EP2356079A1

EP2356079A1 - Method and a ship plant for inactivation of planktonic organisms in water ballast by hydrodynamic forces

Info

Publication number: EP2356079A1
Application number: EP08875692A
Authority: EP
Inventors: Josip Lovric
Original assignee: Sveuciliste U Dubrovniku
Current assignee: Sveuciliste U Dubrovniku
Priority date: 2008-10-07
Filing date: 2008-10-07
Publication date: 2011-08-17
Also published as: WO2010041090A1

Abstract

The present invention provides an economically and corrosively neutral method for inactivation of planktonic organisms in ballast water and a ship's plant for the same using hydrodynamic forces, wherein said plant comprises upgradeable hydrocyclone clusters, an UV reactor or advanced oxidation system (AOP), a ballast centrifugal pump of > 6.0 bars which sucks surrounding sea water and presses it through a hydrocyclone cluster and a tank for cascading seawater that has been treated in the hydrocyclone cluster.

Description

METHOD AND A SHIP PIANT FOR INAGTIVATION OP PLANKTONIC ORGANISMS IN WATER BALLAST BY HYDRODYNAMIC FORCES

FIELD OF INVENTION

The present invention describes a method as well as a ship's plant for inactivation of planktonic organisms in water ballast, using hydrodynamic forces. The present invention also includes a method comprising of running seawater through a series of hydrocyclones (upgradeable) working in parallel. By using the ship's centrifugal ballast pump_f with capacity up to 3500 ra3/h and supplied pressure of > 6.0 bars, the inbound water mass achieves very high values of acceleration and decompression in the hydrocyclone, which in turn, results in mechanical inactivation of planktonic organisms by hydrodynamic forces. Separation is achieved to a lesser degree, hence, the content is returned back to the same location from where it is being pumped out.

The present invention includes a plant consisting of specialized hydrocyclones for inactivation of planktonic organisms. The hydrocyclones according to present invention are installed in a simple manner, do not have movable parts, practically require no or little maintenance, require only a restricted space and they are relatively inexpensive.

The present invention includes a process of inactivation along with the ship's plant, which is economically feasible, corrosively neutral as well as an ecologically sound method for inactivation of planktonic organisms, during uptake of ballast water into tanks. The method, along with a ship's plant for inactivation of planktonic organisms, provides an alternative to a traditional use of hydrocyclone, which is exclusively for separation or reduction of suspended material in water medium.

The aim of the present invention is to provide a protocol and equipment that could be easily incorporated on a ship, feasible and manageable, while successfully achieving inactivation of planktonic organisms contained in the water ballast; thereby, preventing their distribution in the coastal area during expel.

BACKGROUND OF THE INVENTION

It is a well-known fact, that transfer of organisms in a water ballast and sediment presents a great threat to biodiversity in the sea, eco systems and even human health. For a long time the ballast waters were considered "clean"; therefore, the procedure of ballasting and deballasting on a ship was not treated as potentially dangerous.

The problem of organism transference in water ballast could potentially be solved by ballast water treatment, which primarily uses mechanical pre-treatment . The pre-treatment is based on centrifugal and gravitational processes, which are applied in ballast water treatment systems onboard, as well as in land based systems. There are sorted into the following processes: filtration (membrane filtration, granular filtration, quick sand filtration and reverse osmosis filtration) , sedimentation, hydrocyclonic separation, centrifugal mechanical separation and centrifugal dynamic separation.

Mechanical pre-treatment successfully removes a portion of suspended organisms and particular material in the first stage of a treatment. A ship's water ballast contains various plankton stages of marine organisms (cysts, larvae and adult forms), which is a well-known fact that most of marine life goes through at least one life stage as a constituent of plankton.

Some marine organisms are capable of forming cysts, especially resistant life forms, intended for survival in unfavorable environmental conditions. Once the conditions become favorable, resting cysts hatch into new living organisms. Even though, a portion of organisms do not live past the entrance to the ballast system, the passage through sea chest, filters, ballast pumps, valves, and/or they are not viable in the ballast tank conditions; however, some portion will survive and live through a journey which may last a few weeks.

A portion of organisms that survive and are released in the new environment have to adjust to the new habitat as well as coexist with the autochthonous species. However, the introduced species often have a completely different effect on the new environment then was the case in their original habitat.

