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Hw9 solutions 16-1

Mohamed Elbehlil
Mohamed Elbehlil

SOLVED HOMEWORK PROBLEMS ON BASICS OF ENVIRONMENTAL ENGINEERING CALCULATIONS SUCH AS SOLIDS ANALYSIS AND ALKALINITY

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Lafayette College Department of Civil and Environmental Engineering CE 321: Introduction to Environmental Engineering and Science Fall 2016 Homework #9 Due: Friday, 11/18/14 SOLUTIONS 1) Differentiate between water quality regulations and drinking water regulations. Briefly review the evolution of the water quality regulations in the United States. 2) A water sample is found to contain the following: pH = 8.2 Na+ = 14 mg/L Ca+2 =15 mg/L Mg+2 = 12 mg/L Sr+2 = 2 mg/L K+ = 13 mg/L HCO3 - = 80 mg/L NO3 - = 9 mg/L Cl- = 28 mg/L SO4 -2 = 45 mg/L What is the TDS, conductivity, and alkalinity of this sample. Express your alkalinity result as mg/L of CaCO3. 3) A water treatment plant has reported that a TC test has come up positive (20 colonies counted). What does this mean and what do the technicians need to do? Explain you answer in detail, including an explanation of the reported 20 colonies. 4) Jerome Thumbly, a new C.E. student at Lafayette, has conducted a solids test on a water sample. From his data find the TOTAL FILTERABLE SOLIDS of the sample. Test No. 1 (Total Solids Data): Sample = 500 ml. Tare wt. = 18.428 g weight @ 105o C = 18.947 g weight @ 550o C = 18.928 g Test No. 2 (Suspended Solids Data): Sample = 500 ml. Tare wt. = 17.921 g (Gooch crucible w/fritted glass disk) weight @ 105o C = 18.243 g weight @ 550o C = 18.238 g 5) What is the drinking water standard for turbidity based on the most current EPA drinking water regulations (include the web-page information). Provide information from CFR.
Hw9 solutions 16-1
Hw9 solutions 16-1
3. A water treatment plant has reported that a TC test has come up positive (20 colonies counted). What does this mean and what do the technicians need to do? Explain you answer in detail, including an explanation of the reported 20 colonies. Indicator organisms, such as coliforms are used to indirectly test for the possibility that pathogens (disease causing agents) may be present in a sample of water. An ideal indicator organism should be able to survive under a greater variety of conditions than the pathogen it is being used to test for so that it will always be present when the pathogen is present. As a result, the presence of the indicator does not imply that the pathogen is present, but merely the possibility that it is present. When we report coliforms we report as # of Colonies/100 ml of sample, therefore 20 colonies in a Total Coliform (TC) test refers to 20 Colonies/100 ml. The EPA recommends a Total Coliform count of zero for drinking water. The standard mandated by the EPA is slightly less strict: No more than 5.0% samples total coliform-positive in a month. (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive per month.) Every sample that has total coliform must be analyzed for either fecal coliforms or E. coli if two consecutive TC-positive samples, and one is also positive for E.coli fecal coliforms, system has an acute MCL violation. (http://water.epa.gov/drink/contaminants/index.cfm#4) In order to more accurately determine if pathogens are in fact present in the water, more extensive testing should be done, beginning with Fecal Coliform (FC) Tests and additional Total Coliform Tests. This will also help the plant to comply with the EPAs standards. If this was a sample of the Plants effluent, a boil-water-notice should be issued (as a precaution, and for legal reasons), and a serious investigation should be conducted to determine why the plants chlorination system is not functioning properly. If the sample was taken from the plants influent, the technicians should test the plants effluent. Presumably, the plant was designed to remove coliforms from the water. If these coliforms are not being removed, then the plant may need to be redesigned to meet the EPAs specifications. For example, they might need to increase the length of their Clearwell or use more chlorine.
Hw9 solutions 16-1
Hw9 solutions 16-1
Hw9 solutions 16-1
Hw9 solutions 16-1
Hw9 solutions 16-1
Hw9 solutions 16-1

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Hw9 solutions 16-1

  • 1. Lafayette College Department of Civil and Environmental Engineering CE 321: Introduction to Environmental Engineering and Science Fall 2016 Homework #9 Due: Friday, 11/18/14 SOLUTIONS 1) Differentiate between water quality regulations and drinking water regulations. Briefly review the evolution of the water quality regulations in the United States. 2) A water sample is found to contain the following: pH = 8.2 Na+ = 14 mg/L Ca+2 =15 mg/L Mg+2 = 12 mg/L Sr+2 = 2 mg/L K+ = 13 mg/L HCO3 - = 80 mg/L NO3 - = 9 mg/L Cl- = 28 mg/L SO4 -2 = 45 mg/L What is the TDS, conductivity, and alkalinity of this sample. Express your alkalinity result as mg/L of CaCO3. 3) A water treatment plant has reported that a TC test has come up positive (20 colonies counted). What does this mean and what do the technicians need to do? Explain you answer in detail, including an explanation of the reported 20 colonies. 4) Jerome Thumbly, a new C.E. student at Lafayette, has conducted a solids test on a water sample. From his data find the TOTAL FILTERABLE SOLIDS of the sample. Test No. 1 (Total Solids Data): Sample = 500 ml. Tare wt. = 18.428 g weight @ 105o C = 18.947 g weight @ 550o C = 18.928 g Test No. 2 (Suspended Solids Data): Sample = 500 ml. Tare wt. = 17.921 g (Gooch crucible w/fritted glass disk) weight @ 105o C = 18.243 g weight @ 550o C = 18.238 g 5) What is the drinking water standard for turbidity based on the most current EPA drinking water regulations (include the web-page information). Provide information from CFR.
  • 4. 3. A water treatment plant has reported that a TC test has come up positive (20 colonies counted). What does this mean and what do the technicians need to do? Explain you answer in detail, including an explanation of the reported 20 colonies. Indicator organisms, such as coliforms are used to indirectly test for the possibility that pathogens (disease causing agents) may be present in a sample of water. An ideal indicator organism should be able to survive under a greater variety of conditions than the pathogen it is being used to test for so that it will always be present when the pathogen is present. As a result, the presence of the indicator does not imply that the pathogen is present, but merely the possibility that it is present. When we report coliforms we report as # of Colonies/100 ml of sample, therefore 20 colonies in a Total Coliform (TC) test refers to 20 Colonies/100 ml. The EPA recommends a Total Coliform count of zero for drinking water. The standard mandated by the EPA is slightly less strict: No more than 5.0% samples total coliform-positive in a month. (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive per month.) Every sample that has total coliform must be analyzed for either fecal coliforms or E. coli if two consecutive TC-positive samples, and one is also positive for E.coli fecal coliforms, system has an acute MCL violation. (http://water.epa.gov/drink/contaminants/index.cfm#4) In order to more accurately determine if pathogens are in fact present in the water, more extensive testing should be done, beginning with Fecal Coliform (FC) Tests and additional Total Coliform Tests. This will also help the plant to comply with the EPAs standards. If this was a sample of the Plants effluent, a boil-water-notice should be issued (as a precaution, and for legal reasons), and a serious investigation should be conducted to determine why the plants chlorination system is not functioning properly. If the sample was taken from the plants influent, the technicians should test the plants effluent. Presumably, the plant was designed to remove coliforms from the water. If these coliforms are not being removed, then the plant may need to be redesigned to meet the EPAs specifications. For example, they might need to increase the length of their Clearwell or use more chlorine.