Nutrient Control Abstracts
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Maintaining Water Quality at
Urban Aquaria Isao Ishida, Osaka Aquarium KAIYUKAN Watch Video (Login required) Full Abstract
Osaka Aquarium Kaiyukan is situated in the bay of Osaka, the second largest city in Japan. The water quality of nearby sea is not suitable for maintaining aquatic species. The “Pacific Ocean” exhibit, the main exhibit holding 5,400 m3 of water, houses elasmobranchs (e.g. whale sharks, Rhincodon typus) and pelagic fishes. For long term health of the animals, water quality parameters including NH4-N, NO2-N, PO4-P, NO3-N, and pH have specific targeted ranges. The technological approach for water purification includes vacuum cleaning to remove leftover food and feces accumulated on the tank bottom, operation of a circulating filtration system, effective water changes, introduction of fresh seawater at low cost, pH control via chemical application, and other special devices. |
Biological Cycles - Imports and Exports of Heavy Metals and Nutrients in the Seas Main Tank System
Kent Semmen & Craig Duxbury, Disney's The Seas with Nemo and Friends Watch Video (Login required) Full Abstract
In 1985, the 24-million liter Seas Tank at Epcot, was filled with synthetic seawater. Since that time, there have been no significant water changes. A one year (38 LPM) water change is planned, resulting in the addition of nearly 20-million liters of new saltwater by dilution, effecting a calculated maximum reduction of contaminants as high as 65%. It is important to understand potential changes in water chemistry during this planned process. Throughout the history of the Seas Main Tank, we have identified important fluxes of nutrients and trace metals, and have used chemical and biological means to manage water quality. Inputs include sea salt, animal feed, and metal ions from corrosion. Remediation methods include chemical precipitation, and biological removal of metals and nutrients with algae and microbes. In addition, there are conceptual designs for a constructed wetland system engineered specifically for continuous biological treatment of the Seas system water. A pilot-scale biological phosphorus (P) removal system was recently tested at a smaller (1.7 million L) closed marine system. Shallow raceways (1.49 m2) at a hydraulic loading rate of 0.77 cm d-1 were used to grow and harvest naturally colonizing algae. Algae harvest rates were 11,000 mg m-2 d-1, or 55 mg P m-2 d-1. Minimal differences were found in phosphorous removal rates at different flow rates, and no differences were seen between seasons. A larger scale system is being designed to reduce P to < 20 ppb in about one year. |
Methods to Control Phosphate for Algae Management
Skip Young, Vancouver Aquarium Watch Video (Login required) Full Abstract
The uncontrolled growth of unwanted algae is one of the scourges aquarium staff deal with on a daily basis. It detracts from the pristine look of an exhibit and can be quite labor intensive to maintain. Even the use of chlorine and ozone for algae management can produce unwanted disinfection by-products, a health risk to the animals. Life support system design can be quite different for aquatic invertebrates, fishes, and mammals, yet they share similar problems concerning phosphate loading and management. Since orthophosphate is an essential nutrient for algal growth, removing it can control the growth of unwanted algae. Lanthanum-based products, granular ferric oxide (GFO), cerium chloride and others have been quite successful in decreasing the concentration of orthophosphate. A comparative evaluation between these products has provided the optimal conditions for various animal exhibits for minimizing orthophosphate concentrations and their impact of algae growth. The use of La35, a lanthanide element product from Lo-Chlor Industries, to physically remove phosphate build up in coral, fish, and marine mammal life support systems is the most cost effective method. |