1) The two possibilities are water purification tablets and ultra-violet light water purifier. Comparing these two possibilities, both are similar in terms of their cost. Both methods are cost effective where water purification tablets are only sold for an estimated cost of (50 tablets for $6.20) and ultraviolet light water purification only requires the user to replace the lamp and sleeve of the purifier annually. However, both of these methods differ in their effectiveness. For the water purification tablets, it is less effective since it requires a long duration of 30 minutes to purify the water as compared to ultraviolet light water purifier which only takes 90 seconds. Both of these methods are similar to the tertiary treatment of purifying municipal water supplies where both engages in the step of purifying water.
2) Firstly, desalination techniques are energy intensive. Distillation requires a huge amount of heat energy to evaporate the seawater.As for reverse osmosis, this technique requires high pressure to be applied to the seawater through a semi-permeable membrane. These translates to large amount of investment in both energy usage and infrastructure required.
Secondly, desalination techniques also result in environmental concerns. This problem arises due to the problem of disposal of residue. Highly concentrated brine, which is a form of inorganic salt can result in environmental degradation, especially aquatic ecosystems if dilution of brine is not done properly before disposal.
Besides, in economic terms, desalination techniques also require high cost. Since there are other cheaper options available currently, for an instance, water catchment and groundwater source, the cheaper options are highly preferred over the costly desalination methods to reduce the overall production cost of potable water. Moreover, investment into the energy source to carry out desalination and the advanced equipment and to desalinate water require high expenses too.
3) a)Possible sources of lead can be due to contamination by lead fuel, batteries or hazardous waste sties that seeps into the underground water storage. The major source in this case is most likely water contaminated by rusting and corrosion of piping made of lead, resulting in lead dissolving into the drinking water.
b)It is unlikely for the research activity to affect the lead levels as the waste products should have been properly disposed in the lab. Even if the waste is not properly disposed, the water supply to the drinking fountains should be supplied by PUB and not directly pumped from the underground water storage in the location.
4)We expect only water-soluble vitamins to be polar compounds. Water is a polar compound and according to the ‘like dissolves like’ rule, polar compounds will be able to solubilize other polar compounds. Thus polar compounds are hydrophilic and are “Water-loving”. On the other hand, vitamins that are fat-soluble, are hydrophobic, also known as ‘water-hating’ compounds. This is due to their non-polar nature. As mentioned above, according to the ‘like dissolves like’ rule, fat being a non-polar compound will only be able to solubilize other non-polar compounds. Thus fat-soluble vitamins must be non-polar in order to be able to solubilize in fat. being non-polar, they will not be able to solubilize in water due to the opposing polarities.