Invited Talk

Using CFD for Enhancing Ballast Water and Biofouling Management
Ranade VV^*
Industrial Flow Modeling Group, Catalysis, Reactors and Separations Unit, National Chemical Laboratory, Pune, India
^*E-mail: vv.ranade@ncl.res.in

Bio-fouling and ballast water exchanges introduce harmful aquatic organisms into alien environments. This may cause irreversible changes affecting human health and industries as well as the ecological balance of the seas. Several institutes including the International Maritime Organization (IMO) and researchers have been working on developing effective ways to manage dangers posed by bio-fouling and ballast water. At present, IMO recommends ballast water exchange at sea as a measure to manage threats posed by ballast water. Many of the proposed approaches rely on use of biocides, UV or heat to kill harmful organisms. In recent years, there is also significant work on harnessing hydrodynamic cavitation for this purpose (for example, see Pandit et al, 2006 and Ranade et al, 2007). Almost all of these approaches require effective and efficient handling of large amount of water (of the order of 3500 m3/hr) and associated mixing or cavitation issues. Computational Fluid Dynamics (CFD), which allows ‘a priori’ predictions of flow, mixing and heat transfer in complex equipment, provides unprecedented opportunities to optimize ways of managing bio-fouling and ballast water. State of the art CFD capabilities make it possible to account for complex shapes of ballast water tanks, network of pipes, valves and pumps and complex ways of ballast water exchange protocols. In this presentation, an attempt is made to illustrate the potential and power of CFD for enhancing effectiveness and efficiency of bio-fouling and ballast water management technologies. Basic methodology is described with the help of several examples. The developed methodology and the presented results will be useful to facilitate such enhancements in practice.

Keywords: Ballast water, Biofouling management,  Hydrodynamic cavitation, Computational fluid dynamics

Investigations on the probability of biomineralisation of manganese on titanium surfaces exposed to coastal waters of Kalpakkam
George RP¹, Judy Gopal¹, P Muraleedharan¹, H Sarwamangala², RK Dayal¹, BVR Tata³, KA Natarajan²
¹Materials Characterisation Group, IGCAR, Kalpakkam, Tamil Nadu, India,
²Materials Science Division, IGCAR, Kalpakkam 603102,
³Department of Metallurgy, IISc, Bangalore, India
E-mail: rani@igcar.ernet.in

Titanium is widely used in seawater-cooled power plants as heat exchanger material owing to its superior corrosion resistance. However, being an inert material, titanium is prone to attachment of micro- and macroorganisms. Formation of biofilm on titanium surfaces reduces the efficiency of heat exchangers that employ this material. Besides, some of the marine bacteria in the biofilm can also oxidize soluble Mn(II ) in seawater  to insoluble oxides; this  phenomenon is  called biomineralization.  A two-year long study was carried out to isolate and characterize various bacterial species present in the biofilm formed on titanium surfaces exposed to coastal waters of Kalpakkam and to assess the manganese oxidizing potential of the marine isolates.  The amount of manganese present in the biofilm was also measured using atomic absorption spectrometry (AAS). The results of this study showed that titanium was susceptible to biofouling and more than 50% of marine bacterial isolates were capable of bringing about oxidation of Mn(II). All these manganese-oxidizing bacteria were heterotrophic. The AAS results confirmed that the manganese content in the biofilms increased with increasing exposure time. Hence, the study indicates that the titanium surfaces when exposed to seawater were colonized by a large number of heterotrophic bacteria, which have the ability of bringing about biomineralisation of manganese. Thus the probability of biomineralisation of titanium surfaces in Kalpakkam coastal waters cannot be ruled out.

Keywords: Titanium, Seawater, Biomineralisation, Biofilm, Heterotrophic bacteria

Signatures of amyloid-like nanofibrils discovered in barnacle adhesive
Gunari Nikhil A¹^*, Sullan Ruby May A², Walker Gilbert C¹,²
1Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, 2Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
^*E-mail: ngunari@chem.utoronto.ca

Nanoscale properties of barnacle adhesive, a natural bioadhesive (Balanus amphitrite) has been studied using fourier transform infrared (FTIR) spectroscopy, chemical staining and Atomic Force Microscopy (AFM). FTIR data of the bulk glue shows predominantly beta-sheet conformations while chemical staining with congo red and thioflavin-T dyes confirmed the presence of the amyloid-like structures. The self assembly of the proteinaceous multimer has been imaged under artificial sea water conditions exhibiting amyloid-like fibrils ranging in lengths from a few hundred nanometers to a few microns. The force spectra reveal a “sacrificial” bond mechanism involving the unzipping of a proteinaceous multimer giving rise to a saw-tooth profile. The reversible nature of the force spectra predicts the “self-healing” property of the material. Nanoindentation measurements on the amyloid-like fibril structures yielded an elastic modulus value of 20-70 MPa. Results of this study indicate that the strength of the barnacle adhesive is significantly derived from the modular nature of the proteins and the intrinsic strength of the amyloid-like fibrils.  

