To measure suspended solids in water, the sample was filtered using a machine from the Limnology Department at BFAR. Solids stuck to the filter paper, which was then dried in an oven and placed in a desiccator to remove any leftover moisture. The dried filter paper was weighed with an analytical balance. Here’s the formula used to calculate the total suspended solids:
– W.S: Weight of samples
– F: Filter (Weight)
– W.F.P: Weight of filter paper
– S.S: Suspended solids
For the analysis, 100 ml of sample water was placed in an Erlenmeyer flask, and a buffer solution was added. This buffer was made by mixing 67.5g of ammonium chloride, 570ml of concentrated ammonium hydroxide, and 1 liter of distilled water. Then, 8 drops of Eriochrome Black T indicator were added, followed by titration with an EDTA solution. The Eriochrome Black T was prepared by dissolving 4.5g of hydroxylamine hydrochloride and 0.5g of Eriochrome Black T in 100 ml of 70% ethanol. The EDTA solution was made by dissolving 3.723g of EDTA and 0.1g of magnesium chloride hexahydrate in distilled water, then diluting to 1 liter. This was standardized against a standard calcium solution. The titration endpoint was reached when the solution turned from wine red to pure blue.
Water samples were placed in BOD bottles, shaken until the dissolved oxygen (DO) matched the recorded value, and incubated for five days. The DO of the incubated water was measured using titration. The difference between the initial and final DO readings is the Biological Oxygen Demand (BOD):
– B.O.D = DO before incubation – DO after incubation
For further analysis, 10 ml of filtered water was placed in a test tube, and 0.2 ml of sulphanilamide and 0.2 ml of N-(1-Naphthyl) ethylenediamine were added. The solution was transferred to a cuvette, left to stand for 20 minutes, and then placed in a spectrophotometer set to a 530 nm wavelength.
Another 10 ml of filtered water was placed in a test tube, and 5 ml of ammonium molybdate, 12.5 ml of sulfuric acid, 5 ml of ascorbic acid, and 2.5 ml of antimonyl potassium tartrate were added. This solution was also transferred to a cuvette, left to stand for 20 minutes, and placed in a spectrophotometer set to an 885 nm wavelength.
For further testing, 250 ml of water samples were collected in plastic bottles, with 0.5 ml of HgCl2 added, and stored on ice. A mixture of 100 ml of Reagent A (phenol melted with 30g of glacial acetic acid and 1.36g of sodium acetate trihydrate in 1 liter of distilled water) and 2 ml of Reagent B (3g of nitroprusside dissolved in 100 ml of distilled water) was prepared. 1 ml of this mixture was added to 10 ml water samples. Reagent C (300g of potassium carbonate and 60g of sodium phosphate in 1 liter of distilled water) was mixed with a hypochlorite solution, and 1 ml was added to 10 ml water samples. The mixture turned blue after standing for about 30 minutes and was centrifuged for 10 minutes at 5000 RPM. The absorbance was read at a 625 nm wavelength.
The following terms were used in the analysis:
– SSV: Absorbance of standard solution
– BV: Absorbance of blank
– SV: Absorbance of sample
To interpret the laboratory results, descriptive analysis was conducted. The mean was calculated from data collected at five stations to address the study’s first research question. The mean is the average value of the data. Additionally, a one-way ANOVA was performed at a 0.05 significance level to determine significant differences between sampling sites along the Pantal River.
The following statistical terms were used in the analysis:
– CF: Correlation factor
– TSS: Total sum of squares
– SSB: Between sum of squares
– SSW: Within sum of squares
– df: Degree of freedom
– N: Number of data points
– n: Number of rows
– k: Number of columns
