20-Jan-2010 electrical, computer and energy engineering
Environmental Engineering
Linking Mathematics and Chemistry to Engineering
Dr. AbbazadeganGraduate Students: Lauren McBurnett and Otto Schwake
Engineering Grand Challenges
DRINKING WATER
SOURCES FOR PHOENIX:
THE SALT RIVER
Salt River
Saguaro Lake
Salt River Project (SRP) Canal
Drinking Water Sources for Phoenix:Colorado River
Central AZ Project (CAP) Canals
Lake Pleasant
Agua Fria River
Coagulation/Flocculation/ Sedimentation
n Formation of floc (precipitate) which attaches to pollutants and removes them as they settle
n Chemical reaction used to destroy harmful microorganisms
Disinfection
Ultraviolet Lamps (UV)
Ozonation
Calculating Chlorine Demandn Bleach (NaClO)
– Na=23.0 g/mol– Cl=35.5 g/mol– O=16.0 g/mol
n Density of bleach = 1.11 g/ml
n Need 2 mg/L Cl
n Total molecular weight of NaClO (bleach)– 23.0 g/mol + 35.5 g/mol +16.0 g/mol = 75.5 g/mol
n bleach neededn Density of bleach = 1.11 g/mln bleach neededn Commercial Bleach is 5% NaClOn You are given a concentration of 0.5%
n What volume of 0.5% NaClO solution do you need to treat 1L of water?
Calculating Chlorine Demand
Advanced Treatment
Pipe Scale
Algae
Additional treatment for removal of specific chemicals (pharmaceuticals), pH adjustment, softening, and/or removal of odor or color causing compounds
What is turbidity?
What is turbidity?n Measure of cloudiness caused by suspended particlesn Turbidity is the measurement of how much light can travel through
water with scattered living or nonliving particles in the watern Usually measured in Nephelometric Turbidity Units (NTU)n Water with high turbidity is murky and dark, and is unhealthy to
aquatic lifen Low turbid water is more transparent and is healthier for aquatic life
Why is turbid water a problem?n Excessive turbidity in drinking water is aesthetically
unappealing, and may also represent a health concernn Turbidity can provide food and shelter for microbes
– By reducing their exposure to attack by disinfectantsn If not removed, turbidity can promote growth of microbes in
the distribution system– Leads to waterborne disease outbreaks which have caused significant
cases of gastroenteritis throughout the United States and the worldn Although turbidity is not a direct indicator of health risk,
numerous studies show a strong relationship between removal of turbidity and removal of protozoa
What is pHn The pH of a liquid is a measure
of its acidity or basicityn Mathematically, pH = - log[H+],
where [H+] = concentration of hydrogen ions in moles/liter
n A pH of 7 is considered neutraln Liquids with pH less than 7 are
acidic and greater than 7 are neutral
n A scale of pH values and common liquids is provided
pH Scale
Alkalinity
n A measure of a liquid’s capacity to neutralize acids – Buffer against changes in pH when an acid is added
n Important in determining a stream's ability to neutralize acidic pollution from rainfall, industry, or wastewater
n Influenced by rocks and soils, salts, certain plant activities, and certain industrial wastewater discharges
Hardness
n Sum of the multivalent cations in a water – Positively charged ions
n The majority water hardness is due to calcium and magnesium ions – Cause scaling in water pipes
Hardness
n Harder waters make it is more difficult to form suds with soap
n Soft waters tend to feel “slimy”
Dissolved Oxygen
n Dissolved oxygen (DO)– The amount of oxygen dissolved in a liquid
n Oxygen concentration in water is important to fish and other aquatic life
Dissolved Oxygen
n Insufficiently treated wastewater released into a body of water can decrease DO concentration
n Nitrogen and phosphorous runoff from fertilizers or from wastewater can cause eutrophication in bodies of water– Leads to decreased DO as plants decompose
Eutrophicationn Hypertrophication is the
ecosystem response to the addition of artificial or natural substances through fertilizers or sewage, to an aquatic system. – Such as nitrates and phosphates
n “Bloom" of phytoplankton in a water body as a response to increased levels of nutrients
n Negative environmental effects include hypoxia– Depletion of oxygen in the water
which causes a reductions in specific fish and other animals
Conductivity
n Used to measure the ionic content in a solution
n In many cases, conductivity is linked directly to the total dissolved solids (TDS)
Total Solids
Dissolved particles (TDS)
Suspended particles (TSS)
Total Solids (TS) = Total Dissolved Solids (TDS) + Total Suspended Solids (TSS)
Total Solids
Salinity ClassificationsFresh Water <1,000 mg/L
Brackish Water >1,000 - 25,000 mg/LSeawater >25,000 mg/L
• United States Environmental Protection Agency (EPA)
• TDS is a secondary standard
• < 500 mg/L
• Excessive TDS can be harmful to plant life
Nitrogen Cyclen The process by which nitrogen is converted between its
various chemical formsn This transformation can be carried out through
– Biological processes– Physical processes
n Fixationn Ammonificationn Nitrificationn Denitrification
Carbon Cycle
27
DAY 2Review Lesson with Lauren and Otto at the school visit
28
DAY 3Have fun at ASU
At ASU
n The students will be provided with several unknown water sources
n The students will then design an experiment using water quality parameters to identify and distinguish between the “unknown” water sources
At ASU
n Water Quality Parameters which the students will have at their disposal are:
– Nitrate– Nitrite– Bromide– Chlorine– Iron– Copper– pH– Conductivity– Turbidity– Ammonium– Ammonia