种养结合BAF工艺对密闭循环养殖水净化效果分析

Analysis on purification effect of closed circulating aquaculture water by planting and aquaculture combined with BAF process

为了满足受控生态生保系统对鱼类生长和水资源循环利用的需求,该文围绕密闭循环水产养殖系统(recirculatingaquaculture system,RAS)平台构建以曝气生物滤池(biological aerated filter,BAF)工艺为核心,辅以蔬菜栽培系统的水质净化工艺,探讨其对RAS持续运行的作用及原理。试验初始,向平台养殖池内输入300 L市政原水和60尾罗非鱼鱼苗,随后系统连续循环运行200 d,通过分析系统水质及鱼类生长状况,考察BAF耦合蔬菜栽培工艺在RAS中的适用性。结果表明,1~60 d单独BAF工艺对密闭RAS内水质污染物控制效果较差,运行60 d后水中TOC、N和P类污染物均出现大量累积。针对该问题,构建2级BAF和蔬菜栽培耦合工艺,在后续140 d内,TOC和NH4^+-N累积浓度分别由60.3和2.9 mg/L降低至11.2和1.2 mg/L;NO2^--N持续稳定在0.1 mg/L以下;NO3^--N和PO4^3--P分别由累积浓度114.2和43.1 mg/L降低并稳定至54.7和15.6 mg/L左右。在BAF耦合蔬菜栽培工艺保障下,密闭RAS内95%以上水资源持续再生;罗非鱼生长状态良好,零死亡率,最大养殖密度达41.9 kg/m^3;同步收获4批次蔬菜,总质量达23 420 g,平均株质量达195.17 g/株。试验结果说明,BAF耦合蔬菜栽培可有效保障RAS持续稳定运行,可为密闭受控生态生保系统的水生动物养殖提供技术借鉴。

For achieving the requirement of fish production and water sustained regeneration in controlled ecological life support system,a pilot-scale modified biological aerated filter(BAF)coupled with vegetable cultivation system was constructed as a purification plant for the closed recirculating aquaculture system(RAS).The performance of the modified purification process on RAS was investigated,and its principle was also discussed in this research.At initial stage,300 L municipal water as well as 60 tilapia mossambica were inset in the freshwater pond of RAS.In the followed experimental 200 days,the variation of water quality and fish growth was tracked and investigated,and then the navigability of purification process for RAS was analyzed and discussed.The experimental results showed that in the first research period(1-60 days),the single BAF process showed poor performance on the pollutant removal,and there were a mount of TOC,N and P accumulation after 60 days raising period.For resolving this problem,a modified BAF process coupled with vegetable cultivation system was constructed and carried out in the following 140 days.The followed experimental results exhibited that the modified BAF process coupled with vegetable cultivation showed significant good performance on the pollutant control,where the concentration of TOC and NH4^+-N decreased form 60.3 and 2.9 mg/L to 11.2 and 1.2 mg/L,respectively,and the concentration of NO3^--N and PO4^3--P obviously decreased form 114.2 and 43.1 mg/L to around 54.7 and 15.6 mg/L,respectively.Besides,the concentration of NO2^--N remained below 0.1 mg/L.Modified purification process could provide health-safety environment for the tilapia mossambica growth and vegetable cultivation in closed RAS,more than 95%water was regenerated,and the maximum aquiculture density was 41.3 kg/m^3 and without fish death.At the same time,four batches of vegetables were harvested.The total weight of vegetables was 23 420 g,and the individual weight was 195.17 g,respectively.The results showed that the modified BAF process coupled with vegetable cultivation could ensure the sustainable and stable operation of RAS and provide technical reference for fish culture in the controlled ecological life security system.