Comparison of the Zeolite Sodium Chabazite and Activated Charcoal for Ammonia Control in Sealed Containers

Abstract

Zeolites are often used for water quality control in live fish transport. Activated charcoal has also been proposed for this purpose. In this experiment, the effects of the zeolite sodium chabazite and granular activated charcoal on water quality were studied in nine sealed 500 ml flasks held at 22 o C. Three treatments were commercial grey zeolite (90% pure herschelite-sodium chabazite), commercial granular activated charcoal and control, each in triplicate. To each treatment was added 10 mg·l total ammonia-nitrogen (TAN) and for simulated stress control 9 g·l un-iodized salt (NaCl). Zeolite and activated charcoal were added at the rate of 20 g·l. In 96 h, total ammonia-nitrogen (TAN) means in the zeolite treatment and in the activated charcoal treatment both decreased significantly from 9.59 to 4.02 mg·l, and 9.40 to 7.91 mg·l, respectively. However, the mean pH of the zeolite treatment increased from 7.85 to 7.95, while the mean pH in the activated charcoal treatment increased from 8.12 to 9.13. Calculated un-ionized ammonia (UIA) levels of the zeolite treatment decreased from 0.35 to 0.16 mg·l, after 96 h, although not significantly. In the activated charcoal treatment, UIA increased significantly from 0.50 to 3.02 mg·l. Significant differences were observed in TAN, UIA and pH between the activated charcoal treatment and the zeolite treatment. Zeolite significantly controlled TAN and UIA, with stable pH. Activated charcoal slightly decreased TAN, but greatly increased pH and UIA. Therefore, this kind of activated charcoal reduced water quality and is judged to be not useful in fish transport. Commercial grey zeolite, even with salt addition, was effective in removing toxic ammonia for live fish transport.