MWRA 2009-2010 Writing Contest Winners

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Alejandro Winsor
Grade 5, Galvin Middle School, Wakefield


A Typical Day on the Job

Hello, my name is Alejandro Winsor. I am a Microbiologist in the Water Systems Department at the Massachusetts Water Resources Authority (MWRA). I am writing this to tell you what I do on a typical day. Microbiologists perform tests on our drinking water, and we use our knowledge of microbiology to read test results.

Every morning I start by recording the temperatures in our incubators and water baths. We need to do this because the bacteria we are looking for grow best in certain temperatures so we check once in the morning and after lunch to make sure it is in a good range for bacteria to grow.

After we open the incubators, we look at the specimens from the day before. The goal of testing is to make sure the water has no dangerous bacteria in it. Not all of the bacteria are bad for people. The ones that are bad are the total coliform family, which includes Klebsiella, Citrobacter, Enterobaccter and E.coli. There are several tests that we perform on drinking water: total coliform membrane filtration (CMF), Colibert, and Heterotropic Plant Count (HPC).

For the CMF test we run a small amount of water thought a filter that catches any bacteria nearby. When Bacteria grow larger in size and than split, they form thing called colonies. Since usually one bacterium forms a colony, we are looking for colony forming units (CFU). The nondangerous colonies are white or pale pink and it don’t have a darker center. We only really need to worry when there are more than 200 of these “background colonies: and we then send those out for further testing.

Total coliform colonies will be green or red, dark, and shinny. We really don’t want E.coli. It makes people really sick. After 4 hours of incubation it has a blueish glow to it when you turn off the lights.

We also test the water from our water plant to make sure the treatment process is going will. After all this we enter our data into our computers and that info is sent to communities that use MWRA's water and some other employees in our plant. The majority of our day is spent entering data and running tests.

I would like to thank Heather Slater, Microbiologist, and Kristin MacDougall, Communications Specialist, both real employees of the MWRA, for the information they sent me that I used for this assignment.

The End!!!!

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