循环水养殖中水动力特性对鱼类影响的研究进展

水产养殖业在我国拥有重要的地位。在过去50多年间,以中国为代表的水产养殖业的发展速度已超过全球人口增速,全球已经有39个国家和地区的水产养殖产量超过了捕捞产量,中国则以水产养殖产量占渔业总产量的73%位列第一[1-2]。随着经济的发展和养殖规模的不断提升,养殖业出现了生产方式落后、效率低下、养殖环境污染、水域生态破坏、病害频发等一系列亟待解决的问题[3-4]。     

冷水性鱼类工厂化养殖过程管理

冷水性鱼类封闭循环式工厂化水产养殖模式的过程管理主要包括:养殖水源、规格品种的选择、养殖密度、饲料、投喂的定量方法、水质管理和鱼病预防等,以及涉及冷水性鱼类设施养殖的一些特殊技术要求。     

海水鱼类工厂化养殖循环水处理系统研究现状与展望

一、概况 鱼类养殖是继海带、扇贝、对虾以后我国海水养殖业的第四次发展浪潮,特别是大菱鲆的引进,及半滑舌鳎、漠斑牙鲆、塞内加尔鳎等新品种的相继开发,和“深井海水＋温室大棚”工厂化养殖模式的确立,使我国的海水鱼类养殖近年来取得了举世瞩目的成就,目前我国工厂化养殖水体己达500万米^2,年产值超过40亿元。在巨大的成绩面前我们应该清楚地意识到,我国的海水鱼类工厂化养殖主要以农户为主体,规模小、设施简陋,是建立在对地下海水资源的过量开采和对沿岸生态环境的破坏基础上的,     

海水对虾工厂化循环水养殖系统模式分析

对虾养殖由于受到水资源和虾病的困扰,工厂化循环水养殖已经成为今后对虾养殖的一个重要方向。对虾工厂化循环水养殖系统的结构包括了养虾池、水处理技术、消毒杀菌、增氧技术、水温调节装置等。目前,典型的养殖模式有美国德州跑道式对虾养殖系统、台南室内自动化循环水养虾系统、美国佛罗里达三阶段养殖系统和美国夏威夷基于微藻的循环水对虾养殖系统。文中对这4种典型的对虾工厂化循环水养殖系统的养殖试验情况进行分析比较。     

工厂化养殖循环水系统的管理要点

工厂化水产养殖中配备循环水系统的目的是为了减小养殖设施对水交换的依赖.循环水系统在水产苗种孵育场、工厂化养殖场和城市水族馆中的应用非常广泛,能够克服水源供应不足的困难和满足将水交换量降至最低的要求,并且使养殖对环境的污染大大下降,同时又具有保持养殖系统自身水质稳定、有效防止病害传播的特点,可以在水交换量极小的情况下维持水质条件满足养殖动物的需求.循环水系统的设计多种多样,但要达到高效都必须做好以下几方面的管理:(1)充气;(2)清除颗粒物质;(3)生物过滤祛除氨氮和亚硝酸盐;(4)缓冲pH值.     

海水鱼类 节约型工厂化养殖构建工程技术

循环水养鱼的主要特点表现在生产的连续性、无季节性和主动控制性,而主动控制养殖环境质量和营养供给是循环水养殖的核心。循环水养鱼系统由于采用先进的水处理技术和消毒杀菌技术,能有效防止养鱼过程中疾病的发生和传播,提高养殖品种的成活率和产品的品质,实现健康养殖和无公害产品生产。海水鱼类节约型工厂化养殖系统是以实用、节能、高科技为原则设计的循环水养鱼系统。     

“循环水工厂化淡水鱼类养殖系统关键技术研究与开发”通过鉴定

日前，上海市科技兴农重点攻关项目管理办公室组织专家对上海水产大学等单位完成的“循环水工厂化淡水鱼类养殖系统关键技术研究与开发”项目进行了鉴定。     

人工湿地在工厂化鱼类养殖系统中的应用

人工湿地就是人工设计的、模拟自然湿地结构和功能的生态复合体，它由水、处于水饱和状态的基质、挺水植物、沉水植物和动物组成，它通过其中一系列生物、物理、化学过程实现污水净化，换句话说，人工湿地就是为处理污水需要，采用湿地理论，模拟湿地构造人为筑造的湿地工程。2003～2005年我们在工厂化鱼类养殖车间养殖污水处理实践中，对人工湿地构成与效果作了研究，现将研究隋况报告如下：     

欧洲循环水养殖系统研究进展

欧洲循环水养殖系统技术随着欧盟和欧洲各国环保法规的加强而不断创新和发展。本文对欧洲正在使用生命周期法对循环水养殖进行环境影响评估的状况,以及欧洲应用独特的循环水养殖系统技术增加了养殖的品种进行了介绍和分析。并着重介绍了欧洲循环水养殖系统新技术的应用及其发展状况,特别阐述了脱硝反应技术、淤泥浓缩技术和臭氧技术等新技术在循环水养殖系统的应用情况。在此基础上,指出了循环水养殖可能面临的新挑战。     

