TDS vs. Conductivity

The dissolved solids in the pool may be due to body wastes, suntan lotion,stabilizer,chlorine, algicide, dirt , dust, pollen etc.

Since this is an outdoor pool, the TDS value is less than usual because of dilution by rainwater.

TDS increases with conductivity as the more salts are dissolved in the water; the higher is the electrical conductivity. The majority of solids, which remain in the water after a sand filter, are dissolved ions. Sodium chloride for example is found in water as Na+ and Cl-. High purity water that contains in the ideal case only H2O without salts or minerals has a very low electrical conductivity. The water temperature affects the electric conductivity so that its value increases from 2 up to 3 % per 1 degree Celsius.

TSS vs. Turbidity

Theoretically, turbidity increases with total suspended solids. The insoluble particles ranging from coarse to fine dispersions (depending on the nature of the water body), will interfere with the passage of the light.

The value of the TSS of the swimming pool is supposed to be higher than that of the pond.


The wrong trend of the graph may be due to experimental errors such as

• Filter discs were not dried before initial weight was taken
• Drying should be done to constant weight
• Measured by method which is less precise(i.e. gravimetric method)
• Sample is not stirred and mixed properly before it is poured
  

BOD vs. DO

Theoretically, the BOD value in the pond should be higher due to the large population of microorganisms and aquatic organisms like fish and turtles. Aquatic plants may use up the dissolved oxygen as well during respiration. There might be also microorganisms from the surrounding soil due to surface runoff.

The BOD value in the swimming pool is lower due to the high amount of dissolved oxygen as there are less microorganisms that are present to utilize the dissolved oxygen. The constant maintenance of the pool water prevents the growth of microorganisms in the water.

The wrong values of the graph may be due to experimental errors:

The DO probe is not washed properly with DI water, giving inaccurate results

The DO probe is not calibrated to the correct value.

As the amount of dissolved oxygen decreases, the BOD values will increase and vice versa. This is because the demand for oxygen by the bacteria is high and they are utilizing the oxygen that is dissolved in the water. If there is no organic waste present in the water, there won't be as many bacteria present to decompose it and thus the BOD will tend to be lower and the DO level will tend to be higher.

BOD vs. COD

Colour vs. Nitrate

•It is a source of nutrients for algae. Algae growth rate increases. Population multiplies. The water body becomes green.

•The nitrates could come from the fertilizer application, bird droppings, fish waste, waste fish food, waste plant and animal matter.

•Naturally, lightning (combination of oxygen and nitrogen) produce nitrates. It is common in regions experiencing tropical climate (Singapore) where there is rain accompanied by lightning.

•Other occurrences such as the process in nitrogen cycle; oxidation of nitrites by nitrobacter bacteria in the soil which produce nitrate.

•In swimming pool, human waste (skin) also contribute to nitrates.

•Based on the standards set from USEPA, the MCL for nitrate in any surface water is 10mg/L.

•Color µ Nitrate

Colour vs. Phosphate

Phosphate Source

•Clay soil, rocks & minerals, plants, animal waste, urine

Bacterial decomposition in plants and animals contribute to the total dissolved solids in the water body.

•Improper treatment water body.

•Fertilizer runoff from urban landscape

•Storm water percolate the soil

•Atmospheric deposition

•Similar to nitrate, provide nutrients for aquatic weeds

•Color µ Phosphate

•No visible pattern for phosphate

The recommended concentration limit for Phosphate is 0.1mg/L

Reflections of Colour

• Huge difference in the measurement of color between the swimming pool (7 Hazen units) and the pond (avg. 46.5 Hazen units)

• It is true as the pond has a dark green color and the pool is crystal clear that the base of the pool can be seen.

• The color in the pond is affected by the waste of the aquatic creatures living in the pond, the food given, the soil particles around the pond, the dissolved ions, leaf litter which in all affect the clarity of the water body.

• The color of the swimming pool is crystal clear as it has no living organisms, or solids in it except for humans.

• Moreover, it is well maintained for hygiene and aesthetic purposes. Based on NEA requirements, the color should be 5 Hazen units.

• The difference may be due to the fact that they were cleaning the pool when the measurement is taken

TDS vs. Hardness

1. Blk 54 Pond, Girl Group
2. Swimming Pool
3. Pond

The swimming pool has the highest TDS. This may be due to the body wastes, suntan lotion, stabilizer, chlorines, algaecide, dirt, pollen. Sometimes people wear slipper wad walk around the pool area hence the soil under the slipper may have swept into the pool.

The hardness is highest in the pond which mean there is a higher concentration of Calcium and Magnesium.

COD vs. Hardness

1. Blk 54 Pond
   
2. Swimming Pool
3. Pond

Since the chemical oxygen demand test is used to measure the pollution strength of domestic and industrial wastewater, hence the readings of the cod of both the pond and the swimming pool are considered to be acceptable. The pond is slightly more polluted than the swimming pool from the results shown. It has a lot of living organism hence it has the highest amount of organic compound. It also has the highest level of hardness because of the mineral from the soil that's being dissolve into the pond.

COD vs. TDS vs. Chloride

1. Swimming Pool
2. Pond ( General )
3. Pond ( Girls )

From the bar graph, we can see that the cod, TDS and chloride are being compared between the pond and the swimming pool

Two readings from the pond was taken and the results are slightly different. This is so as one sets of the reading is proven to be inaccurate.

The readings of the total dissolved solids of the pond stands at 84.5 and 74. (the main difference between the 2 sets of results)

Other than the TDS measured, the other sets of readings, both the cod and the chloride, is almost identical in both sets of the pond readings. other than the TDS measured , both the cod and the chloride, is almost identical in both sets of the pond readings.

As compared to the pond, the swimming pool has a much higher content of chloride. This is so as chlorine is used to disinfect the swimming pool.

The swimming pool also has much more total dissolved solids than the pond due to the fact that many people swam inside the pool. Copper sulphate, chloride, suntan lotion from human skin and algicide are plentiful, hence resulting in a high level of TDS(756.4).

The chemical oxygen demand test is used to measure the pollution strength of domestic and industrial waste water. Therefore, the cod level of the pond should be higher than that of the swimming pool due to the fact that the pond contains a higher level of biodegradable and non-biodegradable components. Another reason is that the swimming pool is usually cleaned and maintained. Although the pond is also cleaned and maintained every week, but the presence of fishes and birds produces wastes which contributes highly to the cod level of the pond.

Colour vs. TDS

The TDS for pool is relatively high because of the use of high % of chlorine, algicide used while in the pond, chlorine is not used at all.

Colour in pool is low to indicate the pool is clean for use.

The colour for ponds is higher than swimming pool since it is not clean and it is probably polluted with faeces of fishes and also algae, which contributes to euthropication.

Colour vs Turbidity

Theoretically, Colour increases with turbidity. This is because as colour increase, it prevent more light from entering the water thus increasing the turbidity.

However, the trend is wrong due to experimental errors such as:

Probe is not washed properly with DI water- giving inaccurate results.
Probe is not calibrated to the right value.

The trend is wrong as the swimming pool results which have low colour should have lesser turbidity than the pond results. However the graphs shows that the turbidity of the swimming pool is the high