Assessment of imaging-in-flow system (FlowCAM) for systematic ballast water management.

Assessing the disinfection of ballast water and its compliance with international standards requires determining the size, viability, and concentration of planktonic organisms. The FlowCAM (Flow Cytometer and Microscope) is an Imaging Flow Cytometry designed to obtain the particle concentration, images, and quantitative morphologic information. The objective in this paper is to establish the basis for transforming the FlowCAM from being a laboratory analyzer into a tool for systematic monitoring of ballast water. The capacity of the FlowCAM was evaluated by analyzing artificial microbeads, phytoplankton monocultures, and real seawater samples. Microbead analyses reported high accuracy and precision in size and concentration measurements. Monoculture analyses showed the effect of disinfection treatments in cell appearance and growth. Low concentration and heterogeneity of particles in real seawater analyses require the comprehensive observation of images by experts. Additionally, some physical characteristics of the device must be improved. The optimization of device configuration enables the quick transferring of files and information between parties involved in ballast water management. FlowCAM may become a feasible technology for this after the device and protocols are adapted.

Micro-Flow Imaging as a quantitative tool to assess size and agglomeration of PLGA microparticles.

The purpose of this study was to explore the potential of flow imaging microscopy to measure particle size and agglomeration of poly(lactic-co-glycolic acid) (PLGA) microparticles. The particle size distribution of pharmaceutical PLGA microparticle products is routinely determined with laser diffraction. In our study, we performed a unique side-by-side comparison between MFI 5100 (flow imaging microscopy) and Mastersizer 2000 (laser diffraction) for the particle size analysis of two commercial PLGA microparticle products, i.e., Risperdal Consta and Sandostatin LAR. Both techniques gave similar results regarding the number and volume percentage of the main particle population (28-220µm for Risperdal Consta; 16-124µm for Sandostatin LAR). MFI additionally detected a 'fines' population (<28µm for Risperdal Consta; <16µm for Sandostatin LAR), which was overlooked by Mastersizer. Moreover, MFI was able to split the main population into 'monospheres' and 'agglomerates' based on particle morphology, and count the number of particles in each sub-population. Finally, we presented how MFI can be applied in process development of risperidone PLGA microparticles and to monitor the physical stability of Sandostatin LAR. These case studies showed that MFI provides insight into the effect of different process steps on the number, size and morphology of fines, monospheres and agglomerates as well as the extent of microparticle agglomeration after reconstitution. This can be particularly important for the suspendability, injectability and release kinetics of PLGA microparticles.

Assessment of didecyldimethylammonium chloride as a ballast water treatment method.

Ballast water-mediated transfer of aquatic invasive species is considered a major threat to marine biodiversity, marine industry and human health. A ballast water treatment is needed to comply with International Maritime Organization (IMO) ballast water discharge regulations. Didecyldimethylammonium chloride (DDAC) was tested for its applicability as a ballast water treatment method. The treatment of the marine phytoplankton species Tetraselmis suecica, Isochrysis galbana and Chaetoceros calcitrans showed that at 2.5 µL L(-1) DDAC was able to inactivate photosystem II (PSII) efficiency and disintegrate the cells after 5 days of dark incubation. The treatment of natural marine plankton communities with 2.5 µL L(-1) DDAC did not sufficiently decrease zooplankton abundance to comply with the IMO D-2 standard. Bivalve larvae showed the highest resistance to DDAC. PSII efficiency was inactivated within 5 days but phytoplankton cells remained intact. Regrowth occurred within 2 days of incubation in the light. However, untreated phytoplankton exposed to residual DDAC showed delayed cell growth and reduced PSII efficiency, indicating residual DDAC toxicity. Natural marine plankton communities treated with 5 µL L(-1) DDAC showed sufficient disinfection of zooplankton and inactivation of PSII efficiency. Phytoplankton regrowth was not detected after 9 days of light incubation. Bacteria were initially reduced due to the DDAC treatment but regrowth was observed within 5 days of dark incubation. Residual DDAC remained too high after 5 days to be safely discharged. Two neutralization cycles of 50 mg L(-1) bentonite were needed to inactivate residual DDAC upon discharge. The inactivation of residual DDAC may seriously hamper the practical use of DDAC as a ballast water disinfectant.

Microbial dynamics in acetate-enriched ballast water at different temperatures.

The spread of invasive species through ships' ballast water is considered as a major ecological threat to the world's oceans. For that reason, the International Maritime Organization (IMO) has set performance standards for ballast water discharge. Ballast water treatment systems have been developed that employ either UV-radiation or 'active substances' to reduce the concentration of living cells to below the IMOs standards. One such active substance is a chemical mixture known as Peraclean(®) Ocean. The residual of Peraclean(®) Ocean is acetate that might be present at high concentrations in discharged ballast water. In cold coastal waters the breakdown of acetate might be slow, causing a buildup of acetate concentrations in the water if regularly discharged by ships. To study the potential environmental impact, microbial dynamics and acetate degradation were measured in discharge water from a Peraclean(®) Ocean treatment system in illuminated microcosms. In addition, microbial dynamics and acetate degradation were studied at -1, 4, 10, 15 and 25°C in dark microcosms that simulated enclosed ballast water tanks. Acetate breakdown indeed occurred faster at higher temperatures. At 25°C the highest bacteria growth, fastest nutrient and oxygen consumption and highest DOC reduction occurred. On the other hand, at -1°C bacterial growth was strongly delayed, only starting to increase after 12 days. Furthermore, at 25°C the acetate pool was not depleted, probably due to nutrient and oxygen limitation. This means that not all acetate will be broken down in ballast water tanks, even during long voyages in warm waters. In addition, at low temperatures acetate breakdown in ballast water tanks and in discharged water will be extremely slow. Therefore, regular discharge of acetate enriched ballast water in harbors and bays may cause eutrophication and changes in the microbial community, especially in colder regions.