Need of Project: To reduce the cost of H2S Strip Test Kit.

What is the H2S Strip Test?

H2S test performs to check the microbial contamination in water. H2S is produced if the sulfur compound is reduced by the bacterial strain. It shows that the microbe reduces sulfur-containing compounds to sulfides during this process.  

Chemicals to prepare H2S bottles

Bacteriological peptone                                                                        40.0g

Dipotassium hydrogen phosphate                                                         3.0g

Ferric ammonium citrate                                                                         1.5g

Sodium thiosulphate                                                                                 2.0g

Liquid detergent                                                                                      2.0ml

Water                                                                                                   100.0ml

We need to find Water holding Capacity of the different papers to select the paper type for the strips

The procedure of the H2S Strip Test?

Step-1: Clean the glassware. 

Step-2: Dissolve above mentioned chemicals in Distilled water or in tap water.

Step-3: Take absorbent paper, place a measured quantity of media on it. (Each paper strip for a 10 ml test sample needs to contain 0.5 ml of media.)

Step-4: Dry the paper strips at 55 degrees Celsius. After drying, store it in a dry container.

Step-5: While using strips keep it in the sterilized container and add the sample.

Expected Results of this test

The blackening of samples denotes the presence of H2S.

How to use H2S strips?

Step1: Autoclave the test tube and dry it completely.

Step2: Keep the stored H2S strips in the test tube.

Step3: Add a 5ml water sample to the test tube and cover the opening of the tube.

Step4: Observe the tubes after 48 hrs and not the observations as written above.

Costing of the H2S bottle:

Sr. No.ChemicalsQuantity of Chemicals Used in gmCost/100ml waterCost/Bottle 500gm
1Di Potassium Hydrogen Phosphate30.58 Rs97 Rs
2Bacteriological Peptone40118.96 Rs1487 Rs
3Ferric Ammonium Citrate1.51.84 Rs614 Rs
4Sodium Thiosulphate21.36 Rs340 Rs
5Liquid Detergent2 ml0.32 Rs80 Rs
Sr. No. Other MaterialsQuantityCost/120 bottles
1Filter Paper2 A3 Size Papers4 Rs
2Electricity for Oven2KW for 2Hrs40 Rs
3Cost of Bottle120 bottles480 Rs
4Cost of 1 Sticker120 Stickers89 Rs
5Labour Charge (25% of the material used)2 Days368 Rs

Manufacture cost per bottle is 9.20 Rs

The sticker for H2S Kit Bottle

Trials of H2S Kit:

For the testing of kit we had taken the water samples from Grey water, Vigyan Ashram Kitchen, Dream House, Tap water, UV filter

Observation Chart of Trial tests:

First Set of Experiment :

Second Set of Experiment :

From the above table we can say that our H2S Kit is showing Dissimilar results for UV filter.

Pictures of the test bottles

References:

1.       THE HYDROGEN SULPHIDE PAPER-STRIP TEST, Luke M. Mosley & Donald S. Sharp (February 2005)

2. H2S PAPER STRIP METHOD – A BACTERIOLOGICAL TEST FOR FAECAL COLIFORMS IN DRINKING WATER AT VARIOUS TEMPERATURES J. Pillai, K. Mathew, R. Gibbs, and G. E. Ho.