8/14/2019 Environmental Engineering Quiz

1/4

According to the information introduced in the lecture and Lab workbook, choose thecorrect statements about oxygen demand.Answer

Oxygen demand determines the concentration of a specific organic compound.

Oxygen demand is a pollutant.

Oxygen demand measures the level of dissolved oxygen.

Oxygen demand measures the effect of a combination of organic compounds.

Oxygen demand measures the effect of a combination of organic compounds.

The primary environmental concern of organic wastes in natural waters is the consumption ofdissolved oxygen.Answer

True

False

True

The Total Organic Carbon (TOC) test indirectly measure oxygen demand by determiningthe amount of:Answer

Organic carbon in the compound

CO2produced in the test

Dissolved oxygen of the sample

Chemical oxidant consumed in the test

CO2produced in the test

Oxygen demand is widely tested in the following applications.Answer

Measuring waste loadings of wastewater treatment plants.

Evaluating the efficiency of removing organic compounds.

Evaluating organic pollution in lakes and streams.

Measuring the water quality of the finished water from drinking water treatment

8/14/2019 Environmental Engineering Quiz

2/4

plants.

Measuring waste loadings of wastewater treatment plants.

Evaluating the efficiency of removing organic compounds.

Evaluating organic pollution in lakes and streams.

Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) directly measure the

oxygen demand.Answer

True

False

True

BOD test is easy to conduct, is highly accurate, and requires less time compared withCOD test.Answer

True

False

False

During the oxidation process, which ion the dichromate ion is reduced to?Answer

Cr +

Cr +

Cr +

Cr +

Cr +

To determine the amount of oxidant consumed in the COD test, you can measure eitherdichromate ion or chromic ion at the same wavelength using the colorimetric method.Answer

True

8/14/2019 Environmental Engineering Quiz

3/4

False

False, different wavelengths

According to the Lab Workbook, choose the correct chronological order of the experiment you

will do for Lab X5. (There is only one correct response)Answer

Turn on the spectrophotometer and the COD reactor (preheat to 150 C);Open reaction vials and add the specified volume of the sample;Prepare a reagent blank;Place the reaction vials and reagent blank in the reactor for digestion (2 hours);Remove the vials after the digestion, cool down, mix, and cool to ambienttemperatureSelect the required wavelength and measure the absorbance;

Determine the COD for each sample using the calibration curve given.Prepare a reagent blank;Open reaction vials and add the specified volume of the sample;Turn on the spectrophotometer and the COD reactor (preheat to 1500C);Place the reaction vials and reagent blank in the reactor for digestion (2 hours);Remove the vials after the digestion, cool down, mix, and cool to ambienttemperatureSelect the required wavelength and measure the absorbance;Determine the COD for each sample using the calibration curve given.

Turn on the spectrophotometer and the COD reactor (preheat to 150 C);Prepare a reagent blank;

Open reaction vials and add the specified volume of the sample;Select the required wavelength and measure the absorbance;Place the reaction vials and reagent blank in the reactor for digestion (2 hours);Remove the vials after the digestion, cool down, mix, and cool to ambienttemperatureDetermine the COD for each sample using the calibration curve given.

First

The oxidation of potassium hydrogen phthalate (KHP) (an example organic compound) is shown

in the following equation.KC8H5O4+ 7.5 O2= 8 CO2+ 2 H2O + KOH

What is the theoretical oxygen demand of 5 mg KHP?Answer

1.175 mg O2

5.875 mg O2

8/14/2019 Environmental Engineering Quiz

4/4

2.938 mg O2

none of the above

5 mg KHP(1.175 mg O2/1mg KHP) =5.875 mg O2