Basic HTML Version
Ref. No. [UMCES] CBL 11-037
1
1.0. MERC Background and Objectives
The Maritime Environmental Resource Center (MERC) is a State of Maryland initiative
that provides test facilities, information, and decision tools to address key environmental issues
facing the international maritime industry. The Center’s primary focus is to evaluate the
mechanical and biological efficacy, associated costs, and logistical aspects of ballast water
treatment systems and the economic impacts of ballast water regulations and management
approaches. A full description of MERC’s structure, products, and services can be found at
www.maritime-enviro.org.
To address the need for effective, safe, and reliable ballast water treatment systems to
prevent the introduction of non-native species, MERC has developed as a partnership between
the Maryland Port Administration (MPA), Chesapeake Biological Laboratory/ University of
Maryland Center for Environmental Science (CBL/UMCES), U.S. Maritime Administration
(MARAD), Smithsonian Environmental Research Center (SERC), and University of Maryland
(UMD) to provide independent performance testing and to help facilitate the transition of new
treatment technologies to shipboard implementation and operations.
The following report is a summary of an assessment of the Hydac AutoFilt ® RF3
automatic backflushing filter to remove ballast water organisms. Detailed protocols and formal
MERC Test Plan can be downloaded at www.maritime-enviro.org.
2.0. Introduction to Hydac Technology
Hydac has been active in the field of fluid condition monitoring and filtration for over 30
years. This evaluation focused on the AutoFilt® RF3 automatic backflushing filter. AutoFilt®
RF3 is a self-cleaning system for extracting particles from low-viscosity fluids. The principle
application is the filtration of industrial water either as the main filter or as an offline filter. The
conical slotted tube filter elements are stainless steel with the filter size ranging from 25 to 3,000
µm. The contamination condition of the elements is monitored by means of differential pressure
measurement. When the filter reaches a certain pressure drop, automatic cleaning begins, during
which all the filter elements in turn are back-flushed with a small volume of fluid without
interrupting the flow of filtrate. The design system is currently used for continuous filtration of
water in water plants, power plants and cooling towers.
3.0. Summary of Test Protocols
Sampling Design:
Six sequential trials were conducted: three in January/February, 2011 and three in May,
2011. Water was continuously pumped sea-to-sea, from Baltimore Harbor (Patapsco River, MD,
in the mesohaline region of the Chesapeake Bay) into the US Maritime Administration vessel
MV Cape Washington
via the sea chest.
The duration of each trial (from 4 to 6 hours) was dependent upon a specific filtered
amount of 1,000 m
3
, pressure, and the flow rate. Water samples were collected before and after
the Hydac filter, then analyzed for total suspended solids (TSS), particle size distribution (PSD),
zooplankton, and phytoplankton (between 10 and 50 microns and between 5 and 10 microns).
Test Parameters:
Trial #1
– 3 sampling periods; high pressure 30 psi, 211 m
3
/h flow; 6 back flushes; differential
pressure ranged between 0.11 and 0.9 psi