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Water is a colourless and odourless liquid, and is very important for human development and survival. It covers 75% of the earth's surface and is mostly found in lakes, rivers and seas. In addition, the human body comprises 78% of water. Water is an interesting molecule and consists of one oxygen atom and two hydrogen atoms. It is covalently bonded and possesses a very interesting characteristic, i.e. polarity. Polarity ensures that water is an effective medium for the dissolution of other polar compounds. In so doing, water is an enabler for many biological reactions (“The Chemistry of Biology”, 2016). Society in general is very dependent on water for the survival and sustainability of all living organisms.
In the human body, water is responsible for the digestion of food and the transport of essential nutrients and vitamins to various cells within the body (“Nestle-waters”, 2016). Water is furthermore responsible for the chemical and metabolic reactions occurring in the body, the regulation of the human body temperature and the elimination of waste products from the body. It is said that the human body can survive without food for approximately 30-40 days but can only survive without water for about 3-4 days (“Businessinsider”, 2016). In order for the human body to consume water, there is a vital need for the water to be purified, otherwise microorganisms such as E.coli, Cholera and Cryptosporidium would cause serious illness.
In a conventional water purification system, impurities are removed using four main processes: Coagulation, Sedimentation, Filtration and Disinfection (‘Safewater”, 2016). Coagulants such as aluminium sulphate or ferric sulphate is added to the water to neutralise the negatively charged particles dissolved in the water. These coagulated particles then settle due to the gravitational forces, and are finally removed by filtration using a combination of coarse and fine sand particles. Some of the bacteria and viruses present in the water become trapped in the coagulated particles and are also removed. However, some harmful substances remain in the water and hence there is a need for a disinfectant phase. The most common disinfectant used for the purification of water is chlorine. The water purification process is quite intriguing and undeniably effective. Nevertheless, due to the standards for drinking water becoming more stringent, there is a growing need for additional water treatment options to be developed.
Huiqin, Zhaoxiang, Weixing, Weihong and Wanqin studied the combination of micro-filtration and ultra-filtration membranes for the purification of river water. The membranes that were used were Al2O3 and ZrO2 based. Their findings showed that the pore size of the membrane had no influence over the water quality. Nonetheless, the hybrid combination of membrane and coagulation was found to be an effective way to purify the river water containing micro impurities.
The use of porous copper for water treatment has also been investigated (Michailidis, Stergioudi, Seventekidis, Tsouknidas, and Sagris, 2016). It was concluded that the high surface area of copper enhanced the water purification system. It is said that because copper is an electron donor, it partakes in efficient redox reactions and is consequently good for water treatment. Copper functions predominantly as a reductant and is very capable of removing heavy metals. In addition, its capability for the decomposition of organic pollutants has been proven.
Although much research has been undertaken in the field of water purification, there is still a social perception that the quality of water delivered to households is poor. In Uganda, the people tend to further treat the tap water with activated charcoal in order to increase the purity levels (Prouty and Zhang, 2016). The purchase of activated charcoal further increases the household expenditure. A shocking discovery was that certain households believed that rain water had a higher purity than tap water. Consequently, the water was never purified prior to ingestion and this led to high infection rates within the population. It is therefore quite imperative that the perceptions of society are always taken into consideration when executing technical studies that would have an environmental impact.
Water plays a central role in everyday life from the most mundane task of drinking a glass of water to the more complex task of ensuring the continuation of biological reactions. One important aspect to consider is: What would happen if there was no more fresh water on earth? Consider for a minute what would happen if there was a severe drought and if water became almost a priceless commodity. Initially, there would be worldwide panic followed by rationale means of water replenishment. This brings us to the Technological Age.
One method of conserving the amount of water used and controlling the use of natural resources is to recycle water. Recycled water can be used to sustain plant life, animal life and other living organisms. The thought of using waste water does not seem very appealing but research has shown that it is fairly effective. Pio et al. (Pio et al., 2015) successfully investigated the use of a combination of zeolite, activated carbon and sodium hypochlorite to remove elevated levels of arsenic in drinking water. Inferring from another cited article by Michailidis et al. , copper can also be used to reduce Cr (VI) to the Cr (III) oxidation state which forms an insoluble hydroxide. This would allow for safer drinking water.
