海水循环养殖系统冬季运行水温和水质控制

为探讨江苏沿海地区海水鱼类养殖过程中的越冬问题,构建了基于温室保温与微藻净水的封闭式循环水养殖系统,用于开展黑鲷越冬试验。通过在线监测系统记录冬季运行期间系统内外水温与气温,研究太阳能温室的保温性能;通过定期采样检测养殖系统水质,比较投加微藻前后养殖池水质的差异,研究微藻净水的可行性。结果显示:冬季温室内海水循环养殖系统的平均水温显著高于温室外水温,有利于黑鲷顺利越冬并延长生长期;在养殖系统内接种微藻可有效降低水体氨氮(NH+4-N)浓度,并将亚硝酸盐氮(NH-2-N)浓度维持在较低水平,有利于维护养殖系统水质稳定。研究表明:集成温室保温与微藻净水的海水循环养殖系统可实现黑鲷越冬养殖。本研究可为存在积温不足和越冬问题的区域发展海水鱼类养殖提供参考。     

Water quality and rainbow trout performance in a Danish Model Farm recirculating system: Comparison with a flow through system

The objective was to compare water quality and fish growth and mortality in a pilot scale recirculating system (RS) and a control tank in flow through system (FTS). The RS was designed after the Danish Model Trout Farm and operated with a make up water renewal rate of 9 m³ kg^-1 of fish produced. RS water quality did not decrease significantly with water flow rate decrease in the RS. During the experiment, the RS water treatment system presented solids removal efficiency of 59.6 ± 27.7% d⁻¹, ammonia oxidation of 45 ± 32 g m⁻³ d⁻¹, oxygenation yield of 392 ± 132 g of O₂ kWh⁻¹ and CO₂ degassing of 23.3 ± 11.9% pass⁻¹. In the RS, nitrite concentration was 0.15 ± 0.07 mg l⁻¹, close to the toxicity threshold; a N₂ supersaturation phenomenon was measured, probably due to the air injection depth. The biofilter and sedimentation area management has to be improved to avoid organic matter decomposition and release of dissolved elements. Even if no N₂ over-saturation apparent effect on fish performance and aspect were detected, the airlift depth has to be modified in the case of industrial development of the RS. Some improvements of the water treatment system, especially on the airlift and sedimentation area, are suggested.Concerning fish growth, no significant differences were observed between the RS and the FTS. No pathologies were detected and cumulative mortality rates (0.1%) were similar to the farm's usual data. There were no significant effects of water flow rate decrease in the RS on fish performance and energy savings were recorded to be 0.7 kWh kg⁻¹ of fish produced between RS₁ and RS₂. The global energy cost of the RS was 3.56 kWh kg⁻¹ of fish produced (0.107 € kg⁻¹ of fish produced). Even if the energy consumption of the water treatment system can be improved, the results confirm that recirculating system can be used for industrial trout on growing, without fish performance deterioration.     

Water quality,waste production,and off-flavor characterization in a depuration system stocked with market-size Atlantic salmon Salmo salar

Land-based Atlantic salmon, Salmo salar, grow-out facilities utilize depuration to remediate off-flavor. Water used in this process is either discharged or repurposed as supply water in recirculating aquaculture systems (RAS). Both approaches require an understanding of water quality and waste production for water treatment decisions and compliance with pollution discharge standards; however, these data were lacking. Therefore, a study was carried out to characterize these parameters. To begin, 311 salmon (5–6 kg) originally cultured in freshwater RAS were stocked at 100 kg/m³ in an 18 m³ depuration tank. Feed was withheld 1 day before transfer and throughout the 7-day study period. Hours after stocking, total suspended solids (TSS), total phosphorus (TP), and total ammonia nitrogen (TAN) levels spiked, and concentrations declined thereafter. Delta TSS and TP were negligible by the end of the trial; however, TAN plateaued, indicating that salmon began to catabolize somatic tissue in the absence of feeding. Geosmin and 2-methylisoboreol levels in water and fish were low throughout the study. This research indicates that residual waste production occurs while depurating Atlantic salmon. Procedural refinements and recommendations were gleaned including locality for introducing depuration system water within RAS and extension of the feed withholding period before depuration.     

