Hey Sandip;

I assume you are thinking about setting up a bioreactor to treat this effluent, and are wondering about the necessary hydraulic residence time (HRT). PVA has been shown to be biodegradable by a variery of different bacteria, often through an initial reaction with polyvinyl alcohol dehydrogenase. However, the rate of this reaction is going to vary based on the average MW of the PVA, as well as the organisms performing the reaction. If the PVA is of high MW, an initial extracellular enzyme reaction may be required to reduce polymer size, prior to complete biodegradation. Some people have tried to increase biodegradation rate of PVA by using an initial chemical oxidation step (e.g., with Fenton's reagent) prior to biodegradation. With all of that said, you probably would need to set up a small batch bioreactor to understand how readily biodegradable the specific textile effluent is - and how long the process takes to meet your remediation goals (which is also very important - what do you need to reduce the COD to?). This information would allow you to perhaps determine the necessary HRT, and then select an appropriate reactor design and size for the application.

Thank you Paul.

As PVA used in this case with a degree of polymerization 1700-1800 and having a molecular weight approximately 14,000 g/mol and also wish to mention that, after treatment of PVA containing effluent, textile industry expects to meet stringent norms of COD