There are many different processes for BWT being offered on the market. At the same time the analytic procedures[ds_preview] (biological and chemical) to judge the performance of such plants are obviously quite complex. How can the perfect function and performance of BWT plants be proven and who is qualified to provide such expert assessment?
Stephan Gollasch: In principle two different phases have to be distinguished. In the first phase the system developers have to demonstrate the performance of their processes in a series of land- and seabased tests and approvals according to the procedures stipulated by IMO, in order to finally obtain their type approval. Authorized for the land tests are more than ten international institutes or test facilities, which must have an approval by the certifying administration. Some of these, if in possession of mobile analytics equipment, provide also sea test services, which are also offered by specialized proveders like my company. For all sea tests usually a concept, fitting to the individual ship and process, must be drafted and approved by the flag state administration. If a type approved BWT plant is in operation and its performance is to be proven (which is a »phase 2« task and not so much common practise today, with only few plants in operation), then the controlling national authorities will likely authorize a number of qualified consultants to do the analysis on request. The proper operation of the BWT plant will have to be documented under the Ballast Water Management Plan (BWMP).
How will be guaranteed that approval sea tests, but also later in service tests (e. g. in the framework of port state control), will be equally handled and judged by different service providers, testing institutions and authorities? How wide is the range of possibly deviating results for the same plant, when tested by different institutions?
Gollasch: This is indeed a tricky question. It has already happened, outside the ballast water management world, that the same process was approved in one country while another stated a failure. The reason for this situation is the present absence of agreed procedures for the mobile measurement in such compliance control events. However, a value for a possible variation of results, caused by different testing and analytic methods cannot seriously be stated. Actually an IMO discussion group tries to harmonize the different practices and will issue a report for the 2012 spring meeting of IMO, which hopefully will contain proposals for a common standard.
How can the compliance of the effluent with the permitted maxima for residuals (e. g. oxidants) be measured in practice? In other words, how can be proven that the neutralisation of the treated discharged ballast water, which is necessary for some processes, has been done properly?
Gollasch: First of all the retention times – which are specified by all BWT manufacturers – must be kept, which is to be documented under the BWMP. Furthermore, an authority may require a direct probe from the ballast water effluent and do measurements with respective sensors, e.g. regarding total residual oxydants.
