What is Environmental Engineering?

“The application of science and engineering

principles to minimize the adverse effects of
human activity on the environment.”
Or
application of fundamental scientific principles to the
development and implementation of technologies needed to
satisfy human needs without affecting natural Ecosystem

Environmental Science

Environmental Engineering
 Major Environmental Problems
Urbanization

– radical shift from a rural to an urban society

– essential outcome of industrialization
 Associated with:
– challenges to human security and sustainable development.
– rapid population growth and concentration of people and
industries.
– converting prime agricultural land into residential and
industrial uses
– construction of high-rise buildings and vertical commercial
development
 Causes of Urbanization
• Urban biased development strategies
• Rural-urban migration
• High birth and low mortality rates
The effects of urbanization on nature
• Complexity of environmental problems
• Over-population
• Growing demand for food and facilities
• Pollutants to air, soil and water
 Air pollutants
Water pollutants
 Solid wastes
 Noise
 Water Resources and urbanization
 Water resources
 Access to water
 Water quantity
 Water quality
 Salinity
 Acidity
 Organic and inorganic substances
 Microbiological and biological organism
 Water related diseases
 Sanitation and waste water treatment
 Water reliability and sustainability
 Groundwater
 Coastal waters
 Flooding
 Environmental Problems (…ctd)
Rapid Urbanization Challenges
• Inadequate sanitation, air and water pollution
• Inadequate housing and overcrowding
• Environmental degradation such as
deforestation, soil erosion etc.
• Climate change, food insecurity
• Competition for water and land
• Exposure to higher risks of accidents
• Crime and diseases e.g., HIV/AIDS
• Poverty and deprivation and natural disasters
 Environmental Problems (…ctd)
Human and Environmental Outcomes of Rapid Urbanization
 Chapter 2

Water Pollution and Its Control

 Water Quality Definitions
• Contaminant - any constituent in the water
harmful to a particular end use regardless of its
origin and whether it occurs in the watershed,
source or in a water supply system
• Pollutant - any constituent in the water source
deleterious to a particular end use that is of
anthropogenic origin
• Pollutant = subset of contaminant

Contaminants
Contaminants
Pollutants
 Water Pollution
Pollution = the release of matter or energy into the environment
that causes undesirable impacts on the health and well-being of
humans or other organisms.
Water Pollution: Any chemical, biological and/or physical change in
water quality that has a harmful effect on living organisms or makes it
unsuitable for its desired uses
 The massive quantity of pollutants produced by > 6 billion
humans, their machines, plants, animals
 The limited supply of fresh liquid water into which most water-
destined pollutants are discharged
 The growing number of ‗technological pollutants‘ released into
the environment, i.e. manufactured synthetic materials
• Global problem
• According to the WHO, 1 in every 5 people on Earth don‘t have
access to clean drinking water. Every day 9300 people die from
infectious diseases from contaminated water.
Surface (Coastal/Ocean) Water Pollution
 Polluted Streams
• Factors influencing stream recovery from pollution
• Oxygen sag curve
• Importance of wastewater treatment plants- so you don‘t put
contaminated water back into streams, lakes, and bays
• Improvements in quality of US streams- water pollution control
laws in 1970 increased the amount of wastewater treatment plants
in the US
• Cuyahoga River of Ohio- Caught fire twice in a ten year span.
Resulted in new laws prohibiting the discharge of industrial
wastes into rivers
• Effect of regulations in US- cleaner streams, loss of pollution
• Problems with nonpoint, accidental and illegal releases- can‘t
really stop it easily
• Problems in developing countries- Half of the world‘s 500 rivers
are heavily polluted, most of them going through developing
countries. Only 10% of sewage from Chinese cities is treated.
 Pollution of Surface Water: Streams
 D.O., B.O.D., fecal coliform bacteria count
 Lake Pollution
• Dilution less effective than with streams
• Stratification (layers in the lake) and relatively little flow hinder rapid dilution
of pollutants
• Lakes more vulnerable to pollutants than streams
• How pollutants enter lakes- runoff from watersheds, farmland, animal feedlots,
urban areas, mining sites, sewage
• Eutrophication: name given to the natural nutrient enrichment of lakes mostly
from runoff of plant nutrients such as nitrates and phosphates from surrounding
land. In hot weather or drought the nutrient overload produces algae, creating
green lakes.
• Oligotrophic lake- low in nutrients (clear)
• Eutrophic lake- green lakes
• Cultural eutrophication- Human activities accelerate the input of plant
nutrients.
• Preventing or removing eutrophication
– Advanced waste treatment to remove nitrates and phosphates
– Ban or limit the use of phosphates in household detergents
– Employ soil conservation and land use control to reduce nutrient runoff
 Pollution of Lakes
• Eutrophication
Discharge of untreated
municipal sewage Nitrogen compounds
(nitrates and phosphates) produced by cars
and factories

Natural runoff
Discharge of (nitrates and
detergents phosphates
( phosphates)

Manure runoff
From feedlots
(nitrates and
Phosphates,
Discharge of treated ammonia)
municipal sewage
(primary and secondary
treatment:
nitrates and phosphates)
Runoff from streets,
lawns, and construction
Lake ecosystem lots (nitrates and
nutrient overload phosphates)
and breakdown of
chemical cycling

Runoff and erosion

Dissolving of (from from cultivation,
nitrogen oxides mining, construction,
(from internal combustion and poor land use)
engines and furnaces)
 Oligotrophic and Eutrophic Lakes

Oligotrophic (clear lakes) Eutrophic (green lakes)

 Lake pollution (...ctd)
Classification by trophic level (biological condition):

Trophic lake classification based on the primary source of carbon

Groundwater Pollution: Causes and Persistence

• Sources of groundwater pollution: oil spills, paint thinners,

sewage, hazardous wastes injection wells, waste lagoons, landfills
• Slow flowing: Groundwater flows so slowly (1 foot per day) that
contaminants are not diluted and dispersed effectively.
• Consequences of lower dissolved oxygen: dissolved oxygen
helps decompose many contaminants
• Fewer bacteria to decompose wastes
• Cooler temperatures: slow down chemical reactions
• ―Degradable‖ and non-degradable wastes in groundwater
Extent of Groundwater Pollution
• Not much is known about groundwater pollution
• Organic contaminants, including fuel leaks
• Arsenic- contaminates drinking water that comes from
underground wells
• Protecting groundwater: Prevention is best
 Gd Water Pollution
Leaking
tank

