养殖池塘增氧机制与装备性能比较研究

水产养殖过程中,池塘生态系统可分为自成熟期和人工维持期。在养殖容量提高的情况下,养殖生物呼吸需氧量在不断增加,缺氧条件下有机物分解成有害物质,影响养殖生产。维持池塘生态系统稳定的主要工程机制为:通过上下水层交换、平衡营养元素等方法,强化光合作用,提高营养物质转化规模,提升初级生产力;形成生态增氧为主、机械增氧为辅的高效增氧机制。以中国养殖池塘生态系统为研究对象,分析探讨养殖池塘生态机制、水体溶氧理论、增氧机作用机理、不同类型增氧机的机械性能等,提出了大宗淡水鱼混养池塘及几种典型单养池塘增氧机配置方式,从而为池塘养殖系统增氧机的配置提供技术参考。     

Engineering investigation of design procedures for closed containment marine aquaculture systems

The objective of this paper is to investigate potential design procedures for rigid, closed containment aquaculture systems deployed in the marine environment. In this context, closed containment is a term used to describe a range of aquaculture technologies that attempt to restrict and control interactions between farmed fish and the external aquatic environment, with the goal of minimizing impacts. The containment units are often closely spaced and moored to the seafloor bottom. The geographical area of interest is the Straits of Georgia, British Columbia in Canada.In this study, the design configurations of multiple closed containment systems are investigated. The design procedures include examining: (1) local environmental conditions, (2) drag forces on multiple containment units, (3) wave loading, (4) undamped heave motions, (5) mooring gear components and (6) material stresses on a rigid containment structure. Operational and other design considerations are also discussed. Preliminary findings indicate that wave forces could be substantial. In addition, little is known about how containment units, which are closely spaced, will respond individually or as a farm when subjected to surface waves.     

Engineering investigation of design procedures for closed containment marine aquaculture systems

The objective of this paper is to investigate potential design procedures for rigid, closed containment aquaculture systems deployed in the marine environment. In this context, closed containment is a term used to describe a range of aquaculture technologies that attempt to restrict and control interactions between farmed fish and the external aquatic environment, with the goal of minimizing impacts. The containment units are often closely spaced and moored to the seafloor bottom. The geographical area of interest is the Straits of Georgia, British Columbia in Canada.In this study, the design configurations of multiple closed containment systems are investigated. The design procedures include examining: (1) local environmental conditions, (2) drag forces on multiple containment units, (3) wave loading, (4) undamped heave motions, (5) mooring gear components and (6) material stresses on a rigid containment structure. Operational and other design considerations are also discussed. Preliminary findings indicate that wave forces could be substantial. In addition, little is known about how containment units, which are closely spaced, will respond individually or as a farm when subjected to surface waves.     

Bubble size distribution in a bubble column applied to aquaculture systems

Bubble size distribution affects the gas-liquid mass transfer rates during aeration and foam fractionation processes employed in recirculating aquacultural systems. The effects of air flow rate, protein concentration and air stone pore size on bubble characterization were investigated. Bubble size was measured photographically in conjunction with image-processing techniques. The study indicated that bubble size increased with air flow rate and air stone pore size, but decreased with protein concentration. Within the tested range of these variables, the geometric diameters of the majority of the bubbles (90%) were within the range of 0·5–3·0 mm, and the bubble sizes followed a normal distribution.     

A novel computer simulation model for design and management of re-circulating aquaculture systems

The aim of this study was to develop a simulation model for finding the optimal layout and management regime for a re-circulating aquaculture system (RAS). The work plan involved: (1) quantifying the effects of fish growth and management practices on production; (2) developing a mathematical simulation model for the RAS, taking into account all factors that directly influence system profitability; and (3) estimating the production costs and, hence, the profitability of an RAS. The resulting model is process-oriented, following the flow of fish through the RAS facility, and generates an animated graphic representation of the processes through which the fish passes as it progress through the system. The simulation assesses the performance in terms of yearly turnover, stocking density, tank utilization and biomass in process, and uses statistics to track the state of the RAS and record changes that affect efficiency. The economic impact of system design and operation was modeled to enable a user to anticipate how changes in design or operating practices, costs of inputs, or price of products affect system profitability. The proposed approach overcomes difficulties in characterizing RAS design and operation. The simulation approach allows all of the RAS's components such as equipment, biological processes (e.g., fish growth), and management practices to be evaluated jointly, so that an initial design can be fine-tuned to produce an optimized system and management regime suited to a specific fish farm within a reasonable time. The methodology was executed step-by-step to design an optimal RAS that meets both economic and stocking-density limits. Optimal design specifications were presented for several case studies based on data from Kibbutz Sde Eliahu's RAS, in which Nile tilapia (Oreochromis niloticus) are raised in 20 concrete raceways. Further research should include more extensive testing and validation of the integrated model, which then should be disseminated to the aquaculture community.     

