Precaution

Precaution

1)During the experiments,we need to wear a pair of gloves when handling with chemicals.Gloves help us to prevent from direct contact with those harmful chemical eg(sulphuric acid and silver compounds) when there is a spillage.

2)When we are using spectrophotometry,

• we must handle quartz curvette with care as they are in match and it is expensive.
• We have to hold the opaque part of the quartz curvette or else our fingerprints will be left on it which will affect the reading
• We have to use lint free tissue to wipe the quartz curvette instead of normal tissue,in order to prevent fingerprints or the fibre of tissue leave at the side of it which will interfere with the passage of light.
• Close the compartment while taking readings to prevent interference with external light.
• Curvette must be filled to the mark.Overflow will result in corrosion of expensive cell holder and other internal parts.If the level is not up to the mark,the absorbance reading will be air,not the sample.
• The curvette should be well cleaned and drained between samples to obtain accurate absorbance values without cross-contamination or dilution.
  

3)When we are probe,we must rinse it with distilled water to prevent cross-contamination of sample which will affect the result.

4)When the reading is shown on the screen,we must wait until it stabilize first,or average reading can be taken.

phosphate

phosphate

NO3 vs CL

NO3 vs CL

Chlorine

• Highest: Pond because there are fishes inside the pond. Fish food particles, fish waste in the pond and chlorides in surface and groundwater are leached from various rocks into the pond by weathering contribute to the increase of chloride.
• Second highest: GreaseTrap because there are food particles, cosmetics, hand soap, cleaning gel consisting of chloride ions.
• Tap water has more chloride elements because water contains chloride. A normal adult human body contains approximately 81.7 g chloride.
• At the C-shaped tank, only C-site 5 has the most Chloride as it is the endpoint for all the C-shaped tanks before flowing into the outlet so it gathers lots of chemical elements there.

Nitrate

• Highest: GT because it consists of cosmetics(silver nitrate,sodium nitrate),cleaning gel, oil,etc.
• The fishes in the c-shaped tank produce waste which increases the nitrate levels.
• Both Cs1,Cs2 are the higher in the C-shaped tank because most of the Nitrate come from GT and the plants on subsurface can trap little NO3 so there is large amount flow to the C-shaped tank.
• Cyperus papyrus(site1) can uptake some nutrients of NO3 but it is widely used as ornamental plant for water garden. Plant at site 2 ,Juncus Effucus, can filter suspended solids, so it can’t really absorb NO3.Cs3 has no nitrate due to some external reason as there are fishes inside tap water has quite a lot of nitrates.
• Maximum allowable level of nitrate-nitrogen in public drinking water is 10 ppm.

BOD VS DO

BOD VS DO

Theoretically ,BOD Increase,DO decrease because the organic matter will be decomposed by bacteria so the DO will decrease as the bacteria absorb the oxygen.

But in this case,BOD increase,DO increase because there is algal exist which will produce more oxygen under photosynthesis,so the DO increase.

cOnDuCtIvItY αTDS

CONDUCTIVITY α TDS

highest value: GT as it due to hand-soap; toothpaste; oil-grease and ect

The level of this graph dropped progressively in C-shaped tank, reaching tap water values similar to Cs4 indicating that the treatment system namely the subsurface flow and the C-shaped tanks are effective in removing TDS. However it increases the level in pond as due to excess waste and food from fish and also air pollution such as SO2,CO2NO can contribute to TDS increase.

TuBiDiTy αTSS

TUBIDITY α TSS

Highest Turbidity and TSS observed in GT due to materials (eg.food particles,oil,grease,cosmetic,etc)

Levels of Turbidity and TSS lowered in the C-shaped tank ,outlet ,pond and tap water.But the height of turbidity in Cs3 is the highest among the C-shaped tank as bottom-feeding fish like carp can stir up sediments on the bed and increase the cloudiness of the water due to the plant provides shelter for macro and micro invertebrates which become food for fishes

Turbidity in outlet is higher because around it has sand, soil and stone which affect the clarity of water when these solid flow down with water

pH vs TDS

pH vs TDS

PH, quite constant except for tap water. TDS, A sharp decrease from GT to CS1 where it gradually decreases until CS4 then gradually increase all the way until Pond, then a slight decrease at tap water.

What is the main cause of this?

The optimum PH level required for the healthy growth of plants is PH 6-7, which is seen in the case of CS1 all the way to the pond. As for Why the GT has a PH of 6.64, this is because of the usage of soap and detergent which are alkalis. As for the tap water with the PH 7.47 , limestone deposits contribute greatly to the alkali levels.

TDS Highest TDS observed in GT due to the presence of grease, oil, cosmetics.

Why the gradual decrease from CS1 to CS4? As CS1 is where the water from the GT just entered, it is where the most polluted water is, in the entire C shaped container. As the water flows to CS2, CS3 and eventually to CS4, it has already undergone the ‘cleaning’ process and thus, the water at CS4 is so much cleaner than compared to the water at CS1.

Why the gradual increase from CS4 to Pond? It is highly possible that its due to the fast motion of the flowing water from the outlet to the pond, the solids get dissolved easier.

Why the sudden increase at tap water? As Tap Water is filtered, thus this greatly decreases the TDS content in the water.