Keywords: Balanus amphitrite, Atomic force microscopy, Amyloid-like nanofibrils

Invited Talk

Environment friendly BAT technology for antifouling: Optimization of biocide dosing through Pulse-Chlorination®
Jenner HA^*, CM Maarten, H Bruijss, JG Polman
KEMA Technical & Operational Services, PO 9035, 6800 ET, Arnhem, The Netherlands
^*E-mail: henk.jenner@kema.com

Seawater as a coolant implies the necessity of an antifouling strategy to ensure undisturbed plant production. Sodium hypochlorite produced by electro-chlorination is the industry standard biocide for controlling biofouling. However, for decades the use of sodium hypochlorite has been associated with negative environmental issues by the residual oxidants and the formation of halogenated by-products in the receiving marine environment.

A new chlorination strategy for fresh- and seawater cooling water, called Pulse-Chlorination® was developed by KEMA. Pulse-Chlorination is based upon the principle that biofouling species like mussels and oysters, in general have a recovery period before fully opening their valves and start filtering water after exposure to a short chlorination period. The new chlorination regime takes advantage of this recovery time by using short successive pulses of chlorine dosing, alternating with periods without chlorine. This chlorine regime methodology is nowadays the Best Available Technique (BAT) under the European Union terms of Integrated Pollution Prevention and Control (IPPC) for macro fouling mitigation in once-through seawater systems. Pulse-Chlorination is investigated and successfully implemented through field tests carried out on-site worldwide on four continents. The method has proven to be universally applicable, but needs to be attuned to local conditions. The overall aim is to ensure optimal performance of cooling seawater system and condenser/ heat exchangers with minimal environmental repercussions.

The backgrounds and main results of the chlorination method at different locations are discussed in the light of (a) how to improve the protection of the seawater distribution system from biofouling organisms and biofilms, (b) how to reduce the amount and concentration of oxidants discharged to the recipient water body in line with the new regulatory requirements and (c) how to lower the operational costs of related equipment, e.g., electro-chlorinators.

Keywords: Pulse-chlorination, Antifouling, Chlorine dosing, Best available technique

Role of β, 1-4 linked polymers in biofilm structure of marine Pseudomonas sp. CE-2
Jain A^*, NB Bhosle
National Institute of Oceanography, Dona Paula, Goa, India
^*E-mail: ajain@nio.org

EPS play role in the biofilm formation, stabilization and persistence of the biofilm on surfaces. Several studies had proved the role of polymers in biofilm formation and stabilization. However, little is published with respect to marine bacterial biofilm. The present study describes the type and role of specific polymers in biofilm formation and stabilization of marine Pseudomonas sp. CE-2. This culture shows attachment to stainless steel, glass and polycarbonate coupons and form thick biofilm. When the cells were grown in the presence of Calcofluor (200µg/ml), a fluorescent dye specific for β, 1-4 linked polymers, adhesion and biofilm formation was reduced. Conversely, when the cells were grown in the presence of Concavalin A (Con A) and Triticum vulgaris (WGA) lectin there was no effect on adhesion and biofilm formation. Epifluorescence microscope observation of calcofluor, Con A and Pisum sativum (PS) lectin treated cells attached to SS showed the binding of these stains by the attached cells. These results suggest the presence of β 1-4 linkage, α-D- glucose, and α- D- mannose in the biofilm matrix. Moreover, protease and lipase treatment did not remove the cells from biofilm. While, cellulase (120U/ml) treatment that degrades β 1-4 linkages in the biofilm matrix resulted in significant cell detachment, creating a central hollow in the microcolonies. These results strongly indicate the role of β 1-4 linked polymers in maintaining biofilm of CE-2 on this surface.

Keywords: Biofilm, β 1-4 linked polymers, Calcofluor, EPS, Con A

Natural product antifoulants – present Scenario and future prospects
Raveendran TV1^*, VP Limna Mol1, PS Parameswaran2
1National Institute of Oceanography Regional Center, Kochi, Kerala, India,
2National Institute of Oceanography, Dona Paula, Goa, India
^*E-mail: tvravi@nio.org

The commonly employed most effective and economic antifouling agent, Tri-n-Butyl Tin (TBT), is currently facing a total global ban imposed by the International Maritime Organisation (IMO) realizing its hazardous impacts on non-targeted marine biota.  The antifouling paint industry, therefore, is presently in a very precarious situation and there is an urgent need for finding an immediate alternative for TBT.  Natural Product Antifoulants (NPAs) have emerged as one of the best alternatives in this context and hence, the research on NPAs has gathered considerable momentum during the last two decades.  Although, commendable effort has been expended by the international scientific community, research on NPAs from the Indian subcontinent is rather limited.  Natural Product Antifouling Laboratory (NPAL) at the regional centre of the National Institute of Oceanography, Kochi, has recently acquired the necessary expertise in screening, isolation, characterization and structure elucidation of NPAs and have successfully identified a few NPAs.  However, much challenges remains ahead before dreaming its applications at an industrial scale.

Keywords: Natural Product Antifoulants, Marine Biofouling, Tri-n-butyl tin