Sean Edward Paquette
Final Exam (Water Pollution)
December 5, 2013
FINAL EXAM (WATER POLLUTION)
Air and Water Pollution Prevention and Control Engineering
PROBLEM NUMBER 1:
Inputted the above data into the Comsol Program, the result are provided below. Figure 4.3.1 is
velocity magnitude. Figure 4.3.2 is pressure. Figure 4.3.7 is concentration in mol/m3. Under steady
state conditions assuming 3 meters from the NaCl rod the concentration is 1.2x104 mol/m3.
Furthermore, under steady state conditions assuming 35 meters from the Nacl rod the concentration
is 0.3x104 mol/m3.
Sean Edward Paquette
Final Exam (Water Pollution)
December 5, 2013
Sean Edward Paquette
PROBLEM NUMBER 2:
Final Exam (Water Pollution)
December 5, 2013
Sean Edward Paquette
Final Exam (Water Pollution)
December 5, 2013
Sean Edward Paquette
Final Exam (Water Pollution)
December 5, 2013
Sean Edward Paquette
PROBLEM NUMBER 3:
Concentration of HaOH = 6.34 E -8
Concentration of Na+ = 0.000199
Concentration of OH- = 0.000199
Concentration of H+ = 5.0015 E-11
pH of the resulting solution = 10.3
Final Exam (Water Pollution)
December 5, 2013
Sean Edward Paquette
Final Exam (Water Pollution)
December 5, 2013
PROBLEM NUMBER 4:
At a pH at which the solubility of a metal hydroxide may be reduced, the solubility of another may be
relatively high. (Cr) is chromium, (Ni) is nickel, (NaOH) is sodium hydroxide, (Zn) is zinc, (Cd) is
cadmium sulfide and (Cu) is copper. Cr and Ni ions have concentration >50mg/L with a pH of 5. It is
required to reduce these concentration levels to about 0.1 mg/L before discharging the solution into
the environment. The most common used method to precipitate heavy metals is a hydroxide
formation, furthermore to raise the pH NaOH is added as a caustic material. A pH adjustmentprecipitation sequence of engineering operations is below for Ni and then Cr.
1. Adding NaOH increases the pH upward to 10.5, this removes the residual nickel from the
solution, this forms nickel hydroxide
2. Ferric sulfate is added to enhance Ni(OH)2 removal and precipitation
3. When the pH is adjusted the flocculated wastewater is introduced into a clarifier. The
particles in this process settled in a sludge chamber and the clarified water flows to further
Sean Edward Paquette
Final Exam (Water Pollution)
December 5, 2013
treatment
4. Clarifier sludge handling is the next step, this is where the accumulated sludge is removed and
sent to a holding tank
5. Finally, there is sludge dewatering, after processing the sludge a filter press is emptied
creating a “chrome cake.” A chrome cake is “a semi solid approximately 20-35% solids and
high in chrome and sulfite”
6. To reduce the Cr concentration below 0.1 mg/L, the pH level needs to be lowered to 2.5 and a
ferric sulfate is added, this reduces the hexavalent chrome to trivalent chrome
7. Next the pH is adjusted upward to 9.5, “to the optimum chrome hydroxide percipient point”
8. Finally the flocculation process, the fluid is slow mixed to agglomerate floc and then the Cr
follows the same process to Ni
A proposed pH adjustment is a pH between 9.5 and 10.5 and the process is detailed above.
Sean Edward Paquette
Final Exam (Water Pollution)
December 5, 2013
PROBLEM NUMBER 5:
1. Reduction of fertilizer and pesticide for crop growing: The growing demands to produce food
and other similar crops have pressured farms to add fertilizer and pesticides to achieve and
sustain higher crop yields. The reduction of fertilizer and pesticides will reduce the total amount
of toxins seeping into the nearby water sources.
http://www.fao.org/docrep/w2598e/w2598e04.htm
2. Increase use of compost and composted products can help reduce water pollution: “Compost
products can reduce can be used to directly prevent pollution or remediate polluted water and
work indirectly by replacing activities with less polluting alternatives. For example
bioremediation uses compost to clean and restore contaminated soils by degrading and binding
contaminants in soil.”
http://compostingcouncil.org/admin/wp-content/uploads/2010/09/Using-Compost-forReducing-Water-Pollution.pdf
3. Overall water reduction use: The cheapest and most effective way to reduce pollution is to
completely avoid consuming large quantities or releasing water into the environment. For
example, turning off the tap water when not being used.
http://zoology.muohio.edu/oris/cunn06/cs6_20.htm
4. Increased Water Control Policies on a Global Basis: The Clean Water Act (CWA) is a federal law
in the United States governing water pollution. World leaders affiliated with international and
national policies similar to CWA need to join together and establish new and improved
regulations for water pollution. For example, new policies to implement regulating point sources
of water pollution. Reduction of direct point-source discharges from water ways.
5. Use more environmentally household products: Population at a large can significantly reduce
domestic water pollution by increasing their use environmentally household products, such as
washing power, household cleaning agents and toiletries.
6.
Reduce and limit what is disposed down your sink or toilet: Another activity that will
significantly contribute to the reduction of water pollution is controlling the pollutants, liquids
and solids thrown away down either a sink or toilet. For example, do not throw paints, oils or
pharmaceutical products and waste down the toilet.
7. Increasing amount of vegetation in your garden or near water sources: Another activity that
will significantly contribute to the reduction of water pollution is establishing protective
Sean Edward Paquette
Final Exam (Water Pollution)
December 5, 2013
agricultural practices such as planting vegetation buffer strips between croplands, gardens and
water sources.
8. Improving individual septic systems and city storm water systems: A distant action that will
significantly contribute to the reduction of water pollution is applying management practices to
replace outdated failing septic systems and storm water systems with environmentally safer
sewer systems.
9. Harvesting rain water: A distant activity that contributes to the minimization of water pollution
is using storm bins to save rain water for future watering of gardens and lawns.
http://www.simple-approach-to-healthy-living.com/water-pollution-solutions.html
10. Recycling Industrial Water: An industrial activity that can contribute to the eliminating water
pollution is through corporations reusing and recycling the water used. Industrial corporations
can use their water for multiple uses, for example, water used in the process or raw materials
can be filtered and reused for cooling systems or steam production.
http://pubs.acs.org/doi/abs/10.1021/es60056a008