The Urban Environment

1
The Urban Environment

• Kara L. Nelson
• Civil and Environmental Engineering
• U.C. Berkeley
• Environmental Leadership Program
• Wednesday, July 9, 2003

2
Outline of Workshop 4

• 900-910 Introduction to the urban environment
  (Kara Nelson)
• 910-1030 Water problems in the urban
  environment (Kara Nelson)
• 1030-1045 Break
• 1045-1115 Appropriate technologies for water
  and wastewater treatment (Kara Nelson)
• 1115-1230 Public-private partnerships for
  provision of drinking water (David Levine)
• 1230-130 Lunch
• 200-245 Agricultural waste (David Zilberman)
• 245-530 Participant panel

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Urban Environmental Issues

• Water pollution
• Air pollution
• Solid waste
• Hazardous waste
• Land use changes
• Greenhouse gas emissions

4
Important Factors

• Geography, Topography, and Climate
• Precipitation water scarcity, flooding
• Temperature heating, air conditioning, survival
  of pathogens
• Meteorology dispersal of air pollution
• Institutional
• Provision of infrastructure and services
• Policies and enforcement
• Income/wealth
• As income increases, pollution near home
  decreases
• Types of pollution change with wealth

5
Source World Resources 1996-97 The Urban
Environment, World Resources Institute
6
Water problems in the urban environment
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Water problems in the urban environment

• I. Water pollution ? poor water QUALITY
• II. Water consumption ? insufficient water
  QUANTITY
• III. Land use changes ? decrease QUANTITY and
  QUALITY

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Impacts of urban water problems

• Water QUALITY
• Loss of aquatic habitat
• Contamination of drinking and bathing water
• Water QUANTITY
• Loss of aquatic habitat
• Subsidence of land surface
• Insufficient water for drinking and hygiene

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Outline of Presentation

• Describe each water problem and provide
  action-based solutions
• Focus on wastewater and drinking water treatment
  technologies

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Water Pollution - Pathogens

• Types of waterborne pathogens
• Viruses Hepatitis A, Enterovirus
• Bacteria Cholera, Salmonella
• Protozoa Entamoeba, Cryptosporidium
• Helminths (worms) Ascaris, Schistosomiasis
• Public health impact
• 4 billion cases of diarrhea/yr
• 5 million deaths/yr due to diarrheal disease
• Improved drinking water, sanitation, and hygiene
  would reduce diarrheal disease by 25-33

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Water Pollution Other types

• Types of water pollution (besides pathogens)
• Organic matter (BOD Biochemical Oxygen Demand)
• Nutrients (Nitrogen and Phosphorus)
• Pesticides
• Metals
• Sediment
• Environmental impact Loss of aquatic habitat
• Low dissolved oxygen (from BOD, N, P)
• Toxicity
• Public health impact contamination of drinking
  and bathing water with pathogens

12
Environmental Health and Public Health Are
Intimately Connected!

• Both can be protected by minimizing water
  pollution
• Top priority is provision of adequate collection,
  and treatment of human fecal waste

13
Water Pollution - Sources

• Human feces
• Direct deposit in environment
• Leaky latrine pits or septic tanks
• Discharge of untreated or inadequately treated
  wastewater
• Greywater (washwater from kitchen, bathroom,
  etc.)
• Industrial discharges
• Stormwater runoff (non-point source pollution)
• Solid waste

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Water quality in USA
Source USEPA National Water Quality Inventory
2000 Report
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Water quality in USA
Source USEPA National Water Quality Inventory
2000 Report
16
Source WHO and UNICEF Global Water Supply and
Sanitation Assessment 2000 Report
17
Source WHO and UNICEF Global Water Supply and
Sanitation Assessment 2000 Report
18
Source WHO and UNICEF Global Water Supply and
Sanitation Assessment 2000 Report
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Source WHO and UNICEF Global Water Supply and
Sanitation Assessment 2000 Report
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Water Pollution - Solutions

• Provide collection, treatment, and disposal of
  fecal waste and greywater for all households via
• Latrine or flush toilet and septic tank at each
  household
• Community sewer system AND treatment plant
• Require industries to collect and treat
  wastewater BEFORE it enters sewer system
• Reduce the non-point sources of pollution, or
  collect and treat stormwater runoff
• Collect solid waste and recycle, compost, or
  landfill

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Assessment of Water Quality

• Environmental health
• More next week during Workshop 6
• Public health - Fecal indicator organisms
• Total coliform bacteria
• Fecal coliform bacteria
• E. coli

22
Water Consumption - Environmental Impacts

• Depletion of groundwater resources
• Degradation of aquatic habitat (e.g., declining
  fish populations)
• Altered flow and temperature in rivers due to
  dams and reservoirs
• Loss of wetland habitat