循环水养殖系统的水处理技术

循环水养殖系统基本上是一个省地、省水、高产量的生产工具。其主要效益体现在可以减少用水量，提高养殖密度，减低受到外界影响感染病害的机率。与传统室外养殖法相比较，循环水养殖系统生产1公斤鱼可节省约30吨的水量，且养殖密度提升35—50倍。本文以一种典型循环水养殖系统为例，简单介绍循环水养殖系统的水处理技术。     

海水工厂化养殖生产能力评估方法

生产能力反映出海水工厂化养殖企业的可蓄养生物资源量,是评估海水工厂化养殖企业生物资源资产的重要指标,本文根据海水工厂化养殖的特点,提出了评估海水工厂化养殖企业生产能力的技术思路与原则,并在详细论述影响生产能力主要因素的基础上,提出了具体的评估方法,同时阐述了此方法的实用性和对完善海域评估方法的意义。     

A comparison of topologies in recirculating aquaculture systems using simulation and optimization

Recirculating aquaculture systems (RAS) are often designed using simplified steady-state mass balances, which fail to account for the complex dynamics that biological water treatment systems exhibit. Because of the very slow dynamics, experimental development is also difficult. We present a new, fast and robust Modelica implementation of a material balance-based dynamic simulator for fish growth, waste production and water treatment in recirculating aquaculture systems. This simulator is used together with an optimization routine based on a genetic algorithm to evaluate the performance of three different water treatment topologies, each for two fish species (Rainbow trout and Atlantic salmon) and each in both a semi-closed (no denitrification) and a fully recirculating version (with denitrification). Each case is furthermore evaluated at both saturated and supersaturated oxygen levels in the fish tank influent. The 24 cases are compared in terms of volume required to maintain an acceptable TAN concentration in the fish tank. The results indicate that the smallest volume is obtainable by introducing several bypass flows in the treatment system of a semi-closed RAS and that the gains can be significant. We also show that recycling already treated water back upstream in the treatment process degrades performance and that if one wishes to have a fully recirculating system with minimal water exchange, then the flows of oxygen, carbon and nitrogen must be carefully considered. For several of the cases, no optimum with denitrification could be found. We thus demonstrate that the best configuration and operation strategy for water treatment varies with the conditions imposed by the fish culture, illustrating the complexity of RAS plants and the importance of simulations, but also that computer-driven optimal design has the potential to increase the treatment efficiency of biofilters which could lead to cheaper plants with better water quality.     

Denitrification in recirculating systems: Theory and applications

Profitability of recirculating systems depends in part on the ability to manage nutrient wastes. Nitrogenous wastes in these systems can be eliminated through nitrifying and denitrifying biofilters. While nitrifying filters are incorporated in most recirculating systems according to well-established protocols, denitrifying filters are still under development. By means of denitrification, oxidized inorganic nitrogen compounds, such as nitrite and nitrate are reduced to elemental nitrogen (N₂). The process is conducted by facultative anaerobic microorganisms with electron donors derived from either organic (heterotrophic denitrification) or inorganic sources (autotrophic denitrification). In recirculating systems and traditional wastewater treatment plants, heterotrophic denitrification often is applied using external electron and carbon donors (e.g. carbohydrates, organic alcohols) or endogenous organic donors originating from the waste. In addition to nitrate removal, denitrifying organisms are associated with other processes relevant to water quality control in aquaculture systems. Denitrification raises the alkalinity and, hence, replenishes some of the inorganic carbon lost through nitrification. Organic carbon discharge from recirculating systems is reduced when endogenous carbon sources originating from the fish waste are used to fuel denitrification. In addition to the carbon cycle, denitrifiers also are associated with sulfur and phosphorus cycles in recirculating systems. Orthophosphate uptake by some denitrifiers takes place in excess of their metabolic requirements and may result in a considerable reduction of orthophosphate from the culture water. Finally, autotrophic denitrifiers may prevent the accumulation of toxic sulfide resulting from sulfate reduction in marine recirculating systems. Information on nitrate removal in recirculating systems is limited to studies with small-scale experimental systems. Packed bed reactors supplemented with external carbon sources are used most widely for nitrate removal in these systems. Although studies on the application of denitrification in freshwater and marine recirculating systems were initiated some thirty years ago, a unifying concept for the design and operation of denitrifying biofilters in recirculating systems is lacking.     

