High rate algal pond treatment for water reuse in a marine fish recirculation system: Water purification and fish health

Regardless of the degree of closure of a recirculation system, effluents are produced and replacement water is needed, which limits the possibility of locating a seawater production system away from the shoreline. At the Palavas Ifremer station, in the south of France, a High Rate Algal Pond (HRAP) was operated during several years to treat the effluent from a recirculating aquaculture system before reusing it. The effect of the HRAP-treated water on the recirculation system and on the fish was investigated and the optimal algae growing conditions were defined. The experiments were carried out in three rearing systems: one flow through, one recirculating and one recirculating with a HRAP. The water flow rate, temperature, pH and salinity conditions were similar in all systems.The effect of reusing the HRAP-treated water is very limited (1) on the functioning of the recirculation system and (2) on fish performance, but it allows a significant reduction of the dissolved inorganic nitrogen and phosphorus concentration in the rearing water. HRAP treatment reduced metal accumulation in muscle and liver of RAS fish, except for chromium and arsenic. All biomarkers presented no significant difference between systems, except for Superoxide Dismutase (SOD) and EROD, which showed a higher concentration in RAS and in both recirculating system respectively.     

工厂化海水养鱼循环系统的工艺流程研究

讨论了一种经济型的封闭式海水养殖水处理技术。包括机械过滤固体废弃物、泡沫分离悬浮物、臭氧消毒、生物膜降解“三态氮”、滴滤除去气态废弃物、贝壳调节pH、氧气罩与溶氧罐混合氧浴增氧等工艺,并就研制的活性生物填料进行了净水实验。结果表明,经过以上系统处理后的水质指标为：COD＜2．8mg／L,SS＜7．2mg／L,非离子氨＜0．02mg／L,细菌含量低于自然海水,养殖牙鲆平均单产为29．92kg／m^2,成活率为95．39％。     

高效藻类塘技术及其在水产养殖中的研究与应用

介绍了高效藻类塘(HRAP)的技术原理,分析了国内外在高效藻类塘方面的研究进展以及在水产养殖方面的研究应用情况,认为高效率藻塘技术是净化养殖富营养化水体的一种有效途径。应用高效藻类塘净化养殖水体,应充分利用养殖生态系统中的能量和物质转化关系,并与生态工程化技术、藻菌固定化技术、微生物技术等相结合。     

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.     

The effects and control of algal blooms in fish ponds

It has been demonstrated that large quantities of ammonia may be released into the water of a fish pond following the collapse of an algal bloom. Some blue-green algae are thought to release toxins. This paper puts forward another explanation for this occurrence. A review of the disease known as Infectious Dropsy of Carp (IDC) based on the findings of this paper shows it to be caused by ammonia. Various methods to counteract this disease are described. Particular emphasis is placed on the policy concerning the addition of fertilizers. It is shown that dense blooms of nitrogen-fixing algae can be controlled by manipulation of the nitrogen: phosphorus balance of ponds. Determination of the aetiology of carp dropsy will probably lead to a better understanding of other diseases of fish which are manifested by similar symptoms. The disease of trout known as Viral Haemorrhagic Septicaemia (VHS) is discussed in this context. For clarification it is proposed that infectious dropsy of carp be renamed Environmental Ammonotelic Syndrome (EAS).     

A novel combined recirculating treatment system for intensive marine aquaculture

This study established a pilot‐scale recirculating treatment system that coupled an ecological process with a biological process to achieve adequate water quality and to minimize the water consumption for intensive marine culture. The recirculating treatment system consisted of a settling cell, a biofilter tank, a bivalve tank and gravel beds. The toxic pollutants, threatening the growth of bivalves, were reduced by the settling cell and the biofilter tank, so that the polyculture of shrimp and bivalves could be achieved. The living bivalve tank could function well as a remover of remaining small suspended solids (SS), and other pollutants. As the SS was reduced to a very low level by bivalve tank before the water flowing into the gravel beds, the risk of clogging was prevented. The studies suggested that the system maintained high removal efficiencies of SS, ammonium nitrogen () and nitrite nitrogen () and could contribute to the increase in shrimp yield.     