Performance of a recirculating fish production system stocked with tilapia hybrids

To demonstrate whether practical quantities of food fish could be produced in an inexpensive closed system suitable for family-scale use, 424 tilapia hybrid fry weighing a total of 177 g were stocked on 8 May 1981 into a 7600-liter (10·7 m²) steel-walled, vinyl-lined pool equipped with a rotating biological contactor, a settling basin, supplemental aeration and a passive solar collector. Ammonia, nitrite, nitrate, oxygen, temperature, pH and turbidity were monitored. New water was added at intervals during the experiment, at an average rate equivalent to 4% per day. Floating catfish chow was fed. To establish a growth curve and biomass estimate, 30 fish were removed, weighed and restocked every two weeks. After 146 days of grow-out, 48·6 kg of fish were harvested. Food conversion was 1·25:1. With suitable temperatures, 2·5 crops totaling at least 121 kg could be produced at a rate equal to 121000 kg/ha/yr of water surface.     

Rates of fish waste production and effluent discharge from a recirculating system (biofish) under commercial conditions

Application of the regulatory principle of ‘best available technology’ (BAT) to fish farm effluent control has, to some extent, been a driving force for the development of new culture and treatment technology. In Norway today, there are a number of farms for the production of Atlantic salmon, Salmo salar L., smolts and brown trout, Salmo trutta L., fingerlings that utilize microstrainers for the removal of particles from the effluent water. At least one commercial farm also utilizes a simplified recirculation system called BIOFISH as a demonstration of new and alternative technology for the production of brown trout restocking fish. In this paper, calculated effluent discharge and rates of waste production from the biofish demostration trials are compared to literature data and to measurements on un-treated as well as microstrained effluents from the production of Atlantic salmon smolts in a traditional flow-through tank system. Rates of fish waste production in the biofish trials were obtained from mass-balance calculations based on measured concentrations of water quality parameters at several points in the system. The results of these calculations show fish waste production rates that are low, but comparable to data found in the literature. Given the level of waste treatment that takes place in the biofish tanks, the specific effluent discharge levels from those tanks, in terms of grams per kilogram biomass and grams per kilogram feed, are considerably lower than those found for salmon smolt production in traditional flow-through tanks. There are also substantial differences in hydraulic self-cleaning properties of the two systems and a corresponding difference in the distribution of effluent discharge during normal tank operation and during tank/effluent pipeline flushing. The results presented here give valuable information related to: (1) waste output characterization; (2) the long-term efficiency of commercially available particle separation systems; and (3) the capabilities of the simplified biofish recirculation technology under field conditions.     

Identification of conditions underlying production of geosmin and 2-methylisoborneol in a recirculating system

Geosmin and 2-methylisoborneol (MIB) are semi-volatile terpenoid compounds produced as secondary metabolites by benthic and planktonic cyanobacteria, several genera of fungi, and various actinomycetes. These off-flavor compounds pose a heavy economic burden in the aquaculture industry rendering fish unmarketable unless purified by purging with large quantities of clean water. In the present study, the presence of off-flavor compounds was examined in a recirculating aquaculture system (RAS) for tilapia culture. In this zero-discharge system, where water from the fish basins is recirculated through parallel aerobic (drum filter and a trickling filter) and anaerobic treatment loops (sedimentation/digestion basin), concentrations of geosmin and, in particular, MIB were highest in the aerobic treatment loop. Lowest concentrations were detected in the anaerobic treatment loop. This latter finding pointed toward a possible reduction of these compounds in this basin. Two bacterial strains of the streptomycetes family were isolated from the aerobic, organic-rich, drum filter and the nitrifying trickling filter. In vitro tests with these isolates, closely related to Streptomyces roseoflavus and Streptomyces thermocarboxydus, revealed that MIB production exceeded geosmin production under all conditions tested and was significantly higher under aerobic than under anoxic conditions. Under the latter conditions, with nitrate as an electron donor, the S. roseoflavus-like isolate was capable of denitrification. Based on the results obtained in this study, it was concluded that aerobic, organic-rich conditions stimulate the growth of actinomycetes and subsequent production of geosmin and MIB in the system. The observed reduction of these compounds in the anaerobic water treatment component may serve in designing treatment steps aimed at alleviating the problem of geosmin and MIB accumulation in recirculating systems.     

