Frank Fuhr
1
KiTe Aquatic Resources Consulting, Den Helder, The Netherlands 2
Royal Netherlands Institute for Sea Research (NIOZ), Texel, The Netherlands (affiliated until November 2011)
6.1 Abstract
This paper describes the most important characteristics of land-based testing of ballast water treatment systems (BWTS). These general features are independent of any specific test fa- cility. Based on this, options are presented for a closer cooperation between test facilities and entities conducting risk-assessment.
6.2 Introduction
In order to discuss the possibilities of cooperation between institutions that perform risk- assessment and those performing land-based testing of ballast water treatment systems (BWTS) it is useful to first have a closer look at what land-based testing encompasses. To avoid confusion it is necessary to clearly define the term risk in the respective context. Test- ing of the systems is first and foremost concerned with the risk of biological invasions via ballast water and subsequently the risk reduction through the use of the BWTS. This is a different type of risk than the risks which are addressed by the risk-assessment this and the other papers of this volume are dealing with. The latter deals with the risks that are posed by operating the BWTS itself. These risks include human health, work safety and environmental issues alike. These are the factors that will be referred to as risks from here onwards. For a more detailed discussion on these factors see the papers of Banerji, Wieck et al, and Linders in this volume.
6.3 Land-based testing of BWTS
The primary scope of land-based testing as described in guideline G8 (IMO, 2008a) of the International Maritime Organization (IMO) is to evaluate the effectiveness of BWTS in remov- ing organisms. Therefore these tests are conducted at full scale. This encompasses flow rates of 200 cubic meters per hour and a minimum holding time for as well treated as control water of five days. The framework for land-based testing is currently defined by guidelines G8 (IMO, 2008a) and G9 (IMO, 2008b) of IMO. Similar protocols are being developed or tested right now to suite national laws (e.g. the ETV protocols by the EPA and USCG in the US). However these guidelines are generic in nature and certainly at the time the first version of G8 was released in 2004/2005 there were no standard methods available. Test facilities had to find their own means of putting the intention of the guidelines into practice. Harmoni- sation efforts by the IMO via the GloBallast program and by the EU via the North Sea Ballast Water Opportunity project (NSBWO) show quite similar approaches to the problem by the different test facilities.
The ballast water tanks of ships are simulated by tanks in a size range of 200 to 500 cubic meters, with tanks of 200 to 300 cubic meters being the most common ones. Almost all test facilities use ambient, natural water. However the degree to which this water is altered to
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meet certain criteria varies between the facilities. Test facilities that are located in biologically high productive and turbid areas need less manipulation. Others, who either do not have suitable water conditions or want to test independent of surrounding conditions use the water and add surrogate organisms and suspended matter. Between these approaches there is various degrees of manipulation and preparation of the test water. It is beyond the scope of this paper to discuss all of these options. However, it should kept in mind, that water chemis- try and preparation might have an influence on risk-assessment studies, e.g. the formation of by-products. Working with natural water makes the tests less predictable, while working with heavily modified waters increases the possibility of artefacts. Both approaches have pros and cons as well from a biological as from a chemical point of view and it is important to keep this in mind when analysing data from certification tests of BWTS.
Samples are generally taken on intake and on discharge. Samples are taken in-line from the pipes to avoid spatial and / or time bias. Analysis of the samples focuses on the biological parameters. Furthermore basic parameters characterizing the water body are measured. These are salinity, temperature, TSS, POC, DOC, pH and oxygen. Additional samples for, e.g. nutrients or chemicals can easily be taken. The taking of additional samples is facilitated by two factors. First the tests are conducted at full scale. Guideline G8 (IMO, 2008a) calls for a minimum volume of 200 cubic meters of treated water to be stored. Therefore the volumes involved do allow sufficient sampling, when considering the usual sample sizes of a few litres for most chemical analysis. Secondly, in order to take good and representative samples on intake and discharge, land-based test facilities are equipped with numerous sampling points at different locations.
Despite the comparable volume, the holding tanks used for land-based testing differ signifi- cantly from a ship's ballast water tanks. Tanks used for land-based testing usually have less internal structures than a ballast water tank. This is less trivial than it might appear at first glance. Structures do influence the movement of the water within the tank, while filling and discharging. Furthermore they can act as sediment traps. However, the role of sediment cannot be assessed during land-based certification, since the protocols unfortunately call for cleaning of the tanks between each test. In any case remains a tank of several hundred cu- bic meters a better representation of the real situation on board a vessel than any laboratory scale container. It is more complicated to keep stable conditions, e.g. temperature, in a labo- ratory scale set-up from a few hundred litres to maybe a few cubic meters as compared to a tank of at least 200 cubic meters. Furthermore the latter show spatial differentiation that can be tested for by sampling from the tank.
Tests that are conducted with natural water cover a range of different conditions. This is equally true for facilities that manipulate their intake water considerably as for those that do not. The variation in (chemical) water conditions is only lost if the test water itself is made artificially.
6.4 Linking land-based testing with G9 risk assessment
Based on the above, land-based test facilities can be used in a number of ways for risk- assessment. Examples include, but are in no way limited to:
• validation of laboratory findings on the chemical behaviour of active substances or the collection of such data when no or insufficient laboratory data is available,
• the same studies for by-products of treatments,
• identification and comparison of potential risks of different BWTS in a certain range of conditions, i.e. the environment of the test facility when working with natural water, • safety of the BWTS in full-scale operation for the crew, e.g. noise levels, maintenance etc.,
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• properties and fate of the treated water once discharged, • validation of sampling and monitoring techniques,
• validation of models.
The advantage of designing such studies with and at land-based test facilities is the logistics. Test facilities are either having laboratories themselves or are in very close proximity to them due to the fact that the biological samples have to be analysed alive in most cases. There- fore it is possible to design studies that are logistical nearly impossible on board of a com- mercial vessel, while using an operational BWTS at full scale. Unfortunately not many formal connections are made between the physical testing of BWTS and the risk-assessment, so that such studies are not part of the validation and certification process of a BWTS.
Another aspect to be considered is, that the test facilities in turn can also profit from a closer cooperation with the various institutions involved in risk-assessment. An obvious example is, that there are no procedures on identifying health risks a BWTS might pose to testing per- sonnel and subsequently a ship's crew at an early stage of the certification process. Less obvious maybe, but probably even more important is, that there is no cooperation on pilot studies. Test facilities and developers will of course gather and assess the relevant informa- tion on used active substances and environmental feasibility thereof. However an in-depth analysis of by-products and potential risks of these is usually beyond the means of both test facility and vendor. A more formalized cooperation between the two parties at an earlier stage of the process is desirable here.
6.5 References
IMO 2008a. Guidelines for approval of ballast water management systems (G8). Annex3 Resolution MEPC.174(58) Annex: Parts 1,2,3 and 4
IMO 2008b. Procedure for approval of ballast water management systems that make use of active substances (G9). Res MEPC.169(57)
References are available on the IMO website
http://www.imo.org/KnowledgeCentre/HowAndWhereToFindIMOInformation/IndexofIMORes olutions/Pages/Marine-Environment-Protection-Committee-(MEPC).aspx
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