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Step 2 BODAC: Biological Oxygen-Dosed Active Carbon Filter

A common, yet tricky problem in pure water systems is the accumulation of biofouling on osmosis membranes, which is usually combated with chemical biocides. NWTR was the first in the world to develop a better solution: an intermediate step with a biological active carbon filter.

This filter has a large surface area for bacteria to attach to. After a start-up period of a few months, this filter will be full of bacteria. Adding oxygen optimises the conditions for bacterial growth, to the point that they will use up all the nutrients present in the water. Now the water has been depleted of all nutrients, bacteria will no longer be able to grow, thus preventing the accumulation of biofouling in the rest of the process. The filters are rinsed periodically to remove any excess bacteria, which are then returned to the WWTP. In order to optimise the process, the system consists of a series of two filters.

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