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Water Consumption - Facts

• Largest use of freshwater is for agricultural
  irrigation
• Globally, about 2/3 of freshwater
• In some regions often more than 90 (e.g.,
  California, many developing countries)
• By 2025, 50 of global population may live in
  water-stressed regions (WRI)
• Per capita household consumption is higher in
  urban areas

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62 countries report per capita water use less
than 50 L/d (more than 1/3 of global population)
Source Gleick (2000) The Worlds Water
2000-2001
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Water Consumption - Solutions

• Conservation policies
• Metering of water use
• Equitable (incremental) price structure
• Conservation measures
• Household (Low-flow showerheads, toilets, washing
  machine, dishwasher) or waterless toilets
• Industrial
• Fix leaking water distribution systems (40 loss
  is typical)
• Wastewater reuse

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Wastewater Reuse (Reclamation, Recycling)

• Wastewater must be treated to protect public
  health and the environment
• Benefits
• Reduce consumption of freshwater
• Reduce water pollution (reduce discharge of
  wastewater)
• Examples
• Agricultural irrigation
• Landscape irrigation
• Industrial processes
• Aquifer recharge

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Recycled Water Service Area
12,000 acres irrigated with tertiary-treated
wastewater Crops include artichokes, lettuce,
broccoli, and strawberries
Monterey Bay
Monterey County, CA
30
Wastewater Irrigation in Mezquital Valley, Mexico
(using untreated wastewater from Mexico City)
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Land Use Changes Examples and Environmental
Impacts

• Increase in impervious surfaces
• Rainfall doesnt filter into soil
• Can cause both flooding and drought
• Washes pollution into surface waters
• Deforestation
• Can cause both flooding and drought
• Increased erosion, washes soil into surface
  waters
• Development in watersheds used for drinking water
• Contamination of drinking water
• May cause expensive treatment to be required

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Land Use Changes Solutions

• Preserve green space
• Use pervious surfaces for parking lots, roads,
  etc.
• Collect stormwater runoff in ponds and wetlands
  (retain and treat)
• Sustainable forestry management
• Manage development in watersheds used for
  drinking water (may be cheaper than treating!)

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Appropriate technology for water and wastewater
treatment
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Key Points

• Emphasis on WASTEWATER COLLECTION, TREATMENT and
  SANITATION (adequate disposal of feces)
• Protect the environment AND human health
• Lower cost of drinking water treatment
• Protect valuable natural resources
• Typical US approach may be inappropriate in other
  urban areas
• May not provide adequate removal or inactivation
  of pathogens
• Not developed using a risk-based approach (and
  therefore not necessarily cost-effective)

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West Point wastewater treatment plant, Seattle, WA
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Factors to consider in choosing an
approach/technology

• Decentralized (household or community) vs.
  Centralized (city)
• To sewer or not to sewer, that is the
  question
• Removal or inactivation of pathogens
• Energy use
• Costs construction and operation and
  maintenance
• Degree of operation and maintenance necessary
• Availability of replacement parts

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Household Sanitation

• When to use
• Only option if households do not have piped water
• Too expensive or no room to install sewer system
• Political unwillingness to provide services (like
  sewer)
• Advantages
• More affordable
• Does not require large amounts of water to carry
  wastes
• Opportunities for microenterprise
• Challenges (mostly due to high density!)
• Contamination of nearby wells or
  rivers/lakes/beaches
• No room to build another pit once the first one
  fills up
• Must also provide for disposal of greywater (wash
  water)

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Household Sanitation Technologies

• VIP Latrines (empty and treat)
• Pour-flush toilets (empty and treat)
• Bucket collection (collect and treat)
• Urine-separating latrines (treat onsite and
  reuse)
• Flush toilet

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Squatting platform
For more info www.sanplat.com
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Ventilated Improved Pit (VIP) Latrine
For more info Mara, D. (1996). Low-cost Urban
Sanitation, John Wiley Sons, Chichester,
England.
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Vacutug for emptying latrine pits
Vacutug demonstration in Kenya
For more info http//www.irc.nl/themes/sanitation
/smallpit.html
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Bucket system in Shanghai, China
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Ecological Sanitation

• Recognize that urine and feces are valuable
  resources (nutrients and organic matter)
• Provide treatment to prevent the spread of
  pathogens

• For more info
• Esrey, S. A., J. Gough, D. Rapaport, R. Sawyer,
  M. Simpson-Hebert, J. Vargas, and U. Winblad.
  (1998). Ecological Sanitation, Swedish
  International Development Cooperation Agency
  (SIDA), Stockholm. (http//www.worldbank.org/watsa
  n/topics/tech_sanitation.htmleconsan)

