HOW CLEAN IS YOUR WATER ?
S.M.Khopkar

Urbanization, industrialization and employment of auxiliary means of agriculture has deteriorated the quality of water bodies in many regions. A portable water testing kit can circumvent such problems. An attempt was made using simple and rapid analytical techniques (with the help of handy field test equipments) to develop a kit for pollution monitoring.

Water Quality Parameters:- The selection of parameters to be analyzed was done on the basis of the known characteristics of natural waters. They included color, temperature, turbidity and pH (physical).

 

Water Quality Standards:

Water quality standards are usually issued on the national level (IS – 10500, 1983). Drinking water standards are of significance since they are based on scientific criteria related to human health.

 

Ring – Oven Technique:

This is a simple technique used for semi – quantitative analysis of metals. It has been recommended by SCOPE for analysis of several components. This technique provides an elegant and rapid method for concentration of small amounts of materials to permit the increased selectivity and qualification of spot reactions.

 

Comparator Technique:

         The sample was taken in Nessler tube and treated with specific reagents. The color produced in the sample was compared against the standards. The nitrogen measurements (NH3 – N; NO2 – N; and NO2 – N) were done by visual comparison. Color and turbidity determinations were also performed by visual comparison against their standards.

 

Volumetry:

         The samples taken for determination of dissolved oxygen and total hardness were analyzed by simple titration method involving Winkler’s method or complexometric titration.

 

Biological Examination in Laboratory:

         The sample was passed through a membrane filter disc. This filter disc was placed on the surface of a plate containing M – 7hFC agar medium. The plate was then kept in an incubator at 41.5° C for 7 hours. The growth of yellow colonies of filter disc indicate the presence of coliforms in the water sample.

 

         The sensitivity study of selected methods was carried out by using synthetic samples to know the least determinable concentrations of the parameters of interest. The diphenylcarbazide method was most acceptable for chromium detection due to its high sensitivity. The values of molar absorptivity for manganese by formaldoxime and nitrate by saltzman method were also found above 1 x 104 1mol – 1 cm – 1 which confirm their high sensitivity. Similarly SPADNS for fluoride and alizarin red – s for aluminum were found ideal compared to other methods.
         The laboratory trials were carried out for all the methods selected for inclusion in the kit. The precision of the methods depended on the concentration of the parameters and on the technique of analysis, the ring parameters and on the technique of analysis. The ring – oven technique for the analysis of all metals and few anions was found suitable, as the errors connected with chemical operations were minimum. Visual methods gave results with a precision of 0.5 to 2% under suitable measuring conditions.
         The analysis carried out was in a minimum number of steps with commonly available reagents and apparatus. The methods required no sophisticated instrumentation. The ring – oven technique was found very simple and useful for rapid investigations. The time required for each determination was not more than 10 minutes. The simple titrimetric methods for dissolved oxygen and total hardness were more accurate compared to the other methods of analysis.
         The cost estimate or the kit developed for water quality monitoring in all was Rs.8,000/-. The data presented demonstrates that the kit is suitable for analysis of natural water samples. The overall methodology employed was suitable for samples collected from various water resources.