Abstract Recirculating aquaculture systems (RAS) using biofloc biofilters can address the high accumulation of nitrate (NO3−-N) and total suspended solids (TSS) in in-situ biofloc technology (BFT) aquaculture systems. A RAS was divided into the following four zones: reaction zones of the BFT biofilters, settling zones of the BFT biofilters, culture tanks, and a buffer tank. During the 95-day experimental period, the water quality parameters and microbial communities in different zones of the RAS were compared. The NO3−-N, nitrite (NO2−-N), total ammonia nitrogen (TAN), and TSS in the culture tanks were continuously controlled at average concentrations of 9.84 ± 5.15, 0.28 ± 0.15, 0.10 ± 0.18, and 96.92 ± 33.82 mg·L−1, respectively. Because denitrification produced alkalinity in the BFT biofilters, the alkalinity of the culture tanks reached an appropriate concentration of 109.40 ± 10.57 mg CaCO3·L−1 without intentional adjustment. The concentrations of NO3−-N, NO2−-N and TAN in the reaction zones were significantly lower than those in the influent (buffer tank) and culture tanks. However, there was no significant difference found for major water quality parameters between the reaction zones and the settling zones. There was also some removal of soluble reactive phosphate by the BFT biofilters, although there was no significant difference between the biofilters and influent. Microbial communities in the reaction zones were more diverse than those in the culture tanks, buffer tank and settling zones. Denitrifiers, nitrifying bacteria and important functional microbial populations for phosphorus removal were all present in the reaction zones, and at higher levels than those in other zones. Nitrogen and phosphorus removal were mainly achieved in the reaction zones of the BFT biofilters, and the microbial communities in the other three zones were similar. Besides, Scortum barcoo grew from an individual weight of 347.7 ± 73.0 to 472.1 ± 106.2 g, achieving a final stocking density of 32.81 kg·m−3 at the end of the experiment.

中文翻译：

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使用生物絮团生物过滤器表征循环水产养殖系统不同区域的水质和微生物群落

摘要 使用生物絮凝生物过滤器的循环水产养殖系统 (RAS) 可以解决原位生物絮凝技术 (BFT) 水产养殖系统中硝酸盐 (NO3--N) 和总悬浮固体 (TSS) 的高积累问题。RAS 分为以下四个区域：BFT 生物过滤器的反应区、BFT 生物过滤器的沉降区、培养罐和缓冲罐。在为期 95 天的实验期间，比较了 RAS 不同区域的水质参数和微生物群落。培养池中的NO3--N、亚硝酸盐(NO2--N)、总氨氮(TAN)和TSS连续控制在9.84±5.15、0.28±0.15、0.10±0.18和96.92±33.82的平均浓度mg·L−1，分别。因为反硝化在 BFT 生物过滤器中产生碱度，培养罐的碱度在没有刻意调整的情况下达到了109.40±10.57mg CaCO3·L-1的合适浓度。反应区中NO3--N、NO2--N和TAN的浓度显着低于进水（缓冲池）和培养池中的浓度。然而，反应区和沉降区之间的主要水质参数没有发现显着差异。BFT 生物过滤器也去除了一些可溶性活性磷酸盐，尽管生物过滤器和进水之间没有显着差异。反应区的微生物群落比培养池、缓冲池和沉降区的微生物群落更加多样化。反硝化菌、硝化细菌和重要的除磷功能微生物群都存在于反应区，并且水平高于其他区域。脱氮除磷主要在BFT生物滤池的反应区实现，其他三个区的微生物群落相似。此外，Scortum barcoo 的个体重量从 347.7 ± 73.0 增长到 472.1 ± 106.2 g，在实验结束时达到了 32.81 kg·m-3 的最终放养密度。