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