循环水养殖系统管式射流集污特性试验研究

工厂化养殖池内的污物聚集效果是养殖池设计建造和运行管理的重要指标,对提升养殖技术和管理水平具有重要意义。针对一种典型的工厂化鱼类养殖池,对边侧管式射流系统驱动下的流场特性和污物聚集效果进行研究,探讨了射流角度、射流流速和循环抽吸方式等因素对养殖池内水体流场特性及污物聚集分布规律的影响。利用手持式ADV流速仪在养殖池内进行布点测量,获得各点流速数值,然后利用MATLAB软件进行流场插值构图,研究养殖池的流场分布特性;污物聚集特性采用图像法进行处理分析。研究表明:管式射流驱动作用下,流速从池心向外呈"V"型变化。在射流角度固定为40°条件下,射流速度越大,池心低流速区域范围越小,污物聚集效果越好。当射流速度达到0.3 m/s时,污物基本聚集于池心;在流速固定的情况下,对污物聚集效果存在一个最佳的射流角度,约为40°。池内循环抽吸模式对流场和污物聚集效果同样有着显著的影响。研究表明,采用底部抽吸时,排污孔附近的径向流速与切向流速均高于边侧抽吸模式,且污物聚集效果明显优于边侧抽吸模式。该研究成果可用于工厂化鱼类养殖池管式射流水力驱动系统的优化设计,在不影响养殖对象生长的前提下,可尽量提高射流流速,最佳射流角度一般为40°左右,并尽量采用底部抽吸模式。     

An evaluation of solid waste capture from recirculating aquaculture systems using a geotextile bag system with a flocculant-aid

Two separate geotextile bag systems were evaluated as a means for capturing and dewatering bio-solids in the effluent stream from recirculating aquaculture systems (RAS). Each geotextile bag system used a high molecular weight cationic polyacrylamide (PAM) polymer as a flocculant-aid. The two systems were operated under freshwater and brackish water conditions. A complete analysis including water quality and agronomic sludge analysis was conducted at the North Carolina State University Fish Barn – a large-scale, freshwater RAS demonstration and growout facility. An evaluation of water quality and performance of a similar geotextile bag system was also conducted at the Marine Aquaculture Research Center near Marshallberg, North Carolina, USA, under brackish conditions (15 PPT). Results indicated that performance of each of the systems was similar with TSS, COD, TN, and TP removal greater than 95%, 65%, 50%, and 38%, respectively, for both systems. Analysis of the sludge collected in the freshwater system after 70 days in a dewatering, inactive mode, showed a moisture content (MC) of 86%, or 14% dry matter (DM), indicating the system was effective at passively dewatering the bio-solids. Nutrient removal efficiency may be system specific based on the geotextile bag size and influent flow rate.Geotextile bag systems using flocculant-aids are an efficient means for capturing and dewatering waste solids from RAS effluents. Optimized geotextile bag system designs depend on flow rate, feed rate, and solids dewatering time, and fate of the treated effluent. This evaluation will aid in predicting the expected performance and determining the appropriate size of a geotextile bag system. The type of treatment required downstream from the geotextile bag system used for solids capture in a RAS wastewater treatment system will depend on the intended fate of the treated effluent.     

Controlled production of Artemia cysts under standard conditions in a recirculating culture system

A flow-through culture system is described for the controlled production of Artemia cysts in 10 litre aquaria using 50%. artificial seawater enriched with Fe-EDTA as culture medium, micronised ricebran as food source and cyclic flushes of the cultures with N₂-gas as induction mechanism for oviparity. The culture water is recirculated over a rotating biological contactor, a settling tank and a UV disinfection unit. Cysts are continuously harvested by filtration of the culture effluent. Production yields average 0·5 g dry cysts per day and per aquarium.     