For example, the introduction of shellfish Dreissena polymorphs Pallas into the Great Lakes has spread to 40% of inland waters and caused monitoring and prevention expense of one billion dollars. Introduction of Ctenophorae Mnemiopsis leidly Agassiz into Black Sea resulted in destruction of plankton, which consequently destroyed the fishing industry.

Introduction of toxic dinoflagelates of genus Alexandrium, which occurred in Australian waters, is particularly dangerous because the filter feeding shellfish's soft tissue absorbs it. Such infested shellfish, oysters for example, when ingested raw may cause paralysis or even death. Likewise, transference of Vibro cholerae bacteria was a cause of cholera epidemic in Chile.

It is possible to remove larger organisms and sediments with mechanical pre-treatment and prepare the ballast for further processing with alternative method for removal of remaining organisms. One example of mechanical treatment using centrifugal and dynamic processes is hydrocyclonic separation.

Hydrocyclonic filtration could ensure successful processing of water ballast in the first degree of a treatment. The obvious advantages are reliability, negligible expenses and the ability to incorporate in the already existing ship's ballast system.

The particular matter and organisms, which are removed, are mainly the ones that may cause damage in the facility during the second stage of a treatment, where smaller organism removal is foreseen. The first study on the topic of hydrocyclon separation application in water ballast treatment is recorded on pilot- facility of capacity 55 m³/h {Cangelosi A, Knight IT, Balcer M, Gao X, Huq A, McGreevy JA, McGregor B, Reid D, Sturtevant R & Carlton JT (1999) . The Biological Effectiveness of Filtration as an Onboard Ballast Treatment Technology. Proceedings of the Ninth International Zebra Mussel and Aquatic Nuisance Species Conference, Duluth, MN, April 26-30, 1999) . The results were not encouraging because a very little success of organism removal was achieved.

The improved hydrocyclone, measuring 5 m, with capacity of 100 m³/h and input pressure of 2 bar, demonstrated 13,7% success rate for removal of Artemia cysts, 30% for dinoflagelates, while bacteria removal was insignificant (A. Jelmert , Preliminary Results a pilot study on a treatment for ballast water with vortex separation and UV radiation. Report of the ICES/IOC/IMO Study group on Ballast Water and Sediments, The Hague, 1999) .

Even though hydrocyclone separation is not able to achieve great success in organism removal, this method is suitable as a primary treatment, instead of filtration. During filtration treatment, the problems that arise are loss of ballast water flow and waist of time on filter cleaning. On the contrary, hydrocyclones, which do not have such movable parts, usually come in small dimensions, require negligible maintenance and have low purchasing cost, seem to be a suitable alternative for installment on ships.

Current technology allows facilities with capacity of up to 3.000 m³/h, with large tanker and bulkcarrier ballast pumps. American manufacturers produce ultrahydrocyclone which are capable of achieving accelerations greater than 100 g. Therefore, it is necessary to further research the effectiveness of such a facility.

The principal of operation of hydrocyclone is based on particle acceleration and separation. It separates lighter and heavier phases due to difference in density. Hydrocyclonic separators do not have rotational parts; they consist of a housing, which is cone shaped narrowing down toward one end.

The energy of water flow through narrowing cross sections causes whirl formation. Tangential introduction of pressurized ballast water into the top portion of hydrocyclone causes centrifugal rotational flow downstream (outer whirl) .

Due to its cone shape, the lower end obstructs the whirl that causes pressure to increase in the vicinity of the lower opening. The flow layers get detached and are directed in the opposite direction, central and upstream, toward the area with lower pressure (inner whirl) . At this place - area of lower pressure, the discharge nozzle carries purified ballast water out. The whirl flow creates centrifugal force, which presses organisms and sediment, due to their greater mass, toward the walls of the hydrocyclone . They slide down the wall and are expelled at the lower discharge.

In the light of above-mentioned facts, the hydrocyclone has been exclusively used for separation, more precisely, for reduction of suspended material content. Such application has not shown sufficient effectiveness.

The technical problem that is solved by present invention is effective inactivation of planktonic organisms using hydrodynamic forces applied within a specially constructed hydrocyclone. The type of hydrocyclone, as claimed in the present invention, is capable of achieving lethal degree of decompression and acceleration for the organisms in ballast water. It also refers to the construction of a ship's plant that is easily incorporated, of which the most important advantage is its low maintenance and low cost.

