The objective of sampling are:

• To obtain reliable data on characterization and quantification of any type of waste, waste water, sea-water etc.

• The sampling technique is used for industrial waste water survey and analysis must assure that representative samples are obtained because data from analysis will ultimately serve as a basis for designing treatment facilities.

• To understand complete variation, the sampling can be done at hourly, daily, weekly, monthly, yearly and seasonal basis.

There are 3 types of samples:

• Grab sampling: Samples are collected during any time of the day using standard procedure. The grab sample shows only the prevailing condition at the time of sampling and cannot represent average conditions hence it should not be used as a basis of treatment. Sampling point for grab sampling can be at flow measurement device or distance pipe of the pump.

• Composite sampling: Composite samples provide more measuring flow data when the composition of waste varies either time or flow. Composite sample can be collected either manually or with automatic sampler on the basis of flow or time. This is used where preferably recording device is present. It is suitable for process with flow and variation.

• Continuous sampling: In this type of sampling the samples are not proportional but are taken at constant rate. Suitable for instrument measurement. For continuous sampling, samplers are to be installed at different sections inorder to find out different changes at different phases.

Procedure for sampling includes:

• Total number of samples

• Points of collection

• Method of collection

• Data to be obtained

• Frequency.