Meeting world's most stringent Hg criterion: a pilot-study for the treatment of oil refinery wastewater using an...

A membrane ultrafiltration (UF) technology was tested using an oil refinery's end-of-pipe effluent to demonstrate the proof of concept, i.e. can the Great Lakes Initiative criterion of less than 1.3 ppt be consistently met at the pilot-scale, and to provide the data necessary for preliminary full-scale process design. This study presents the successful pilot test conducted with continuous but varying feed conditions over a protracted period. The UF membrane process consistently provided a constant permeate quality at all tested operating conditions, virtually independent of the feed water characteristics and the feed Hg concentration (0.5-22.7 ppt). The treatment target of less than 1.3 ppt of Hg was met and exceeded for all tested conditions during the pilot study. Turbidity measurements were <0.5 NTU (with a MDL of 0.5 NTU) 85% of the time and <0.16 NTU 95% of the time when analyzed on-line. The TMP values were below the specification of (negative) 7-12 psi at all tested conditions during the pilot-study. Weekly maintenance cleans and monthly clean in place (CIP) events were very effective in consistently restoring the membrane permeability during the pilot-study.