Water
table

Groundwater
flow
Free gasoline
Gasoline dissolves in
leakage plume groundwater
(liquid phase) (dissolved Migrating
phase) vapor phase
Contaminant plume moves Water well
with the groundwater
 Groundwater Pollution
Polluted air

Hazardous
waste injection
Pesticides well
and fertilizers
Coal strip De-icing
road salt Buried gasoline
mine runoff and solvent tank

Pumping Gasoline station

well
Water Cesspool
Waste lagoon pumping well septic tank
Sewer
Landfill
Leakage
Accidental from faulty
spills casing

Discharge

Confined
aquifer

Groundwater
flow

Fig. 11-26, p. 258

 Ocean Pollution
• How much pollution can oceans tolerate? Oceans can dilute,
disperse, and degrade large amounts of pollutants, especially
in deep ocean areas
• Ocean dumping controversies
– Some scientists think that it is best to dump pollutants in
deep water instead of burying them.
– We don‘t know enough about the ocean so we may not
know the harmful effects in the long run
• Most ocean pollution comes from human activities on land
such as changing and dumping motor oil, by cities, industries,
and people.
• Oil pollution can have a number of harmful ecological and
economic effects, but most disappear within 3 (crude oil) to 20
(refined oil) years.
 Sources of Water Pollution
• The surface water and groundwater systems
• Surface water is the water we see in streams, rivers,
wetlands, and lakes across the country. Every square mile of
ground drains into one of these bodies of water. The area
drained is known as a watershed. As smaller creeks and
rivers feed into larger ones, the size of the watershed
increases.
• While surface water is found in the form of rivers and lakes,
groundwater is stored in aquifers. Aquifers are formations
of cracked rock, sand, or gravel that hold water and yield
enough water to supply wells or springs. More than 95
percent of the world‘s usable water resources are stored in
its groundwater.
 Sources (…ctd)
Natural sources
Human-generated
Point source: specific source
Nonpoint source
Polluted runoff
Enters over a large area

NPS Pollution
• Agriculture
– 72% of water pollution
– Fertilizers, pesticides, manure
– Soil erosion
• Urban runoff
– Variety of contaminants
 Sources of Water Pollution (Cont)
• Non-point source pollution (Diffuse pollution): refers to
pollutants that come from a widespread area and cannot be
tracked to a single point or source.
• Soil erosion, chemical runoff, and animal waste pollution are all
examples of non-point source pollution.
• Non-point source pollution is major water quality problem by
sheer volume and in terms of current and future economic costs
to nation.
• Nonpoint sources- pollution from multiple cumulative inputs over
a large area or scattered and diffuse and can‘t be traced to any
single site of discharge
– Farms, cities, streets, neighborhoods
 Sources of Water Pollution (Cont)
• Point source pollution – also known as ―the end
of the pipe pollution‖– can be traced to a specific
source, such as a leaking chemical tank, effluents
coming from a waste treatment or industrial plant,
or a manure spill from a hog confinement lagoon.
• Although this may seem easy to control, there are
economic, political, and other factors involved.
• For known point source pollution threats,
households, communities, industry, and
agribusiness must deal with the problem of
disposing of wastes and by-products.
• Point sources- discharge pollutants from specific
or discrete locations.
– Factory or sewer pipes
Point and Nonpoint Sources (…ctd)
 Sources (…ctd)
NONPOINT SOURCES

Rural homes

Urban streets Cropland

Animal feedlot

Suburban POINT
development SOURCES
Factory

Wastewater
treatment
plant
 Sources of water pollution

POINT SOURCES NONPOINT SOURCES

Power plants: Agricultural runoff
Heated water Sediments, fertilizers,
pesticides, organics,
Feedlots
T microorganisms
Organics, solids,
nutrients, Mining
Water body
microorganisms Suspended solids, acid-
Industries mine drainage
Organics, chemicals, T
Urban runoff
color and foam, salts,
toxins, heated water Litter, sediments,
Municipalities organics, nitrogen,
phosphorus, heavy metals,
Domestic wastewater: T petroleum substances,
Microorganisms, microorganisms
nitrogen, phosphorus
Differences b/n point and nonpoint sources of pollution

Point sources Nonpoint (diffuse) sources

• Single or multi-point location • Diffuse, source not easily located
• Discharge contains pollutants • Highly variable in time and
• Volume of discharge generally correlated with weather
unaffected by weather • Prevention more effective (more
• Permit may be required to difficult to treat)
discharge • Largely unregulated, hence,
• Controls required (usually through voluntary
water treatment)
Cont...
 Sediment Erosion and the Pollutant transport Process
Types of Erosion That May Contribute to Nonpoint Source
Pollution
 Types of Water Pollution
• Disease-causing Agents – pathogens

• Oxygen Demanding Agents – organic waste: manure

• Inorganic Plant Nutrients – nitrogen and phosphorus

• Sediment or Suspended Material – erosion, soil

• Toxic Chemicals – acids, heavy metals, organics

• Heat (Thermal)– electric and nuclear power plants

Major Water Pollutants and Their Sources
 Pathogens and Waterborne Diseases
• Enters water supply via inadequately treated human waste
and animal waste via feedlots
• Causes more human health problems than any other type of
water pollution
• Fecal coliform bacteria indicate fecal contamination of
water
– The water can hold other pathogens, such as giardiais,
typhoid, hepatitis A
• Disease symptoms usually are explosive emissions from
either end of the digestive tract
 Waterborne Pathogens

Giardia sp.*

Escherichia coli
Vibrio sp.
Indicator Tests

Total coliform Fecal coliform Fecal streptococci

[Endo agar] [m-FC agar] [M-enterococcus] Prescott et al.,
Microbiology
 Pathogens cause massive human health problems

• Currently, 1.1 billion people are without safe

drinking water
• 2.4 billion have no sewer or sanitary facilities
– Mostly rural Asians and Africans
• An estimated 5 million people die per year
• Solutions:
• Treat sewage
• Disinfect drinking water
• Public education to encourage personal hygiene
• Government enforcement of regulations
 Biological Oxygen Demand (BOD)
• BOD: Oxygen is removed from water when organic
matter is consumed by bacteria.
• Low oxygen conditions may kill fish and other organisms.