STATE OF THE ART

Procedures for treatment of ballast water with various mechanical, chemical and other methods have been patented in many countries. Below is the analysis of the most relevant documents describing the methods for ballast water treatment.

Patent No. US 7,198,713 of Hamman AG from Germany discloses installation for the removal and the deactivation of organisms in the ballast water, with the following characteristic features: a first feed pump for conveying the ballast water, an equipment for gravity precipitation of coarser solids and bigger organisms, connected to the first feed pump, and/or a backwashable filtration equipment, a downstream side connected equipment for the deactivation of micro-germs.

It is obvious that this patent protects the gravitational proces treatment method and it is intended for larger organisms. It is obvious that this document does not disclose the method for inactivation of microorganisms using the same method as it is claimed in the present patent application.

Patent Nr. US 4,415,452 disclose a method and apparatus for treating a continuous stream of organic wastewater using highly concentrated activated sludge (10,000 mg/1 MLSS), elevated atmospheric pressure, and high levels of dissolved oxygen. The apparatus consists of three pressurized vessels linked in series by piping, and maintained at equal pressure by means of a common manifold. The first vessel receives the mixed liquor consisting of macerated sewage and return activated sludge and thoroughly aearates it with diffused air bubbles. The liquor then flows by gravity into the second pressurized vessel where flocculation and further aeration occur. From an overflow/transfer box in vessel 2, the liquor flows by gravity into the bottom tier of the third vessel which functions as a cyclone separator. The concentrate is drawn from the bottom of the vessel by a return sludge pump and recycled to the first vessel. The concentrate rises into the upper tier of the third vessel where it is clarified and discharged as tertiary quality effluent.

The cited invention does not describe a ballast facility concept or method as claimed by present invention.

Patent Nr. EP133728 (WO0238191) discloses a method of inactivating microorganisms such as viruses within a fluid such as a biological fluid is disclosed. The method includes the steps of providing a UV reactor, which may take the form of an elongated UV lamp, moving the fluid within the reaction chamber in a primary flow directed along the length of the UV lamp, and including a circulating secondary flow within the fluid with the secondary flow being superimposed on the primary flow. As the fluid moves through the reaction chamber in the primary flow, it is circulated rapidly toward and away from the UV lamp in the circulating secondary flow to provide uniform and controllable exposure of the entire volume of fluid to ultraviolet radiation. Microorganisms such as viruses are thus inactivated while desirable components in the fluid, such as proteins, are preserved without the use of a free radical scavenger.

The described procedure does not disclose the features of a method that is described in the present invention.

Patent Nr. JP2006102283 discloses a method for processing ship ballast water and method for manufacturing sterilized liquid.

The procedure does not relate to the procedure of inactivation applying hydrodynamic forces, nor with the use of a ship's plant concept, for inactivation of planktonic organisms by hydrocyclone, as claimed by the subject patent application.

It can be concluded that by analysis of documents from the prior art, there are no existing processes/methods or ship's plants for inactivation of planktonic organisms, using hydrodynamic forces, similar to the one that is claimed by the present invention. The subject matter of the present invention introduces a new technology that is economically feasible, corrosively neutral, as well as an ecologically sound method for inactivation of planktonic organisms during uptake of ballast water into tanks.

The present invention describes a new method that consists of pumping water into ballast tanks through an upgradeable system of hydrocyclones, which are connected in parallel. Using a ship' s centrifugal pump with capacity up to 3500 m³/h and incoming pressure of > 6.0 bars, great acceleration and degree of decompression are achieved, which in turn, generate the effect of mechanical inactivation of planktonic organisms by hydrodynamic forces (separation is achieved to a lesser degree, and this content is returned back to where it is pumped from) .

A ship' s plant as described in the present invention uses processed water, which is transferred into a smaller tank, specially allocated for this equipment (measuring, for example 600 m³) . From here water is pumped with a centrifugal pump (incoming pressure of up to - 3.5 bars, and capacity equal to the above mentioned pump) into a UV reactor, which is an advisable secondary component of a plant. Additional application of advanced oxidation system - AOP is also possible. The processed water is then transferred into individual tanks through a network of pipes, thereby achieving the proposed goal.

Hydrocyclones are easily installed; they do not have movable parts, and practically require no maintenance. They can be fixed in an appropriate place on the ship since they do not require much space, and are also relatively inexpensive. DESCRIPTION OF THE FIGURES

Brief description of figures

Figure 1 represents schematic overview of various modes of plant installation on a ship

Figure 2 represents schematic overview of laboratory pilot plant for water ballast treatment.

