At the commencement of the experimental runs, each column
was filled with pre-conditioned clinoptilolite to a height of either
27 cm or 32 cm. The term “Bed Volume” (BV) in this study refers to
the volume of the empty column, i.e., without packed clinoptilolite.
Table 2 summarizes the bed volume values used.
To prevent air bubbles being trapped within the column, dry
pre-conditioned clinoptilolite was added to each column, which
were isolated at inlet and outlet. Each column of zeolite was
washed with deionized water several times after which each
column was reconnected to the inlet and outlet. The water used
in each experiment was supply.water filtered in a commercial
PUR 3-stage faucet filter. The synthetic wastewater was made up
and stored in a 120 L reservoir tank. The ammonium ion concentration
and pH were measured before use. Solution was lifted
up to the feed tank (90 Lt capacity) using a VESTIL hand winch lift
truck and was maintained at 30 C using a bath circulator (Isotemp
3016p, Fisher Scientific). The solution was fed from the
storage tank to the column and into the clinoptilolite bed, with
the eluent solution collected in graduated receiving tanks which
were calibrated at 4 L volume intervals. After a specified time
interval, the effluent solution was sampled and analyzed for
ammonium ion concentration, oxygen concentration, pH, and
nitrite concentration. Experiments on biologically active clinoptilolite
followed the same procedure but with aeration present
Fig. 1. Aeration studies apparatus. via the membrane module.