Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
Center of Excellence for Marine Biotechnology, Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
J Environ Sci (China). 2013 Aug 1;25(8):1557-64. doi: 10.1016/s1001-0742(12)60248-4.
A bottom substrate denitrification tank for a recirculating aquaculture system was developed. The laboratory scale denitrification tank was an 8 L tank (0.04 m2 tank surface area), packed to a depth of 5 cm with a bottom substrate for natural denitrifying bacteria. An aquarium pump was used for gentle water mixing in the tank; the dissolved oxygen in the water was maintained in aerobic conditions (e.g. > 2 mg/L) while anoxic conditions predominated only at the bottom substrate layer. The results showed that, among the four substrates tested (soil, sand, pumice stone and vermiculite), pumice was the most preferable material. Comparing carbon supplementation using methanol and molasses, methanol was chosen as the carbon source because it provided a higher denitrification rate than molasses. When methanol was applied at the optimal COD:N ratio of 5:1, a nitrate removal rate of 4591 +/- 133 mg-N/m2 tank bottom area/day was achieved. Finally, nitrate removal using an 80 L denitrification tank was evaluated with a 610 L recirculating tilapia culture system. Nitrate treatment was performed by batch transferring high nitrate water from the nitrification tank into the denitrification tank and mixing with methanol at a COD:N ratio of 5:1. The results from five batches of nitrate treatment revealed that nitrate was successfully removed from water without the accumulation of nitrite and ammonia. The average nitrate removal efficiency was 85.17% and the average denitrification rate of the denitrification tank was 6311 +/- 945 mg-N/m2 tank bottom area/day or 126 +/- 18 mg-N/L of pumice packing volume/day.
循环水产养殖系统底部基质反硝化罐的开发。该实验室规模的反硝化罐为 8 L 罐（0.04 m2 罐表面积），底部基质填充深度为 5 cm，用于自然反硝化细菌。水族箱泵用于在罐中进行温和的水混合；水中的溶解氧保持在需氧条件下（例如> 2 mg/L），而缺氧条件仅在底部基质层占主导地位。结果表明，在所测试的四种基质（土壤、沙子、浮石和蛭石）中，浮石是最优选的材料。比较使用甲醇和糖蜜作为碳源补充，选择甲醇作为碳源，因为它提供的反硝化速率高于糖蜜。当甲醇以最佳 COD:N 比 5:1 施加时，硝酸盐去除率达到 4591 +/- 133 mg-N/m2 罐底面积/天。最后，用 80 L 反硝化罐评估了 610 L 循环罗非鱼养殖系统中的硝酸盐去除。通过批量将高硝酸盐水从硝化罐转移到反硝化罐中，并以 COD:N 比 5:1 与甲醇混合，进行硝酸盐处理。五次硝酸盐处理的结果表明，成功地从水中去除了硝酸盐，而没有亚硝酸盐和氨的积累。硝酸盐去除的平均效率为 85.17%，反硝化罐的平均反硝化速率为 6311 +/- 945 mg-N/m2 罐底面积/天或 126 +/- 18 mg-N/L 浮石填充体积/天。
