John E. Huguenin

Physical models of integrated waste recycling- marine polyculture systems

Abstract A combined tertiary sewage treatment—marine aquaculture system has been developed, tested and evaluated using several different experimental sizes and configurations located both at Woods Hole, Mass. and Fort Pierce, Fla. Domestic wastewater effluent from secondary sewage treatment, mixed with sea water, is used as a source of nutrients for growing unicellular marine algae and the algae, in turn, are fed to oysters, clams, and other bivalve molluscs. Solid wastes from the shellfish are fed upon by polychaete worms, amphipods, and other small invertebrates that serve as food for flounder, lobsters, and other commercially valuable secondary crops. Dissolved wastes excreted by the shellfish and other animals and any nutrients not initially removed by the univellular algae are removed by various species of commercial red seaweeds (Chondrus, Gracilaria, Agardhiella, Hypnea) as a final ‘polishing’ step. The final effluent from the system is virtually free of inorganic nitrogen and is incapable of supporting further growth of marine life or of contributing to eutrophication of the receiving waters. A description of experiments with the above food chains and preliminary results with some alternative approaches are discussed, including a detailed account of the nitrogen mass balance through all of the components of one of the experimental systems.

A review of the technology and economics of marine fish cage systems

Abstract Current interest in large-scale commerical culturing of marine fish in cages has prompted a detailed look at the technical and economic aspects of this emerging industry. The stage-of-the-art is defined, design and operating problems are discussed and areas needing technological improvements are identified.

Development of a marine aquaculture research complex

Abstract The new Environmental Systems Laboratory of the Woods Hole Oceanographic Institution was designed to be capable of performing a wide spectrum of research in the fields of marine aquaculture, water pollution control and coastal biology. Discussed are the setting of requirements, approaches adopted, design problems encountered, experiences to date and the unique physical plant.

A flowing experimental system with filtered and temperature-regulated seawater

A method of setting up an inexpensive and easily maintained system with flowing filtered and temperature-regulated seawater is described. Filtration is by a combination of filter bags and cartridges of various porosities that results in 1 μ-filtered seawater with particulate carbon concentrations of less than 30 μ-grams/liter. The temperature of the water is regulated by a titanium heat transfer panel. Water is then pumped to a head tank for distribution to experimental trays. Alarm systems for excessive temperature and water level fluctuations are described.

Marine Biofouling of Synthetic and Metallic Screens

Biofouling of meshes can create serious problems in seawater intake or discharge systems, and in aquacultural applications, by reducing water flow and increasing drag forces and pressure drops. Biofouling tests on a number of different meshes in the size range of 1/4 to 1 1/2 in. (0.5 to 4cm), including both synthetic and metallic meshes, were carried out at two sites in New England over a four year period. The limited data available in the literature from other sites and conditions are also identified and discussed. Some of the samples tested, especially the 90-10 Cu-Ni expanded metal mesh, showed considerable biofouling resistance compared to other mesh types.

Heat exchangers for use in the culturing of marine organisms

Marine Biological experiments often require controlling the seawater temperature in flowing culture systems. This heating or cooling of seawater is generally accomplished with a heat exchanger and an intermediary fluid. The major consideration in the choice of a heat exchanger is often finding a unit whose material is compatible with seawater, with the culture organisms and with the objectives of the individual experimental programs. Researchers, over the years, have used a variety of heat exchanger types and materials. Unfortunately there is currently no central source of information on this accumulated experience.

Marketing issues related to waste-grown aquatic foods

Are societal wastes all bad? Some of them, including heat from power plants and certain organic wastes, have been demonstrated to be potentially valuable for growing aquatic food organisms. The use of such wastes promises the double benefit of a cleaner environment and an increased food supply. Research and development effort can be expected to solve, for at least some production methods, the technical, economic, and public health problems that currently exist.But can food grown using potentially objectionable inputs be successfully marketed? All evidence indicates that regulatory agencies will require a much lower health risk for aquaculture food than “wild” ones and will ensure explicit labeling of potentially controversial inputs. Knowledge about potential consumer reaction to such food products is scanty and mixed. Some waste-grown or waste-containing foods (many water supplies, some farm and aquaculture products) are regularly consumed, but the public has also reacted swiftly against foods incriminated on health grounds (shellfish affected by red tide, cranberries contaminated by pesticide) and has sometimes been polarized by controversies (fluoridation).Under these circumstances a likely marketing strategy is to concentrate on aquatic organisms that are not directly used for human consumption but can be used for animal food or processed for their extracts. For sea foods that are eaten directly (fish, shellfish), a promising strategy is to take advantage of the quality control possible in aquacultural products to produce premium foods. These can be sold first to the restaurant trade, with direct distribution to preserve maximum freshness, and later to consumers. An interesting possibility between direct and indirect use is use as components of processed and prepared seafoods (fish sticks, fish cakes). Separately and simultaneously a public information campaign can stress the merits and advantages of waste utilization.