the IHS Ballast Water Guide - RWO Marine Water Technology

IHS Fairplay Solutions Guide to Ballast Water Treatment Systems Sponsored by
RWO recently acquired a means of cutting
out the time-consuming work and expense
of surveying, and acquiring an exact digital
reproduction of the space conditions on
board ship, accurate to the millimetre.
When surveying the location in which the
CleanBallast system is to be installed, a highspeed
360° scanner is used to create a threedimensional
image of the ship’s engine room,
which allows the most advantageous options
for the installation to be ascertained.
Neo-Purimar
Samsung HI 2 7
The Neo-Purimar system from Samsung
Heavy Industries treats ballast on the
uptake and discharge in a two-stage system.
A 50µm self-cleaning filter removes
particles, sediments and organisms during
ballast uptake before being disinfected by
electrolysis-based chlorination.
To minimise the use of the chlorine
compound NaOCl, sodium hypochlorite
solution generated from the electrolysis
unit is injected to maintain a maximum
chlorine concentration of 10mg per litre total
residual oxidants. Water being deballasted
is treated by additional disinfection – the
sodium hypochlorite solution generated
from the electrolysis unit is re-injected – and
by neutralisation, by means of a sodium
thiosulfate solution.
Hydrogen gas, a by-product of the
electrochemical process, is separated
immediately upon exiting from the
electrolytic cell by cyclone separation and is
not allowed to enter into the ballast water
piping. The gas is then transmitted to a degassing
tank, which dilutes the gas to 1% (well
below the 4% lower explosive limit) before
exhausting to atmosphere.
BalPure
Severn Trent de Nora 2 7
BalPure, from the US joint venture of
Severn Trent Services and Gruppo DeNora,
only treats ballast during the uptake on
the ballasting operation although a second
operation during de-ballasting is done to
neutralise and residual oxidants remaining
from the treatment stage.
Ballast water is first cleared of larger
organisms and sediments by a 40µm filter.
Once filtered, a slip stream of 1% of the
total water ballast uptake flow rate is fed to
the BalPure system where a hypochlorite
disinfection solution is generated.
The mixture of seawater, disinfection
solution and hydrogen gas (a by-product of
the electrolytic process) then passes through
a cyclone-type degas separator to remove the
hydrogen gas. The 1% slip stream, now free of
hydrogen, is mixed with the remaining 99%
of the main uptake flow and used to disinfect
the entire volume of ballast water.
The total ballast water flow is then
transferred to the ballast tanks. A residual
disinfectant continues to treat the ballast
water during the voyage.
The BalPure system is used only in
deballasting operations to neutralise the
residual oxidant in the ballast water before
discharging it from the ship.
On deballasting, the filter is bypassed and
all treated ballast water is discharged. Before
overboard discharge takes place, an automatic
neutralisation process occurs.
A separate, small stream of a neutralisation
agent, sodium bisulphite (7.5 litres per
1,000m 3 ), is automatically added at the inlet
of the ballast pump and any other discharge
systems such as aft peak tank systems.
Seawater is then discharged back to the
marine environment.
32 © IHS Global Limited 2012
012_037_CorrectedBW1204.indd 32 01/08/2012 15:36:55