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Topic2Waterpollutionandwastewatertreatment3.pdf
Administrative Reminders
• Online Mini-Quizzes
– Mini-Quizzes #1-4 due by 11:55 pm Friday March 8th
– Timed – 60 minutes each – Answers will be available after quizzes close
• In-class Quiz #1 February 22nd
– Covering Introduction, Topic #1 (water resources and drinking water treatment), and Topic #2 (Water pollution and wastewater treatment)
– Sample questions posted
• Reading – Textbook and articles posted on Titanium
Quick Review - Surface Water Drinking Water Treatment
• Coagulation and Flocculation
• Sedimentation
• Filtration
• Disinfection
– Chlorine
• Chlorine residual
• Disinfection Byproducts
– Ozonation
– UV and Hydrogen Peroxide
• Storage
Quick Review - Groundwater: Purity
• Groundwater is usually cleaner and purer than most surface water sources.
• Water percolates through soil, which filters out most bacteria, suspended
materials, and other contaminants that are present in surface water.
• Groundwater does not typically need to go through the coagulation,
sedimentation, and filtration steps of the surface drinking water treatment because
groundwater has been purified by natural filtration system (through the percolation
process)
• Therefore, most groundwater is pumped out from the aquifer, disinfected with
chlorine, and distributed to residents and commercial buildings
Quick Review – Drinking Water Problems
• Dracunculiasis, Guinea Worm Disease
• Cholera
• E. coli, E. coli O157:H7
• Hot Tub Lung
• Legionella
• Cryptosporidium (Crypto), RWI, Milwaukee, Wisconsin
• Methemoglobinemia, Blue Baby Syndrome
• Lead in drinking water, Flint, Michigan
• Arsenic in drinking water, Bangladesh
Quick Review - Tap vs. Bottled Water
EPA regulates
drinking water from
the tap.
FDA regulates bottled
water.
Topic 2
Water pollution
and
the wastewater treatment
process
Objectives
• Understand what eutrophication is and why it is an indicator of water
pollution
• Understand the wastewater treatment process, particularly the
secondary treatment step
• Understand BOD and DO
• Explain how storm drains attribute to water pollution
Outline
• Sewer Discharge
– Where does it all go?
– Harmful Algal Blooms
– Eutrophication
• Wastewater Treatment
– Treatment Process
– BOD Test
– Group Work (Cruise Ships)
• Stormwater Discharge
Where does it all go?
When you
flush the
toilet where
does the
contents go?
https://youtu.be/Ci090Vgw6Lw
Sewer Lines
Why Treat Wastewater?
“Provision of adequate methods of sewage
treatment, along with the chlorination of
drinking water, has done far more to reduce
the incidence of epidemic disease and to
upgrade standards of public health than has
the more widely acclaimed introduction of
modern medicines and vaccines.”
Our Global Environment
Why Treat Wastewater?
• Clean water is critical to plants, fish,
and animals that live in water
• Protect wildlife habitats for fish,
aquatic life, and migratory birds
• Human recreation and quality of life
• Human health concerns
Why Treat Wastewater? - Nutrients
• Wastewater adds nutrients (nitrate and phosphate) to cause excessive
growth of aquatic plant life usually resulting in the depletion of
dissolved oxygen
– Dissolved oxygen (DO) – the amount of oxygen dissolved in a body of water as
an indication of the degree of health of the water and its ability to support a
balanced aquatic ecosystem
• Increases suspended solids or sediments in streams can kill various
organisms
– Algal bloom
• Reduces DO and may result in
death of aquatic organisms
• Harmful algal bloom (e.g., red tide)
can produce toxins in water
What is in the wastewater?
• Wastewater is mostly water
• Organisms
– Bacteria, protozoa, worms, and viruses
• Some are pathogens – disease causing microbes
• Organic matter
– Organic matter – the carbon-based chemicals that are the
building blocks of most living things
• They come from dead plants, animals, human waste, paper
products, detergents, cosmetics, foods, etc.
• Oil and grease
• Inorganics (such as sodium, potassium, calcium, etc.)
• Nutrients (nitrates and phosphates)
• Solids (organic or inorganic)
Wastewater Treatment - Objective
In order to reduce eutrophication, wastewater must be treated before
discharging into the sea/lake/stream
Wastewater Treatment Plants in O.C.
Wastewater Treatment Process (Three Stages)
• Preliminary and Primary treatment - removes
approximately 50–65% of suspended solids through
screening and sedimentation
– Preliminary treatment
• Screens and grit chamber remove large debris
– Primary treatment
• Sedimentation tank (primary clarifier) removes
smaller solids
• Secondary treatment
– Biological processes digest organic wastes
– Removes about 90-95% of the dissolved pollutants
(nutrients)
• Accomplished by aeration basin, activated sludge or
trickling filter
• Tertiary Treatment
– Disinfection (required) – usually chlorination
– Remove remaining pollutants (nitrates, phosphates,
minerals, chemicals, etc. (optional)
Preliminary Treatment: Bar Screen and Grit Chamber
• Bar screen removes large
debris
• Grit chamber removes smaller
inorganic material like pebbles
and sand that can damage
equipment
Preliminary Treatment: Bar Screen
• Bar screen – catches large objects that have gotten into sewer system
such as bricks, bottles, pieces of wood, etc.
Primary Treatment: Sedimentation
• Removes more grit. Solids that settle down are
removed (sludge)
• Floating wastes (oil and fat) are skimmed from the
surface (scum)
• Scum and sludge are sent to anaerobic digester
Sedimentation Basin: Rectangular Basin
Secondary Treatment: Aeration Basin/Activated Sludge
Aeration Basin or Activated Sludge
• In covered, oxygen-rich aeration tanks, microbes (e.g., bacteria and
protozoa) living in the wastewater consume most of the nutrients
• Oxygen + nutrients (food) = many microbes
• The microbes and remaining solids are separated from the treated water in
the secondary clarifier
• Does not remove viruses, heavy metals, or dissolved minerals
Activated Sludge/Trickling Filter Prevents Eutrophication
• Employs natural selection to remove nutrients
• Removal of nutrients prevents eutrophication
Secondary Treatment #1: Activated Sludge/Aeration Basin
Activated Sludge
Secondary
Sedimentation Tank
(same as secondary
clarifier)
Secondary Treatment #2: Trickling Filters
• Trickling filters – beds of plastics filter media covered with microbial
slime absorb organic material as wastewater is sprayed over the
surface
Plastic media
https://youtu.be/xvi-dRVA9Tg
Tertiary Treatment
• Combination of several biological, chemical, or physical processes
designed to remove such pollutants as phosphates, nitrates, ammonia,
and organic chemicals (optional)
• Reduces the concentration of remaining nutrients to about 1% of that
present in raw sewage
• Disinfection with chlorine or other disinfectants such as ozone or UV
(required)
– Since chlorine is toxic to marine organisms, chlorine is removed (de-chlorinated)
before discharge into the ocean, river, lake, or other environments
Sludge: Anaerobatic Digester
• Sludge from primary and secondary clarifiers,
aeration basin, and trickling filters are sent to
anaerobic digester to produce energy (methane
gas)
• Anaerobic digestion is a series of processes in
which microorganisms break down
biodegradable material in the absence of oxygen
– Produce methane gas
– Produce biosolids (can be used as fertilizers)
• Anaerobic digestion is widely used as a
renewable energy source because the process
produces a methane.
Wastewater Treatment - Overview
OCSD (Fountain Valley)
https://youtu.be/xvi-dRVA9Tg
Group Work
Working in pairs or groups – describe, draw, or list the treatment steps for
the three types of water treatment we have discussed in class.
1. Drinking water treatment
2. Waste water treatment
3. Recycled water treatment
Water Treatment
Drinking Water
1. Coagulation and
Flocculation
2. Sedimentation
3. Filtration
4. Disinfection
1. Chlorine or
2. Ozone or
3. UV
5. Storage
Waste Water
1. Preliminary Treatment
1. Screening (solids to landfill)
2. Primary Treatment
1. Sedimentation (sludge to digester)
3. Secondary Treatment
1. Activated sludge/ aeration basin (sludge
to digester)
2. Trickling filters (sludge to digester)
4. Tertiary Treatment
1. Disinfection (required)
2. Nutrient reduction (optional)
Recycled Water
1. Microfiltration
2. Reverse
Osmosis
3. UV with
Hydrogen
Peroxide
Residential Wastewater Treatment - Septic Tank
- Solids are settled out and wastewater is partially
treated before it reaches distribution system.
- Bacteria, nitrogen, phosphorus removed.
- Septic tanks made of reinforced concrete,
polyethylene, or prefabricated fiberglass.
- Tanks may be one or two compartments.
Multiple compartments improve sludge and
scum removal.
- Sludge (solids) fall to the bottom.
- Sum (fats, oils, grease) floats to top.
https://ossf.tamu.edu/files/2013/01/septic.swf
- Wastewater is dispersed in a subsurface drain
field, typically via gravity flow.
- Drain field consists of gravel filled trenches,
plastic chambers or plastic pipe installed
underground to hold wastewater leaving the
tanks until it can seep into surrounding soil.
- Soil particles filter solids and organic matter from
wastewater.
- Microbes living in soil break down solids and kill
bacteria and pathogens in wastewater.
https://ossf.tamu.edu/files/2013/01/septic.swf
Septic Systems
https://youtu.be/NXgoUpbgo68
Grease Interceptors
Fatbergs
https://youtu.be/lUwAvu2pDuk
Fats, oils,
and grease
+
Items that
don’t break
down in the
sewer
(condoms,
baby wipes,
etc.)
=
FATBERGS
Algal Bloom
Harmful Algal Blooms (HABs) – Produce Toxins
• Harmful algal blooms are caused by certain type of algae (e.g., phytoplankton,
cyanobacteria)
– Phytoplankton are simple photosynthetic plants (e.g., dinoflagellates, diatoms)
– Cyanobacteria are true bacteria that have chlorophyll like algae
• Harmful algal blooms can:
– Produce extremely dangerous toxins that can sicken or kill people and animals
• Neurotoxins (cause paralysis and seizure)
– Common toxins: saxitoxins, domoic acid, brevitoxin
• Hepatotoxins (liver toxins)
• Dermatoxins (irritation, rashes, skin lesions)
– Create dead zones in the water
– Hurt industries that depend on clean water
Read “Article #1 – Harmful algal bloom USGS”
HABs - Neurotoxins
• HABs can kill fish and marine mammals (otters, seals, etc.) that feed on shellfish – Shellfish such as clams and oysters can collect and
concentrate neurotoxins from HABs without killing them
• Examples of HABs – Saxitoxin and brevetoxins disrupt the proper function of ion
channels in neurons, causing paralysis
– Domoic acid causes marine mammals to become lethargic, disoriented, and have seizures that sometimes result in death
• Consumption of HAB toxin contaminated shellfish by humans can be potentially dangerous – Initial signs of poisoning from this toxin is tingling in the
lips followed by a reduction of motor abilities and difficulty breathing and can be fatal if consumed in sufficient amounts
https://youtu.be/b6JzL4NG26k
Eutrophication
• Eutrophication is the enrichment of an ecosystem with chemical nutrients, typically compounds containing nitrogen (N), phosphorus (P), or both, in the form of nitrates and phosphates.
– In other words, eutrophication is an accelerated aging of body of water
• The increase in available nutrients promotes algal bloom
– In aquatic environments, enhanced growth of choking algae (e.g., phytoplankton, cyanobacteria) disrupts normal functioning of the ecosystem, causing a variety of problems, including hypoxia (aka, the dead zone)
Read “Article #2 - Eutrophication Nature”
Sources of Eutrophication
Stages of Eutrophication
1. Nutrients enter water (nitrates and/or phosphates)
2. Algal “blooms” – algae, plankton, and cyanobacteria (blue-green algae) grow rapidly near the surface of the water system
– Depletes dissolved oxygen near surface of the water
3. Algae die and settle to the bottom
4. Dead algae are decomposed by aerobic bacteria, depleting dissolved oxygen (DO) in the bottom of the water system
– Aerobic bacteria use DO to live
– Certain anaerobic bacteria can also release toxic chemicals (hydrogen sulfide)
5. The decomposition process uses oxygen and deprives the deeper waters of oxygen which can kill fish and shellfish and other organisms
The eutrophication process and subsequent formation of sea-bottom
hypoxia in the Gulf of Mexico
https://youtu.be/6LAT1gLMPu4
Food For Thought
• How do you contribute to eutrophication? What do you throw away?
• What can we do to prevent eutrophication from happening in our
waterways?
Indicators for the Risk of Eutrophication
• Heat (Temperature of the wastewater)
• Effluent nutrient concentration
• Oxygen Demand – measure of potential algal growth
– Biological oxygen demand (BOD)
• Amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample.
– Chemical oxygen demand (COD)
• indirectly measure the amount of organic compounds in water.
Disolved Oxygen (DO) and the Survival of Fish
Biological Oxygen Demand (BOD)
• Indirectly measures concentration of biodegradable organic matter (nutrients) present in a water sample.
• When microorganisms reproduce, they use up nutrients and dissolved oxygen (DO) in water.
– By determining the amount of oxygen used up in sealed water container, one can indirectly determine the amount of nutrients.
• The BOD test is carried out by:
1. diluting the sample with pure water saturated with oxygen
2. inoculating it with a fixed amount of bacteria
3. sealing the sample and then placing it in the dark for 5 days at 20°C
4. measure unused dissolved oxygen (DO)
Simplified BOD Calculation #1
Diluted
sample
water
Add known
amount of
standard bacteria
Dark
20° C 5 Days
100% DO
Diluted
sample
water
20% DO
• 80% DO was used up
(100%-20%) by bacteria
that used both DO and
nutrients in the sample
water to survive
• BOD is high, which means,
there is still too many
nutrients in the sample
water
Simplified BOD Calculation #2
Diluted
sample
water
Add known
amount of
standard bacteria
Dark
20° C 5 Days
100% DO
Diluted
sample
water
95% DO • 5% DO was used up (100%-
95%) by bacteria that used
both DO and nutrients in the
sample water to survive
• BOD is low, which means,
there is very little nutrients in
the sample water
BOD and DO
BOD: amount of dissolved oxygen needed by aerobic biological organisms to break
down organic material present in a given water sample.
Chemical Oxygen Demand (COD)
• COD: A measure of the amount of oxygen required to oxidize the organic matter in wastewater using a chemically oxidizing agent. Test takes a few hours
• COD is based on the fact that nearly all organic compounds can be fully oxidized to carbon dioxide with a strong oxidizing agent under acidic conditions
• COD test measures the oxygen demand of biogradable pollutants plus the oxygen demand of non-biodegradable oxidizable pollutants
Group Work – Cruise Ships and Pollution
1. Read “Article #3 - Cruise Ship Report Card FOE 2014”
2. Review
– List the three stages of wastewater treatment and explain how and what is treated in these
steps (try not to use the lecture notes)
– Discuss the relationship between BOD and DO. Explain to one another how BOD test is
conducted.
3. Solution for pollution is dilution…at least for cruise ships? What do you think?
Should the government require all ships to have advanced wastewater treatment
system (AWTS) onboard?
https://youtu.be/UtjjyqcBjdg
Food For Thought
• Make a list of all toxic things that can
enter the storm drains after a heavy rain.
• Talk about pros and cons of treating
storm drain discharge.
• Do you think we should treat storm drain
discharge? Support your view.
Read “Article #4 - stormwater runoff EPA”
and
Read “Article #5 - paving paradise”
Sanitary Sewer vs. Storm Sewer
Storm Drain Discharge
• A typical beach outfall.
• There are approximately
• 63 outfalls of varying sizes all along
the Santa Monica Bay.
• Interior view of a clogged storm drain
line. This photo was taken via remote
control camera and reveals a high
frequency rate of illegal dumping
coming from the neighborhood.
“First Flush”
The "First Flush" - refers to the season's first rainstorm (winter - spring) following
many months of dry weather that in essence, "flushes" out the debris which has
accumulated inside of the storm drain system. This accumulation is the combined
effects of littering, illegal dumping, windblown trash and a wide array of toxic liquids
and chemicals (such as from automotive leaks).
https://youtu.be/OkhoC2_YeXQ
Seal Beach, CA 2/4/2019
Trash is strewn along the sand south of the San Gabriel River in Seal Beach, CA, on Monday, Feb 4, 2019. (Photo by Jeff Gritchen, Orange County Register/SCNG)
Stormwater Pollution Prevention
Questions?