Sources of organic matter

• Natural inputs-- bogs, swamps, leaf fall, and vegetation
aligning waterways.
• Human inputs-- pulp and paper mills, meat-packing
plants, food processing industries, and wastewater
treatment plants.
• Nonpoint inputs-- runoff from urban areas, agricultural
areas, and feedlots.
Water Quality as Measured by DO Content in Parts
per Million
 Nutrient pollution

• Nutrient pollution from fertilizers, farms,

sewage, lawns, golf courses
– Leads to eutrophication
• Solutions
• Phosphate-free detergents
• Planting vegetation to increase nutrient uptake
• Treat wastewater
• Reduce fertilizer application
 Sediment pollution

• Sediment can impair aquatic ecosystems

– Clear-cutting, mining, poor cultivation practices
– Dramatically changes aquatic habitats, and fish may
not survive
– Solutions: better management of farms and forests;
avoid large-scale disturbance of vegetation
 Toxic chemicals
• From natural and synthetic sources
– Pesticides, petroleum products, synthetic chemicals
– Arsenic, lead, mercury, acid rain, acid drainage from mines
• Effects include: poisoning animals and plants,
altering aquatic ecosystems, and affecting human
health
• Solutions:
• Legislating and enforcing more stringent regulations of
industry
• Modify industrial processes
• Modify our purchasing decisions
 Thermal pollution
• Warmer water holds less oxygen
– Dissolved oxygen decreases as temperature increases
– Industrial cooling heats water
– Removing streamside cover also raises water
temperature
• Water that is too cold causes problems
– Water at the bottom of reservoirs is colder
– When water is released, downstream water
temperatures drop suddenly and may kill aquatic
organisms
 Causes of Water Pollution

1. Factories throw their waste in water bodies.

2. People bath and wash clothes in water bodies.
3. Some oil ships drown in water which hardly effects the aquatic
life.
4. Smoke from vehicles lets the river to dry.
 Effects of Water Pollution
(Effects of Oil on Ocean Life)
• Crude and refined petroleum- most oil pollution comes from human
activities on land
• Tanker accidents and blowouts
• Exxon Valdez- tanker that spilled oil into Alaska‘s Prince William
Sound (waterway)
• Volatile hydrocarbons kill larvae- hydrocarbons immediately kill
aquatic organisms
• Tar-like globs coat birds and marine mammals
• Oil destroys insulation and buoyancy
• Heavy oil sinks and kills bottom organisms
• Coral reefs die
• Slow recovery
• Oil slicks ruin beaches
• Limited effectiveness of clean up methods
 Water Quality/Pollution Indicators
• Scientists measure properties of water to characterize its
quality.
– Physical indicators: temperature, odour and taste, colour,
turbidity, transparency, water conductivity, suspended solids (Total
Solids (TS), Total Suspended Solids (TSS), Total Dissolved Solids
(TDS), Volatile Solids (VS)) and dry residua.
– Chemical indicators: Acidity, pH, alkalinity, salinity, hardness,
redox-potential, dissolved or saturated oxygen (DO), Chemical
Oxygen Demand (COD); Biochemical Oxygen Demand (BOD);
metals such as zinc (Zn), iron (Fe), calcium (Ca), magnesium
(Mg), silica (Si), copper (Cu), manganese (Mn), nickel (Ni) and
Boron (B) processing,Principal inorganic ions, Trace constituents,
Synthetic organic matters.
 Water Quality Indicators (… ctd)
– Nutrients: nitrogen, phosphorus, silica, nitrates (NO3),
nitrite (NO2), phosphate (PO4), silica (SiO2) and ammonia
(NH3) .

– Biological indicators: presence of disease-causing

organisms (Total coliforms, E.coli, Plants and animals);
benthic macro-invertebrate diversity: phytoplankton
(Bacillariophyceae, Cyanophyceae, Chlorophyceae)
counted per liter.

– Microbiological indicators: bacteria and fungi

Water Pollution Control (WPC)

WPC at Source-Water Pollution Prevention

Preventing and Cleaning Up Groundwater Pollution
Prevention Clean-up
Find substitutes for toxic chemicals Pump to surface, clean, and
return to aquifer (very
expensive)
Keep toxic chemicals out of the environment Inject microorganisms to
clean up contamination (less
expensive but still costly)
Install monitoring wells near Pump nano-particles of
landfills and underground tanks inorganic compounds to
Require leak detectors on underground tanks remove pollutants (may be
Ban hazardous waste disposal the cheapest, easiest, and
in landfills and injection wells most effective method but is
Store harmful liquids in aboveground tanks still being developed)
with leak detection and collection systems
 Preventing ground water pollution …
 Monitoring
Mrs aquifers - expensive
- expensive
 Leak detection systems
 Strictly regulating hazardous waste disposal
 Protecting recharge areas
- aquifer classifications
 Storing hazardous materials
above ground
 Preventing and Cleaning Up Pollution in
Groundwater
Solutions
Groundwater Pollution
Prevention Cleanup

Find substitutes for toxic Pump to surface, clean,

chemicals and return to aquifer
Keep toxic chemicals out of the (very expensive)
environment
Install monitoring wells near
landfills and underground tanks Inject microorganisms to clean
up contamination (less
Require leak detectors on expensive but still costly)
underground tanks
Ban hazardous waste disposal Pump nanoparticles of
in landfills and injection wells inorganic compounds to
remove pollutants (may be the
Store harmful liquids in cheapest, easiest, and most
aboveground tanks with leak effective method but is still
detection and collection systems being developed)

Fig. 11-27, p. 259

Preventing and Reducing Surface Water Pollution
Nonpoint Sources Point Sources
 Reduce runoff
 Water Pollution
 Buffer zone vegetation
Control Act (1972)
 Reduce soil erosion
 Clean Water Act
 Storm water BMP requirements:
allow storm-water to infiltrate (1977)
allow storm-water reuse - set effluent standards
reduce runoff - secondary treatment
fit existing landscaping
 Rain gardens, Tree trenches, Landscape
conversions (lawn to fields, planting areas,
reforestation), Cisterns, and Water quality inlets

