The general flow of procedures for water quality analysis is as follows:
1. Selection of parameters
The parameters of water quality are selected entirely according to the need for a specific use of that water. Some examples are: Drinking Industries As per WHO/CPCB Standards As per specific requirement Irrigation Domestic Consumption pH As per BIS Standards Conductivity Sodium & Potassium Water Bodies Nutrients As per CPCB guidelines Specific compounds M.Tech.
However, some of the most common parameters followed for checking portability and industrial use in India are as follows:
Physical Inorganic / Toxic Metals Organic, Bacteriological Biology Radioactive Chemical Nutrient & Elements Demand Temperature Copper Total Coliform Phytoplankton Colour Hardness Chromium Zooplankton Alpha Emitter Faecal Coliform Odour Calcium Cadmium BOD Beta Emitter Taste Magnesium Zinc COD Chloride Lead Phenols Turbidity Sulphate Mercury Oil & Grease pH Fluoride Iron Pesticides Conductivity Alkalinity Manganese NitrateTotal Dissolved Solids Nitrate Phosphate.
2. Selection of methods
The methods of water quality analysis are selected according to the requirement. The factors playing key role for the selection of methods are:
(i) Volume and number of sample to be analyzed
(ii) Cost of analysis
(iii) Precision required
(iv) Promptness of the analysis as required.
Properly designed and executed chain-of-custody forms will ensure sample integrity from collection to data reporting. This includes the ability to trace possession and handling of the sample from the time of collection through analysis and final disposition.
This process is referred to as chain-of-custody and is required to demonstrate sample control when the control when the data are to be used for regulation or litigation. Where litigation is not involved, chain-of-custody procedures are useful for routine control of samples.
4. Proper sampling
Proper sampling is a vital condition for correct measurement of water quality parameters. Even if advanced techniques and sophisticated tools are used, the parameters can give an incorrect image of the actual scenario due to improper sampling. The proper sampling should fulfill the following criteria:
- Representative: The data must represent the wastewater or environment being sampled. So, the following factors must be well planned for proper sampling:
(i) Process of Sampling
(ii) Sampling size/volume
(iii) Number of Sampling Locations
(iv) Number of Samples
(v) Type of Samples
(vi) Time Intervals during sampling, these factors must also be taken care of:
(a) Choosing of proper sampling container
(b) Avoiding contamination
(c) Ensure the personal safety of the collector.
- Reproducible: The data obtained must be reproducible by others following the same sampling and analytical protocols.
- Defensible: Documentation must be available to validate the sampling procedures. The data must have a known degree of accuracy and precision.
- Useful: The data can be used to meet the objectives of the monitoring plan.
5. Proper labeling
Proper labeling prevents sample misidentification and ensures the responsibility and accountability of the collector. The sample container should be labeled properly, preferably by attaching an appropriately inscribed tagor label.
Alternatively, the bottle can be labeled directly with a water-proof marker. Barcode labels are also available nowadays. Information on the sample container or the tag should include at least:
(i) Sample code number (identifying location)
(ii) Date and time of sampling
(iii) Source and type of sample
(iv) Pre-treatment or preservation carried out on the sample
(v) Any special notes for the analyst
(vi) Sampler‘s name
There is usually a delay between the collection and analysis of a sample. The nature of the sample can be changed during this period. Therefore proper preservation is required in the way to laboratory after collection, and in the laboratory up to when analysis starts.
Complete and unequivocal preservation of samples, whether domestic waste water, industrial wastes, or natural waters, is a practical impossibility because complete stability for every constituent never can be achieved.
At best, preservation techniques only retard chemical (especially, hydrolysis of constituents) and biological changes that inevitably continue after sample collection. No single method of preservation is entirely satisfactory; the preservative is chosen with due regard to the determinations to be made.
Preservation methods are limited to pH control, chemical addition, the use of amber and opaque bottles, refrigeration, filtration, and freezing.
In conclusion, water quality standards are put in place to ensure the efficient use of water for a designated purpose. Water quality analysis is to measure the required parameters of water, following standard methods, to check whether they are in accordance with the standard.
Why Water Quality Analysis is required?
Water quality analysis is required mainly for monitoring purpose.
In summary, some importance of such assessment includes:
- To check whether the water quality is in compliance with the standards, and hence, suitable or not for the designated use.
- To monitor the efficiency of a system, working for water quality maintenance.
- To check whether up gradation / change of an existing system is required and to decide what changes should take place.
- To monitor whether water quality is in compliance with rules and regulations.