Treatment of produced waters for removal of soluble organics and toxicity reduction using the GAC-FBR process

Pilot studies were conducted using 550 gallon per day biological Granular Activated Carbon-Fluidized Bed Reactor (GAC-FBR) systems to treat four different produced waters obtained from on-shore and off-shore production facilities. The organic and inorganic composition of these produced waters varied greatly from site to site. Total dissolved solids ranged from 0.8% to 18.5%; BTEX concentrations varied from 470 {mu}g/L to greater than 4500 {mu}g/L. Organic carbon concentrations of up to 440 mg/L were observed. Sulfide concentrations ranged from nil to greater than 800 mg/L as S. Organic loading rates up to 86.6 kgCOD/cu.m-day were applied to the GAC-FBR. Successful treatment was achieved at hydraulic retention times as low as 7 minutes. Essentially complete removal of BTEX and total volatile hydrocarbons was demonstrated for each of the produced water samples; significant removal of non-purgable dissolved organic carbon was also observed. Overall BTEX removals of >99.9% were consistently achieved. Results from several different toxicity assays indicated that the GAC-FBR was able to achieve complete reduction of toxicity with several of the produced waters tested.