Water is vital to life, and it is also easily contaminated. Organisms such as E. coli and Legionella pneumophila (which causes Legionnaire’s Disease) can easily find their way into a water supply. Lack of access to clean drinking water is a problem affecting millions worldwide. Even in developed nations, water sources must be tested in order to ensure water is safe to drink. Water that is safe to drink is called potable water.When testing water sources for contamination, it is often prohibitively expensive to test for every possible contaminant. Instead, tests for indicator bacteria are used. An indicator bacterium is a nonpathogenic bacterium used to estimate fecal contamination of water. Some common indicator bacteria are fecal coliforms, microbes found in the intestinal tracts of warm-blooded animals. While some of these are pathogenic, others are not. A common process for testing water for fecal coliforms is to filter the water and then apply the filter to a growth medium. After a few days, colonies are counted on the growth medium. For water to be considered potable, no colonies may be present. However, water used for other purposes, such as recreation, can have slightly higher counts. For example, in recreational bodies of water (such as lakes where people can swim), the federal standard in the United States says that 10% of samples taken over a 30-day period should not exceed 400 fecal coliforms per 100 milliliters of sample, with at least five samples taken during the 30-day period.
Filter Test for Water
Water is commonly used to remove human and other waste from households and businesses. Wastewater of this type is called sewage, and it requires treatment before being released into the environment. Sewage does not encompass industrial wastewater, which must be treated prior to joining the sewage stream. Treatments for industrial wastewater vary according to the type of pollutants that exist in the water.Sewage treatment is divided into primary, secondary, and tertiary treatment stages, which together make up a five-step process. Primary treatment involves steps 1 and 2, which entail filtering out large debris from the sewage and holding the sewage in a storage tank. There, heavy solids called sludge settle to the bottom of the tank while light materials such as oil float to the top. Sludge can be collected and treated for other uses, such as creating fertilizer. The remaining liquid is passed on to secondary treatment. Secondary treatment includes step 3 and involves the decomposition of biological matter, which is carried out by aerobic and anaerobic microorganisms. The microorganisms used for this process are indigenous to the region where the sewage treatment is carried out so that if they end up in the environment they do not cause damage. Because the secondary system relies on microorganisms, the treatment system is known as a bioreactor, an industrial system that relies on a biological process. Tertiary treatment includes steps 4 and 5 and represents any kind of treatment that follows secondary treatment, which varies by region and by the destination of the effluent (the treated water). This includes pH adjustment, disinfection, and desalination. The effluent is then released back into the environment.
In addition to sewage treatment, microbes can also be used to treat industrial wastewater. Some naturally occurring microbes, such as Alcanivorax borkumensis, have been found to break down oil. They are vital to cleanup efforts when an oil spill occurs. Genetic engineering has also produced microbes capable of breaking down plastics and other harmful compounds. These microorganisms provide a safe and effective means of keeping pollutants out of the environment.