Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 8499000, Israel.
Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 8499000, Israel.
Sci Total Environ. 2018 Jul 1;628-629:603-610. doi: 10.1016/j.scitotenv.2018.02.089. Epub 2018 Feb 20.
The development of intensive recirculating aquaculture systems (RAS) with low water exchange has accelerated in recent years as a result of environmental, economic and other concerns. In these systems, fish are commonly grown at high density, 50 to 150kg/m, using high-protein (30%-60%) feeds. Typically, the RAS consists of a solid treatment and a nitrification unit; in more advanced RAS, there is an additional denitrification step. Nitrous oxide (NO), a byproduct during nitrification and denitrification processes, is a potent greenhouse gas that destroys the ozone layer. The aim of this study was to measure and assess NO emissions from a near-zero discharge land-based saline RAS. NO flux was monitored from the RAS's fish tank, and moving-bed nitrification and activated-sludge (with intrinsic C source) denitrification reactors. NO emission potential was also analyzed in the laboratory. NO flux from the denitrification reactors ranged between 6.5 and 48mg/day, equivalent to 1.27±1.01% of the removed nitrate-N. Direct analysis from the fish tank and nitrification reactors could not be performed due to high aeration, which diluted the NO concentration to below detection limits. Thus, its potential emission was estimated in the laboratory: from the fishponds, it was negligible; from the nitrification reactor, it ranged between 0.4 and 2.8% of the total ammonia-N oxidized. The potential NO emission from the denitrification reactor was 3.72±2.75% of the reduced nitrate-N, within the range found in the direct measurement. Overall, NO emission during N transformation in a RAS was evaluated to be 885mg/kg feed or 1.36g/kg fish production, accounting for 1.23% of total N application. Consequently, it is estimated that NO emission from aquaculture currently accounts for 2.4% of the total agricultural NO emission, but will decrease to 1.7% by 2030.
近年来，由于环境、经济和其他方面的考虑，低换水率的强化循环水产养殖系统（RAS）得到了快速发展。在这些系统中，鱼类通常以高密度（50-150kg/m³）养殖，使用高蛋白（30%-60%）饲料。通常，RAS 由固体处理和硝化单元组成；在更先进的 RAS 中，还有一个额外的反硝化步骤。氧化亚氮（NO）是硝化和反硝化过程中的一种副产物，是一种破坏臭氧层的强效温室气体。本研究的目的是测量和评估近零排放陆基咸水 RAS 的 NO 排放。从 RAS 的鱼池、移动床硝化和活性污泥（含内在 C 源）反硝化反应器监测 NO 通量。还在实验室分析了 NO 排放潜力。反硝化反应器的 NO 通量在 6.5 至 48mg/天之间，相当于去除硝酸盐-N 的 1.27±1.01%。由于高曝气使 NO 浓度稀释到检测限以下，因此无法直接从鱼池和硝化反应器进行分析。因此，其潜在排放量在实验室中进行了估算：从鱼塘中几乎可以忽略不计；从硝化反应器中，它在总氨氮氧化的 0.4 到 2.8%之间变化。反硝化反应器中潜在的 NO 排放量为还原硝酸盐-N 的 3.72±2.75%，在直接测量的范围内。总体而言，RAS 中 N 转化过程中的 NO 排放量估计为每公斤饲料 885mg 或每公斤鱼产量 1.36g，占总氮施用量的 1.23%。因此，据估计，目前水产养殖的 NO 排放量占农业总 NO 排放量的 2.4%，但到 2030 年将降至 1.7%。