双层浮球生物滤器设计及其水产养殖水处理性能试验

工厂化水产养殖水体的处钾主要包括增氧、分离（分离固体物和悬浮物）、生物过滤（降低BOD、氨氮和亚硝酸盐）、曝气（去除二氧化碳等）和杀菌消毒等处理过程。其中,悬浮物和氨氮去除是主要技术难点。自20世纪80年代,各国学者深入研究了固定滤床和流化滤床、喷淋滤床和浮球生物滤器（bead filter）等悬浮物和氨氮综合处理装置的性能。     

不同增氧方式对盐碱养殖池塘pH的影响

以盐碱池塘水体为研究对象,比较叶轮+底增的复合增氧方式和传统叶轮单一增氧方式下盐碱池塘水体pH的变化趋势,以探讨复合增氧方式对盐碱池塘水体pH的影响。试验包括室内和野外试验两部分,室内试验为通气量和叶绿素a浓度交互作用下对室内普通水体pH的影响,野外试验为复合增氧和传统叶轮单一增氧方式对盐碱池塘水体pH、溶解氧和叶绿素a浓度的影响。室内试验结果显示,通气可以显著降低水体pH值(P<0.05),且降低值(ΔpH)随通气量增大而增大。野外试验结果显示,开机时,不同天气条件下复合增氧池塘pH均显著低于单一叶轮池塘(P<0.05),复合增氧池塘DO和CO2浓度均显著高于单一叶轮池塘(P<0.05);不开机时阴天和雨天条件下两者差异亦显著(P<0.05)。整个养殖期复合增氧池塘DO显著高于单一叶轮池塘(P<0.05),而pH值下降及CO2浓度上升较明显,且均在第45天后低于和高于单一叶轮池塘(P<0.05)。经双变量相关性分析发现,复合增氧与单一叶轮增氧方式下叶绿素a浓度与水体pH均呈显著正相关,相关系数分别是0.913和0.738。以上结果表明,复合增氧方式能够增加水-气接触面积,有效提高盐碱池塘水体DO和CO2浓度,降低池塘水体pH值。     

Introduction to the design of coastal aquaculture systems in Taiwan

The traditional culture of shellfish in the coastal waters of Taiwan has a long history. The culture area was limited to the sandy beaches of the south and southwest coast. In the past decade, due to the shortage of land resources and water pollution, coastal water aquaculture has been extended to intertidal rocky areas and the sublittoral zone. Concrete ponds have been constructed on the intertidal zone of the rocky coast specifically for culturing such species as small abalone, Haliotis diversicolor supertexta, grass shrimp, Penaeus monodon, grouper Epinephelus sp. etc. Fish culture in floating cages and oyster culture on floating long-lines and rafts are also practiced. This paper presents details of construction designs, with emphasis on utilizing water circulation, construction costs and wave resistance. Some examples are selected to illustrate the layouts used and the problems faced.     

Solar heating systems for recirculation aquaculture

The literature over the past 25 years indicates that there has been a continued interest in using passive and active solar technologies to reduce the conventional energy required to maintain water temperatures in small recirculation aquaculture systems. Although all of the experimental systems reviewed report favourable results, there is little information available to guide system designers. This paper describes the use of a simulation model to predict the annual conventional energy consumption of a 10.6 m³ RAS enclosed in a double layer polyethylene greenhouse in two different climates. The water was maintained at 22.5 °C and the recirculation rate was 10% of tank volume per day. Simple unglazed solar collectors have also been combined with the greenhouse to further reduce energy consumption. The effect of increasing collector area on the solar fraction and utilization of useful energy was predicted. Finally, the model was used to investigate the relationship between the occurrence of condensation on the inner cover, ventilation rates and energy use.

It was found that in a hot dry climate, the greenhouse alone was sufficient to reduce the conventional energy requirements by 87%; while in the cooler temperate climate reductions of 66% were possible. When solar collectors were added to the system, conventional energy requirements were reduced further and depended on the area of collector used. For example, in the temperate climate location, conventional energy requirements were reduced to 23% of a RAS enclosed in a non-solar building when 26 m² of solar collector inclined at the optimum angle for winter energy collection were used. Although condensation could be successfully reduced by ventilation of the greenhouse, this increased conventional energy requirements because the potential for evaporation was increased. Covering the tanks at night was found to be a more effective strategy because it reduced condensation and conventional energy use simultaneously.     