Effects of formalin chemotherapeutic treatments on biofilter efficiency in a marine recirculating fish farming system

Formalin (a 33–38% aqueous formaldehyde solution) is currently used for bath treatments to control ectoparasitic infections of fish. Its effects on nitrification were evaluated in a semi-closed pilot scale saltwater recirculating turbot culture system. Tested treatments included 1 h static exposure to 20, 30, 40, 50, 60, 70, 90 mg l⁻¹ formaldehyde without flushing, and long-term (i.e., 2, 4 and 6 h) exposures with constant 60 mg l⁻¹ formaldehyde in a recirculating system. Formaldehyde has no apparent effect on the ammonia oxidative bacterial community. However, a significant effect on nitrite oxidation was observed in 1 h static exposures of concentrations higher than 40 mg l⁻¹, and in recirculating system exposures of 60 mg l⁻¹ formaldehyde for more than 4 h. Repeated treatments may be hazardous for nitrifying bacteria, which could induce an increase in nitrite concentration. Nitrite concentrations should be monitored when treatments are repeated or when they last a long time in recirculating aquaculture systems.     

Use of maize as a food source for sea urchins in a recirculating rearing system

Six diets were tested on the somatic growth and mortality of the sea urchin Paracentrotus lividus reared in a semi-closed system. Three of the diets were algal-based (Palmaria palmata, Laminaria digitata and a mix of L. digitata (80%) plus P. palmata (20%)), the other three being based on maize (pure maize or a mix of maize (80%) plus P. palmata (20%) and maize (80%) plus L. digitata (20%)). Best growth rates were obtained with the mix maize plus P. palmata, the lowest conversion rates were obtained with the algal-based diets. Mortality rates were not significantly different between the diets. Sea urchins (3791) were reared in a semi-closed circuit and fed a mix of maize plus P. palmata. Growth, size distribution and mortality were studied to an age of 23 months, when their mean diameter was 21.4 mm (size distribution from 6 to 46 mm). The fastest growing urchins reached 40 mm in 15 months. Size frequency histograms were extrapolated to show that 25% of the urchin population reach a size >40 mm in 41 months. Forty-nine months would be necessary for 50% of the population to reach that size and 63 months for 75% of the population. © Rapid Science Ltd. 1998     

The bacteriology of power station effluent used to farm marine fish

Duplicate water samples from an unstocked tank and from each of four tanks stocked with starved “1-group” plaice were analysed both quantitatively and qualitatively. It was found that bacterial counts obtained from samples taken from stocked tanks were significantly higher than those taken from an unstocked tank. Allowing for limited sampling, the flora of the water circulating through an unstocked tank did not radically differ from the flora of the water following the addition of starved fish. The predominant group was the Pseudomonas Group IV/Achromobacter/Alcaligenes/Agrobacterium group.     

冷水鱼循环水养殖中的低温氨氮处理技术研究

为解决冷水鱼养殖过程中养殖水体中的氨氮累积问题,根据低温生物滤器及臭氧催化氧化处理氨氮的特点,设计了冷水鱼工厂化养殖氨氮处理系统并进行了试验。试验基于以臭氧氧化为主、低温生物处理为辅的处理工艺,试验鱼为虹鳟鱼,养殖密度为23 kg/m3,试验水体约为10 m3,试验周期为7 d。结果表明,该系统能够满足冷水鱼工厂化养殖过程中有关氨氮处理的水质指标要求,处理后的养殖池进水口的水质指标总氨氮≤0．18 mg/L,硝酸盐氮氮≤29．43 mg/L,亚硝酸盐氮氮≤0．1 mg/L;养殖水体氨氮浓度监测表明,臭氧在水中残留低于0．008 mg/L,符合养殖鱼类对水体臭氧浓度的安全要求。     

Observations of flow patterns in a model of a marine fish larvae rearing tank

There are few studies on flow fields generated by aerators in fish larvae rearing tanks. The flow varies with aeration rates and tank proportions resulting in different larvae survival rates. The effects of aeration rate and aspect ratio AR (the ratio of liquid depth to tank radius) on overall flow patterns were investigated experimentally using flow visualization techniques. Two distinct types of flow patterns, a single-pair vortex system and a two-pair vortex system, were observed as the value of tank aspect ratio varied from about 1.0 to 2.0. In addition, corner vortex structures were observed in both the region between the free surface and the upper sidewall, and between the bottom wall and the lower sidewall of the tank. On the sidewall, reattachment and separation points were found, which were closely related with these vortex structures.     

