DISCUSSION

4.1 Key findings and analysis of results


Sediments


There is a very small change between Day 1 and 2 for the A Tanks however there is no change in the B tanks. Day 3 seems to be the anomaly causing a huge jump from both tanks.Unfortunately, the Day 4 samples are inconclusive because a negative mass is impossible and so the data is unusable.
The cause of these of these changes could be due to the fact that when the water hyacinth decays, it creates sediments.


Dissolved Oxygen


For the A Tanks, there has been a steady increase throughout the period of experimentation.
For the B Tanks, there is also a fairly steady increase in dissolved oxygen with the exception of day 2 which happens to be the anomaly in this case.
Seeing as though there was a similar increase despite the variable of the water hyacinth, this leads us to believe the aerators in all  tanks caused this increase in dissolved oxygen.


Fecal Coliform


The general trend is that A Tanks have an increase in Fecal Coliform Bacteria and the B Tanks experience a general decrease in Fecal Coliform Bacteria.


Normal Samples
For the A samples, there is an obvious increase with the exception of the anomaly at Day 3 where there is a drop in Fecal Coliform. Again however, we are unsure what could have cause this anomaly.
As for the B samples, there is a general decrease just like the general trend stated however there is an unusual spike on Day 2 which we don’t know the cause of.


Diluted Samples
For the A samples, they follow the general trend of an increase of Fecal Coliform Bacteria with the exception of the anomaly of the spike on Day 4.
For the B samples, they too follow the general trend of an decrease of Fecal Coliform Bacteria with an anomaly occurring between Day 1 and 2 which was a big drop.


The increase in A tanks could be due to the Fecal Coliform Bacteria being able to thrive under the oxygen from the aerators and the water hyacinth coming with the bacteria itself.

4.2 Explanation of key findings


Sediments
When the water hyacinth decays, it causes for there to be more sediment because it creates sediment as it decays. However, before we could get an accurate sample with these sediments present within it, sedimentation had already occurred within the tanks and so our results had turned out to be inaccurate.


Dissolved Oxygen


Considering the increase was present and similar for all tanks with or without the water hyacinths, the dissolved oxygen increase would have been caused by the aeration of the tanks through the aerators.The sudden increase,however,  in day 3 of tank B could have been caused by a different collection method.


Fecal Coliform


The tanks with the water hyacinths had a substantially bigger number of bacteria colonies than the tanks without, leading us to believe that the water hyacinth had come with the fecal coliform bacteria and together with the dissolved oxygen from the aerator, more fecal coliform bacteria was able to grow and thrive.


4.3 Evaluation of hypothesis


In our hypothesis we stated that,”The water in the tank with the water hyacinth would be purified.” Now, we have come to the conclusion that our hypothesis was wrong because the tanks with the water hyacinth had a huge amount of fecal coliform bacteria, still making it unsafe to consume and not “purified”. Fecal Coliform can make water unsafe to drink because there are illnesses linked to  the bacteria that cause upset stomach, diarrhea, ear infections, and rashes.However, some pathogens, such as E coli, hepatitis, and Salmonella, can have very severe health effects like anemia and kidney failure. (State Department of Ecology, W. ,2005)
As for dissolved oxygen, the water hyacinth was not the factor that led to that slight increase. It was the aerators  Lastly for sedimentation, our results are inconclusive due to inaccurate testing on our part and sedimentation that had already occurred in the tank.


4.4 Limitations and areas for improvement
During this experiment, we had done testing for the phytoremediation properties of the water hyacinth wrongly by testing for the wrong parameters. This had come from either a lack of equipment or a lack of knowledge on our part to use the sophisticated equipment to test for the right parameters. Those coorect parameters being electrical conductivity, total dissolved solids (TDS), sulphates, phosphates, total hardness, pH, nitrates, nitrites and total nitrogen.
An analysis of nitrates should have been done because nutrients from sewage such as nitrates and phosphates in excess may lead to the process of eutrophication- excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life. Excessive concentrations of nitrate-nitrogen or nitrite-nitrogen in drinking water can be hazardous to health, especially for infants and pregnant women. The primary health hazard from drinking water with nitrate-nitrogen occurs when nitrate is transformed to nitrite in the digestive system. The nitrite oxidises the iron in the haemoglobin of the red blood cells to form methemoglobin, which lacks the oxygen-carrying ability of haemoglobin. This hazard further drives the imperativeness of removing excess nitrates from water to be used for consumption.


Another analysis to be done is for heavy metals in water because heavy metal pollution has become a problem can be toxic to both humans and animals even at very low concentrations. This has become more pronounced due to the accumulation and concentration of the heavy metals in organic matter at sewage treatment works and their ability to persist in environments for a long time. Also because excessive heavy metals in drinking water can also be detrimental to one’s health. Severe effects include reduced growth and development, cancer, organ damage, nervous system damage, and in extreme cases, death. This proves that removing heavy metals as well as excessive nitrates from water is important.


In fact, water hyacinth has been reported to have accumulated and concentrated zinc, nickel and copper in their roots to levels 20 000, 1200 and 1300 more than its concentration in a river respectively. This shows us that water hyacinth does in fact have the ability certain pollutants in water however since we did not test for that this information went unnoticed. Now we know that we should have done a more in depth analysis on the water hyacinth and using parameters that the water hyacinth actually had an effect on.
Lastly when recording data, we should be more vigilant of when, where and how we recorded it. When it came to doing our logbook, we had forgotten to note some of details of when we recorded the data.We also sometimes had missing data because we forgot where we had wrote it or typed it out. If we had the opportunity to do an experiment like this again, we would also take more photos and videos to back our data.

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