循环水养殖系统生物滤器负荷挂膜技术

Dual-Culture Techniques for the Rapid Start-up of Recirculating Aquaculture System

中文关键词: 循环水养殖系统  负荷挂膜  水质指标  红鳍东方鲀

英文关键词: Recirculating aquaculture system  Biofilm dual-culture techniques  Water quality  Takifugu rubripes

中文摘要:

      循环水养殖系统启动运行前往往需要经过一段时间的生物膜预培养，使生物膜达到成熟稳定，从而保证系统的水质净化功能。本研究通过养殖试验，研究了生物滤器负荷挂膜的技术方法，以期实现生物膜的快速成熟和系统的快速启动。为此，构建了6组循环水系统组成的养殖车间，建成后立即投入试验生产。试验为期120 d，养殖种类为红鳍东方鲀，初始放养平均体重(632.5±2.26) g。期间，红鳍东方鲀平均增重29.91%，养殖成活率98.7%，养殖密度由(19.34±1.89) kg/m3增加到(32.17±3.40) kg/m3，投饵率由0.2%增加到0.5%–0.7%，每日换水量由50%逐渐减至10%。结果表明，在生物膜的生长期，通过对投饵量及新水补充量的有效调节，可以把养殖水体中的氨氮和亚硝氮浓度控制在安全范围以内，以保证养殖鱼类的生长。生物膜在50天左右达到完全成熟，此后便可依靠生物膜的净化作用将氨氮浓度控制在0.51.2 mg/L、亚硝氮浓度控制在0.20.5 mg/L、pH值控制在6.5–7.5、COD值低于4 mg/L、细菌总数控制在800–2100 cell/ml的安全范围内。利用生物滤器负荷挂膜技术，在合理调控水质指标的条件下，循环水养殖系统建成后可以立即投入生产，实现生物滤器挂膜与养殖生产的同步进行。

英文摘要:

      Recently recirculating aquaculture system (RAS) has become popular in large scale land-based aquaculture in China because of its high productivity, less water consumption, better control on the effluent and pollutants, and lower demand for land space. The function of RAS relies largely on the efficiency and stability of the bio-filters which need to be carefully cultured and maintained throughout the culture period. The conventional start-up of RAS usually takes about 70 days before the pre-cultured biofilm maturates for the steady high-capacity water purification. In this study, a technique for the rapid maturation of a bio-filter and RAS start-up was developed through dual-culture of the biofilm and finfish Takifugu rubripes. The experiment was carried out in a newly-built workshop with 6 separate RASs. Each RAS consisted of 9 fish culture tanks. Each tank had a volume of 48.4 m3 and included parts shown below: 1) a model 316 L stainless steel bend sieve with a surface area of 5 m2; 2) a centrifugal pump with a water flow volume of 400 m3/h; 3) a submersible air pump with an air-production volume of 35 m3/h; 4) an ozone generator with an ozone-production capacity of 50 g/h; 5) three bio-filters with a volume of 144 m3 each; 6) a suspended UV disinfector with the power of 2 kW; 7) an aeration tank with a volume of 10 m3. T.rubripes with the initial body weight of (632.5±2.26) g were transferred into the tanks with the density of (19.34±1.89) kg/m3 in the beginning and were cultured for 120 days. During this period, their body weight increased by 29.91% to a final value of (821.72±3.26) g; the survival rate was 98.7%; the stocking density of the fish increased to (32.17±3.40) kg/m3; daily feeding rate increased from 0.2% to 0.5%0.7%; and the daily water exchange rate decreased from 50% to 10%. Observations mentioned above indicated the good growth and maturation of the bio-filters. Through the proper control of daily feeding rate and water exchange rate, good water quality in the culture tanks can be maintained during the culture of the bio-filter. After the bio-filter became maturate around day 50, water quality can be maintained by the purification function of the bio-filter, with the concentrations of ammonia and nitrite at 1.20.5 mg/L and 0.50.2 mg/L respectively, pH at 6.57.5, COD value below 4 mg/L, and the total bacterial count of 8002100 cell/ml. These results suggested that with effective water quality control, a newly-built RAS could be put into operation immedia¬tely by using biofilm dual-culture technique, and the biofilm culture and fish culture could be carried out simultane¬ously. This technique will provide valuable supports for the operation of newly-built RAS by lowering both the time consumption and the operation costs.