Lab 2 – Water Quality and Contamination
Abstract
In this lab, the water quality, contamination, and treatment were investigated. The ability of contaminants (oil, vinegar, and laundry detergent) to remain in the water after passing through the ground was examined. Also, the simple filtering procedure was assessed for its effectivity in purifying water contaminated with soil. The quality of tap water, Fiji, and Dasani bottled waters by the content of ammonia, chlorides, iron, phosphates, total alkalinity, total chlorine, total hardness, and pH was analyzed and compared. All of the studied contaminants proved to remain in the volume of water after passing through the soil; the proposed filtering procedure was able to cleanse water from contamination, and the bottled water had better quality in all the categories, except for total chlorine.
Introduction
It is needless to say that water is the critical element of any life on Earth. And, obviously, it is not less important for humans. Today, the issue of water contamination stands very acutely. The surface waters are facing unprecedented pollution; they get contaminated with nitrogen, phosphorus, heavy metals, other dissolved salts, organics, pathogenic bacteria, and viruses (Perk, 2014, p.63). In this context, the need for cheap and simple water treatment processes constantly grows.
One of the solutions to the problem of drinking water contamination offered by the market is the bottled water. The bottles contain either artesian of purified tap water. The purified water producers claim to use sophisticated methods for water purification, however, in fact, the most widely used treatment technique is filtering and reverse osmosis (Dege, 2011, p.172) which are employed in the most basic purification systems for home use. According to Hadley (2016), the market of bottled water will overthrow the soda market by the 2017 judging by the volume consumed. In this light, the question arises whether the bottled water is worth the price. Bosque (2010) stresses the point that the regulations for the tap water are now actually much stricter than the regulations for the bottled water which makes the question even more complicated.
This lab focused on three main points described – whether the water contaminants will persist in water after the filtration through the layer of soil, whether simple filtering procedure will be able to purify water contaminated with soil, and whether there is a difference between tap and bottled water quality.
The hypotheses suggested were the following. For the first experiment: the oil, vinegar, and laundry detergent contaminants will persist after filtration through the ground. For the second: the proposed filtering procedure will be able to cleanse the water contaminated with soil. For the third experiment: the tap water will have the worst quality while Dasani bottled water will have the best quality.
Materials and Methods
The experimental part of the lab consisted of three experiments. They were the test of contamination effect on groundwater, water treatment, and testing the quality of drinking water.
For the first experiment, the following materials were used: eight 250 mL beakers, permanent marker, 3 wooden stir sticks, 100 mL graduated cylinder, 10 mL vegetable oil, 10 mL vinegar, 10 mL liquid laundry detergent, 100 mL beaker, 240 mL soil, funnel, cheesecloth, water, and scissors.
All the 250 mL beakers were labeled from 1 to 8. Into each of the first four beakers, 100 mL of water were poured using a graduated cylinder. The first beaker was used as a reference point; nothing was added to the water. To the second beaker, 10 mL of vegetable oil were added, and its contents were thoroughly mixed using a wooden stick. The observations of the water in the beaker were recorded. Into the third beaker, 10 mL of vinegar were added, all was thoroughly mixed, and similarly to the second beaker, the observations of water were recorded. Into the fourth beaker, 10 mL of laundry detergent were added, and the same procedure was repeated. Next, the cheesecloth was cut into pieces and folded, so that four-layered pieces fitted the funnel. After placing a cheesecloth piece inside the funnel, 60 mL of soil were measured using a 100 mL beaker and placed in a cheesecloth-lined funnel. The funnel was placed inside the beaker 5 and water from beaker 1 was poured into a funnel and allowed to filter for one minute. The observations of water characteristics were recorded after the time passed. Using fresh pieces of cheesecloth and fresh portions of soil, using the same procedure, the contents of beakers 2, 3, and 4 were filtered into the beakers 6, 7, and 8 recording all the pertinent observations.
For the second experiment, the following materials were used: 100 mL potting soil, two 250 mL beakers, two 100 mL beakers, 100 mL graduated cylinder, 40 mL sand, 20 mL activated charcoal, 60 mL gravel, wooden stir stick, alum, funnel, cheesecloth, bleach, stopwatch, and water.
Firstly, the soil solution was prepared: 100 mL of soil were added to the 250 mL beaker and filled to the 200 mL mark with water. After pouring the solution back and forth between the two beakers 15 times, 10 mL were transferred into a clean 100 mL beaker for further comparison. Then, 10 g of alum were added to the 250 mL beaker containing soil solution, the mixture was thoroughly mixed with a wooden stick and let to sit for 15 minutes. For treating water, the funnel based filter was assembled. The cheesecloth-lined funnel was prepared the same way as in the first experiment, then 40 mL of sand, 20 mL of activated charcoal, and 40 mL of gravel were poured into it in layers in the respective order. The filter was solidified by pouring clean water into it several times and letting filter for 5 minutes. Then without mixing the sediment, about 3/4 of the soil solution from the 250 mL beaker were poured into the funnel and were let to filter for 5 minutes. To the filtered water, few drops of bleach were added, and it was mixed for 1 minute. The treated water was then compared to the initially taken sample of 10 mL contaminated water.
For the third experiment, the following materials were used: ammonia, chloride, phosphate, iron, and 4 in 1 test strips, three 250 mL beakers, three foil packets of reducing powder, Parafilm, stopwatch, Fiji, and Dasani bottled water.