Membrane performance and fouling behavior of membrane bioreactors installed in marine recirculating aquaculture systems

Accumulation of fine suspended solids and colloids in a recirculating aquaculture system (RAS) can be avoided by integrating a membrane filtration unit into the system, where the inclusion of a membrane bioreactor (MBR) may be an alternative. The main purpose of the study was to identify how the feeding regime affected membrane performance and fouling phenomena caused by dissolved and submicron colloidal particles in the system, and how the membrane impacted general water quality and particle characterization. To be able to evaluate membrane performance and fouling behavior, transmembrane pressure (TMP) was monitored and assessed in relation to changes in rearing conditions and different water quality parameters observed. From this study the positive influence on the chosen water quality parameters was apparent, where an improved water quality was observed when including a membrane filtration in RAS. Selected water quality parameters and TMP changed during the experimental period in response to the feeding regime, where algae paste, decaying rotifers and dry feed seemed to contribute the most to membrane fouling. Analysis of the concentration of submicron particles and particle size distribution (PSD) (particles < 1 μm) showed both a higher concentration and a more spread distribution in the rotifer/algae paste and dry feed period compared to the Artemia period, which might explain the observed increase in fouling. This study also showed that adapted procedures for concentrate removal are important to prevent hydrolysis of retained particles in the concentrate and leakage of nutrients and organic matter back to the system.     

Effects of mechanical aeration on evaporation rate and water temperature in aquaculture ponds

Water temperature and water loss by evaporation were monitored in control ponds and in ponds with different rates of aeration (9.2, 18.4, 27.6 and 36.9 kW/ha). The mean decrease in water temperature at 70‐cm depth was greater than that at the surface in aerated ponds than in control ponds. The greater the aeration rate, the cooler was water, both at the surface and at 70 cm. Evaporation rates were found to increase with greater aeration rate. Water loss increased by 32%–92% over 24‐hr periods in ponds with one to four 0.37‐kW Air‐O‐Lator aerators, respectively. The nutrient‐enriched control pond was more turbid, had cooler surface and deep water temperature, and had greater evaporation loss than the control pond without nutrient addition and less turbid water. But, aeration did not increase turbidity. Aeration can increase water loss from ponds and result in lower water temperature. Although aeration should not be used excessively in order to conserve water and reduce production cost, it is essential for many types of feed‐based aquaculture.     

Performance of packed column aerator at low hydraulic loading

A laboratory-scale packed column aerator filled with ceramic Raschig rings was tested for its performance with hydraulic loadings in the range of 16–86·3 m³ m⁻² h⁻¹. Two columns of 0·19 m and 0·24 m inside diameter and packing sizes of 15, 25 and 36 mm were used. The system equation developed by previous workers for trickling filters in waste-water treatment was not generally applicable across the lower hydraulic loadings. The system coefficient incorporating the oxygen absorption coefficient (k_La) was found to vary within the range of hydraulic loadings studied. The oxygen transfer rate equation developed for surface and submerged aerators was used for estimating standard oxygen transfer efficiency of the packed column aerator, which, in this case, ranged from 6·2 to 22·6 kg O₂ kWh⁻¹.     

Growth performance of disk abalone Haliotis discus hannai in pilot- and commercial-scale recirculating aquaculture systems

The study investigated the growth performance of abalone from juvenile to marketable size in a commercial-scale recirculating aquaculture system. The rearing system consisted of 12 raceways (4.0 × 0.8 × 0.6 m) with a protein skimmer and a submerged biofilter for juveniles and 10 raceways (6.6 × 1.3 × 0.6 m) with a protein skimmer and a trickling biofilter for on-growing. Sea mustard (Undaria pinnatifida) and kelp (Laminaria japonica) were fed to the abalone. The total weight of abalone in the recirculating aquaculture system at the juvenile stage increased from 22.0 kg (average shell length 24.5 mm) to 75.5 kg (average shell length 42.5 mm) after 180 days. Feed conversion ratios increased slightly from 13.7 for the first 90 days to 16.3 thereafter. The shell growth rate of juvenile abalone between 24.5 mm and 34.8 mm was 3.4 mm month⁻¹, while for juveniles between 34.8 mm and 42.5 mm it was 2.6 mm month⁻¹. The total weight of abalone in the recirculating aquaculture system for the on-growing stage increased from 100.0 kg (average shell length 44.0 mm) to 433.3 kg (average shell length 72.7 mm) after 570 days. The feed conversion ratios for the first 173 days, the next 320 days, and the last 570 days were 19.6, 22.1, and 24.8, respectively. The growth rate of the average shell length during the on-growing period was 1.5 mm month⁻¹. Total ammonia nitrogen (TAN) concentrations were stabilized below 0.12 mg l⁻¹ in the juvenile recirculating system and 0.14 mg l⁻¹ in the on-growing recirculating system after conditioning of the biofilters.     