Reduce non-point pollution by preventing it from

reaching bodies of surface water.
Reduce soil erosion (cover crops/soil conservation) and
the amount of fertilizer (slow-release/none on sloped
land/plant buffer zones of plants) that runs off.
 Preventing Nonpoint Source Pollution
Approaches for controlling nonpoint source pollution include:
• Reducing agricultural wastes (limiting broad application of pesticides
(use pesticides only when necessary), herbicides, and fertilizer);
• Improving urban storm water management systems;
• Restoring wetlands to help absorb and filter runoff ;
• regulating land uses (Use vegetation to reduce soil erosion, Use plant
buffer zones around fields, Use plant buffers around animal feedlots
and Keep feedlots away from slopes, surface water and flood zones
• No-till and minimum-till farming, Contour farming, Terraces, Grassed
waterways, Grasses and filter-strips along streams and river banks.
• Sets standards for allowed levels of key water pollutants and requires
polluters to get permits ( for both point and nonpoint source pollution)
www.learner.org
Preventing and Cleaning Up Pollution in Coastal Waters

Prevention Cleanup
Reduce input of toxic pollutants Improve oil-spill cleanup
capabilities
Separate sewage and storm lines Sprinkle nano-particles over
Regulate coastal development an oil or sewage spill to
dissolve the oil or sewage
Protect sensitive areas from development,
without creating harmful
oil drilling, and oil shipping.
byproducts
(still under development)
Ban dumping of wastes and sewage by Require at least secondary
maritime and cruise ships in coastal waters treatment of coastal sewage
Ban ocean dumping of sludge and Use wetlands, solar-aquatic, or
hazardous dredged material other methods to treat sewage.
Require double hulls for oil tankers
 Reducing Water Pollution
•Prevent groundwater and surface water contamination
•Reuse treated wastewater for irrigation
•Find substitutes for toxic pollutants
• Work with nature to treat sewage (using various
organisms and wetlands)
•Practice 3 R's of resource use (reduce, reuse, recycle)
•Reduce resource waste
•Reduce air pollution
•Reduce poverty
•Reduce birth rates to limit population growth
 What Can We Do to Prevent Water Pollution?
•Fertilize our garden and yard plants with manure or compost
instead of commercial inorganic fertilizer.
•Minimize our use of pesticides.
•Never apply fertilizer or pesticides near a body of water.
•Grow or buy organic foods.
•Compost our food wastes.
•Do not use water fresheners in toilets.
•Do not flush unwanted medicines down the toilet.
•Do not pour pesticides, paints, solvents, oil, antifreeze, or other
products containing harmful chemicals down the drain or onto the
ground.
What Can We Do …?

1.Factories should not throw their waste in water bodies.

2.People should not bath and wash clothes in rivers or lakes.
3.People should not take their animals to take bath in rivers or
lakes.
 What Can We Do to Reduce Water Waste?
• Redesign manufacturing processes to use less water
• Landscape yards with plants that require little water
• Use drip irrigation
• Fix water leaks
• Recycle water in Industries
• Use water meters and charge for all municipal water use
• Use waterless composting toilets
• Require water conservation in water-short cities
• Use water-saving toilets, showerheads, and front-loading cloth washers
• Collect and reuse household water to irrigate lawns and non-edible plants
• Purify and reuse water for houses, apartments, and office buildings
• Raise water price.
 For a Sustainable Use of Water
 Not depleting aquifers;
 Preserving ecological health of aquatic systems;
 Protecting forests, wetlands, glaciers, watersheds, and other systems
storing and releasing water;
 Agreements among regions and countries sharing surface water
resources;
 Outside party mediation of water disputes between nations
 Marketing of water rights;
 Raising water prices and Wasting less water;
 Decreasing government subsidies for supplying water and increasing
government subsidies for reducing water waste;
 Slowing population growth;
 Reducing Blue revolution;
 Cut waste;
 Drier waste treatment.
Water Treatment as a Tool for WPC
Municipal Water Purification Plant
 Water Treatment Stages
Depending on the type of treatment plant and the
quality of raw water, treatment generally proceeds
in the following sequence of stages:
1. Screening 5. Sedimentation
2. Aeration 6. Pre-chlorination and
dechlorination
3. pH correction 7. Filtration
4. Coagulation and 8. Disinfection
flocculation 9. pH adjustment

• As required, adsorption or other advanced process will be

added, depending on the chemistry of the treated water.
 Initial Stages
• Screening - the removal of any coarse floating
objects, weeds, etc. from the water.
• Aeration - dissolving oxygen into the water to
remove smell and taste, promote helpful bacteria to
grow, and precipitate nuisance metals like iron and
manganese.
• pH correction - preparing for coagulation and to help
precipitate metals.
 Major Clean Up
• Coagulation and flocculation - causes the
agglomeration and sedimentation of suspended solid
particles through the addition of a coagulating agent
(usually aluminum sulfate and/or iron sulfate) to the
raw water along with a polymer to help form a floc.
• Sedimentation - Floc settles out and is scraped and
vacuumed off the bed of large sedimentation tanks.
Clarified water drains out of the top of these tanks in a
giant decanting process.
• Pre-chlorination and dechlorination - mostly to kill
algae that would otherwise grow and clog the water
filters. Also kills much of the remaining unprotected
bacteria.
 Coagulation

• Rachel Casiday, Greg Noelken, and Regina Frey, Washington University

(http://wunmr.wustl.edu/EduDev/LabTutorials/Water/PublicWaterSupply/PublicWaterSupply.html)
isis.csuhayward.edu/alss/Geography/
 Sedimentation

