低動力循環水系統對淡水長臂大蝦池水質、成長及活存率之影響

Abstract

全球的內陸養殖漁業以淡水養殖居多，2014年內陸養殖魚產量約佔總養殖量64%。養殖方式也由粗放養殖轉為集約型。這些養殖池的養殖水及排放水，營養鹽過多，造成生物及環境危害。本研究目的係利用省水節能之池內循環水系統，降低淡水長臂大蝦養殖池中營養鹽累積對生物及環境影響。本研究在約1,400 m3池水及放養1,5000尾，平均3.67g體型的淡水長臂大蝦養殖池，放置250w低動力馬達及0.31m3串聯式槽體的生物濾床，設計負壓式水力系統，處理底水層水質，每日可處理底層水體約23m3。設備的水力停留時間為14.5分鐘，設備每日電費支出為9.4元，相較於其他水質過濾系統更為節能。 經過126日的現場實驗結果得知，水質改善部分，總氨氮去除效率最高達62.5%，硝酸氮的入出水變化率最高達23.7 %，藻相維持穩定，未產生負面影響。生物養殖部分，得知實驗池與對照池的活存率分別為54%及44%，養殖期間蝦體之平均成長速率分別為0.193及0.187(g/pic/day)，飼料轉換率分別為2.032及2.467。以上結果顯示，實驗池的生物養殖成績優於對照池。本設備利用低動力即可達到降低底水層之總氨氮量，提高水中硝酸鹽濃度，讓藻類可快速吸收營養，達到穩定水質之作用 ，有利於增進養殖戶的養殖成效。

Most of land-based fish farming are freshwater aquaculture. In 2014, land-based aquaculture fish production has accounted for 64% of the total harvest of aquaculture. The aquaculture patterns have gradually become more intensive. The waste water which contains excess nutrients is disposed into the river. It may causes biological and environmental damage. The purpose of this study is to reduce the negative effect of Macrobrachium rosenbergii aquaculture by water-saving and energy-saving circulating water system. A 0.31 m3 biological filter and the 250 w low-power motor was set in the pond. We treat the bottom layer water of pond with the negative-pressure hydraulic system to purify the water. The area of this pond is about 1,400 m3 which can stock 15,000 shrimp. This system can purify about 23 m3 water per day. The hydraulic residence time of system is 14.5 minutes and the electricity is 9.4 NTD per day. That means the system can save more energy. After 126 days, the maximum reduction rate of total ammonium nitrogen was 62.5%. The contamination of nitrate of output-water increased 23.7% compared with input-water. The dynamic of algal biomass was stable. Besides, the survival rates of shrimp in experiment and control group were 54% and 44%. The growth rates were 0.193 and 0.187 g/pic/day. And feed conversion ratio is 2.032 and 2.467. The growth index of shrimp in the experiment group is better than control group. This low-power system could reduce total ammonia, and increase nitrite and nitrate in the bottom layer of pond water. Therefore, algae can absorb nutrients efficiently and stabilize water quality. The system can enhance the effectiveness of aquaculture.