In the early days of its existence, no one had to worry about treating America's waste water. Left to nature, the purification process took place slowly but surely. However, now that the population has grown by leaps and bounds and more contaminants are ending up in the water supply, steps need to be taken in order to speed up nature's cleaning process. The Clean Water Act of 1972 was designed to provide a basis for maintaining the country's most valuable resource, clean H20.
Up until the mid 1900s, the nation's waterways in urban areas were filled with pollutants, but no one was overly concerned about it. Now, however, we not only realize that clean drinking water is a precious commodity but also that it is imperative to maintaining the ecosystems of our world and critical in maintaining national health. Cities, then, have became responsible for taking the steps necessary to treat the waste water generated in their community and ridding it of dangerous pollutants. Municipal water treatment plants were built to take care of the problem of filtering the liquid and making it clean again.
Different types of filtration have been tried with varying amounts of success. Back in 1892, there were only 27 American cities that provided waste water treatment for their citizens. Now we have over 16,000 water treatment facilities spread throughout the country. Filtration starts when waste water enters the treatment plant where it passes through screens of varying densities. Some screens with holes about ½" square remove large debris from the liquid, while screens with finer mesh remove even very small particulates.
Ion-exchange resins are often used in the water purification process. These are made up of insoluble beads with a surface covered with highly-structured pores where ions are easily trapped and released. Ion-exchange resins are used successfully to remove poisons and heavy metals from the liquid. Sometimes the resins are mixed with an activated-charcoal filter in order to remove organic contaminants from water.
The filtration methods used by municipal water treatment plants are complex. After all, waste water can be filled with microorganisms or pathogens that cause human diseases. Therefore, the methods used to clean our primary drinking source are all important in the lives of everyone.