尼罗罗非鱼池塘养殖尾水颗粒物质沉降特征分析

Sedimentation Characteristics of Suspended Solids in Aquaculture Wastewater of Nile Tilapia Pond

【目的】养殖尾水中固体颗粒物的沉积和分解会导致养殖水体恶化并影响鱼类健康,了解尼罗罗非鱼(Oreochromis niloticus)池塘养殖尾水中固体颗粒物的沉降规律及其对养殖水体的影响,为其养殖尾水处理系统的研发与设计提供理论依据。【方法】采用静置沉降处理尼罗罗非鱼池塘养殖尾水,分别于不同沉降时间采集不同深度的养殖尾水样品,对养殖尾水中颗粒物的粒径分布、溶解性有机物组分及水质指标进行分析。【结果】静置沉降对养殖尾水水质无显著影响(P>0.05),仅降低了养殖尾水表层中总氮(TN)、总磷(TP)及化学需氧量(COD)的浓度;静置沉降可显著分离养殖尾水中的悬浮固体和藻类(P<0.05)。经5.0 h静置沉降后,2.0 m高处水体总悬浮固体(TSS)浓度减少3854 mg/L,叶绿素a浓度减少42 mg/L,浊度减少0.23 NTU,色度减少309度,养殖水体中的TSS和叶绿素a浓度随沉降时间的延长而降低;粒径分布结果显示,静置沉降可有效分离养殖水体中粒径大于100μm的易沉降颗粒,但无法分离粒径低于30μm的微细颗粒。固体颗粒的沉降速度与其粒径分布范围和浓度有关,固体颗粒沉降速度随其粒径分布范围减小和浓度的上升而降低;三维荧光光谱结果表明尼罗罗非鱼养殖尾水中的溶解性有机物主要以类富里酸质为主,静置沉降无法完全改变养殖尾水中溶解性有机物组分。【结论】短时间静置沉降能有效去除养殖尾水中的易沉降颗粒,TSS和叶绿素a的浓度随沉降时间的延长而降低,但静置沉降无法完全改变尾水中的溶解性有机物组分,也无法显著降低养殖尾水中的氮、磷等污染物的浓度。

【Objective】The deposition and decomposition of solid particles in aquaculture wastewater will lead to the deterioration of aquaculture water and affect the health of fish.The study was conducted to understand the sedimentation rule of solid particles in aquaculture wastewater of Nile tilapia(Oreochromis niloticus)and its influence on the aquaculture water body,with an aim to provide a theoretical basis for the research and development and design of aquaculture wastewater treatment system.【Method】The aquaculture wastewater of Nile tilapia pond was treated by static sedimentation.Samples of aquaculture wastewater at different depths were collected at different sedimentation times,and the particle size distribution,soluble organic components and water quality indexes of aquaculture wastewater were analyzed.【Result】Static sedimentation had no significant effect on the quality of aquaculture wastewater(P>0.05),and only reduced the mass concentrations of total nitrogen(TN),total phosphorus(TP)and chemical oxygen demand(COD)in aquaculture wastewater surface.Suspended solids and algae in aquaculture wastewater could be separated by static sedimentation(P<0.05).After static sedimentation for 5.0 h,the TSS,chlorophyll a mass concentration,turbidity and chromaticity of two-meter-high water decreased by 3854 mg/L,42 mg/L,0.23 NTU and 309 degrees respectively,and the TSS and chlorophyll a mass concentrations in aquaculture water decreased with the extension of sedimentation time.The results of particle size distribution showed that the settleable particles larger than 100μm could be effectively separated by static sedimentation,but the fine particles lower than 30μm could not be separated.The sedimentation velocity of solid particles was related to its particle size distribution range and mass concentration.The sedimentation velocity of solid particles decreased with the decrease of particle size distribution range and the increase of mass concentration.The results of three-dimensional fluorescence spectrum showed that the soluble organic compounds in the wastewater of Nile tilapia were mainly fulvic acid-like,and the soluble organic components in the wastewater could not be completely changed by static sedimentation.【Conclusion】Short time static sedimentation can effectively remove settleable particles in aquaculture wastewater,and the mass concentrations of TSS and chlorophyll a decrease with the extension of sedimentation time.However,static sedimentation cannot completely change the soluble organic components in the wastewater,nor can it significantly reduce the mass concentrations of nitrogen,phosphorus and other pollutants in aquaculture wastewater.