No one can deny that water is very important in supporting life, in both plants and animals. Human beings equally need water for proper functioning of the body on a daily basis, with doctors recommending at least eight glasses in twelve hours. This supports the fact that water is an integral element in the life of a person.
Extreme lack or loss of water may lead to dehydration of the body and other health complications. For this reason, governments ensure that citizens have access to clean and safe water for domestic use. Clean water is essential in ensuring that no pathogens or impurities are ingested by people, either through direct drinking or through food.
To attain these standards of water, purification is important. Water purification involves physical and chemical processes, which are carried out stepwise to ensure the water is safe and free from any harm. This directional process essay synthesizes the steps, which have to be followed to achieve this task.
In essence, water purification denotes the process used to free water from impurities like bacteria and contaminants. Since the process is aimed at eliminating all the impurities present in the water, it is necessary to apply chemical and physical methods of separation in an orderly manner.
Nevertheless, the steps involved depend on the nature of impurities present. An important fact is that the water, which people consider to be pure, could be highly toxic, including rain water, which has a host of dissolved chemicals and dust. On the other hand, water from rivers is considered to be more contaminated than that from wells. As a result, the former requires more purification steps.
The first step in water purification is aeration. During this process, impure water is passed through special aeration tanks, in order to expose the water to sufficient air. This exposure is vital in removing some impurities, which are capable of interfering with the rest of the process.
For instance, dissolved gasses like carbon dioxide are removed. Additionally, the oxygen present in the air plays a major role in oxidizing some metals like iron into oxides, which can easily be removed (Wake 1). Besides the removal of chemical elements present in water, aeration is essential in removing water tastes and odor, which may have been caused by others factors.
The second step during water purification is flash mixing. Some people consider this to be first step in water treatment since aeration can be omitted depending on the status of the raw water. During this stage, chemicals are added into to the water to eliminate some impurities and aid in the coagulation process, which takes place after flash mixing.
Importantly, the amount of chemicals added at this stage largely depends on the nature of impurities identified in the water. Lime and sodium carbonate are commonly used in cases where the water is hard, say it has traces of calcium and magnesium (Wake 1). Chlorine is added if there are organic materials and bacteria. At this level, chlorine acts as a disinfectant.
The water is then agitated for a period of between thirty and sixty seconds. If flax mixing is done in less than thirty seconds, there is likely to be poor mixing of chemicals, which are added. On the other hand, excess mixing time may result into fragmentation of the floc formed into finer particles. It is therefore significant to establish flow rates, in order to be sure of the amount of time required to carry out the flax mixing.
The third step in water purification is coagulation. This step is also called flocculation. During this process, the mixing of water, initiated in the previous step is continued slowly to allow complete reaction of chemicals. Upon reacting, there is formation of removable solid particles called flocs. If mixing is done at a higher speed, the flocs are likely to break into smaller particles, which might not be easily separated using filtration or any other viable method (Wake 1).
Basically, coagulation is essential to eliminate turbidity, which is described as the hazy appearance of impure water, caused by soluble impurities. Water with high turbidity is usually hard to disinfect during the purification process. Besides lowering the turbidity of water, coagulation also eliminates bacteria and color from water. Surface water is known to have higher turbidity as compared to groundwater.
The removal of floc is done through the process of sedimentation, where water is passed through a sedimentation basin. Due to gravity the solid particles settle at the bottom of the basin, depending on their sizes.
Obviously, large particles settle first, while smaller ones take time to settle. After this stage, the water contains fine particles of floc and is moved to the filtration stage. During filtration, most of the floc is removed even though some tiny particles remain suspended in the water. Sand filtration is also applied, with an aim of eliminating any solid particles, which might be present in the water (Wake 1).
Apart from this, sand filtration plays a major role in purifying water, as it allows more solid particles to be removed as they get attached to the granules. For efficient sand filtration, the sand is occasionally cleaned to remove a covering of floc, which forms during the filtration process. The removal of this sheath is done by use of purified water, which is poured on the sand by stopping the flow of partially treated water.
Once the water has been purified, it goes through a disinfection process also known as chlorination. This stage is very important in guaranteeing the safety of water before it is channeled into the distribution system. Of great significance is the fact that disinfection removes bacteria, which might be present in water. This process also ensures that there are no disease-causing organisms in water before it is distributed for drinking (Wake 1).
Chlorine is the commonly used chemical during this process because of its chemical properties. Unlike any other chemical that one may prefer, chlorine is a strong oxidizing agent. It is therefore capable of removing ammonia, which is not healthy. Additionally, chlorine is important in the oxidation of iron, manganese, and hydrogen sulfide. Lastly, chlorination regulates the taste of water and destroys any organic matter present in water.
From the above stepwise view, it is obvious that water purification requires organized procedures in order to obtain water that is safe for drinking. The most important role of water purification is the removal of impurities, micro organisms, organic matter, dissolved chemicals, bad odor, and color. Nevertheless, the state of the raw water is imperative in determining the number of steps to be used and the concentration of chemicals required to achieve safe water.
Bibliography
Wake, Pamela. The Six Steps to Purifying Water. Live Strong, 2010. Web.