Influence of Physical Properties of Biofilter Material and Equipment on Water Treatment Efficiency in Recirculating Aquaculture System

• Main Authors: Chai-Hong Gan, 顏在宏
• Other Authors: Wen-Shang Hou
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/59689837361683959294

碩士 === 國立臺灣大學 === 生物環境系統工程學系暨研究所 === 91 === Accumulation of solids and dissolved inorganic nitrogen (DIN) in aquacultural ponds is lethal to aquatic creatures and must be removed for water reuse. The treatments for recirculating culture water can be divided into two parts, which are biofilter media and equipment. As the biofilter media, in this study, influence of hydraulic retention time (HRT), packing rate of Hairbrush, Ring, TBR, Migring, Pall, windball and Heilex in seven media types on solid and DIN removal efficiency in fresh water were examined. The HRT were set for 3, 5 and 10 minutes, and the packing rate were 50% and 100%. The highest removal efficiency occurred in Hairbrush media, next came ring type and TBR. However, the cost of Heilex type was most economical, the second was Hairbrush type . If took the cost and removal efficiency into consideration at same time, Hairbrush type was the best of all combinations, the second was Heilex type. The media with higher effective surface area provided higher removal efficiency in this study. As the equipment part, we treated the wastewater by combining low cost settling tank and hairbrush tank at a prawn pond in I-Lan. Five PVC wavy boards were added into the settling tank as a settler to enhance the capability. The removal efficiency of solids and DIN was examined with different HRT and density of hairbrushes in the tank. The HRT were set for 1, 1.25 and 1.5 hours, and the density of hairbrushes in the tank were designed for 24, 32, 48 branch/m3. In this study, the best HRT operation of the settling tank was 1.5 hours, and the additional PVC wavy boards were verified for improving the removal efficiency of solids, which diameter was smaller than 80 µm. As the hairbrush-tank, the relationship of the solids removal efficiency and the HRT found no profound effect, however, it was proportional with hairbrush density. The solid removal efficiency rate was about 0.11~0.12 %/branch in the last phase. There are about 33.5~49.5 % removal efficiency of DIN in hairbrush tank. To sum up, hairbrush type was proven as a suitable biofilter media, and the addition of PVC wavy board as a settler attest to improve the removal efficiency of solids which diameter were smaller than 80 µm. Operation condition were adjusted according to quality of wastewater to meet it’s highest efficiency.