If there was absolutely no fresh water in society to even consider recycling, would there be another option? Or would humanity together with all existing life perish? One thing to remember as far as technology advancement goes, there is always light at the end of the tunnel. That said, another method of providing purified water is desalination. As mentioned previously, water comprises 75% of the earth. The most common mass aggregate is the ocean, which unfortunately contains a considerable amount of salt. Consumption of large volumes of water containing salt can lead to imminent death due to dehydration.
According to Zou and Liu , China has a desperate need to increase water resources and desalination was found to be an effective way of improving the situation. Desalination involves the removal of salts from water (“Water Desalination Processs”, 2016). This is accomplished using pressure to drive the membrane process, or the use of direct current or osmotic pressure. Although the desalination technique is costly and requires a vast amount of energy, the output and availability of purified water drives the researchers to continue to improve on the technology.
One of the crucial concerns of the desalination process is the removal of the microbiological impurities present in non-purified water. In a study carried out by Belila et al. , micro-bacteria were found to be present in the purified water after the reverse osmosis and chlorination process. They concluded that in order to be able to successfully remove the pathogens, further research is required to understand the nature of the bacteria. Another equally important issue preventing the widespread application of desalination plants is the biofouling of the membranes by dissolved organic carbon. Monnot, Laborie and Cabassud effectively used granular activated carbon to reduce the amount of dissolved organic matter thereby reducing the extent of biofouling.
Water is a vital component in everyday life. Researchers are continually finding new ways of improving the technology for the conventional water treatment, waste water treatment and the desalination process. Even though there are many technologically advanced desalination plants being built in the coastal areas where researchers are striving to better improve the processes involved, there is always a rural population, especially in Africa, that cannot afford conventional purified drinking water and resort to drinking contaminated water from rivers and dams. Society needs to address the growing demand for purified water, whilst at the same time make provision for fresh purified running water to be easily accessible to the under-privileged nations of the world.
References
Belila, A., El-Chakhtoura, J., Otaibi, N., Muyzer, G., Gonzalez-Gil, G., Saikaly, P.E., van Loosdrecht, M.C.M., Vrouwenvelder, J.S. (2016). Bacterial community structure and variation in a full-scale seawater desalination plant for drinking water production. Water Research, 94, 62-72.
Businessinsider. (2016, March 22). Retrieved from Here's How Many Days A Person Can Survive Without Water: http://www.businessinsider.com/how-many-days-can-you-survive-without-water-2014-5
Huiqin, Z., Zhaoxiang, Z., Weixing, L., Weihong, X., Wanqin, J. (2014). River water purification via a coagulation-porous ceramic membrane hybrid process. Chinese Journal of Chemical Engineering, 22, 113-119.
Michailidis, N., Stergioudi, F., Seventekidis, P., Tsouknidas, A., Sagris, D. (2016). Production of porous copper with high surface area for efficient water purification. CIRP Journal of Manufacturing Science and Technology.
Monnot, M., Laborie, S., Cabassud, C. (2016). Granular activated carbon filtration plus ultrafiltration as a pretreatment to seawater desalination lines: Impact on water quality and UF fouling. Desalination, 383, 1-11.
Nestle-waters. (2016, March 22). Retrieved from The functions of water in the human body: http://www.nestle-waters.com/healthy-hydration/water-fonctions-in-human-body
Pio, I., Scarlino, A., Bloise, E., Mele, G., Santoro, O., Pastore, T., Santoro, D. (2015). Efficient removal of low-arsenic concentrations from drinking water by combined coagulation and adsorption processes. Separation and Purification Technology, 147, 284–291.
Prouty, C., Zhang, Q. (2016). How do people’s perceptions of water quality influence the life cycle environmental impacts of drinking water in Uganda? Resources, Conservation and Recycling, 109, 24-33.
Safewater. (2016, March 22). Retrieved from Conventional water treatment: Coagulation and Filtration: http://www.safewater.org/PDFS/resourcesknowthefacts/Conventional_Water_Filtration.pdf
The Chemistry of Biology. (2016, March 22). Retrieved from Infoplease: http://www.infoplease.com/cig/biology/water.html
Water Desalination Processs. (2016, March 23). Retrieved from American Membrane Technolgy Association: http://www.amtaorg.com/water-desalination-processes
Zou, Q., Liu, X. (2016). Economic effects analysis of seawater desalination in China with input–output technology. Desalination, 380, 18-28.