循环水养殖罗非鱼氮收支及对水质影响的初步研究

为提供实际生产理论依据,改良系统水处理工艺,开展循环水养殖系统中吉富罗非鱼氮收支和对水质情况的初步研究。起始养殖密度8 kg/m3,投饲率2%,系统循环量1 m3/h,总水量0.8 m3。试验期间溶解氧大于6 mg/L,pH 7.0～7.2,水温23～25℃。每周监测水质2～3次,监测指标包括氨氮、亚硝酸盐氮、硝酸盐氮,每2周检测1次水中总氮。用凯氏定氮法测定实验前后饲料、试验鱼体、粪便、悬浮颗粒的氮含量。结果显示,摄食氮有50.00±1.50%转化为生长氮,32.61±1.38%转化为排泄氮,17.39±4.0%转化为粪氮;58%的粪氮为悬浮颗粒物,42%为可沉淀颗粒物。     

封闭循环水养殖系统中池塘覆膜对水质的影响

2005—2010年,对天津市天祥水产有限公司封闭循环水养殖系统水质进行了检测。结果显示:养殖池塘是否覆膜、覆膜面积大小,均会使整个养殖系统中的总硬度(TH)、总碱度(AT)、NH3-N和PO4-P在时空上产生差异。时间上,它们年份间差异极显著(P<0.01);空间上,各采样点的AT和NH3-N差异显著(P<0.05)。覆膜使系统的TH和AT稳定性减弱,CV上升了166.5%～241.7%,这种情况在养殖中期尤为突出,但对NH3-N和PO4-P稳定性的影响并不明显。养殖系统中较大面积的覆膜(43.65%)对养殖池塘TH、AT和NH3-N稳定性的影响比非覆膜池塘的大,CV分别高出了75.9%、135.6%和21.6%;而小面积(19.2%)覆膜的养殖池塘相对非覆膜池塘稳定,CV分别降低了71.9%、41.5%和91.4%。导致它们间差异及稳定性变异的原因主要归结于覆膜影响了物质与土壤间的物质交换及其间的生物活性强度。     

循环养殖系统中多级生物处理对水质的调控作用

研究了根据不同生物的功能特性及其间的协同作用,建立的由芦苇湿地、沉水植被群落、人工基质固定化微生物膜、软体底栖动物和滤食性鱼类组成的自净型多级生物修复系统,对养殖塘环境改善情况。结果显示:与实施修复前的系统相比,营养盐NO2-N、NO3-N和PO4-P的去除率分别达87.46%、62.99%和75.74%;浮游动、植物的生物量分别减少92.83%和15.90%。养殖塘排水营养盐NO2-N、NO3-N和PO4-P的去除率分别为27%～96%(年均87%)、37%～84%(年均84%)和30%～17%(年均9%),CODMn的去除率为1%～17%(年均9%)。经系统多级处理后水体透明度分别提高了75%和17%,最高值达52 cm。浮游植物生物量平均减少63.93%,尤其是蓝藻,平均减少68.17%。浮游植物群落结构转好,硅藻大量繁殖,成为优势种。浮游动物群落结构也由小型原生动物占优向大型枝角类、轮虫转变。受控于滤食性鱼类,浮游动物生物量维持在较低水平。     

Water quality in a closed recirculating fish culture system influenced by addition of a carbon source in relation to feed uptake by fish

Abstract. In a closed recirculating fish culture system with a rotating disc filter serving as 'biofilter", waterquality was maintained by the addition of hydrolysed corn starch in the settable solids tank. According to the feed uptake by rainbow trout . Salmo gairdneri Richardson, starch was introduced to adjust a nutrient relation of organic C:N of 1·6:1 for the bacterial biomass. Trout grew from 42 g to 254 g in body weight in 118 days. No differences in feed uptake and feed conversion rate were observed in a control group held in a flow-through system with tap water as culture medium.     