Predation risk from piscivorous fish influencing the diel use of macrophytes by planktivorous fish in experimental ponds

Abstract— This study investigated interactions between zooplanktivores (roach and perch) and piscivorcs (pike and large perch) in experimental ponds (16 m²) with open water habitat and three densities of natural macrophytes. Fish habitat selection was determined both day and night and was supported by daytime observations to study anti-predator behavioural patterns. Diel migration out from among macrophytes was seen in the absence of predators, particularly for roach, which changed from 13% of individuals being in open water during the day to 90% at night. The risk of predation from piscivores influenced the habitat selection of the zooplanktivores. Roach seemed to be the most vulnerable to predation from pike and selected the open water (90-92%) during daylight hours, but kept a 1-m distance from the macrophytes edge. The presence of pike thus reduced the use of macrophytes by roach, which in turn may improve macrophytes and the edge area as a refuge for zooplankton. Pike appeared to have less impact on the gross habitat selection of O+ perch, which were associated with the macrophytes (58–89%), though they were still vulnerable to predation. Adult perch, which was a generally less effective predator than pike, showed subdued behavior, concealing them selves in the macrophytes most of the time. No effect of the simultaneous presence of two predator species was found.     

闭合循环水产养殖系统生产过程中生物过滤器功能的形成

生物过滤器对维持闭合循环水产养殖系统水质稳定起着核心的作用。生物过滤器存使用之前需要对生物膜进行培养、驯化,使生物过滤器有充分的硝化能力。生物过滤器硝化功能的建立一般需要较长的时间,淡水需要14～20d海水需要40～80d。在生产中因会产生较高浓度的氨氮、亚硝酸氮对饲养对象产生不良影响,增加养殖风险。     

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.     

复合池塘循环水养殖系统生态足迹分析

生态足迹模型已广泛应用于可持续发展的评估中。将生物塘、人工湿地、生态沟渠等生态工程系统与传统养殖塘有机结合而构建形成的复合池塘循环水养殖系统,作为一种新养殖模式,它具有循环微流水养殖、种养结合、水陆交互作用的特点。本文运用生态足迹方法对这一新养殖模式进行了定量分析。结果表明:就单位利润生态足迹量而言,复合池塘循环水养殖模式为2.92 ghm2/万元,而传统池塘养殖模式为4.91ghm2/万元,复合模式具有更高的生态经济综合效益,更符合可持续发展要求。     

海水对虾养殖塘排放废水生态处理设计

针对海水对虾养殖废水中主要污染物悬浮颗粒物和氨氮的去除,构建了排水沟中沉淀及大型海藻吸附、贝藻协同净化和人工红树林湿地深度净化的生态处理工艺路线,并在相关研究基础上对各处理单元的关键设计参数进行了总结,得到一组相对较切合实际的设计参数和计算公式。     

鳔器官的发育对人工培育鱼苗的影响

论述了鳔器官的发育对海水鱼类人工培育苗种的影响，仔鱼期鳔的形成和充气是影响闭鳔海水鱼类人工育苗成效的重要因素之一，鳔发育异常一是导致仔稚鱼死亡，二是导致脊柱前凸。在人工养殖条件下，影响海洋闭鳔鱼类鳔器官充气的因子有营养因子和环境因子，充气量，水表面的油膜，温度，盐度和光照等环境因子影响仔鱼水表面吞饮空气，影响鳔的充气率，仔鱼摄食EPA和DHA含量低的饵料后，活力差，仔鱼到达水表面吞饮空气的能力下降，鳔的开腔率降低，此外仔鱼体内甲状腺素的含量可能对仔鱼鳔的开腔率产生影响。     