• Rachel Casiday, Greg Noelken, and Regina Frey, Washington University

(http://wunmr.wustl.edu/EduDev/LabTutorials/Water/PublicWaterSupply/PublicWaterSupply.html)
isis.csuhayward.edu/alss/Geography/
 Filtering Out What‘s Left
• Either slow or rapid filtration (depends on size of
plant/volume of water considerations)
• Rapid-sand filters force water through a 0.45-1m
layer of sand (d=0.4-1.2mm) and work faster,
needing a smaller area. But they need frequent back-
washing
• Slow-sand filters (d=0.15-0.35mm) require a much
larger area but reduce bacteriological and viral levels
to a greater degree due to the Schmutzdecke layer.
The top 1 inch must be periodically scraped off and
the filter occasionally back-washed
Filtration
 Final Touches
• Disinfection - water completely free of suspended
sediment is treated with a powerful oxidizing agent
usually chlorine, chlorine then ammonia (chloramine),
or ozone.
– A residual disinfectant is left in the water to prevent
reinfection.
– Chlorine can form harmful byproducts and has suspected
links to stomach cancer and miscarriages.
– Many agencies now residually disinfect with Chloramine.
• pH adjustment - so that treated water leaves the plant
in the desired range of 6.5 to 8.5 pH units.
 Additional Steps
• Heavy metal removal: most treatment plants do
not have special stages for metals but rely on
oxygenation, coagulation and ion exchange in
filters to remove them. If metals persist, additional
treatment would be needed
• Troublesome organics: Activated carbon filters
are required where soluble organic constituents are
present because many will pass straight through
standard plants, e.g. pesticides, phenols, MTBE
and so forth
 Wastewater Treatment as a Tool for WPC
Treatment Methods:
 There are various levels of treatment that prevent raw
waste products from being dumped into surface waters.
Industrial wastes may require special treatment to
remove harmful chemicals before re-entering the water
system.
 For the more common problem of organic wastes, the
three main treatment methods for treating waste water
are:
septic systems, lagoons, and sewage treatment plants.
• Each method must be properly sized so that the
treatment system is able to handle the volume of waste
entering it.
• Septic systems are designed for individual households,
• lagoons may meet the needs of small towns, and
• sewage treatment facilities are necessary for controlling
pollution.
 P2 by Treatment …
1. Septic systems
• Septic systems are generally used in rural areas to handle household wastes.
They usually use a large tank buried in the ground to contain and break
down household sewage. Attached to the tank is a series of perforated pipes
that are buried in a drain field and are usually surrounded by crushed rock or
gravel to facilitate drainage. Fats, oils, and grease, as well as large waste
particles, are stored and later pumped out of the holding tank, while the
water and suspended solids in the water flow into the soil through the
perforated pipes. The soil around the septic system filters many harmful
compounds, and bacteria break down organic matter.
• STANDARD: Septic systems are most popular in rural and suburban areas
and must be located in soils that meet standards for percolation or the ability
to drain away water. standards require a maximum percolation rate of one
inch of water in 60 minutes. A slow percolation rate allows soil bacteria to
break down wastes as they move into soil layers.
• CONCERN: Septic systems are generally a greater source of concern for
groundwater pollution than for surface water pollution. However, septic
systems are a real concern for surface water pollution when they are located
near lakes, rivers, and streams. Of particular concern are lakes with high
concentrations of tourist homes.
 Technological Approach: Septic Systems
Require suitable soils and maintenance
 TREATMENT …
2. Lagoons
• Many communities, feedlot operators, and industries use lagoons
to control wastes. A lagoon is simply one or a series of shallow
holding pits into which wastes are pumped and treated. In a well-
designed lagoon system, the material is aerated so bacteria can
break down the organic matter.
• STANDARD: In municipal lagoons, the water generally stays in
the lagoon for at least 30 days for this process to be completed.
Then the water is removed and treated with chlorine as needed to
destroy remaining bacteria. The remaining solids must be
disposed of by spreading on farm fields or burying.
• CONCERN: Lagoons are inexpensive to construct and operate
compared to other systems. However, poorly constructed
lagoons and lagoons built where the water table is very high
have been found to leak. The most often found contaminant
tends to be nitrates.
 Treating Sewage by Working with Nature
Technological Approach: Using Wetlands to Treat Sewage
 TREATMENT …
3. Treatment plants
We usually require two levels of sewage treatment.
• Primary sewage treatment simply filters out unwanted items
such as sticks, stones, garbage, and other debris that arrive at the
treatment plant and allows time for the solid materials to settle
out.
• Secondary treatment uses aeration and aerobic, or oxygen-
using, bacteria to break down organic wastes. The water is then
treated with chlorine to kill bacteria and discharged into adjacent
rivers and streams.
• Treatment plants remove approximately
 90 percent of the organic waste and suspended solids,
 less than 70 percent of the toxic metals and synthetic organic
chemicals,
 50 percent of the nitrogen in the form of nitrates, and
 30 percent of the phosphorus in the form of phosphates.
• CONCERN: This remaining discharge is still high in nutrients
and is not pure water entering the surface water. More advanced
treatment systems are available, but they are rarely used due to
their high cost. The remaining sludge is sent to a landfill as waste
or applied to the land as a soil additive.
 Technological Approach: Sewage
Treatment
Mechanical and biological treatment
Reducing Water Pollution through Sewage Treatment
 Wastewater Treatment Objectives
• Wastewater treatment systems take human and
industrial liquid wastes and make them safe
enough (from the public health perspective) to
return to the aquatic or terrestrial environment.
• In some cases, wastewater can be clean
enough for reuse for particular purposes.
• Wastewater treatment systems use the same
processes of purification that would occur in a
natural aquatic system only they do it faster
and in a controlled situation.
 Sewage or Wastewater Treatment
• Sewage or wastewater is composed of
sewage or wastewater from:
– Domestic used water and toilet wastes
– Rainwater
– Industrial effluent (Toxic industrial water is
pretreated)
– Livestock wastes
** microbes degrade organic compounds
** elimination of pathogens occurs
 Wastewater Treatment

