生物絮团养殖凡纳滨对虾系统中沉淀桶效率评估

Evaluation of settling tank efficiency and water quality in a biofloc culture system for Penaeus vannamei

  • 摘要: 生物絮团总悬浮物 (Total suspended solids, TSS) 浓度是养殖水质的一项重要指标,不仅影响养殖动物生长,还关系到系统溶解氧 (DO) 有效利用和水处理效率。为评估自行设计的竖流沉淀桶在凡纳滨对虾 (Litopenaeus vannamei) 养殖生产中对TSS的去除效果,本研究测定了其水力参数,并监测了沉淀前后水质指标的变化。结果表明,在本实验条件下,该沉淀桶进水流速为 (779.47±18.19) m·h–1,水力停留时间为 (1.09±0.03) h,TSS去除率达到 (78.09±1.35)%,沉降效果显著。水质指标中,进水TSS和DO浓度显著高于出水 (p<0.05)。养殖末期,氨氮 (\rmNH_4^ + \text- \rmN ) 浓度大幅升高,亚硝酸盐氮 (\rmNO_2^ - \text- \rmN ) 浓度降低,TSS浓度明显降低。沉淀桶使用期间,pH和总碱度 (T-Alk) 呈升高趋势。水质因子相关性分析结果表明,进水中TSS浓度与\rmNO_2^ - \text- \rmN 浓度呈显著负相关,\rmNH_4^ + \text- \rmN 浓度与pH存在显著正相关、与\rmNO_2^ - \text- \rmN 浓度存在负相关。硝酸盐氮 (\rmNO_3^ - \text- \rmN ) 浓度与pH存在显著正相关、与DO浓度存在显著负相关 (p<0.05)。出水中\rmNH_4^ + \text- \rmN 浓度与pH存在显著正相关,\rmNO_3^ - \text- \rmN 浓度与pH和T-Alk均存在显著正相关 (p<0.05)。进水和出水的pH和T-Alk相关系数分别为0.8和0.7。结合水质指标及其相关性分析,建议适当增加沉淀桶容积,并增强气提曝气强度,减少水力停留时间,同时通过水体营养物质调节定向调控水体微生物,进一步减少养殖管理中换水量和换水频率。利用沉淀桶对养殖水进行沉淀-回流,操作简捷且节能,适合大规模推广应用。

     

    Abstract: Total suspended solids (TSS) concentration is an important aquaculture indicator that affects the growth of farmed animals and relates to the effective utilization of dissolved oxygen (DO). To evaluate the TSS removal efficiency of a self-designed vertical-flow sedimentation tank in Litopenaeus vannamei culture, we determined its hydraulic parameters and monitored changes in water quality before and after sedimentation. The results show that under the culture conditions of this experiment, the influent flow rate of this settling tank was (779.47±18.19) m·h–1, the hydraulic retention time was (1.09±0.03) h, and the removal rate of TSS concentration was (78.09±1.35)%, exhibiting a significant sedimentation effect. Among the water quality indicators, the TSS concentration and dissolved oxygen (DO) concentration of the influent water were significantly higher than those in the effluent water (p<0.05). At the late stage of culture, the ammonia nitrogen (\rmNH_4^ + \text- \rmN ) concentration increase significantly, the nitrite nitrogen (\rmNO_2^ - \text- \rmN ) concentration decrease and the TSS concentration decreased significantly. During the use of the settling tank, pH and total alkalinity (T-Alk) exhibited an increasing trend. Correlation analysis of water quality factors show that influent TSS concentration was significantly negatively correlated with nitrite concentration, \rmNH_4^ + \text- \rmN concentration was significantly positively correlat with pH and negatively correlated with \rmNO_2^ - \text- \rmN concentration. \rmNO_3^ - \text- \rmN concentration was significantly positively correlated with pH and significantly negatively correlated with DO concentration (p<0.05). There was a significant positive correlation between \rmNH_4^ + \text- \rmN concentration and pH in the effluent, and a significant positive correlation between \rmNO_3^ - \text- \rmN concentration and both pH and T-Alk (p<0.05). The correlation coefficients of pH and T-Alk for influent and effluent water were 0.8 and 0.7, respectively. Based on water quality indicators and their correlation analysis, it is recommended to moderately increase the sedimentation tank volume, enhance airlift aeration intensity, and reduce hydraulic retention time. Meanwhile, aquatic microorganisms should be regulated in a targeted manner through the adjustment of water nutrients to further reduce the volume and frequency in aquaculture management. The sedimentation-reflux of aquaculture water using sedimentation tanks features simple operation and energy saving, which is suitable for large-scale implementation.

     

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