Living Lab 2nd Year Fellows Toggle navigation

Group Members:  Diana Samaroo, Ralph Alcendor, Urmi Ghosh-Dastidar, Muhammad Ali Ummy

Title of Activity:  Chemical and Biological Analysis of Water Quality

Location/outside partner: Beach-front at Brooklyn Bridge

Detailed Description of Activities (supplemental to Group 2 Agenda)

Activities (working template)

1. Collect water samples from two locations, stagnant and flowing, at the Brooklyn Bridge Park. Participants will decide sampling area.
2. Collect water samples from City Tech or bottled water.
3. Measure the temperature of the water sample collected.
4. Return to City Tech P304 where the following test will be conducted
   1. pH – using a pH meter
   2. Microbial contamination – using phenol red dextrose tubes and phenol red broth.

Part I:  Biological Analysis of Water Quality

Procedure

pH reading

To determine the pH of samples collected, follow the following steps.

Note: The pH meter is calibrated and ready to use. However, ensure that the pH reading is around 7 ( the probes are stored in pH 7 buffer).

Rinse the probe in distilled water.

1. Insert the probe into the water specimen.
2. Swirl the container and wait until the reading stabilizes.
3. Record the displayed reading.
4. Give the probe a final rinse and return it to the calibration buffer or continue measuring the pH of other samples.

Microbial level

To measure microbial levels we will use the Colony Forming Unit (CFU) method.

Samples will be collected two days prior. 1 ml of each sample will be used to prepare a 10 fold serial dilution using phenol red glucose broth and nutrient agar plates. This dilution will be carried out to observe the minimum number, usually one, of bacteria in the water sample. All inoculated tubes will be incubated and fermentation and growth will be observed 48 hrs later. (More to come)

Interpretation of results;

Growth or no growth – Nutrient agar plate

Number of colonies – Nutrient agar

Number of different colonies – nutrient agar

Red media  – no fermentation

Yellow media – fermentation

Bubble or gas in the upside tube – gas production

To determine the most probable number of bacteria within each sample,

1. Observe the change in color of each tube and record the number of positive tubes in each set (3 tubes).  The order of positive and negative results in each set is important.
2. 2.       Use the 3-tubeThe number of positive tubes are then used to determine the number of inoculums in each sample using the 3-tube MPN Table.
3. 3.       Record your

Part II:  Chemical Analysis of Water Quality

The following quality control tests will be performed with the collected water samples.

1) Using a multi-factor test strip, assess the level of nitrate and nitrite (NN)

2) Using a multi-factor test strip, assess the level of hardness, pH and iron (HPI)

Instructions for test strip use:

1) Insta-Test Analytic Nitrite (NO2) & Nitrate (NO3) Strips

• Using a cup-size sample, immerse strip for 2 seconds and remove with pads face up.  DO NOT SHAKE OFF EXCESS WATER.   Wait 60 seconds and immediately compare to color chart.

• Use one strip for each water sample.  (You will use a maximum of three strips).

(Keep wet fingers out of test strip bottle)

Results:  Based on the color chart you will report the level of nitrite and nitrate in the water samples as:  0 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm.

ppm:  part per million

Think about the following:  Why should the levels of nitrate and nitrite be regulated?

Read the following: http://www.freedrinkingwater.com/water-contamination/nitrates-nitrites-contaminants-removal-water.htm as well as  Facts Nitrate and Nitrite in Water (NJ State Health/EOH)

2)  Insta-Test:  Hardness, Wide Range pH and Total Iron

There are two kits provided.  One kit will be used to test only one sample of collected water from Brooklyn Beach front and the second kit will test one sample of CityTech or bottled water.

• Using the tube provided with the test kit, fill the tube with 30 mL (milliliters) of sample water.

• Immerse end of total hardness and pH pads into sample and immediately remove with pads face up.  DO NOT SHAKE OFF EXCESS WATER.  Wait 15 seconds and compare to chart to read Total Hardness and pH.  (Allow each group to perform the test, before continuing).  Do not discard strips as yet.

After each group has done the hardness and pH test:

• Add 2 Iron RT tablets to sample water (use gloves).  Cap the tube and shake until tablet has disintegrated.

• Immerse end of Iron pad into sample and remove immediately.  Wait 15 seconds and compare to chart to read Iron level.  (Allow each group to perform this test).  Discard strips once complete.

Repeat the above procedure with second test kit, but use CityTech or bottled water.

Results: Based on the color chart you will report the level of: Iron (ppm):  0, 0.3, 0.5, 1, 3, 5
pH:  4, 5, 6, 7, 8, 9, 10 and Hardness (ppm):  0, 50, 100, 200, 400

Each group will present a hypothesis, report data and form a conclusion