In this webinar, experts assess the efficacy of compliance monitoring devices and total residual oxidant measurement devices, what is working and what is needed, and how lessons learned will guide future operational, technical and regulatory development
In Riviera’s Learning from BWMS implementation: where do we go from here? webinar, three panellists provided their expertise on the latest developments in compliance monitoring devices and total residual oxidant measurement devices. Device manufacturers were represented by De Nora Marine Technologies sales manager EMEA Dimitrios Tsoulos and Halogen Systems president Michael Silveri, with DNV GL principal engineer, environmental protection Michael Lehmann providing class input.
The webinar was sponsored by De Nora and Halogen Systems.
The central issue of the importance of having compliance monitoring devices and total residual oxidant (TRO) measurement devices was revealed in a poll. 50% replied that having a monitoring device was a very important part of the ballast water management system (BWMS) decision-making process. Another 29% rated it as important. The remainder were indifferent (19%) or had not factored compliance monitoring devices and TRO measurement devices into the decision making process (2%).
Mr Silveri opened proceedings and said, “TRO measurement is becoming a critical part of shipping infrastructure. BWMS malfunctions can bring a halt to cargo operations. Anything that reduces TRO failure will pay dividends down the road,” he said.
He noted that most ballast water treatment systems (BWTS) are designed for frequent use and that periods of non-usage are critical. Infrequent use can create problems: water sitting in long sampling lines, absorption of chlorine, and can result in an inaccurate readings from the TRO measurement device.
Halogen Systems is an amperometric technique measurement device that uses three sensors to measure electrons and acts opposite to a chlorine generator. It sits in the ballast line, eliminating long sampling lines. It cycles a TRO reading every 45 seconds, is self-cleaning and is unaffected by high turbidity. “It doesn’t use any reagents,” said Mr Silveri. “Which is a saving of around US$600 per year, per instrument, and is one less thing for the ship’s crew to worry about.”
The application of amperometric techniques to TRO measurement is relatively new. A survey suggests there may be an appetite for a new technique but the majority seemed satisfied with the current technology. In a poll, asking how satisfied attendees are with the overall performance (efficacy and maintenance requirements) of their TRO analyser, 11% were very satisfied, 21% were satisfied and 32% had no strong feelings. A quarter were dissatisfied (25%) and 11% very dissatisfied.
Mr Tsoulos represents a company that produces a well-known ballast water treatment system BALPURE, which is based on filtration and slip-stream electrochlorination. The BALPURE BWMS uses oxidation reduction potential (ORP), and this is the basis of the measurement, not simply the amount of chemical dose or remaining TRO. The ORP sensor is used to provide qualitive measurement of total residual oxidants (in mV) in the ballast water prior to entering the ballast water tanks and prior to discharge.
“The continuous measurement of ORP provides a trend which can be related to the oxidant residual in the ballast water treatment system,” he said. “In this way ORP measurements provide a simple method to monitor and record proper ballast water treatment.”
One of the advantages of ORP over TRO was that ORP is an inline instrument which provides real-time monitoring, simple calibration and can be fitted in hazardous areas.
Mr Lehmann was on board to talk about compliance monitoring devices (CMD). There has been some debate about whether CMD’s should be compulsory. A CMD would prove to port state control (PSC) that the BWMS complied – but it would also show if the BWMS was out of compliance – a potentially difficult position for the owner/operator.
“Most CMDs used in commissioning testing are based on ATP or fluorometry,” said Mr Lehmann. He noted that a report from global testing service SGS found that the indicative analysis being done with CMDs did not allow a conclusion, while a detailed analysis showed that discharge did meet the criteria.
“CMDs are for indicative analysis. It will not give you the number of organisms but will give you a value that is indicative for the presence of organisms,” he said. “For organisms greater that 50 microns, CMDs still have a weakness.”
Even though CMDs are being used, Mr Lehmann noted there is no agreed standard. Protocols for verification and standards for CMDs are being discussed by ISO, and IMO (at PPR), noted Mr Lehmann. “At PPR 8 (22-26 March) ICES submitted a revised protocol, based on previous PPR meetings, for verification,” said Mr Lehmann.
In a survey, 87% strongly agreed or agreed that having a standardised IMO test protocol for CMD is essential for the application of CMD in BWMS commissioning and PSC. 6% neither disagreed or agreed, 6% disagreed to some extent and 1% strongly disagreed.
However, the proposed protocol presented to PPR refers to using culture water as the test medium. IACS and France, noted Mr Lehmann, have opposed this, and suggested that treated ballast water be used, which would more accurately reflect reality.
Another issue with CMDs, noted Mr Lehmann, is that to meet the D-2 standard of less than 10 organisms greater than 50 microns, the large sample of water will need to be concentrated. Currently, this means 1 m3 of water run through a plankton net and the concentrated sample carefully washed from the net into a sample container.
In a survey, there was doubt as to the suitability of CMDs for the analysis of organisms greater than 50 microns. 46% felt that CMDs were only suited to organisms in the 10-50 micron range, 27% though CMDs were suitable for the 50 micron range alone and 27% for above the 50 micron range.
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From left to right: De Nora Marine Technologies sales manager EMEA Dimitrios Tsoulos, Halogen Systems president Michael Silveri, DNV GL principal engineer, environmental protection, Michael Lehmann