การตรึงไนไทรต์ออกซิไดซิงแบคทีเรียบน ไคโตซานเพื่อใช้ในการบำบัดน้ำในบ่อเลี้ยงสัตว์น้ำ

• Main Author: ดวงชีวัน บุญเผือก
• Other Authors: วิบูลย์ลักษณ์ พึ่งรัศมี
• Format: Theses and Dissertations
• Language: Thai
• Published: จุฬาลงกรณ์มหาวิทยาลัย 2010
• Subjects: ไคโตแซน; น้ำเสีย > การบำบัด; Chitosan; Sewage > Purification
• Online Access: https://digiverse.chula.ac.th/Info/item/dc:43803
• Institution: Chulalongkorn University

This research involved the immobilization of nitrite-oxidizing bacteria on chitosan for water treatment in aquaculture pond. The experiment was divided into 2 parts; the first part involved the study for optimal condition in treating nitrite via chitosan including time duration for bacterial acclimation; pH value for modifying chitosan surface, size, degree of deacetylation and chitosan molecular weight. It was found that the appropriate condition for bacterial immobilization was 24 hr immobilization period using 1- 2 mm chitosan particles with the degree of deacetylation more than 80 percent and surface modification at pH 6.5. This optimized condition provided the highest nitrite removal rate of 0.72±0.07 mg-NO2-N/g-day. Chitosan molecular weight, however, had no effect on bacterial immobilization. Subsequently, the second part of the experiment involved the use of chitosan immobilized with nitrifying bacteria for nitrite treatment in aquaculture system. The experiment was conducted with simulated shrimp culture tanks resembled to the outdoor soilless pond. Nitrite oxidizing bacteria immobilized on chitosan was applied in the treatment tanks during shrimp cultivation and nitrite removal efficiency was evaluated. Control tanks, on the other hand, consisted of shrimp tanks without chitosan addition and shrimp tank with new chitosan (without bacterial immobilization). The experimental animal was 6.29±0.98 g. Pacific white shrimp (Litopenaeus vannamei), cultured at 0.6 kg/m3 for 35 days in 80-L tanks containing 30-psu seawater. Water alkalinity was adjusted to 150 mg/L and the experiment was performed without water exchange throughout the experiment. The results showed that chitosan immobilized with nitrite oxidizing bacteria could significantly reduce nitrite concentration in shrimp culture tank, as well as providing the highest shrimp survival rate. The nitrite removal rate of immobilized chitosan was 1.40±0.11 mg-NO2-N/g-day.