Contamination of Drinking Water

Recently in class, we discussed the privatization of water and the potential benefits and pitfalls of both municipal and private water sources. We learned that in many areas all over the world where poverty is rampant, the infrastructure necessary for the transportation and treatment of water is lacking or even nonexistent when under governmental control. As a result, the poor have to pay exorbitant amounts to buy their water and often have to spend copious amounts of time to transport it. In many cases, this highly expensive water can be unhygienic. Privatization can help alleviate the burden placed on local governments for the cost of infrastructure and allow the poor to receive water at greatly reduced rates. However, private companies can often skimp on the decontamination of water if the companies’ leaders become corrupt. The contamination of a water source—whether under governmental or private control—is a prime concern, especially when that source is used as drinking water. Many forms of algae, such as blue-green algae, can bloom in fresh water sources in the right conditions, and some species of blue-green algae are toxic.

Although there are many types of algae that inhabit fresh water, blue-green algae are some of the most ubiquitous. Unlike most algae, which are classified as protists, blue-green algae are actually a family of photosynthetic bacteria known as cyanobacteria. Different species of cyanobacteria can be found in either fresh or salt water. Many species of cyanobacteria produce toxins that can affect the nervous, hepatic, and dermatologic systems. Some toxins can cause tumors or other health risks as well. Most species that produce toxins tend to produce multiple toxins, making water treatment even more difficult.

Like other forms of algae, cyanobacteria will often bloom in the right conditions. Most cyanobacteria tend to live on the surface of a body of water, where they can receive the most sunlight. Any surface drinking water sources, such as lakes and reservoirs, are at risk for contamination as they provide the perfect habitat for cyanobacteria if not properly treated. Blue-green algae bloom when there is sufficient sunlight and nutrients in the water. Many human pollutants, such as fertilizer runoff and untreated sewage, can add nutrients to the water that can, in turn, creating a more hospitable environment for cyanobacteria to thrive in.

During a harmful bloom, the species of cyanobacteria that produce toxins rapidly becomes more concentrated. Once the cyanobacteria die, their cells lyse and the toxins are released into the water. As a result, the water source can remain contaminated until the toxins are able to completely decompose. In addition, any water treatments intended to kill the blue-green algae can make problems worse by inducing the release of the harmful toxins. While many treatments, such as chlorination, the addition of activated carbon, and ozonation, can be used to lower toxin levels, most treatments are less effective against certain toxins, such as microcystins.

Ideally, in order to reduce toxin levels, measures need to be taken to filter out cyanobacteria from water sources. However, the technology to do so is, as of yet, relatively undeveloped and extremely expensive. Some experimental treatments include ultraviolet light, titanium dioxide and filtration using ultrafine membranes. In addition, cyanobacteria tend not to inhabit groundwater, making that a safer source of drinking water than lakes. However, in both cases the cost to adapt infrastructure to combat the algal problems of an area would be high, and in many locations, local governments would not be able to afford it. Aside from the cost of infrastructure, groundwater—which may be a more feasible solution than specialized filtration systems at the present for most communities—can have other contamination issues when pollutants seep through the soil and is not always a viable option in areas where water is scarce and not enough seeps into the ground to create a large enough source to sustain a population. Privatization can help alleviate the burden of cost on municipalities and provide adequate decontamination of drinking water as the necessary technology advances and becomes more readily available; however, careful oversight must be maintained to prevent corruption and maintain water quality standards.

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For further reading:
http://www.rsmas.miami.edu/groups/niehs/science/bluegreen.htm