多营养级池塘养殖系统设计与试验

Design and experiment of the Multi-trophic Aquaculture Pond System

为有效解决水产养殖环境污染、提高水产品品质,本研究构建了一套1.33 hm2的多营养级池塘养殖中试试验系统,主要包括草鱼养殖区、河蟹养殖区、螺蛳鲢鳙养殖区和水处理设施等。养殖的草鱼、河蟹作为饲料营养的Ⅰ级利用层级,投放的螺蛳、鲢鳙作为Ⅱ级利用层级,种植的沉水植物作为Ⅲ级利用层级,按时打捞水草、螺蛳作为草鱼、河蟹的生物饵料,从而提高饲料营养物质向鱼蟹等主养对象的转化比例。利用计算流体动力学(CFD)软件建立了试验系统水循环过程的1∶1比例计算模型,研究了全域水循环过程和单个草鱼养殖池的流动特性,并开展了水质调控试验,在试验系统内设置14个采样点,对一个养殖周期的水质参数进行监测。结果显示:草鱼养殖池壁附近的水体流度大于轴心区域的水体流速,有利于颗粒废物的沉淀,及时集排污;系统开启运行300 s后,水体在整个系统中的流态趋于稳定,营养物质在系统各个池塘中的分布基本均匀,保证物质能量的高效循环;系统对养殖水体氮、磷的去除效果显著,养殖全程的总氮质量浓度低于5 mg/L,总磷质量浓度低于1 mg/L,符合淡水养殖排放水标准,但对化学需氧量(COD)的控制效果不显著,应进一步改进系统结构,加强系统对有机污染物的处理能力。本研究为多营养级分隔池塘养殖系统的设计提供了参数参考。

In order to solve the environmental pollution of aquaculture and improve the quality of aquatic products,a Multi-trophic Aquaculture Pond System was developed.The experimental system mainly consisted grass carp culture section,Chinese hairy crab culture section,snail and feeding-feed carp culture section as well as water treatment facilities.According to the biological habits of the aquaculture objects,the ponds were partitioned into several units,and the discharge of eutrophic substances was reduced through increasing the material circulation of nutrients in multiple aquaculture organisms of different ecological niches.In this study,a pilot scale system of 1.33 hm2 was constructed.The calculation model of water cycle process of the experimental system was established using CFD numerical calculation software.The flow characteristics of the whole system and the grass carp culture tank were studied,and the research of the water quality control performance was carried out.The results showed that the velocity value near the wall of grass carp culture tank was greater than that in the central area,which was conducive to the precipitation of particle waste and timely discharge.After the system was started for 300 s,the flow state of water in the whole system tended to be stable,thus,the concentration of nutrients in each pond became well-distributed,which ensured the efficient circulation of substance and energy.The total nitrogen concentration was lower than 5 mg/L and the total phosphorus concentration was less than 1 mg/L,which met the discharge standard of freshwater aquaculture,but the decrease of COD was not significant.So,the structure of the Multi-trophic Aquaculture Pond System should be further improved to strengthen the treatment capacity of organic pollutants.This study provides a parameter reference for the design of Multi-trophic Aquaculture Pond System.