海水循环水养殖系统中生物膜生长调控与水体循环优化研究

发布时间：2018-06-27 04:20

  本文选题：海水 + 生物膜　； 参考：《浙江大学》2016年博士论文

【摘要】：高效、环保的循环水养殖模式是未来水产养殖的必然发展选择,在海水循环水养殖系统中生物滤池实际运行时常出现启动慢、耗时长等问题,影响循环水养殖系统的可靠性和稳定性。循环水养殖系统平均化负荷设计忽略了鱼类污染物排放变化规律,导致养殖水体存在氨氮和亚硝酸盐氮超标的风险。针对以上问题,本文从海水淡水环境中生物膜生长、填料表面修饰、成熟填料接种和变速流调控等方面研究了硝化生物生长特征和关键作用因子以及水体循环优化和调控措施。论文主要结果如下：(1)海水环境中当亚硝酸盐氮浓度分别不小于100mg/L和12mg/L时氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)活性分别受到抑制,淡水环境中AOB没有受到明显抑制,而NOB抑制浓度不小于50mg/L；游离亚硝酸(FNA)对海水和淡水环境中NOB活性的完全抑制浓度分别不小于0.05mg/L和0.21mg/L。海水环境中NOB以Nitrobacter为主而淡水环境则以Nitrospira为主,盐度可能降低了Nitrospira对基质的竞争能力。然而海水生物膜生物量和胞外聚合物(EPS)蛋白质组成含量明显高于淡水生物膜含量,此点与总有机碳(TOC)和荧光光谱检测(3D-EEM)结果一致,这种现象源于硝化生物膜对盐度环境的适应机制。(2)表面修饰填料可在25d内建立完全硝化能力,早于普通空白填料(35d)；修饰填料能够明显地促进NOB在生物膜生长早期定殖过程,避免亚硝酸盐氮积累,减轻游离亚硝酸(FNA)对AOB和NOB的生长抑制。修饰填料表面物质组分变化研究发现修饰填料表面作用物质为蛋白质和多糖,这些大分子物质为生物膜生长提供潜在的有机物源和空间结构。(3)利用成熟填料接种生物滤池,接种量越大(如10～15%接种比例)生物滤池启动越快,越早形成完全硝化能力。然而新生物膜生长(如硝化能力、胞外聚合物(EPS)组分、细菌丰度等)更易被成熟生物膜抑制,这是由两者之间基质竞争引起的。硝化生物膜生长过程主要产生3种高丝氨酸内脂(AHL) (C4-HSL C8-HSL和3OC8-HSL),后两者可能促进硝化生物膜生长,因此在充足基质的基础上投加人工AHL是促进生物膜快速生长的途径之一。(4)罗非鱼摄食后12h内0～4h和8～12h为氨氮排放低谷期(4.2～4.7mg/(h*kg)),4～8h为氨氮排放高峰期(11～12mg/(h*kg));低循环率下无机氮浓度高于高循环率对应浓度,排放高峰期总氨氮(TAN)为3.26-3.37mg/L,亚硝酸盐氮(NO2-N)为1.32～1.45mg/L,超出罗非鱼健康生长限制浓度(TAN≤3mg/L,N02--N≤1 mg/L)。变速流通过增加氨氮排放高峰期内循环流量明显地降低了高峰期氨氮和亚硝酸盐浓度(TAN:2.03～2.24mg/L,NO2--N:0.56～0.62mg/L),方法易于实现、成本低,为系统水质调控和低成本养殖技术提供参考。
[Abstract]:Efficient and environmentally friendly recycling water culture model is the inevitable choice of aquaculture in the future. In the seawater circulating water culture system, the actual operation of biofilter often has some problems such as slow start-up, long time consuming and so on. The reliability and stability of circulating water culture system are affected. The design of average load of circulating water culture system neglects the change rule of fish pollutant emission, which leads to the risk of ammonia nitrogen and nitrite nitrogen exceeding the standard in culture water body. In order to solve the above problems, the characteristics and key factors of nitrification were studied from the aspects of biofilm growth in seawater and fresh water environment, surface modification of fillers, inoculation of mature fillers and regulation of variable velocity flow, as well as optimization and control measures of water circulation. The main results are as follows: (1) the activities of AOB and NOB in seawater environment were inhibited when nitrite nitrogen concentrations were not less than 100 mg / L and 12 mg / L, respectively, but AOB was not significantly inhibited in fresh water environment. The total inhibitory concentration of free nitrite (FNA) on NOB activity in seawater and fresh water was not less than 0.05 mg / L and 0.21 mg / L, respectively. In seawater environment, Nitrobacter is the main component of NOB, while in freshwater environment Nitrospira is dominant. Salinity may reduce the competitive ability of Nitrospira to matrix. However, the biomass of seawater biofilm and the content of extracellular polymer (EPS) protein composition were significantly higher than that of fresh water biofilm, which was consistent with the results of total organic carbon (TOC) and fluorescence spectroscopy (3D-EEM). This phenomenon originates from the adaptation mechanism of nitrification biofilm to salinity environment. (2) Surface modified fillers can establish complete nitrification ability within 25 days, which is earlier than normal blank fillers (35 days), and modified fillers can obviously promote the colonization process of NOB in the early stage of biofilm growth. Nitrite nitrogen accumulation was avoided and free nitrite (FNA) inhibited the growth of AOB and NOB. The changes of the composition of the surface matter of the modified packing were found to be proteins and polysaccharides, which provided potential organic source and spatial structure for the growth of biofilm. (3) the biofilter was inoculated with mature fillers. The larger the inoculation amount (such as 10 ~ 15% inoculation ratio), the faster the biofilter started, and the earlier the complete nitrification ability was formed. However, the growth of new biofilms (such as nitrification ability, extracellular polymer (EPS) components, bacterial abundance, etc.) is more easily inhibited by mature biofilms, which is caused by the competition of matrix between the two biofilms. Three kinds of high serine internal lipids (AHL) (C4-HSL C8-HSL and 3OC8-HSL) were produced during the growth of nitrifying biofilm, which may promote the growth of nitrifying biofilm. Therefore, adding artificial 4.2~4.7mg/ on the basis of sufficient substrate is one of the ways to promote the rapid growth of biofilm. (4) the peak of ammonia nitrogen emission (11 ~ 11 ~ 8 h) is observed in 0 ~ 4 h and 812 h within 12 h after feeding in tilapia (4.2~4.7mg/ (h*kg). The concentration of inorganic nitrogen at low cycling rate of h*kg); (12mg/) was higher than that at high cycling rate. Total ammonia nitrogen (Tan) and nitrite nitrogen (no _ 2-N) were 3.26-3.37 mg / L and 1.32 卤1.45 mg / L respectively, which exceeded the healthy growth limit (Tan 鈮，

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