Research of dissolved oxygen prediction in recirculating aquaculture systems based on deep belief network

Recirculating aquaculture has received more and more attention because of its high efficiency of treatment and recycling of aquaculture wastewater. The content of dissolved oxygen is an important indicator of control in recirculating aquaculture, its content and dynamic changes have great impact on the healthy growth of fish. However, changes of dissolved oxygen content are affected by many factors, and there is an obvious time lag between control regulation and effects of dissolved oxygen. To ensure the aquaculture production safety, it is necessary to predict the dissolved oxygen content in advance. The prediction model based on deep belief network has been proposed in this paper to realize the dissolved oxygen content prediction. A variational mode decomposition (VMD) data processing method has been adopted to evaluate the original data space, it takes the data which has been decomposed by the VMD as the input of deep belief network (DBN) to realize the prediction. The VMD method can effectively separate and denoise the raw data, highlight the relations among data features, and effectively improve the quality of the neural network input. The proposed model can quickly and accurately predict the dissolved oxygen content in time series, and the prediction performance meets the needs of actual production. When compared with bagging, AdaBoost, decision tree and convolutional neural network, the VMD-DBN model produces higher prediction accuracy and stability.     

Abnormal swimming behavior and increased deformities in rainbow trout Oncorhynchus mykiss cultured in low exchange water recirculating aquaculture systems

Two studies were conducted to evaluate rainbow trout Oncorhynchus mykiss health and welfare within replicated water recirculating aquaculture systems (WRAS) that were operated at low and near-zero water exchange, with and without ozonation, and with relatively high feed loading rates. During the first study, rainbow trout cultured within WRAS operated with low water exchange (system hydraulic retention time (HRT) = 6.7 days; feed loading rate = 4.1 kg feed/m³ daily makeup flow) exhibited increased swimming speeds as well as a greater incidence of “side swimming” behavior as compared to trout cultured in high exchange WRAS (HRT = 0.67 days; feed loading rate = 0.41 kg feed/m³ daily makeup flow). During the second study, when the WRAS were operated at near-zero water exchange, an increased percentage of rainbow trout deformities, as well as increased mortality and a variety of unusual swimming behaviors were observed within WRAS with the highest feed loading rates and least water exchange (HRT ≥ 103 days; feed loading rate ≥ 71 kg feed/m³ daily makeup flow). A wide range of water quality variables were measured. Although the causative agent could not be conclusively identified, several water quality parameters, including nitrate nitrogen and dissolved potassium, were identified as being potentially associated with the observed fish health problems.     

我国鲆鲽类循环水养殖系统的研制和运行现状

全封闭式海水循环养殖系统,是当前国际上先进养殖模式的代表,也是未来养殖产业发展的重要方向,备受世界关注。我国最早走上工厂化养殖道路的海水鱼类是鲆鲽类,现正由开放式向封闭式循环水养殖方向迈进,目前各项技术与工艺已经取得了长足进步。但是,根据对国内循环水系统装备的研制及其运行情况的跟踪调查,发现循环水处理的核心部分存在着稳定性、可靠性、经济性等问题急待研究解决。本文在分析循环系统主要配套装备和工艺参数的基础上,结合几家典型养殖企业的运行特点进行了分类剖析,针对现有装备和系统中发现的几个关键问题,提出了改进、提高的对策,可为今后鲆鲽类全循环养殖系统的升级、定型和走向国产化提供借鉴。     

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.     

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.     

An integrated recirculating aquaculture system (RAS) for land-based fish farming: The effects on water quality and fish production

To mitigate the serious water pollution caused by the rapid expansion of the aquaculture industry in recent years, the development of improved aquaculture systems with more efficient water usage and less environmental impact has become essential. In this study, a land-based recirculating aquaculture system (RAS) was established that consisted of purification units (i.e., a primary biological pond, two parallel horizontal subsurface flow constructed wetlands [CWs], and a long ecological ditch) and 4-5 series-connected recirculating ponds. This system was mainly designed to stock channel catfish (Ictalurus punctatus), fifteen spine stickleback (Spinibarbus sinensis) and yellow catfish (Pelteobagrus fulvidraco), and the culture efficacy was evaluated based on a 2-year field experiment covering two growing seasons. According to the results, the primary biological pond played a role in sedimentation or nutrient retention, although this was not as evident when the CWs were functioning. The water flowing through the wetland system at a hydraulic loading rate (HLR) of 600 mm/day displayed lower values for the temperature, pH, dissolved oxygen (DO), suspended solids, organic matter and nutrients, whereas the electrical conductivity (EC) was higher, suggesting the accumulation of dissolved solids in the system. Due to the recirculation treatment, the trophic status of the recirculating ponds increased gradually along the direction of the flow and was notably lower in comparison to the control. As a result, the fish production responded to the variation of the water quality, which was reflected in the measurements of culture efficacy (final weight, survival rate, SGR and yield). The three main rearing species showed a decreasing trend along the direction of the flow, which was higher compared to the control, whereas an opposite trend was observed for filter-feeding fish. A Pearson correlation analysis revealed that the main culture species were inclined to live in meso- or oligotrophic conditions, and the silver carp adapted to more eutrophic conditions. Because RAS can provide better environmental conditions year-round, the present culture method could be more suitable for species that are sensitive to water quality in typical subtropical areas.