|
Items in cart [0] |
Questions? Call 888-624-8373 |
HARDBACK PDF BOOK Free Resources |
||||||||||||||||
|
||||||||||||||||
The following HTML text is provided to enhance online readability. Many aspects of typography translate only awkwardly to HTML. Please use the page image as the authoritative form to ensure accuracy. SHIPBOARD TREATMENT OPTIONSShipboard treatment provides the most flexibility in managing ballast water. The committee identified 10 major categories of candidate shipboard treatment technologies: biocides (oxidizing and nonoxidizing), filtration, thermal treatment, electric pulse/pulse plasma treatment,2 ultraviolet, acoustics, magnetic, deoxygenation, biological, an anti-fouling coatings. A number of these technologies are used extensively in waste-water treatment. However, the requirements for the shipboard treatment of ballast water are somewhat different. The space and power available on board ship are limited, and very large volumes of ballast water must be treated without compromising the safety of the ship or crew. As a basis for gathering information on candidate systems, the committee developed a questionnaire about the options for treating ballast water. Two representative scenarios of ballasting requiring treatment were defined: System A. Flow rate of 2,000 m3/h and tank volumes of up to 25,000 m3, with residence times as short as 24 hours. System B. Flow rate of 20,000 m3/h and tank volumes of up to 25,000 m3, with residence times as short as 24 hours. Data were sought on a range of system characteristics, including equipment and space requirements; capital and operating costs; safety; effectiveness in destroying or removing a range of aquatic organisms; byproducts of treatment; operation, training, and manpower requirements; and performance over a range of temperatures and salinities in the presence of sediment. Responses to the questionnaire were received from equipment suppliers, technology developers, and research organizations. Additional information on candidate treatment technologies was obtained from product literature and articles in scientific and technical journals. The committee identified a series of parameters for rating technologies for potential application in shipboard treatment of ballast water. Safety is critical in evaluating strategies for managing ballast water. In addition, strategies are only worthwhile if they effectively reduce the number of viable organisms in ballast water. Therefore, safety and effectiveness were used as the first gate in evaluating candidate systems. Four technologies were judged by the committee to meet requirements for safety and effectiveness: biocides, filtration (media and film), thermal, and electric pulse/pulse plasma. Biological treatment and antifouling coatings were not evaluated in any detail. The other candidate systems were deemed safe but did not meet the criterion for effectiveness in treating the wide range of organisms found in ballast water.
|
|
|||||||||||||||
