Effects of tertiary methods on total organic carbon removal in saline, closed-system marine mammal pools

Organic matter accumulates in marine mammal pools that are not diluted continuously with clean influent water. Some of this material may be carcinogenic or mutagenic. Four tertiary methods were tested for effectiveness in lowering the total organic carbon (TOC) concentration in saline marine mammal pools. The TOC concentration at the start of each trial is shown in parentheses. Ozonation alone in duplicate trials had no effect on TOC during sequential contact periods of 25, 30, and 30 minutes (13.66 mg of TOC/L of sample water) and 30, 30, and 30 minutes (12.85 mg of TOC/L) when the dosage levels were 4.13, 4.03, and 4.52 mg of O3/L, respectively. Contacting marine mammal water with granular activated carbon in a single trial (12.91 mg of TOC/L) removed approximately 37% of the TOC in 10 minutes, but only an additional 11% was removed in 60 minutes. The amount removed in 10 minutes was equivalent to 20 days' accumulation at previously determined rates of increase. Brief ozonation of the water, followed by contact with granular activated carbon, was the most effective method tested. When results of the duplicate trials (12.95 and 12.65 mg of TOC/L) were averaged, the amounts of TOC removed were 60% (5 minutes), 70% (10 minutes), and 78% (30 minutes). Two experiments using superchlorination (114 mg of free available chlorine/L of water contacted for 4.5 hours) reduced the TOC concentration from 15.6 to 11.2 mg/L (28%) reduction), and from 15.6 to 10.2 mg/L (35% reduction).