Bryozoans are among the most difficult pests plaguing wastewater treatment facilities. They are usually carried in on the feet and feathers of ducks and other waterfowl. Often they grow on the walls and rotor in secondary clarifiers; but they can also clog tertiary filters and interfere with ultraviolet disinfection. A number of management strategies are available, depending on the bryozoan species and size and configuration of the facility. Once they settle in, bryozoans seldom go away by themselves.
Sponges are becoming the latest nuisance in wastewater treatment. The white or green masses feel like rough plastic foam, not at all like soft bath sponges. Under suitable conditions they can grow rapidly on almost any surface. Scraping and power-hosing the sponges is extremely time-consuming and almost futile. It is easy to miss the reproductive bodies (gemmules) embedded in the smallest crevices. So far only one species has become troublesome in North America, but the problem is widespread.
Common Wastwater treatment plant fouling micro-organisms:
