Twenty pieces of plastic biofilter media (BCN-009) with
active NOB biofilm were transferred into a container
containing 40 mL of sterilized 30 PSU seawater with 2
mg-N/L nitrite and sonicated for 4 min to the detached
NOB cells. Thereafter, the biofilter media were replaced
with 0.60 g of sterilized chitosan flakes under 150 r/min
agitation at 25°C. With this immobilization process, a
significant number of bacterial cells could be transferred
from the biofilter media to the chitosan flakes. The chitosan
agitation period was varied at 3, 6, 12 and 24 hr. The
efficiency of NOB immobilized chitosan on nitrite removal
was determined by placing 0.60 g of NOB immobilized
chitosan flakes in 40 mL seawater containing 2 mg N/L of
nitrite. The decrease in nitrite concentration was monitored
using the standard method of seawater analysis (Strickland
and Parson, 1972). Moreover, bacterial attachment on the
surface of the chitosan flakes was visualized by scanning
electron microscope (SEM).