Laboratory Testing

· COD
1) The sample is refluxed with known amounts of potassium dichromate and sulphuric acid.
2) The excess dichromate is measured by spectrophotometry, as the amount of organic matter is proportional to the potassium dichromate consumed.

· Phosphate
1) Ammonium molybdate is combined with the sample containing phosphate ion and form a yellow colour solution
2) A reducing agent, ascorbic acid is added to produce a blue colour solution that is proportional the amount of phosphate present.

· Hardness
1) EDTA, a tritrating agent is added into the sample.
2) Hardness is present if the dye turns reddish-pink from blue colour.

· Suspended Solids
1) Weigh the filter paper with the ceramic dish.
2) Filter paper is placed on the filtration unit and a sample vessel is attached to filter assembly.
3) The filter paper is left to dry in the over at ±105®C for an hour in the oven
4) Then it is being measured again for the amount of solids on the filter paper

· Chloride
1) An indicator, potassium chromate is added into the sample
2) Silver nitrate is used as a titrant in the process of titration.
3) The titred value is noted when the solution turns reddish-brown and calculated by the formula.

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