The three beakers were labeled, and one kind of water (Fiji, Dasani, and tap) was poured into each of them. Firstly, all the three water samples were tested for ammonia content using ammonia test strips; all the results were recorded. Next, the samples were tested using chloride test strips. Using 4 in 1 test strips, the pH, total alkalinity, total chlorine, and total hardness of the water samples were assessed. Next, the phosphate concentration was measured using phosphate test strips. To test the water samples for iron content, 70 mL of water was discarded from each beaker (to leave 30 mL). The content of the foil packet was added to the tap water sample, the beaker was covered with Parafilm and vigorously shaken for 15 seconds. After that, it was tested with the iron test strip. The same procedure was repeated with two remaining samples.
Results
Observations for the first experiment are summarized in the Tab. 1:
Out of the three initial contaminants, oil had the least potent effect on the water quality, while laundry detergent had the most. The addition of oil only made water greasy on the surface but did not affect the whole volume. Vinegar altered the taste and smell strongly but water remained clear. Laundry detergent changed the taste and smell of the water so that it became undrinkable. It also became bubbly.
It is important to note that after filtering contaminated water through the soil, the effect of contaminant present before the treatment did not significantly change for all the three contaminants (oil, vinegar, detergent).
In the second experiment, the initially prepared soil solution or contaminated water was dark and not transparent. It had a dirty color, was murky and had a damp smell. After being filtered, the water regained transparency and clear color. It looked very clear and uncontaminated, the smell became weaker but still persisted. After adding few drops of bleach to the treated water, it got even clearer, and the dirty smell disappeared, water smelled fresh again with a hint of the chlorine odor.
The results of the third experiment are summarized and presented in the Tab.2, 3:
Discussion
All of the hypotheses for the three experiments were at least partly accepted by the results of the experiments. All of them will be further discussed one by one.
In the first experiment, the hypothesis stated that all the three substances will be able to contaminate groundwater, i.e. permeate through the layer of soil and remain in the water. After the initial contamination, the characteristics of the water significantly changed (one sample became oily, the second gained sour smell, and the third became bubbly and started to smell like a detergent). Their ability to contaminate water was never put to doubt. However, when these water samples were filtered through the funnel containing soil, all of them gained green color, reduced visibility, and a damp smell. Still, the characteristics pertinent to the water samples prior to filtration persisted in it after the filtration. These observations clearly support the hypothesis stated for the experiment. It is important to study the mixtures of contaminants because the effect of one contaminant can significantly vary when combined with another contaminant. For example, oil itself is easily removed from the water, however if coupled with detergents, it can form stable emulsions which are much harder to remove from water. ("Exploring the importance of the Oil/Detergent water phase", 2016)
In the second experiment, the hypothesis was also supported by the experimental results. The hypothesis stated that the suggested treatment process will be able to clean the contaminated water. The soil solution or contaminated water initially had a dirty color, was not transparent and had an earthy smell. After the filtration and bleach addition, all of these signs of contamination were gone and the water was clear again and even had a fresh smell. The results of the first two experiments imply a sequence of interesting answers and questions. The answers first: it can be inferred from the results that the contamination with natural substances such as earth, sand, or mud is much easily removed than the contamination with chemical substances which are soluble in water or have a liquid form (oil, vinegar, detergent). Next is the most interesting part – the questions. If water contaminated with soil can be returned back to normal by simply filtering it through charcoal, gravel, and sand, then what treatment will be sufficient to remove the oil, vinegar, and especially detergent. It is evident that a number of such ways already exist, however, the problem of water contamination is very acute nowadays, and cheaper and simpler ways of purifying contaminated water are still needed.
The third experiment showed the most interesting results. The hypothesis for the experiment was that the tap water would have the lowest quality of the three while Dasani bottled water would be the purest. The hypothesis was supported by all of the test results except for the total chlorine test. In this test the tap water performed best with 0.2 mg/L while, Dasani bottled water had 80 mg/L. In all other tests, the results were almost uniform – the tap water had the worst results, Dasani had the best results, and Fiji was in between them of had similar values to Dasani. The hypothesis was chosen based on how each water sample is treated and produced. Tap water is generally taken from open water sources such as rivers, is industrially treated and delivered through the pipes which are often contaminated. Fiji is an artesian water and is just taken from the well where water is rather clean. Dasani is a purified water; this is why the initial suggestion was that it would be the purest of all. Although bottled water comes for a price, it can be concluded that it is worth it. The tap water quality is extremely dependent on the conditions of the pipes while the quality of the bottled water is stable. It has been shown experimentally that bottled water is much purer than the tap water.
It should be noted that some experimental errors occurred during the third experiment and specifically pH measurement. The results of the experiment are far too extreme to be true, this is why it can be concluded that some contamination by other samples have occurred, also the values might have been affected by the temperature of the environment in which the experiments were conducted.
Conclusions
During the experiment, the first and second hypotheses were fully accepted while the third was partly accepted. It can be concluded that water contamination is a strong problem since the pollutants remain even after the water passes through the ground. Also, it was shown that simple filtering procedure is enough to purify the water contaminated with soil. The bottled water also proved to have better quality than the tap water and to be worth purchasing as drinking water.
References
Bosque, T. (2010). The True Ingredients of Bottled Water | Ban the Bottle. Banthebottle.net. Retrieved 16 June 2016, from https://www.banthebottle.net/articles/the-true-ingredients-of-bottled-water/
Dege, N. (2011). Technology of Bottled Water, 3rd Edition. John Wiley & Sons.
Exploring the importance of the Oil/Detergent water phase. (2016). mint.ua.edu. Retrieved 16 June 2016, from http://mint.ua.edu/wp-content/uploads/2010/05/Background.pdf
Hadley, M. (2016). Bottled water about to top soda as most consumed beverage. KGW. Retrieved 16 June 2016, from http://www.kgw.com/news/health/bottled-water-about-to-top-soda-as-most-consumed-beverage/240061078
Perk, M. (2014). Soil and water contamination. London: IWA Publishing.
