Purpose:

The purpose of this project is to reduce acquisition and lifecycle costs of oily waste membrane systems through the application of a non-porous polymer coating to the membrane surface. Ceramic oily waste membrane systems have been developed by Naval Sea System Command, Carderock Division (NAVSEA Carderock) as a secondary treatment system to the existing parallel-plate separator. The oily waste membrane systems have demonstrated the ability to reliably produce effluent containing less than the 15 parts per million oil content as currently governed by OPNAVINST 5090.1. Ceramic membranes were selected early in membrane system development for their fouling resistant properties; however, these membranes contain small pores that over time (typically one-year of operation) will foul due to the highly variable bilge constituents, requiring membrane cleaning and/or membrane replacement. Membrane Technology and Research (MTR), Inc. has developed a novel non-porous polymer to coat the ceramic membranes and provide improved fouling resistance.

Description:

NAVSEA Carderock in conjunction with MTR, Inc. will demonstrate the improved fouling resistance of the commercially available ceramic membranes by coating them with a non-porous polymer. In addition, the coating will be applied to less expensive polymeric membrane modules. Past laboratory and preliminary shipboard tests have suggested that polymeric membranes have a number of process reliability issues. However, new spiral-wound polymeric membranes such as the ones coated and tested by MTR, Inc. appear to have substantially improved performance over commercially available polymeric membranes. These polymeric ultrafiltration membrane modules will be modified to fit the shipboard test system and tested alongside commercial ceramic modules. Both polymer-coated ceramic and polymeric membranes will be vigorously tested in the laboratory and shipboard to demonstrate improved fouling performance. The non-porous membrane fouling performance will be compared to non-polymer coated, commercially available, ceramic membrane fouling performance.

Benefits:

Membrane fouling can directly impact membrane lifecycle costs. Membrane cleaning and replacement are the leading drivers for membrane system lifecycle costs. Current ceramic membranes require cleaning every year and replacement every five years, resulting in a $30 thousand cost per unit per ship per year. For the DDG 51 class of ships, this correlates to approximately $1.5 million per year. Reducing membrane fouling will linearly reduce this cost. Additionally, the cost of fabricating non-porous, polymeric, spiral-wound membrane modules will be compared to the acquisition and replacement cost of commercially available membranes. The use of a spiral-wound membrane has the potential to reduce membrane acquisition costs by half, further reducing both acquisition and lifecycle costs. (Anticipated Project Completion - 2005)

Contact:

Ms. Holly Nestle
Naval Sea System Command, Carderock Division
Solid and Oily Waste Management Branch
9500 MacArthur Blvd, Code 634
West Bethesda, MD 20817
Telephone: (301) 227-0373
Fax: (301) 227-5549
E-mail: nestlehl@nswccd.navy.mil