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Chlorine residual and bacteria in water #CE341-UTBiome Activity

Chlorine residual and bacteria in water #CE341-UTBiome Activity

 

Tomorrow, 11/20/14, students from CE 341 will be sampling in ECJ! They will be testing the chlorine residual in the premise plumbing in ECJ. Dr. Bae, PhD student Sarah Keithley and I will be coordinating this effort.

The City of Austin uses chloramines as the residual disinfectant. The United States Environmental Protection Agency (USEPA) requires that a chlorine concentration of at least 0.2 mg/L be present throughout the distribution system. USEPA regulations do not have any bearing on premise plumbing, i.e., after the water has left the City’s distribution system. Water quality can deteriorate in buildings due to old infrastructure. The USEPA requires that the total coliform concentration be less than 1 colony forming unit (CFU)/100 mL in at least 95% of monthly samples, but they do not regulate the total bacterial concentration. It is possible that as the residence time in the plumbing increases, the disinfectant concentration decreases and the bacterial concentration increases. We want to test these related processes in ECJ by sampling (1) in the morning and in the afternoon and (2) in the basement of the building and on the 10th floor. The samples will be taken in these intervals; 9.30-11 and 2-3.30.

The hypotheses behind the sampling are: (1) The disinfectant residual will be lower and the bacterial concentration will be higher in the morning than in the afternoon, given the higher usage during the morning. (2) The disinfectant residual will be lower and the bacterial concentration will be higher as we go up in the building.

Students from both classes will be divided into 10 groups. Each group will go to a different floor of the building. They will take a water sample (first flush) from the left faucet. Right after that they will be measuring monochloramine residual, pH, and temperature. They will also plate their samples to do bacterial counts.

 

Results to come! Stay tuned!

 

Thanks Sarah K. for helping with this post too .

 

Picts: Left) in an attempt to normalize across water usage overnight and in the early morning, this late afternoon we have put signs for people not to use the left faucet. The tap water was run for 30 seconds and the sign posted.

Right) Sungwoo Bae prepping glass hockey sticks for the students to plate tomorrow.