Development of polythene film bag as a respirometer

Respirometric film bag relies upon reoxygenation of a wastewater sample through a quality controlled polyethylene membrane. The film bag is fabricated by interposing two layers of polyethylene membrane in between two stiffening frames. The projecting collars on the frames form the collapsible mouth of the film bag. The film bag provides a shallow depth liquid housing for the wastewater sample. The film bag was initially standardised and rate of oxygen transfer, when the sample in it is not stirred, was modelled based on an analogy between conduction of heat through infinite bodies with surface and internal resistance. Oxygen uptake study of up to 250 mg/l BOD5 may be carried out with or without imparting stirring action to the wastewater sample. In the oxygen uptake studies, DO versus time plots (DO profiles) were obtained. The course of oxidation of organic contents in the wastewater may be obtained.