A design study on the optimal water refreshment rate in recirculating aquaculture systems

Refreshment (make-up) water is used in recirculating aquaculture systems (RAS) mainly to purge off-flavors, to add alkalinity and sometimes for temperature control. Alternatively, alkalinity may be added by means of a chemical base and heat may be supplied by a heating system. The objective of this study is to show how the optimal (minimizing cost) mix of the three controls: water, base and heat, can be found for given temperatures and water prices.The optimal solution varies over the temperature space and also depends on the price of water. For conditions at Eilat, Israel (on the Red Sea), using supplementary heating to maintain a constant temperature may become prohibitively expensive. If heating is given up, the remaining choice is between the supply of alkalinity via the refreshment water and adding a base. The supply of alkalinity with the water requires 2.0 m³[water]/kg[feed], much more than the minimum refreshment rate required to purge off-flavors, which is thought to be 0.3 m³[water]/kg[feed]. If the price of water is more than 0.03 USD/m³, the use of sodium bicarbonate for alkalinity control is justified.     

Impact of net positive suction head on the design and operation of seawater pumping systems for use in aquaculture

There are a number of different types of pumping systems that can be used for marine aquaculture systems. Five common types include: (a) pier mounted pumps, (b) package pump stations, (c) submersible pumps, (d) float mounted pumps, and (e) pumps that only operated over part of the tidal cycle. The ability of these systems to successfully operate under tidal conditions at 48 sites along the United States coasts was evaluated as a function of pump elevation, suction side head losses, water temperature, and salinity. This analysis provides insight into the relative advantages and disadvantages of each approach and presents procedures to assist in the engineering analysis for specific applications.     

The performance of microbial flocs produced with aquaculture waste as food for Artemia

The performance of microbial flocs as food for Artemia, which were produced using waste from a recirculating aquaculture system stocking European eel (Anguilla anguilla), was investigated in an 18‐day feeding trial. Four dietary treatments were used: Chlorella only (diet 1), flocs only (diet 2), and both Chlorella and flocs offered as mixed diets in different proportions (diets 3 and 4). The survival rate of Artemia fed diets 1 and 4 were significantly higher than those fed diets 2 and 3. The survival rate of Artemia fed diet 4 was the highest among the four diets. Individual length (10.02 ± 2.44 mm) and biomass production of diet 3 (3.2 ± 0.40 g L^–1) were the highest among the four diets. The crude protein contents for Artemia fed diets 2, 3 and 4 were 591.22 ± 30.15, 580.34 ± 22.42 and 533.27 ± 34.19 g kg^–1, respectively, which were significantly higher than that of diet 1 (461.25 ± 10.33 g kg^–1). The concentrations of free amino acids and the fatty acid compositions in the four diets were equal, except for the C24:0 content. The highly unsaturated fatty acid concentration of Artemia fed diet 2 was higher than those of the other three diets. It showed that microbial flocs produced from fish waste can be used for Artemia.     

Phosphorus budget in shrimp aquaculture pond with mangrove enclosure and aquaculture performance

ABSTRACT:   An experiment in which water was circulated between shrimp aquaculture ponds stocked with 10 000 or 20 000 PL-15 stage Penaeus monodon , and mangrove enclosures each planted with 476 Rhizophora mucronata per enclosure, was carried out at the Samut Songkhram Coastal Aquatic Research Station, Faculty of Fisheries, Kasetsart University, Thailand. Shrimp survival rate was significantly higher ( P  < 0.001, Fisher's exact test) in ponds where 10 000 larvae was stocked and water was exchanged with the mangrove enclosure, compared with the control pond with no water exchange, over the 136 day experimental period. Phosphorus transport to the mangrove enclosure was estimated to be 0.41 kgP and 0.18 kgP over the experimental period and change in phosphorus content in mud was reduced there compared with the control pond. A load reduction effect to the environment was confirmed in this aquaculture system with mangrove enclosure compared with the phosphorus budget in the control pond, and 6.2 or 8.9 ha of mangrove area was estimated to be required by 1 ha shrimp ponds to fully process the phosphorus.     

池塘养殖中不同机械增氧技术的组合及效果验证

为解决河南中牟县万滩镇养殖池塘机械增氧技术单一的问题,通过试验研究微孔式、水车式、涌浪式等几种增氧机的性能及使用方式,以达到提升增氧效果和提高养殖效益的目的。结果表明,该地区池塘溶氧含量高而利用率低,养殖户传统增氧方法不当。适宜增氧方式为:涌浪式增氧机适合在晴天下午使用3~6 h,可有效提升周边20 m范围内底层水体的溶氧水平;投食前后半小时开启和关闭微孔式、水车式增氧机,可提升投食期间投饵区溶氧水平1~2 mg/L,保证鱼群的进食效果;夜间搭配使用微孔式和低功率叶轮式增氧机增氧,可使微孔区域底层水体溶氧比不增氧状态高出1 mg/L以上。