Determine the Amount of Phosphate in the Laundry Effluent

Procedure:

Standard Solutions of Phosphate Sodium dihydrogen Phosphate(NaH₂PO₄.H₂O) Stock Solution: Dissolve 1g of PO₄ in 1000ml to get 1000ppm solution of phosphate

So,       1g of PO₄       =   156.01g   = 1.642g of Sodium dihydrogen Phosphate

95

For      1000ppm       =   1.642g are required

For      200ppm          =   1.642g _x 200 = 0.3284g

1000

Dissolve 0.3284g of NaH₂PO₄.H₂O in 1000ml to get 200ppm solution of phosphate. For further dilutions use it as a stock solution.

10ppm:                C₁V₁ = C­₂V₂

10 x 40 = 200 x V₂

                                          V₂   = 10 x 40 = 2ml

200

Take 2ml of stock solution in a beaker and dilute it upto 40ml with distilled water to make a solution of 10ppm. Similarly, take 4ml, 6ml, 8ml, 10ml, 12ml, 14ml, 16ml, 18ml and 20ml of stock solution in a beaker and dilute them upto 40ml with distilled water to make solutions of 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 90ppm and 100ppm.

Procedure

Take 40ml of sample, add 8ml of ammonium molybdate in it and keep it for 10minutes. Add 8ml of ammonium molybdate in each standard solution and keep them for 100minutes. Standard solutions will turn into light blue to dark blue depending upon the concentration of phosphate in them. Now run these standards on spectrophotometer at the wavelength of 690nm. Note down the absorbance and draw a graph of these absorbencies. Now run the sample and note down its absorbance and by plotting it in graph find out the concentration of phosphate in the sample.

Calculations:

Std. Sol Concentration	Absorbance of Standard Solutions			Mean Absorbance
10ppm	0.538	0.539	0.541	0.539
20ppm	0.633	0.635	0.637	0.635
30ppm	0.662	0.664	0.667	0.664
40ppm	0.637	0.643	0.645	0.641
50ppm	0.682	0.684	0.685	0.638
60ppm	0.806	0.807	0.810	0.807
70ppm	0.826	0.827	0.828	0.827
80ppm	0.827	0.833	0.835	0.829
90ppm	0.865	0.867	0.868	0.866
100ppm	0.879	0.880	0.881	0.880
For Sample Solution
55ppm	0.789	0.791	0.793	0.791

Result: The concentration of phosphate in the sample is 55ppm

Environmental Impacts of Phosphate:

• Impacts on Aquatic Environment:

An excessive amount of phosphate in the water will wildly increase the growth of algae and aquatic plants which in turn choke the waterways and utilize large amounts of oxygen, this condition is called eutrophication. This rapid growth of aquatic vegetation eventually stops as a result aquatic plants and animals start dying and remaining oxygen uses up in the process of decaying. This will disturb the whole aquatic ecosystem (ECC, 2004).

• Impacts on Human Health:

An excessive amount of phosphate may cause different health problems like kidney damage, digestive system problems and osteoporosis. Shortages of phosphate may also occur due to extensive use of medicine and too little phosphate can also cause health problems (Sullivan, 2009 ).

• Impacts on Plants:

When there is shortage of phosphate in soil then the plants suffer from chlorosis, necrosis and marginal scorching of old leaves, which may led to shedding of old leaves (MASOOD, 2011).

Standards for PHOSPHATE

Category	Max. limit	Standardizing Agency
Drinking Water	5mg/l	WHO
Drinking Water	0.05-0.10 mg/l	EPA

References:

1. (2004). Canadian Water Quality Guidelines for the Protection of Aquatic Life. Canada.
2. (2005). Source apportionment of nitrogen and phosphorus inputs into the aquatic environment. Denmark: Official Publications of the European Communities.
3. Masood, T. G. (2011). Effect of different phosphorus levels on the yelid of maize . Sarhad J. Agric. (27).
4. Sullivan, C. S. (2009 ). Effect of food additives on hyperphosphatemia among patients with end-stage renal disease: a randomized controlled trial. , 629-35.

Also study related links:

Determine the Amount of Sodium in Water and Soil