Optimised In-Tank Ballast Water Treatment for Tanker Operators.


Coldharbour Marine has designed and developed a Ballast Water Management System (BWMS) optimised for Tankers and Very Large Crude Carriers; the UK’s Marine and Coast Guard Agency (MCA) has just formally approved it under IMO resolution MEPC 174 (58).  Coldharbour believes its innovative ‘in tank-in voyage’ approach offers significant benefits for operators of Large Tankers, LNG Carriers and Large Crude Carriers which typically carry thousands of tons of ballast water which cannot readily be treated by two step BWMS relying on filtration followed by electro-chlorination or UV disinfection. The Coldharbour system has no filtration, no connection to the ballast pumps or ballast lines, it is therefore immune to pump flow rates, pressure losses, power shortages and, perhaps even most importantly, guarantees zero disruption during cargo and ballast operations- including gravity ballasting and deballasting. Furthermore, by treating ballast water during the voyage, which can be up to 30 days for tanker operators, the risk of regrowth on is eliminated.


In 2012, the Coldharbour GLDTM technology was the first BWTS to be retrofitted to a 309,000dwt VLCC (Very Large Crude Carrier) and it was on this vessel that the first ship testing was completed in 2014 under the watchful eyes of Lloyds Register. As a British company, Coldharbour was keen that the UK MCA, which used Lloyds Register to independently audit both the land and sea the results, accredit the system.


Chief Executive, Andrew Marshall, explained, “ We were keen that UK MCA undertook the Type Approval. UK MCA has a worldwide reputation for rigour;


thoroughness and probity that will be welcomed by owners and operators who need to have confidence in their choice of BWTS. We are now looking at USCG AMS approval and, because of the additional effort we invested in our UK MCA/IMO testing, we believe we are very well placed to move forward to full USCG Type Approval within a reasonable timeframe.”


Coldwater’s GLD™BWMS is a space saving, in-tank solution. A Coldharbour Inert Gas Generator (IGG) is linked to GLD™ units mounted inside each ballast tank. The GLDTM uses natural fluid dynamics to stir the ballast water ensuring thorough treatment. Inert gas from the IGG reduces the ballast water oxygen content while its elevated CO2 level lowers ballast water pH. As gas is introduced to the GLDTM  it is made to generate an ultrasonic frequency that physically disrupts the cell walls of any aquatic organisms while gas micro-bubbles amplify the ultrasonic effects. Thus organisms are killed in three ways: by hypoxia, caused by low levels of O2, by hypercapnia caused by the low pH / dissolved CO2 and by ultrasonic cell wall disruption.


Coldharbour’s innovative approach to marine engineering brings a number of benefits to the ship operator. Although IGG technology is well understood, the Coldharbour IGG is smaller, more reliable, cleaner in operation and requires far less maintenance than traditional technology. Because Coldharbour’s BWTS treats the water in the ballast tanks it functions without filters, membranes, active substances or electrical connections. Water temperature, salinity, and quality (suspended solids) have no impact on performance and, by operating when the ship is underway, crew are freed for port duties/essential maintenance. With a small physical footprint, ancillary equipment can be installed anywhere while the IGG can double up if necessary to provide inert gases for blanketing cargo.  Being based upon established marine technology and with few moving parts, the Coldharbour BWMS requires minimal maintenance or staff training. 

Summarizing these, Andrew Marshall explains, “ Coldharbour Marine’s IGG technology is well known to reduce maintenance demands on crew. The Gas Lift Diffusion units have no moving parts and are 100% reliable, the ultrasonic disruption and micro bubble generation is by inert gas so there are no electrical connections, the system only requires an annual inspection and 5 yearly maintenance. It requires a standard marine compressor to deliver the process gas and a simple ballast tank P/V breaker - that is all. We have been told that managing the ballast treatment in voyage reduces time at terminal and minimises the pressures on crew during a vital time in the voyage”



More information contact Rosie Featherstone, +44(0) 1332 862073,  +44(0) 7788 592314: featherstone.rosie@gmail.com


Andrew Marshall +44(0)16











our news