養殖廢污以龍鬚菜充分利用型之循環水系統設計

Abstract

台灣沿岸漁業養殖廢水的處理，以循環水養殖是目前最能有效改善養殖環境的方式之一。有別於傳統以大量換水的流水式養殖，以循環水系統搭配物理與生物法處理養殖廢水，不但可以節省水資源，也可以不受地區限制在內陸養殖，並減少財力與人力的花費，只需定期補助極少量的蒸發水量，就可高密度的水產養殖。 本研究以龍鬚菜為生物處理對象，探討其在九孔養殖循環水系統中廢污減量能力，針對影響龍鬚菜、九孔生長因子調控出適合兩種生物共同生長的環境為鹽度35 0/00、pH 7.0∼8.5及溶氧5ppm以上。另外龍鬚菜三角立體式養殖密度10.2 g/L，不但可以節省土地空間、增加九孔食物的保鮮量，也可提高對氨氮的吸收速率。 當陰天、光照不足、室內養殖或立體養殖水深超過90cm以上時，則必須考慮補充人工光源藍光或紅光。白天龍鬚菜吸收NH4+，夜晚轉而吸收NO3-，但當龍鬚菜受到環境的壓迫時（NH4+濃度高、低溫、高鹽度）也會吸收NO3-。當NH4+≧2 mg/L時，龍鬚菜無法穩定的吸收去除，此時必須提供微細氣泡曝氣，可以幫助養殖廢水降低氮化合物濃度，但當NH4+≦2 mg/L時龍鬚菜能降低NH4+濃度達1 mg/L以下，若加設硝化槽設置培養硝化菌，可以幫助NH4+氧化成NO3-，提高龍鬚菜的吸收率。 因此混養龍鬚菜既可保鮮九孔食物一星期以上，又可以有效利用九孔養殖循環水系統中多餘的有機物作為成長所需之營養鹽，並且提供系統較佳的水質環境，達到循環水體環境的平衡，廢污充分利用型之循環水系統設計。

Aquaculture wastewater mainly derives from leftover feeds and creatures’ excrements. Differing from the running-flow-type culture which causes significant pollution by directly discharging the waste water into the coast, recirculation culture is one of the most efficient improvements on the aquaculture wastewater treatment in coastal area of Taiwan. In addition to decreasing the expenditure of effort, finance and manpower, it can create high density aquaculture only by regularly adding small amount of water due to evaporation. This research uses Gracilaria as the target of biological treatment and investigates the reduction power of waste in abalone aquaculture recycling system. Factors that influence the growth of Gracilaria and Abalone (Haliotis diversicolor supertexta) is salinity 35 0/00,pH 7.0 – 8.5, and dissolved oxygen about 5ppm. In addition, the triangle-solid cultivation density of multilayer culture density of Gracilaria is 10.2 g/L. Not only it is able to save space and increase the fresh quality of Abalone food but also improve the absorption rate to Ammonia. It must consider adding artificial light source such as blue light or red light when cloudy day, insufficient illumination, indoor cultivation or multilayer culture and the water depth is above 90cm. Gracilaria absorbs NH4+ during daytime and soaks up NO3- during night. However, when Gracilaria is stressed by the environment (e.g. the concentration of NH4+ is too high, low temperature, and high salinity), it also absorbs NO3-. When NH4+ concentration is higher than 2 mg/L and Gracilaria is unable to eliminate it stably, it has to add tiny air-bubble device which helps wastewater to lower the concentration of nitrogen compounds. When NH4+ concentration is lower than 2 mg/L, Gracilaria can decrease the concentration NH4+ at below 1mg/L. If setting up a nitrification tank for nurturing nitrifying bacteria, it can aid NO3- in oxidizing NH4+ and increasing the absorption of Gracilaria. Therefore, Gracilaria not only keeps Abalone food fresh for more than one week, but it also can efficiently utilize redundant organic substance in abalone aquaculture recycling system as nutrition salt for the need of growth. Moreover it provides a best water quality environment to reach the balance of recycling water environment and the design of aquaculture waste reduce for water recycling system.