Performance of a commercial recirculating alligator production system employing a paddle-washed floating bead filter

A 2.83 m³ prototype paddle-washed bead filter for combined solids capture and biological filtration was successfully operated in a commercial recirculating alligator (Alligator mississippiensis) facility. The bead filter was originally designed and operated as a downflow filter but due to operational and water quality problems, it was reconfigured to operate in an upflow mode. Water quality conditions and filter performance improved dramatically, with the upflow bead filter capable of handling the equivalent loading of 10.3 kg m⁻³ beads per day of 40% protein feed, despite oxygen limitations and hydraulic problems associated with the retrofitted alligator system.     

循环水养殖系统固体废弃物厌氧消化处理技术与分析

循环水水产养殖系统中产生的残饵、粪便等固体废弃物的处理是实现水产养殖污染零排放的核心技术之一。随着环境法规的完善,政府将逐步要求养殖单位在养殖系统内部对固体废弃物进行处理,已报道的处理方法有堆肥、掩埋等。概述了循环水养殖系统中固体废弃物处理的研究进展,重点介绍循环水养殖系统固体废弃物厌氧消化处理技术的现状及存在的问题,并讨论应用人工湿地法、生物絮凝技术处理水产养殖固体颗粒物的研究状况。     

多层水槽式工厂化循环水养殖系统智能投饲车设计

为解决多层水槽式工厂化循环水养殖模式中人工投料操作空间局促、劳动强度大、饲料利用率低等缺点,设计了一套基于K60单片机的小微型智能投饲车。该投饲车由循迹小车、投饲装置和控制系统等组成,在特定投饲跑道上行驶,根据红外对管采集的轨道信息和压力传感器采集的饲料信息判别是否投饲或补料,进而实现智能定点定量投饲。初步试验运行结果显示,该投饲车运行稳定可靠,运行速度0. 5～2. 2 m/s,投饲的定位精度误差在2 cm以内,投饲量误差在10 g以内,基本满足设计要求。     

工厂化水产养殖中的自动控制技术

本文从工厂化水产养殖自动控制系统的组成、自动控制方法、自动控制技术在水质参数检测与调控中的应用等方面,论述了有关研究的技术成果和未来发展趋势.根据水产养殖工业化和自动化发展,以及自动控制技术在水产养殖中的广阔应用前景,指出了发展水产养殖自动化检测和调控精准技术的必要性,提出发展规范化、标准化的水产养殖自动化技术,以推动...     

工厂化水产养殖中的自动控制技术

本文从工厂化水产养殖自动控制系统的组成、自动控制方法、自动控制技术在水质参数检测与调控中的应用等方面,论述了有关研究的技术成果和未来发展趋势。根据水产养殖工业化和自动化发展,以及自动控制技术在水产养殖中的广阔应用前景,指出了发展水产养殖自动化检测和调控精准技术的必要性,提出发展规范化、标准化的水产养殖自动化技术,以推动水产养殖工业化的发展。     

循环水养殖半滑舌鳎成鱼摄食活动对主要水质因子的影响

在封闭循环水养殖条件下,半滑舌鳎(Cynoglossus semilaevis Günther)的平均养殖密度(15.07±0.22)kg/m3,观测半滑舌鳎的呼吸频率,检测养殖水体中溶氧、氨氮、亚硝酸氮等24 h内摄食和代谢的变化规律。结果表明:(1)半滑舌鳎摄食前、后的呼吸频率平均值分别为27.3次/min和34.7次/min,摄食后的呼吸频率显著高于摄食前;(2)投喂前、后2.5 h内,水中溶氧一直处于下降趋势,在摄食2.5 h后,水中溶氧处于稳定的上升趋势;(3)投喂后,氨氮、亚硝酸氮浓度显著增高,2.5 h后达到峰值,随后缓慢降低,在下次投喂前0.5 h达到最低值。说明半滑舌鳎摄食活动对循环水养殖水质的影响呈现规律性,也说明循环水养殖模式可以满足半滑舌鳎对水质的基本要求。