Types of treatment systems include: Septic

Tanks or Wastewater Treatment Plants
(WWTPs).
• Septic Tanks typically treat small volumes
of waste (e.g., from a single household,
small commercial/industral)
• WWTPs typically treat larger volumes of
municipal or industrial waste.
 Decentralized Alternatives
• In rural areas or in particular urban communities in the U.S.,
human wastewater will be treated through individual septic
tank systems (pumped or leachfield varieties)
• Wastewater is filtered, microorganisms killed and chemicals
adsorbed and/or diluted in its passage through the soils and
rocks of the leachfield
• In developing countries, urban wastewater is seldom treated
and instead flows raw through collectors to receiving water
bodies (like in the US 100 years ago)
• The solution for many developing nations is centralized
oxidation lagoon systems (but this needs space) or the use
of individual ventilated pit-latrines, especially for shanty
towns and rural villages
 Septic Tanks
• Approx. 22 million systems in operation ( 30% of US population)
• Suitability determined by soil type, depth to water table, depth to bedrock and
topography
• Commonly fail due to poor soil drainage
• Potential contaminants: bacteria, heavy metals, nutrients, synthetic organic chemicals
(e.g. benzene)
Overview of Wastewater Treatment Processes
 Sewage Treatment
Wastewater or sewage treatment is a multistep
process:
1. Primary Treatment (Physical Process)
– Removal of large objects using grates and
screens
– Settling to remove suspended solids (primary
sludge)
• flocculating chemicals are added to enhance
sedimentation
 BOD Effects on Water Quality

All streams have some capability to degrade organic waste.

Problems occur when stream is overloaded with biochemical
oxygen-demanding waste.
 Sewage Treatment

• Secondary Treatment (Microbial Process)

– Supernatant or primary effluent contains high
levels of dissolved organic load (Biological
Oxygen Demand)
– Aeration to stimulate aerobic degradation
• activated sludge reactor bacteria degrade organic
carbon to CO2
• trickling filter reactor
 Eutrophication
Accelerated results with human input of nutrients to a lake
 Sewage Treatment
• Tertiary Treatment (Physicochemical
Process) expensive process, sharply reduces
• Precipitation inorganic nutrients (PO4, NO3)

• Filtration
• Chlorination
• Treated water is discharged to waterways
• Used for irrigation
• Recycled into drinking water
 Sewage Treatment
Pathogen Removal by Activated Sludge
• More than 90% of E.coli. and Salmonella are
destroyed
• Bacteria are removed by inactivation, grazing by
ciliated protozoa, and adsorption to sludge solids
• Viruses are removed mainly by adsorption process
 Anaerobic Digestion of Sludge

• Sludges from the primary and secondary

treatment settling tanks are pumped into an
anaerobic digester
• Sludges contain cellulose, proteins, lipid and
other insoluble polymers
• Anaerobic bacteria digest the sludge to
methane and carbon dioxide
Legislative efforts reduce pollution
 Legislative efforts reduce pollution
• Federal Water Pollution Control Act (1972)
– Renamed the Clean Water Act in 1977
– Illegal to discharge pollution without a permit
– Standards for industrial wastewater
– Funded sewage treatment plants
• Because of legislation, the situation is much better
than it was
• Other nations have also reduced pollution
 Legal Attempts to Control Water Pollution

1. Clean Water Act 1977, now a state-federal partnership

2. The Porter-Cologne Water Quality Control Act 1987
3. Federal Water Pollution Control Act 1972 amended to
create:
4. Safe Drinking Water Act, 1974, amended 1996
5. London Dumping Convention (1975) is the international
treaty regulating disposal of wastes generated by normal
operation of vessels
 What is the optimal amount of
pollution? (If there is such a thing?)
• If pollution exceeds the
optimum amount of
pollution
– the harm done exceeds
the cost to reduce it.
• If pollution is small it may
cost too much to control
the small amount.
 Clean Water Act
• The Clean Water Act is a 1977 amendment to the Federal Water
Pollution Control Act of 1972
– Set the basic structure for regulating discharges of pollutants in the US
• The law gave EPA the authority to set water quality standards for
industry and for all contaminants in surface waters
• Attain water quality levels that make these waterways safe to fish
and/or swim in
• Restore and maintain the chemical, physical, and biological integrity
of the nation's water
• The CWA makes it unlawful for any person to discharge any
pollutant from a point source into navigable waters unless a
permit (NPDES) is obtained
• The amounts and types of pollutants than can be discharged or
allowed to run in to waters from watersheds are regulated
 Safe Drinking Water Act
• The Safe Drinking Water Act (1974) was
established to protect the quality of drinking
water in the U.S
• This law focuses on all waters actually or
potentially designed for drinking use, whether
from above ground or underground sources
 It is better to prevent pollution
• It is far better to prevent water contamination than treat it
• Other options are not as good:
– Removing just one herbicide from water costs $400 million
– Pumping, treating, and re-injecting it takes too long
• Restricting pollutants above aquifers would shift pollution
elsewhere
• Consumers can purchase environmentally friendly products
– Become involved in local ―river watch‖ projects
Prevention is better as it provides:
• Improved image,
• Reduced treatment, materials, disposal, compliance, Public
health & environmental costs,
• Reduced risk & liability,
• Reduced insurance costs.
 The best solution is prevention
• Just as there is no single source of water pollution, there is no single
answer to solve the problem. Once water has become contaminated, it is
very difficult, if not impossible, to clean. Surface water flows quickly, and
a pollutant will generally be diluted as it enters larger bodies of water.
However, even large bodies of water, such as the Gulf of Mexico near the
mouth of the Mississippi River, cannot tolerate many years of eroded soils,
increased nutrients, and chemical pollution.
• Groundwater, however, moves very slowly. In heavy clay layers or in
bedrock, water might only move several inches per year. Even in gravel
and sand aquifers, groundwater may move only several hundred to a
thousand feet per year. Once the water is polluted, it will spread out slowly
over a period of many years.
• Some problems, such as hazardous waste sites, require massive, expensive
clean-up procedures. With other problems, such as large manure spills,
little can be done but let the wastes become diluted as they reach larger
bodies of water.
• However, there are steps to take to reduce some of the most serious
problems such as siltation from erosion is passed legislative law to warn
deterrent
 Three Big Ideas
1. We can use water more sustainably by cutting
water waste, raising water prices, and protecting
aquifers, forests, and other ecosystems that store
and release water.
2. The key to protecting wetlands, lakes, streams,
rivers, and oceans is to reduce the flow of
pollutants from land and air, and from streams
emptying into ocean waters.
3. Reducing water pollution requires that we prevent
it, work with nature in treating sewage, cut resource
use and waste, reduce poverty, and slow population
growth.
Water Quality Modeling- General
• What is a model?
– A model is a simplified representation of
the real world
• Two types of models
– Conceptual
– Mathematical
 Conceptual Models
• What are they?
– Qualitative, usually based on graphs
– Represent important system:
• components
• Processes
• Interactions
– Initial step for mathematical model development
Conceptual Model Example
Atmosphere

