ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00237.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA management system, replacing emergency aeration practices with gentle pond circulation, has been employed over an entire catfish growing season. Five waterblenders were used to provide pond circulation for a 1.42 ha catfish pond stocked at a density of nearly 10,000 finger‐lings/ha. Pond water circulation during the daytime hours mixed oxygen‐rich surface waters with the deeper oxygen‐poor waters. The waterblending operation continued long enough after dark to decrease the thermal gradients, so that the diurnal temperature change provided top‐to‐bottom mixing on most nights during the season.Comparisons of yield data, power requirements, and oxygen and temperature profiles show the advantages of the pond receiving water circulation over a neighboring pond that was aerated only on an emergency basis. Comparisons of waterblending with recent aeration studies of other investigators show an order of magnitude reduction in en

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00238.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA new design in a high rate nitrification system has been tested at the laboratory scale. Ammonia removal rates per unit of filter volume at influent ammonia levels of 0.02 mg NH3‐N were observed to be 5 to 10 times more rapid than rates observed in conventional field‐scale nitrification filters. At these levels 95 to 99% ammonia removal has been achieved with filter detention times as short as 3 minutes. The data are compared to data for various field units and the reasons for the observed high removal rates are discussed. The possibility of retaining these high efficiencies in scaled‐up filters is also disc

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00239.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractSince the Bozeman Study in 1972, several pilot plants have been investigated to evaluate the application of the ion exchange systems for water recirculation in fish hatcheries. Pioneering work was made at the biological research laboratory of Kramer, Chin and Mayo, Inc., followed by a pilot plant testing at the Oregon Aqua Fish Hatchery in Newport, Oregon. In 1976, two 50‐gallon per minute capacity ion exchange bed systems were installed and tested at Dworshak National Fish Hatchery in Orofino, Idaho. Recently, water reuse is accomplished by pumping approximately 120 gallons per minute from the raceway and filtering it through the pressure sand filter and the clinoptilolite filters for the removal of ammonia in the Seattle Aquarium.The paper will discuss the physical and chemical properties of ion exchange materials, pilot plant test results, engineering design criteria and application, and economics as compared to conventional biological ammonia removal systems. In addition, discussion will also be made in the area of pretreatment prior to ion exchange bed and regeneration as well as operational procedure adjustment. Further works needed to be conducted to provide optimum operating conditions will be discusse

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00240.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe Seattle Aquarium has reared coho and Chinook fingerlings since 1978 in a 36,000 liter recirculating freshwater system utilizing clinoptilolite (clino) for ammonia removal. The system has effectively produced 140,000 smolts, due in large part to the efficient removal of fish‐excreted ammonia by the clino filters. Quantitative studies were performed to assess clino filter loading capacity and to establish effective recharging techniques. The operational characteristics of the clino filters and suggestions for using them in freshwater recirculating culture systems are discusse

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00241.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA water intake system was designed and installed in Admiralty Inlet, Puget Sound, Washington. The dual system consisted of polyvinylchloride (PVC) pipes, a concrete pit and pumps located on shore at zero tide; and cables attached laterally to the pipelines and terminally between a shoreward anchor and to a seaward intake sled held in place with an 1800 kg Dansforth anchor. The overall construction costs were much lower than those for concrete‐lined ductile iron pipe. Nearly three years after its construction, this system has withstood tides and storms without apparent adverse effect. Its application to lakes or rivers is equally possibl

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00242.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractExperimental culture facilities for juvenile lobsters have been improved, resulting in more uniform water quality, and greater precision of experimental results. Water‐powered rotating arms distribute freshly treated water throughout the system, and a mechanism for rapid flushing aids in maintaining water quality and removing solid waste. These systems which can be used for other benthic invertebrates now provide culture conditions close to optimum for highly controlled nutrition experiment

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00243.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe objective was to design and evaluate a suspension oyster tray unit to optimize conditions necessary for the successful commercial culture of Pacific oysters for the half‐shell trade.Units were located at two sites in Trevenen Bay. One location was sheltered and calm; the other was a natural tidal raceway with intense current flow. The purpose was to test the ability of the design to provide uniform growth, retard fouling, be handled efficiently and be economically feasible to construct. Assessing performance was based on monitoring shell growth, condition index, fouling occurrence, materials handling and the capital costs of the system. Field experimentation began in June and terminated in October 1979. Suspension tray units performed similarly at both sites, exhibited little variation in shell growth in the series of five trays in an assembly, retarded fouling and proved economically feasible for commercial us

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00244.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA prototype oyster production system with a 10‐bushel design capacity has been operating for 6 months in order to demonstrate and document a number of the research‐derived design concepts and operating specifications. This is a technical demonstration project intended to maximize production rates in an intensive, controlled‐environment culture system. The unit functions as a working model yielding quantitative information concerning component and biological performance, material flow, and cost‐related material, energy and labor efficiencies over the long‐term production cycle.The system is comprised of three integrated subsystems: 1) oyster life‐support, 2) algal production, and 3) water and waste handling. The design specifications and the degree of control provided are intended to maximize productivity and efficiency in each subsystem. Integration of the three subsystems involves recycling water (˜77%) without detriment to performance efficiencies.Operation and evaluation of the system have supported some of the original premises. However, such analyses and concurrent experimentation have led to modifications in the system design, and in process procedures. The changes have reflected trade‐off decisions (for example, sacrificing production rates for economic and management considerations) and efforts to enhanc

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00245.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe results of this study include the incorporation of water quality parameters and a growth function into a bioeconomic model of shrimp culture. Since the level of various parameters is unpredictable for future years (i.e., weather, ponds experiencing low oxygen), randomization of these parameters was introduced into the model. The results consist of a mean and standard deviation of profit determined from 25 replications of the model. The baseline model indicates that a mean profit of $679 per hectare would be achieved with only a 5% chance of a loss. Sensitivity tests of profit in the model, consisting primarily of changes in biological and environmental parameters, illustrate the usefulness of the model in directing future research.

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00246.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY