In Situ Testing

Measurement of pH, DO, Conductivity, Salinity and Temperature were done by Polarographic method in situ. The probe we used at the site was a combined pH, DO, Conductivity, Salinity and Temperature probe.

The probe is immersed into a sample and the value of the respective parameters will be shown on the screen after the meter stabilises. The values are recorded down.

In Situ / Laboratory Testing

· Colour
In Situ:
Unit of measurement: “HAZEN”
Colour is determined measured visually with the use of a Colour Comparator.

· Nitrate
In situ:
1) Nitraver 5 Nitrate reagent powder added to 10ml of sample.
2) Shake vigorously for a minute.
3) Allow reaction to occur for another five minutes.
4) If nitrate is present, amber colour develops.
5) Determine concentration of nitrite via colorimetry by comparing against a blank sample using a turntable colour comparator

In lab: Titration - Kjeldahl method titrate (sulphuric acid) indictor (Indicating Boric Acid)

· Nitrite
In situ:
1) Nitraver 5 Nitrate reagent powder added to 10ml of sample.
2) Shake vigorously a minute.
3) Allow reaction to occur for another five minutes.
4) If nitrate is present, amber colour develops.
5) Determine concentration of nitrite via colorimetry by comparing against a blank sample using a turntable colour comparator

Nitrate/Nitrite In Situ Testing: Using a turntable Colour Comparator

Laboratory Testing

We measured the turbidity of the water from the sites using the Nephelometry method.

1) A sample from each site is placed into a quartz cuvette which is covered with a Teflon cap was and then placed in the turbidity meter.

2)Light strikes a suspension at right angles to the photoelectric cell of the instrument.

3) The light reflected by the dispersed particles is recorded and shown on the screen.

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.