DO

NBOD Nitrogenous CBODcarbonacious

SOD Settling
 Mathematical Models
• What are they?
– Mathematical equations that translate a conceptual
understanding of a system or process into quantitative terms
• Purposes of mathematical models of environmental pollutants:

– To better understand the fate and transport of chemicals

– To determine chemical exposure concentrations to aquatic organisms
and/or humans in the past, present, or future
– To predict future conditions under various loading scenarios or
management action alternatives
Categories of Mathematical Models
Type
Empirical Mechanistic
Mathematical descriptions based on
Based on data analysis theory

Time Factor
Static or steady-state Dynamic
Describe or predict system behavior
Time-independent over time

Treatment of Data Uncertainty and Variability

Deterministic Stochastic
Do not address data variability Address variability/uncertainty
Mechanistic Mass Balance Models

Mass inputs
Control Volume
Transport in (Water body)
Physical, chemical & Mass outflows
biological reactions Transport out

Transport
 Transport processes
• Advection: movement of a substance at the flow velocity

Figure 6
• Dispersion: mixing of substances within the water column
Fick’s laws (1D)

1st Law

Figure 7 2nd Law

 Selecting or Developing a Model
• Important first steps
– Define the question or problem to be addressed
with the model
– Determine appropriate spatial and temporal scales
– Identify important ecosystem components and
processes that must be considered to answer the
management questions
 Selecting or Developing a Model
• Some specific questions to ask
– Temporal scale
• Do I need to predict changes over time or are steady-state
conditions adequate?
• If time is important, do I need to look at
– Short-term change (e.g., daily, seasonal) or
– Long-term change (e.g., trends over years)?
– Spatial scale
• Is my question best addressed:
– On a regional scale (e.g., compare streams in a region) or
– By modeling specific processes within an individual system?
 Steps in Model Application
Purpose

Conceptual model Data, processes

Model selection Mechanistic, empirical

Forcings (e.g. flow rates, chemical concentrations,
Inputs temperature, sunlight)
types, resolution, values, format Calibration/validation data
Initial states, parameters
Performance criteria Graphical, objective (e.g. NSE, RMSE, R2 , Chi-square)

Calibration Automatic
Manual
Validation Split approach

Simulation Application

Based on Refsgaard, 1997

 Surface Water Quality Models
 Water quality models include two principal steps:
• Description of the flow and mixing process of the water that constitute
the surface water resulting in contaminant transport,
• Characterization of the chemical and biological transformations of
pollutants in the water column and associated sediments or biota.
 Key decisions in developing/selecting a SW quality model include:
1. Determining if a 0-, 1-, 2-, or 3-dimensional spatial model is appropriate
2. Determining whether transport is captured purely by advection terms or
dispersion is also to be included.
3. Determining if a separate hydraulic or hydrodynamic sub-model is used to
compute water flow profiles, depth, and velocity or whether the advection field
is instead entered into the model as exogenous input
4. Determining if separate transport calculations must be made for non-aqueous
phases, including particles and immiscible fluids
5. Selection of system boundaries and boundary condition types
6. Determining if a dynamic or steady-state calculation is needed
Surface Water Quality Models ...ctd
 Water Quality Standards
• In most countries, water quality standards have gradually
emerged and are still evolving for different water uses
• Standards are a function of
– our ability to detect and remove contaminants
– our understanding and/or fear of their actual or possible
impacts
Setting the WQ standards
•Water quality criterion (water quality guideline) – Needed to
support and maintain a designated water use. who sets the
guidelines in Kenya?
•Water Quality Objective ( water quality goal)- Needed to
support and to protect the designated uses of water at a specific site.
•Water quality standard – An objective that is recognised in
enforceable environmental control laws or regulations of a
government.
 Water quality objectives

• Water quality objectives are the measures that

specify the concentrations of substances permissible
for all intended water uses at a specific location on a
lake, river, or estuary.
• The objectives are based on the water quality
guidelines for the uses at that location, as well as on
public input and socio-economic considerations.
• The objectives not only protect water users and the
environment, but they also promote sustainable
water management strategies.
 Cont..
• Water Quality Objectives are intended to provide
guidance in making water quality management
decisions such as the designation of the surface waters
which should not be further degraded.
• They are often used as the starting point in deriving
waste effluent requirements included in Certificates of
Approval and other instruments issued to regulate
effluent discharges.
• They are used to assess ambient water quality
conditions, assist in assessing spills and monitoring
the effectiveness of remedial actions.
 Advantages of Water Quality Objectives
• Focuses on solving problems caused by conflicts
between the various demands placed on water
resources, particularly related to assimilated
pollution.
• Enables an overall limit on levels of
contaminants within a water body to be set
according to the required uses of the water.
• It treats industry equitably requiring the use of
best available technology for treating hazardous,
as well as a number of conventional water
pollutants whenever the industry is located.
 Drinking Water Quality
• Much of the world's drinking water is contaminated and
poses serious health threats
• Most drinking water is purified by storage in reservoir
(suspended matter settles), and treated by sand filters,
activated charcoal, and addition of chlorine
• U.S. Safe Drinking Water Act of 1974 requires EPA to
establish national drinking water standards
• Many using bottled water and home filters; bottled water
is often more contaminated than tap water
 Drinking Water Quality Standards

•The EPA (Environmental Protection Agency) sets Maximum

Contaminant Levels (MCLs) for drinking water
•There are standards for numerous contaminants, two of which cause
an immediate health threat if exceeded
•Coliform bacteria -because they may indicate presence of
disease causing organisms
•Nitrate - can cause ‗blue baby syndrome‖—nitrate reacts with
blood and blood can‘t carry as much oxygen
Water quality standards
 Common parameters for different water uses
Use Typical quality parameters
Public Water Supply Turbidity, TDS, inorganic and organic compounds,
microbes

