DEPARTMENT OF CIVIL ENGINEERING Subject- Environmental Engineering Lab S.No. Experiments Name 1 2 3 4 5 6 7 8 Study of sampling and preservation methods and significance of characterization of water and waste water Determination of pH Optimum Coagulant Dosage by Jar Test Determination of Residual Chlorine Determination of hardness Determination of chloride Turbidity Determination of Available Chlorine in Bleaching Powder 9 10 11 12 13 14 15 16 17 18 19 Total, Fixed and Volatile Solids Suspended and Dissolved Solids Total Settleable solids Determination of Dissolved Oxygen Estimation of Sulphate Determination of Fluorides Determination of Ammoniacal Nitrogen Determination of COD Determination of Iron Biochemical Oxygen Demand Introduction to Bacteriological Analysis
Ex No: 1 Date: Study of sampling and preservation methods anti Significance of characterisation of water and waste water Aim To study the sampling and preservation methods in water and waste water characterization and to learn the significance of characterisation of water and waste water Sampling Programme and Procedures The collection of a representative sample is the most important function of an environmentalist. The interpretation of results and recommendation for prevention and corrective treatment are all based on the analysis report. Scrupulous care in the collection of samples is therefore necessary to ensure that the sample is representative of the body of water under examination and to avoid spoilage and accidental contamination of the sample during collection and transport. Methods of sampling Three types of samples are often collected depending on situations a. Grab Samples Grab samples are samples collected at a designated place at a particular time. They represent the composition at the time and space. When a source is known to vary in time, as in the case of waste effluents, grab samples collected at various time intervals and analysed separately can be of greater value. b. Composite samples Composite samples are a mixture of grab samples collected at one sampling point at different times. Individual samples are collected in wide mouth bottles every hour and mixed in volume proportional to the flow. The composite values are useful for observing average values. c. Integrated samples Integrated samples are a mixture of grab samples collected from different points simultaneously and mixed in equal volumes. Individual samples are collected from both banks of a river and at varying depths to represent available situations.
Sampling and preservation Requirements: 1. Physical and Chemical Requirements: For general physical and chenica1 examination, the sample should be collected in a chemically clean bottle made of good quality glass fitted with a ground glass stopper or a chemically inert polyethylene container. The volume of sample to be collected would depend on the selection of tests; however, for general examination 3.0 litre sample would be sufficient, The following precautions must be taken while collecting the sample i) The sampling location is representative of the water body ii) The place is devoid of floating material Where ever possible the sample should be collected 15cm, below the surface or as the situation warrants No physical activity is permitted upstream of sampling point Shorter the time between collection and examination, the reliable will be the analytical results. For certain constituents and physical values, immediate analysis in the field is required, because, the composition of water may change before it arrives at the laboratory. The maximum limits of storage are: Unpolluted water: 72 hours Slightly polluted. : 48 hours Grossly polluted: 1 2hours Some determinations are more likely to be affected by storage than others. Temperature may change, pH may change significantly, and dissolved gases may be evolved and lost (O2, CO2. and H2S) Frequency of sampling: Frequency depends on objectives. Yet, collection of samples of both raw and treated waters should be carried out as frequently as possible and at least once in every three months. Some waters undergo more pronounced seasonal variation and therefore require more frequent testing. Samples from treatment units should be collected and analyses frequently, at least one from each unit daily.
2. Bacteriological requirements: The samples for bacteriological examination are collected in sterilized. neutral glass, glass-stopper 80z, and 300 ml bottles. The stopper and the neck should be protected by paper or parchment cover. If the sample is likely to contain traces of residual chlorine, an amount equal to 3.0 mg of sodium thiosul1ite (Na2s203, 51120) to neutralize chlorine is added to the bottle before sterilization. The sterilization is done at 15 psi (121°C) for 20-30 minutes in an autoclave. The sterilized sample bottle should be kept unopened until the time of collection. The stopper should be removed with care to eliminate chances of spoiling and contamination and should never the rinsed. After filling, the stopper should be replaced immediately. The place of collection should be predetermined and procedure of collection conditioned depending on the source. The standard procedure in sampling from a water faucet or tap is as follows: a) Flame the tap briefly to kill clinging bacteria. This can be done with a piece of burning paper. b) Turn on the water and allow it to run for 1 mm. c) Remove the stopper from the bottle, being careful not to touch the inner portions o the stopper or bottle neck. d) Fill bottle carefully, allowing no water to enter that has come in contact with hands. It is sometimes necessary to collect a sample from a reservoir or basin. If the water can be reached, remove the stopper, plunge the bottle below the surface and move the bottle while it is filling, so that no water will enter that has been in contact with hand. If the water is out of reach, as in a dug well, the bottle can be lowered with a cord. The sample after collection should be examined immediately, preferably within one hour. If the conditions do not permit immediate examination, the sample should be stored at low temperatures. This period should in case be more than 24 hours. If storage or transportation is necessary, they should be got at a temperature between 0°C and 10°C.