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MERC ER01-10
1
1. 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.
This report describes the MERC evaluation of the Severn Trent De Nora BalPure™ BP-
1000
Ballast Water Management System through objective and quality assured land-based
testing (dockside at a flow rate of 200m
3
/hr). The goal of this evaluation was to provide shipping
lines, regulators, classification societies, and flag states with an independent and credible
assessment of treatment performance under realistic conditions. Therefore, the data and
information on performance characteristics covers legitimate information to meet the
evaluation's objective, and performance is presented in a way to allow for comparison against the
International Maritime Organization (IMO) International Convention for the Control and
Management of Ships' Ballast Water and Sediments (2004), Regulation D-2
Ballast Water
Performance Standard
.
2. Description of the Severn Trent De Nora (STDN) Ballast Water Management System
The STDN Ballast Water Treatment System (BWTS) applies established chlorination
technology to oxidize and disinfect aquatic invasive species. The BALPURE® BWTS is an
electrolytic process for the on-site generation of dilute hypochlorite on demand without storage
during the ballasting operation and the neutralization of residual oxidants during the de-
ballasting operation. Sodium hypochlorite is generated by means of electrolysis of seawater. In
this process, seawater flows through the electrolytic cells in a ratio of 1 part for every 100 parts
of ballast water. The system can operate effectively in brackish water to 15 PSU. Because the
amount of seawater required to effectively treat ballast water is small, even fresh water ballast
can be treated by BALPURE® BWT with supplemental salt or stored seawater in designated
ballast tanks such as aft peak tanks. The current passing through the seawater causes the salt
(NaCl) and water (H
2
O) to form sodium hypochlorite (NaOCl) and hydrogen (H
2
) as a secondary
by-product. Hypochlorite solution and Hydrogen are produced and separated immediately upon
exit from the electrolytic cells. The weak hypochlorite solution (1 g/L) is injected back into the
ballast stream. Hydrogen that is separated from the hypochlorite is immediately diluted to less
than 1% hydrogen by forced air blowers and discharged to a safe location. The hypochlorite is