Operational Challenges to the Use of Narrow-Slot Wedgewire Screens Under Heavy Biofouling Conditions

In 2013, American Sugar Refining, Inc. performed an 18-month operational feasibility study of a 0.5-mm brush cleaned wedgewire screen at its refinery on the Hudson River in Yonkers, NY.  The tested screen was 30 inches in diameter, 36-inches long, and made of 316 stainless steel.  The screen was operated at ~1.5 million gallons per day to achieve a through-screen velocity of 0.45 ft/sec.  The screen was operational for about 90 percent of the study period.  The brush-cleaned outer surface of the screen appeared clean and free from attached fouling organisms throughout the study. However, the inner brush cleaned areas accumulated significant fouling organisms despite increased cleaning frequency. All internal surfaces not cleaned by the mechanical brush cleaning system and the external frame accumulated hydroids, barnacles, and other motile organisms (amphipods).  The results indicated that a 0.5-mm slot brush cleaned wedgewire screen at this location would be infeasible.  A second 18-month study will assess whether changes to the system (primarily larger 0.75-mm slots, vertical orientation, and application of anti-biofouling coating on the non-brush-cleaned surfaces) will reduce biofouling and provide the refinery with a reliable source of cooling water while reducing entrainment.