Smaller BWMS For Smaller Vessels



Alfa Laval has expanded its PureBallast range to suit smaller vessels taking less ballast water by the introduction of a new reactor for their UV-filtration system.  This widens the scope of usage even to offshore support vessels.

  1. In keeping with the IMO and USCG ballast water discharge standards, this new upgrade is suitable for flow rates from 32m3/h to 170m3/h, whereas the earlier version supported a minimum flow rate of 250m3/h.
  2. Alfa Laval’s PureBallast has been certified to function and handle all water types: fresh, brackish and marine.  The 3-water type certification is important, because, apart from the frigid waters at the Baltic or Great Lakes, many ports have brackish water and some are located to fresh water.  Therefore, the system installed should be able to operate in all sorts of water.
  3. The new BWMS has also proven to be effective in low-clarity water with UV transmittance as low as 42%.

Global business manager for PureBallast, Stephen Westerling Greer is quoted to have said: “Smaller PureBallast systems will be a full match for their larger counterparts.  The reactors are built with SMO for a long and corrosion-free life and the power management is equally effective.  Performance-enhancing CIP [clean-in-place system] is there as well, in a new compact design to meet customers’ need for space savings.”

Operating sequence

PureBallast 3.1 performs in the background, running at just 50% of its potential operating power in most situations.  It can be ramped up to full power for the most difficult operating scenarios.

Operating sequenceBallasting

PureBallast 3.1 is a fully automated system.  When initiated, it undergoes a brief startup sequence.

When ballasting begins, the incoming ballast water first passes through the filter stage.  This removes any larger organisms and particles, which improves the quality of the water for treatment.  The filter stage is of benefit for operation in cloudy coastal waters and freshwater.

After filtration the water continues through the reactor stage, where it is disinfected by means of enhanced UV before entering the ballast water tanks.

Once ballasting is complete, reactor cleaning is performed via an automatic Cleaning-In-Place (CIP) cycle.  This cycle is prompted immediately after ballasting and should be performed within 30 hours.  The reactor stage is rinsed with fresh water when the CIP cycle begins and filled with fresh water upon its completion.

The filter stage is also filled with fresh water once ballasting is completed.


Ballast closeupThe deballasting process is essentially the same as the ballasting process.  However, the filter stage is
bypassed during deballasting since the water has already been filtered.

After leaving the ballast water tanks, the outgoing ballast water passes through the reactor stage to eliminate any regrowth of microorganisms that may have occurred in transit.  Having thus been disinfected to the established limits, it is discharged into the receiving water at the deballasting site.

The same startup and shutdown sequence, including CIP, is employed during both ballasting and deballasting.

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Source: Motorship & Alfalaval