pressure to force water across semi-permeable membrane from saline water side to the
desalinated product water side, leaving salts behind (brine)
OTHER DESALINATION TYPES
- thermal distillation process
- MSF: multi-stage flash
- MED: multiple-effect distillation
SOLID WASTE DISPOSAL
- brine released at area with fast flow to avoid high concentrated spots (but still affects
ecosystem)
- solids hauled to landfills
- liquid waste (particles/cleaning chemicals mixed w/ brine waste)
CONCENTRATION/BRINE MANAGEMENT
- brine = by-product of desalination
- reject, waste water
- salinity greater than brackish water/seawater (x2 more)
- if brine reclaimed for use → zero-discharge process
- methods of disposal:
- discharge to surface water (ocean)
- subsurface injection into deep water-aquifer
- land application irrigation
- thermal evap.
- solar evap. Ponds
PLANNING MANAGEMENT
- eliminate need for additional facilities to transport water over long distance
- provide direct + easy management to assist in meeting growing water demand
4 TOOLS + APPLICATIONS
GPI
- Quality of environment
- Think about future generations → will they be able to sustain themselves?
- Beyond economic development, doesn't merely indicate economic growth
- Economic growth doesn't necessarily indicate well-being or quality of life
- Determine trade-offs
- Marine life
- dumping high concentrated salt = easier for water to warm up
POLITICAL-ECONOMIC APPROACH
See image on left
REDEMPTIVE TECHNOLOGY
1. Technology is not neutral
2. Technology is not preordained
3. Technology can be holistic/prescriptive
4. Technology must be understood as practice, cultural expression
Franklin's 7 Criteria for Classifying the Nature of Redemptive Technologies
1. Does it promote justice?
2. Does it restore reciprocity?
3. Does it confer divisible or indivisible benefits?
4. Does it favour people over machines?
5. Does it maximize gain/minimize disaster
6. Does it favour conservation over waste?
7. Does it favour the reversible over the irreversible?
- By rethinking existing technologies associated with the SCALE and the APPROPRIATENESS of
"useful" prescriptive technologies
- Using existing technologies in a CHANGED structure for a changed task (e.g. nuclear energy, tar
sand development); to PREVENT pollution; and develop technology from the study of things that
WORK
- Technologies directed at solving the unmet needs of society that is developed from the
BOTTOM-UP
BEST PRACTICES
The ecosystem approach (4 core elements)
- To resource management and planning is comprised of major elements…
Knowledge
Of the physical environment and human society including different knowledge systems, the concept
of scarcity
Connectivity
The complexity and interrelationships of human-environment interactions
Uncertainty
About natural systems and the evolution of environment, economy and society
Stakeholders
Recognizing and incorporating the range of interests and concerns when making resource decisions
Managing Uncertainties
Assess factors necessary to maintain biodiversity, ecological integrity and health by…
Creating accurate inventories and developing indicators
Assessing ecosystem resiliency and vulnerability
Monitoring over time (to determine carrying capacities) and over the long term
Doing risk assessments
o ENGAGE in conflict resolution
o DETERMINE trade-offs
o APPLY the precautionary principle
PROS AND CONS
Pros
1. Method proven and effective
2. Method highly understood
3. Massive amount of ocean water as source
4. Not dependent of changing factors/reliable
5. Facilities safely located
Cons
1. Expensive
2. Costly process
3. Requires a lot of energy to process
4. Contributes to world's GHG
5. Brine
6. Risk in producing contaminated water
- Changes the salt concentration in the ocean
○ Red in colour
- Should use as supplement,
not as a source
- Pressure = 1000 psi
- Needs good stewardship
- 97% of the water is seawater
- 2% locked in icecaps
- 0.5% avaliable fresh water supply
- rest is inaccessible
- Constraints of high desalination cost → many countries unable to afford as a fresh
water resource
- Seawater desalination process separates saline seawater into 2 streams
○ A freshwater stream containing low concentration of dissolved salts
○ Concentrated brine stream
- Process req. energy to desalinate + uses diff. technologies for separation
- Technologies are advanced enough to be a reliable source for fresh water →
research + development continues to improve tech. and reduce cost
- Seawater unsuitable for human consumption, industrial/agricultural use
- Removing salts → desalination → fresh water
- Middle east relies on desalination for meeting fresh water needs
○ Saudi Arabia, USA, United Arab Emirates, Spain, Kuwait
○ Over million people worldwide get freshwater from this method
○ = over desalination plants with total of million m/day
- RO tech. increasing over years due to lower cost
Development that meets the needs of the present without compromising the ability of
future generations to meet their own needs
- Essential needs of the world's poor
- The idea of limitations imposed by the state of technology and social organization
on the environment's ability to meet present and future needs
Parameters for saline water:
- Fresh water → 1000ppm
- Slightly → 1000-3000 ppm
- Moderate → 3000-10000 ppm
- Highly → 10000-35000 ppm
(seawater)
- Solar desalination used by
nature to produce rain is the
main source of fresh water on
earth
- Man-made distillation systems
duplicate on a small scale of this
natural process
Document Summary
Seawater intrusion impacts (affects on living organisms) 2 types: surface intake + subsurface intake. Impingement: sufficiently large organisms caught in intake screen due to flow of water (e. g. crabs, fish) Req. on-going maintenance, excavation, dredging, embedment, pipe laying + anchoring. Minimize by sharing intakes w/ other facilities (e. g. power plants) Req. water that prevents erosion, membrane fouling (clogging)/excessive maintenance. Prevent debris, weed, algae, fish, shells, aquatic life, etc . Blend w/ other water for dilution, add chemicals, etc . Can be acidic/have minerals corrosive or unnatural taste. Add chemicals to make it acceptable to customers. Pumps to force water through ro membrane + energy recovery devices. When new plant = must connect to pipeline system. Pros: method proven and effective, method highly understood, massive amount of ocean water as source, not dependent of changing factors/reliable, facilities safely located. Cons: expensive, costly process, requires a lot of energy to process, contributes to world"s ghg, brine, risk in producing contaminated water.
