Danish ballast water treatment systems (BWTS) manufacturer Bawat is carrying out final shipboard tests with its pasteurisation-based BWTS to achieve type approval from the United States Coast Guard (USCG).
The Bawat in-voyage BWTS uses 150-year old pasteurisation technology to 100 per cent kill all microscopic organisms of any size, without the need for chemicals, filters, or ultraviolet radiation.
The system comprises a series of pipes and heat exchanging plates that transport water from either a ballast tank or the sea to the ballast unit. Water is preheated in a regeneration unit and the heat exchangers heat the water to between 64 and 72 degrees Celsius. The heat used to increase the temperature of the water to pasteurisation typically comes from main or auxiliary engine waste heat but can theoretically be taken from any on board heat source, Bawat’s CEO, Kim Diederichsen explained to VPO Global previously.
Water is then transported along the pipes to a regeneration section where it remains for a period of time to reduce phytoplankton and bacteria to levels below those permitted by the IMO’s D2 requirements (in line with the BWM convention). Heat and time leads to pasteurisation of the water, which then flows back through the regeneration section, pre-heating the incoming ballast water on its way and saving significant amounts of energy.
Once completed, water is fully treated and can be pumped over board or to another ballast tank, or the water can be led back to the same ballast tank to carry out a circulation process.
All of the above happens in a very short time period, in as little as one hour of the entire voyage, using heat energy that would otherwise be wasted.
The BWTS functions in all water types, water turbidty, salinity, and temperatures.
The Bawat system has now passed all USCG land-based tests and has one shipboard test left to complete, which is scheduled for April in Port Klang, Malaysia and the Mekong River estuary, Vietnam where there are high levels of organisms. The system has already passed three tests here with “flying colours, eliminating all organisms”, said Diederichsen.
“All of the tests so far – onboard and onshore – have demonstrated rock solid results. By that I mean, not near the threshold of compliance, but total efficacy. This shows what we’ve known all along, that the tried and tested process of pasteurisation is THE best way to eliminate the potentially harmful invasive species carried in ballast water.”
The current USCG testing is being carried out on-board a 38,000 DWT container vessel, with DHI Denmark and Lloyds Register on-board as partners.