Temperature

Temperature of water collected from the sites vary largely.

This may be due to the collection of the water in sample bottles and it was not tested on the spot immediately. For example, the tap water was collected first and left untested for a length of time after it was collected.

This may have resulted in temperature fluctuations during that period of time. Thus, the temperature readings probably do not reflect their initial temperatures and are not accurate, causing the results to be varying.

Suspended Solids

The grease trap has the highest amount of suspended solids because of big molecules such as hair and food, small molecules such as dirty foams from hand soap, and even smaller molecules such as oil.

The amount of suspended solids are low at other sites because the grease trap has successfully trapped the molecules from being passed on to the rest of the system.

Nitrite

The values of nitrite in all sites except tap water is very low and remains fairly constant. Furthermore, nitrites occur very seldom in significant concentration.

The cause of the higher nitrite value in tap water is probably formed by drinking water distribution systems that use chloramines.

Even so, the level of nitrite is safe and has no much adverse effect to human and living organisms.

Nitrate

The nitrate levels for all the sites are relatively constant and lie within the acceptable range of below 50mg/L (following WHO's guidelines).

Nitrate concentration is low as the source, water that flows into the grease trap, contains a low concentration of nitrate as well. This is probably because the detergents or soaps used had a low concentration of nitrate in them.

There were prevalent nitrate content in the next 4 sites. However, having Tank b4 Pond as a control, we know that the concentrations are normal and probably a natural-occurring concentration in the environment.

COD

Grease trap has the highest value of COD, whilst the value for tap water and C1 were low and the rest of the sites had a 0 value of COD.

Grease trap has a high value of COD because the decomposition of organic matter such as food molecules, organic chemicals from detergents and dead skin cells, as well as aerobic respiration by bacteria (BOD that contributes to COD) thriving in the water takes up a large concentration of DO. Hence this causes the amount of COD to increase in the Grease Trap.

In C2, not all unwanted nutrients in the water had been taken up by the plants in the phytoremediation system and hence, the COD value. However, as the water goes through a second round of phytoremediation in the C-shaped pond, almost all the unwanted nutrients had been taken up by the plants and bacterial activity had become negligible.

Hardness

Degree of hardness for all results are in between 0 to 75mg/L. Hence, they fall within the acceptable range.

The hardness of water in Inlet C1 is the highest, the grease trap being the second highest. This is due to the detergent or soaps containing hardness-causing ions in the Grease Trap.

From the grease trap, the water travels through the phytoremediation system(PS) which contains soil, stones and plants. Perhaps the calcium ions from the stones gets washed away by the water passing through the PS and a large concentration of hardness-causing calcium ions ends up in the water of Inlet C1, resulting in the high value for hardness.

Turbidity

Turbidity in results is considered in the acceptable range.
The results of Inlet C1 and Pond 2 are slightly higher. The waste of fishes and tadpoles affects the clarity of water because of microorganisms present. Turbidity reading is the highest in the grease trap. It is most likely caused by suspended matter of insoluble particles in the water. For example, the presence of washed-off hands soap in the water of grease trap causes it to be turbid. It interferes with the passage of light resulting in the reading of turbidity for the grease trap to be the highest because it is most unclear. In this case, the suspended materials are colloidal dispersions.

Biochemical Oxygen Demand

All BOD values tested are within the range of typical values of BOD found in raw water sources, with the exception of Inlet C1 which is significantly lower.
However due to experimental errors the results obtained were not accurate to show a distinct pattern among the different sites tested.

Total Dissolved Solids

Water with higher dissolved solids may give laxative effects. Pond 2 has the highest amount of TDS and tap water has the lowest. Pond 2 has higher levels of ions due to the presence of plants because plants need ions and minerals to grow. Tap water has the lowest level because micro-organisms and other solids are mainly removed in the reservoir’s water treatment system.

pH

In wastewater, pH usually varies with the presence of particular microorganisms involved. Some plants in the researched area provide shelter for macro and micro invertebrates. pH results from the research are in a acceptable range and will not cause much harm to human bodies.

Plants and fishes live in the waters of the pond, proving that the water is in suitable conditions to sustain a living thing.

Chloride

As chloride occurs in all natural waters, there is a slight amount of it existing in the tap water, inlet and outlet, pond 1 and pond 2. However the chloride is significantly high in the grease tap. It could be that students wash off salt minerals from their hands using tap water, which then increases the value of chlorides containing in the grease tap.

Phosphate

There is a minimal amount of phosphate contained in tap water because polyphosphates are used in water supplies as a means of controlling corrosion.

A high level of phosphate in the grease tap is mainly contributed by detergents, soaps and even traces of human wastes (urine) when a person washes their hands at the sink.

Hydroponics in the Phytoremediation System and along the C-shaped pond absorb the high concentration of phosphate, that becomes a pollutant if not removed, as part of the treatment system.

Plants like the Papyrus Sedge absorb Phosphate ions

Dissolved Oxygen

Dissolved oxygen is a measure of the degree of pollution in water. Tap water has the highest level of DO while grease trap has the lowest level. Tap water has the highest level because there is a low amount of micro-organisms in the water, hence not much of oxygen is taken up. Grease trap has low level of DO because there is more organic waste in the water and that the bacteria needs to consume oxygen to survive, thus level of dissolved oxygen in grease trap is low.

Conductivity

The conductivity in all the six sites is relatively high, between 100mho to 200mho, tap water being the lowest. This measurement suggests a high amount of ions dissolved in the water.

The presence of ions in the Grease Trap may have been caused by detergents and soaps which contained ions such as nitrates and phosphates. The decomposition of organic matter by bacteria to ions (e.g. food molecules) and chemicals that get washed down (e.g. pen ink) would have also contributed to the ionic content in the water.

As the water passes out of the Grease trap and into the phytoremediation system, Organic-Nitrogen is decomposed by bacteria into Ammonia-nitrogen and finally into Nitrate-Nitrogen which flows into the C1 Inlet causing the height in conductivity.

Taken up by the hydroponics, ion concentration decreases in C2 Outlet and Pond 1, resulting in the steady decrease of conductivity as well.

However, conductivity increases in Pond 2. We assume this is caused by the wastes generated by the organisms living in the or due to pollution by the air.

Colour

The colour data in the grease tap is significantly high. The main reason is because teachers use the tap water to wash their hands which may be dirtied with pen ink, food molecules, and other coloured particles.

A high amount of colour in the outlet could be due to organic matters, such as decaying leaves and suspended particles, such as soil.

Decaying leaves & Suspended Particles contribute to Colour Data

The inlet, pond 1 and pond 2 colour data is caused by suspended particles especially coloured clay soils.