北方高寒地区池塘养鱼高产试验

我国东北五大连池市拥有可养鱼洼地 3万多亩 ,均位于黑龙江西北部。常年水温偏低 ,鱼类生长期短 ,池塘养鱼产量小 ,效益低。 1997年我们在该市15亩浅水池塘进行高产高效的养鱼试验 ,现报告如下。1　试验条件1 1　气候条件　试验区位于北纬 48° ,东经12 6°,属于第四积温带 ,无霜期短 ,但春夏日照时间较长。1 2　池塘条件　池塘东西走向 ,面积 15亩 ,平均水深 1 0米 ,注排水共用一沟 ,水源为上游草原冰雪溶水和水库水。2　试验方法2 1　池塘　采用漂白粉干法清塘 ,于上一封动前结束。 1996年 10月 15日清塘。2 2　施基肥　施用马粪约 10 0…     

The use of model ponds to evaluate phytoplankton blooms and benthic algal mats for Penaeus monodon Fabricius culture

Abstract. Fibreglass pools (3·5m diameter, 1·2m high) were evaluated as model ponds and used to compare the effects of fertilization strategies, designed to promote either phytoplankton blooms or benthic algal mats, on production of Penaeus monodon Fabricius and water quality over 8 weeks. As production results were similar to those reported from commercial ponds in Australia and Taiwan, the pools were considered appropriate experimental units for assessing pond management strategies. Large blooms of filamentous algae developed in four of the eight pools with benthic algae. In these, individual prawn growth (weight gain), biomass gain, food conversion efficiency and drain harvest efficiency were all lower ( P < 0·05) than in pools with phytoplankton. Abundance of filamentous algae was negatively correlated ( P < 0·05) with prawn weight gain (r =−0·80) and drain harvest efficiency (r =−0·76). Differences in water quality arising from alternative fertilization strategies occurred but did not explain differences in prawn production indices. The results indicate that ponds used for monoculture of P. monodon should be fertilized so as to stimulate and maintain phytoplankton blooms and to discourage blooms of filamentous algae.     

Design and performance of recirculating aquaculture system for marine finfish broodstock development

Tropical and subtropical climatic conditions in India present an ideal and unique opportunity for being the leader in tropical marine finfish aquaculture. However, the problem persist due to non-availability of marine finfish seed for the culture. In response to this problem, broodstock development of different tropical marine finfishes for seed production was started. The present study was undertaken to design a recirculating aquaculture system (RAS) and studying their performance in managing the various water quality required for the marine finfish broodstock development and breeding. The design of RAS, developed in the present study, included a broodstock tank, egg collection chamber, electrical pump, rapid sand filter, venturi type protein skimmer and biological filter. Two RAS were designed, one was stocked with a demersal fish species, orange spotted grouper (Epinephelus coioides) and the other was stocked with a pelagic fish species, Indian pompano (Trachinotus mookalee) at the rate 1 and 0.5 kg/m³ with a sex ratio of 1:1 and 1:2 (female: male) respectively. Various physio-chemical parameters, viz, total ammonia nitrogen (TAN), nitrite, nitrate, pH, alkalinity, temperature, free carbon dioxide (CO₂) and dissolved oxygen (DO) of both tank water were analyzed to assess the performance of recirculating aquaculture system in maintaining the water quality. Gonadal development of the fishes was assessed and the spawning performance was recorded and finally, economic performance of the system was also evaluated. During the entire experimental period, mean monthly total ammonia nitrogen was less than 0.07 and 0.06 mg L⁻¹ and mean monthly nitrite was less than 0.02 and 0.01 mg L⁻¹ in orange spotted grouper and Indian pompano RAS tanks respectively. The pH (7.8–8.2), DO (>4 mg/L) and alkalinity (100–120 mg/L) were found to be in optimum range in both recirculating aquaculture systems. Carbon dioxide was found to be nil during the entire experimental period in both the systems. In fact these levels were comparable or less than that is reported as the permissible limits for broodstock development. Indian pompano and Orange spotted grouper matured and spawning was obtained with production of fertilized eggs round the year. Economic evaluation showed the price of 10,000 fertilized eggs of orange spotted grouper to be US $ 1.33. The design of RAS devised in the present study is efficient in controlling and maintaining optimum water quality for broodstock development of both demersal and pelagic finfishes. The fishes stocked in RAS attained final maturation and round the year spawning was obtained.