Precoat Filtration and Ultrafiltration of Emulsified Bitumen from Water

Consideration of Orimulsion, a bitumen/water emulsion, for use as an alternative fuel in power generation facilities has prompted interest in methods for responding to environment spills during transport. The adhesive nature of the 70% bitumen (asphalt) emulsion, however, poses a unique challenge for cleanup. The results of a study to investigate filtration as a cleanup alternative are presented in this paper. Pilot tests were conducted to evaluate the feasibility of diatomaceous earth precoat filtration and ultrafiltration for cleanup of marine and freshwaters contaminated with Orimulsion. Volatile suspended solids removal rates up to 99.9% were obtained for diluted Orimulsion (<1.0%) at a flux of 2,140-10,700 Lph/m2 (1,440-7,200 gpd/ft2) using a constant flow, plate and frame pilot filter with flux-calcined grades of marine diatomite. Higher permeate quality, less than 2.0 mg/L as volatile suspended solids, with 99.99% rejection was obtained using tubular polyvinyldiene fluoride ultrafiltration membranes, at a flux of 30-220 Lph/m2 (18-130 gpd/ft2) with filtration additives. Recommendations for process selection are suggested based on feed strength, desired effluent quality, and residuals preference.