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Urine-Separating Latrines (aka Ecological Dry
Toilets)
For more info http//www.laneta.apc.org/esac/dryt
oilet.htm http//www.lboro.ac.uk/well/resources/we
ll-studies/full-reports-pdf/task0324.pdf
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Double vault system
From Esrey et al. (1998)
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Ecological dry toilet (Huajuapan, Mexico)
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Ecological dry toilet (San Juan Amecac, Mexico)
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Dry toilet microenterprise
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The Flush Toilet Dilemna
Most likely there is not enough room for the soil
absorption system ? Wastewater must be collected
and treated offsite Flush toilets should not be
installed unless a sewer system AND wastewater
treatment plant are also constructed!
From http//ohioline.osu.edu/aex-fact/0743.html
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Septic tanks
Bad (leaky)
Good (waterproof)
For more info about on-site wastewater treatment
http//www.nesc.wvu.edu/nsfc/
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From Mara, D., (1996). Low-cost Sewerage. John
Wiley Sons, Chichester, England.
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Wastewater Collection and Treatment

• Collection (Sewer system)
• Conventional
• Simplified sewerage
• Treatment
• Objectives
• Options

54
Small-diameter, shallow depth sewerage
Best for transporting settled wastewater (like
septic tank effluent), but can also be designed
for raw wastewater
For more info Mara, D., (1996). Low-cost
Sewerage. John Wiley Sons, Chichester, England.
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Wastewater Treatment Objectives

• Remove sediment
• Remove organic matter (BOD)
• Remove nutrients (N and P)
• Remove or inactivate pathogens

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Levels of Wastewater Treatment

• Level Objective
  _
  
  
• Pre-treatment Remove sand, grit, large objects
• Primary Remove suspended particles by
  sedimentation (BOD, N, P, and some pathogens)
• Secondary Remove dissolved BOD, N, and P by
  biological degradation (bacteria)
• Tertiary Additional treatment, specific to
  situation (nutrients, organics, colloids)
• Disinfection Inactivate pathogens

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Wastewater Treatment Technologies

• Wastewater Stabilization Ponds (WSP) The best
  option if land is available
• Typical US treatment plant (very expensive!)
• Sedimentation ? Activated Sludge ? Secondary
  Clarification ? Disinfection
• Anaerobic sludge digestion
• Other alternatives
• Advanced primary treatment (sedimentation with
  coagulation)
• Trickling filter instead of activated sludge
• Oxidation ditch instead of activated sludge
• Promising technologies
• Upflow Anaerobic Sludge Digester (UASB)
• Membrane Bioreactor (MBR)

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Wastewater Stabilization Pond System
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Wastewater Stabilization Pond in Xalostoc, Mexico
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Wastewater Stabilization Pond (Primary,
Secondary, some Tertiary treatment, and
Disinfection)
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Sedimentation Basin (Primary Treatment)
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Activated Sludge (Secondary Treatment)
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Secondary Clarifier (Secondary Treatment)
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Secondary Clarifier
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Sludge Digestion
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Drinking Water Treatment Objectives

• Pristine source (rare in urban environment!)
• Disinfection recommended but not necessary
• Examples Groundwater (wells), Spring, Rainwater
• Contaminated source (fecal pollution)
• Removal of particles recommended and disinfection
  necessary
• Examples River, Lake, Contaminated well or
  spring
• May need additional treatment for other
  contaminants
• Arsenic (Bangladesh) physicochemical treatment
  necessary
• Nitrate babies should not drink (blue baby
  syndrome)

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Drinking Water Treatment Technologies

• Removal of particles and some pathogens
• Sedimentation community or household
• Filtration
• Slow sand filter - community
• Biosand filter household
• Inactivation of pathogens
• Chlorination community or household
• UV community or household
• SODIS - household

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Sedimentation
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Slow Sand Filtration
Drained slow sand filter in foreground Operating
slow sand filter in background
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Household Filtration
The Biosand filter (www.cawst.org)
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Chlorination

• Most common type of disinfection
• Risks vs. benefits
• Disinfection by-products linked to cancer
• Risk of cancer MUCH lower than risk of pathogens
• Hypochlorite can be manufactured locally

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Ultraviolet (UV) Disinfection Community system
For more info www.waterhealth.com
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Ultraviolet (UV) Disinfection Household system
UV Tube installed in Patzcuaro, Mexico
For more info email nelson_at_ce.berkeley.edu
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Solar Disinfection (SODIS)
For more info www.sodis.ch
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Additional on-line resources

• Salazar, D. (2003). Guia para el manejo de
  excretas y aguas residuales municipales. USAID,
  PROARCA/SIGMA. (http//www.proarca.org/sitio/pags/
  pags.php?area5pghttp//data.proarca.org/publi_s
  igma.asp )
• WRI. World Resources 1996-97 The Urban
  Environment. World Resources Institute.
  (http//www.wri.org/wri/wr-96-97/96tocful.html )