We Love and Hate Chlorine

Overview
Chlorine is our savior. It helps disinfect our drinking water, kills pathogens lurching in our swimming pools, is used in some household cleaners, like bleach, and protects us from harmful diseases and bacteria, such as Cholera and E. coli.



However, in the recent years, chlorine has gained negative attention, because it can cause an increase in bladder cancer and miscarriages, so this has motivated water treatment plants to despise chlorine and turn to other alternative disinfectants.

Why Switch?
Recent studies have shown that in some cities, such as Washington D.C., that when the ammonia diluted version of chlorine, chloramine, is used to coat pipes then this allows for lead to travel from city pipes into residential drinking water. Is it worth the risk to stick to what we know? What if we come up with different techniques to minimize risks, or just use a completely alternative treatment? These are better options than the rising problems from chlorine.

“Recognition of these unexpected consequences of the shift away from chlorine disinfection raises new challenges with respect to the operation of drinking-water and waste water treatment plants,” warn environmental engineers from the US and Switzerland. (Jan. 7, issue of Science)

What Does Chlorine Do?
Chlorine helps to minimize the risk of getting diseases. It disinfects our swimming pools and our drinking water from pathogens, bacteria, and microbes. Microbes and bacteria tend to thrive in organic-rich water. When chlorine mixes with organic matter, it produces toxic by-products to the microbes and bacteria. If chlorine did not disinfect our drinking water, then more people would be susceptible to contract E. coli and Cholera.

Cholera and E. coli
There are a lot of types of E. coli and most are considered harmless. Some strains of can cause urinary tract infections or other infections. Other strains can cause bloody diarrhea, severe anemia, or kidney failure, which can lead to death.

 

Like E. coli, cholera can also cause severe 
watery diarrhea, which can lead to 
dehydration and even death if untreated.
It is an infectious disease that is caused by
eating food or drinking water contaminated
with a bacterium called Vibrio cholerae.

                                                                                                                                           

What are some solutions?

• Enhanced coagulation - a disinfection byproducts pre-treatment technique that tries to remove total organic carbon to control the disinfection byproducts from forming in water. The removal of organic matter by coagulation depends on the total organic carbon concentration, the chemical nature of the organic matter, coagulant type, coagulant dosage, and coagulation pH. Currently, water treatment plants are practicing enhanced coagulation to further increase disinfection byproduct removal. 

• Activated carbon filtration - a method of filtering that uses a bed of activated carbon to remove contaminants and impurities, using chemical absorption. Each particle/granule of carbon provides a large surface area/pore structure, allowing contaminants the maximum possible exposure to the active sites within the filter media.

These solutions are quite expensive and this is why most utilities go the cheap route and just dump ammonia and then chlorine on top of that. However, this solution decreases chlorine's reactivity and reduces the amounts of toxic disinfection byproducts, but we end up with chloramine, which helps lead seep into residential drinking water. So, to help fix this, Washington Aqueduct in 2004 started adding the corrosion inhibitor orthophosphate to drinking water. Today, the lead levels are well below the Environmental Protection Agency limits for drinking water. Cutting out chlorine completely may stop some of its advantages like reducing the effects of antibiotics, beta blockers, and endocrine-disrupting compounds. 

Resources:

1. http://news.discovery.com/earth/a-love-hate-relationship-with-chlorine.htm

2. http://www.watertech.com/wp-content/uploads/2013/07/cloudy-water-background-images-blueglass1.jpg

3. http://s.hswstatic.com/gif/cell-ecoli.gif

4. https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1TSNO_enUS602US602&ion=1&espv=2&ie=UTF-8#q=is+chloera+a+disease%3F

5. https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1TSNO_enUS602US602&ion=1&espv=2&ie=UTF-8#q=what+does+e.+coli+do

6. http://www.tandfonline.com/doi/abs/10.1080/09593332608618567#.VChQn_ldVS0

7. https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1TSNO_enUS602US602&ion=1&espv=2&ie=UTF-8#q=what%20is%20carbon%20filtration