Water contact recreation Turbidity, bacteria, toxic compounds

Fish propagation and wildlife DO, chlorinated organic compounds

Industrial water supply Suspended and dissolved constituents

Agricultural water supply Sodium, TDS

Shellfish harvesting DO, bacteria

Industrial water Varies with type of goods being manufactured

Domestic Wastewater pH, mercury, cyanide, turbidity, DO

Industrial waster water Heavy metals

 Primary drinking water standards criteria

• Microorganisms - • Inorganic Chemicals –

Giardia lamblia; Virus; Arsenic, barium, fluoride,
Legionella;Turbidity copper, lead,
• Disinfection Byproducts- • Organic Chemicals –
bromate, chlorite, Benzine; Carbon
trihomethanes; haloacetic tetrachloride;
acids Dichloromethane
• Disinfectants- • Radionuclides –
chloramines, chlorine and Uranium; Alpha particles;
chlorine dioxides Beta particles and photon
emitters
 Secondary - Drinking water standards (EPA)
Contaminant Secondary Standard
Aluminum 0.05 to 0.2 mg/L
Chloride 250 mg/L
Color 15 (color units)
Copper 1.0 mg/L
Corrosivity noncorrosive
Fluoride 2.0 mg/L
Foaming Agents 0.5 mg/L
Iron 0.3 mg/L
Manganese 0.05 mg/L
Odor 3 threshold odor number
pH 6.5-8.5
Silver 0.10 mg/L
Sulfate 250 mg/L
Total Dissolved Solids 500 mg/L
Zinc 5 mg/L
 Drinking water quality standards
Nb: Standards can be national, regional or international (WHO, EPA)

Parameter WHO guideline Recommended for Ethiopia

pH 6.5-8.5 5.0-9.5
Total solids, mg/L 1000 2000
Total hardness, mg/L 500 600
Chloride, mg/L 250 800
Sulphate, mg/L 400 600
Fluoride, mg/L 1.5 4
Iron, mg/L 0.3 3
E. Coli, MPN/100 ml 10 30
Nitrate , mg/L 10 40
 Irrigation water quality – salinity and sodium
hazards
• the total concentration of soluble salts (TDS or EC)
• the relative proportion of sodium to the other cations,
• the bicarbonate concentration as related to the concentration of
calcium and magnesium, and
• the concentrations of specific elements and compounds.
• Sodium Adsorption Ratio is given
SAR = [sodium]/[calcium][magnesium]
 Irrigation waters quality standards, mg/l
Element FAO Nigeria,
Aluminum 5.0 5.0
Arsenic 0.1 0.1
Cadmium 0.01 0.01
Chromium 0.1 0.1
Copper 0.2 0.2-1.01
Manganese 0.2 0.2
Nickel 0.2 0.2
Zinc 2.0 0.0-5.02
 Chapter 3

Air Pollution and Its Control

 Air Pollution
 Harmful to life or materials
 Materials - soiled, corrosion of metals
 Plants - stunting, damage (crops, forests)
 Animals - respiratory, nervous system damage
 Humans - eye irritation, headache, dizziness,
bronchitis, emphysema, cancer
- young, old, heart and lung patients susceptible
 Air Pollution
 Primary pollutants  Secondary pollutants
 Natural Sources - most primary
pollutants
 Decay processes, winds, volcanic
eruptions, sea spray

 Widely dispersed
- do not reach harmful levels
 Human Sources - more important
 Concentrated where the people are

1) Stationary fuel
combustion

2) Industry

3) Transportation
 Air pollution problems influenced by:
 Topography (thermal inversions)

 Climate (cool-moist, warm-dry)

 Temperature Inversions
 Especially in valleys

 Los Angeles, Denver, Winona

 Industrial Smog
 Cool, moist

 Primary
pollutants

 Worst in winter,
at night

 Chicago, London
 Photochemical Smog

 Warm, dry
NO from cars
 Secondary
pollutants

 Worst in
summer, midday

Los Angeles
Widespread Secondary Air Pollution: Acid
Deposition
 Wet deposition

 Dry deposition
Acid Deposition in the U.S.
 Acid Deposition and Aquatic Systems
 Fish declines
 Undesirable
species
 Aluminum
toxicity
 Acid shock
 Acid Deposition, Plants, and Soil
 Nutrient
leaching

 Heavy metal
release

 Weakens trees
 Industrial Smog Control -
sulfur dioxide and particulates
 Burn less fossil fuels

 Use alternative energy sources

 Burn low-sulfur coal

 Remove sulfur from coal (chemicals)

 Stack scrubbers, electrostatic precipitators

 Photochemical Smog Control - nitrous
oxide emissions
 Use mass transit

 Develop new engines

 Develop new fuels

 Develop new emission controls

 Solutions: Preventing and Reducing Air
Pollution
 Clean Air Acts (1970, 1977)

1) Industrial emissions standards

2) Automotive emissions standards
3) Deadlines for meeting standards

 Standards becoming stricter, requests

to extend deadlines
- better technology needed
 Noise Pollution
• Noise pollution is unwanted human-created sound that
disrupts the environment. The dominant form of noise
pollution is from transportation sources, principally
motor vehicles, referred to as environmental noise.
Examples of Noise Pollution:
Loudspeakers
Aircrafts
 1.Jet planes.
2.Loud speakers and other loud speaking things.
3.Cinema halls.
4.Factories
5.Road traffic
 1.We should not use loud speakers.
2.Factories should be made out of the city.
3.There should be not more noise making
vehicles on the roads.
 Land Pollution
• Land pollution is the degradation of the Earth's land
surface through misuse of the soil by poor agricultural
practices, mineral exploitation, industrial waste
dumping, and indiscriminate disposal of urban wastes .
Examples of Land pollution :
Soil Pollution
Waste Disposal
1.People Cut forest for furniture.
2.Plastic is the main source of land pollution.
3.People throw house garbage on roads.
4.Some industries throw their waste on land.
1.People should not cut trees for making furniture.
2.People should not throw garbage on land.
3.Plastic bags should be avoided for prevention of land
pollution.
4.Industries should not throw there waste on land.