Figure 3, 3a and 3b are vertical sections through a UV reactor.

Figure 4 represents a diagram showing a correlation of flow through and separator exhaust with inbound pressure in the hydrocyclone.

Figures 5, 5a, 5b represents a diagram showing simulation results of water going through a hydrocyclone, with inbound pressure of 3.0, 5.0 and 9.0 bar - acceleration and pressure.

Figure 6 shows test phytoplankton species Tetraselmis sp. and Isochrysis sp. used in experiments.

Figure 7 represents a graphical overview of population densities in a course of 5 days monitoring.

Figure 8 shows cysts and nauplii of species Artemia salina photographed before the treatment.

Figure 9 shows cracked cysts photographed after hydrocyclone treatment .

Figure 10 shows nauplii photographed after hydrocyclone treatment .

Figures 11, 11a and lib show a blueprint of ship's pilot plant. Figure 12 shows a graphical overview of results at the experimental site, Sibenik bay.

Figure 13 is a graphical overview of results at the experimental site, Omisljaj bay.

Detailed description of the figures

Figure 1 represents schematic overview of various modes of installation of a plant on the ship, and the plant comprises of: upgradable hydrocyclone cluster (1); UV reactor as a preferred secundary component (that could be supplemented with "an advanced oxidation process" - AOP) (2); ballast centrifugal pump of > 6.0 bars (depending on the preferred parameters and the cluster position) , pumping the ambient water by pression through the hydrocyclone cluster (3); a tank in which the water is pouring and hissed into the hydrocyclone cluster (4); a conventional centrifugal pump of ~ 3.5 bars that sucks hydrocyclone treated seawater from the spilling tank, hisses through the UV reactor and transmitting it with the ballast pipeline into the ballast ship tanks (5) .

Figure 2 represents schematic overview of laboratory pilot plant for water ballast treatment comprised of: a tank φ 1000 x 1000 mm, with the volume of approximately 800 1 (1) ; a hydrocyclon (2); a hydrocyclone sludge tank with the volume of 200 1 (3); a second tank φ 1000 x 1000 mm, with the volume of 800 1 (4); multimedia filter φ 250 x 2000 mm (5), a sieve filter (22, 25, 100 μm) (6); UV reactor (7); processed water carrying tank, φ 1000 x 1000 mm (8); frequency regulation immersing pump (Pl); an immersing pump with the constant rotation (P2); a pressure indicator (manometer) (PI); a pressure sensing instrument (PC); a flow indicator (FI) and a control unit (CU). Figures 3, 3a and 3b represents vertical sections through UV reactor comprised of: a sterilizer's main body (1) ; an in-and-out pipe connector R 3'' (2); a sampling pipe (3); a flange 0190/085x20 (4); upper plate (5); an offset (6); a bottom ring (7); a bottom plate (8); 0-ring with diameter of φ 5x280 (9); a bolt Ml0x20; an ear (11); a sterlizer's stand (12); a probe carrier (13); an UV-probe (14); reduction (15); glass sildes with diameter of φ 28x3 (16); a gasket with diameter of φ 30/ø 29x2 (17); a test tube (18); a test tube support (19); a bolt (20); UV-lamp (21); lamp support (22); test tube fastener (23); seal holder ring (24); 0-ring with diamter of φ 3,5x40 (25); connector carrier (26); connector (27); a screw M4x7 (28); a bolt M5x8 (29); a ventage 1/2' ' (30); pipes 1/2'' - an acid intake (31); a perforated washing syringe (32); pipes 1/2'' - an acid outlet (33); a bottom box girder (34); shafts with propellers φ 20 (35) ; an upper box girder (36) ; semmering 40/20/7 (37); bearing 57/20/14 (38); an external seger ring with diameter of φ 20 (39); an internal seger ring with diameter of φ 47 (40); a bolt M8x20 (41), a pipe M6x20 (41) .

Figure 4 is a diagram representing correlation of flow through and separator exhaust with inbound hydrocyclone pressure.

Figures 5, 5a and 5b are showing simulation results of water going through a hydrocyclone, with inbound pressure of 3.0, 5.0 and 9.0 bars. Inbound pressure of 3.0 and 5.0 bars generate acceleration measuring > 5000 g, which is labeled in dark colour. Inbound pressure of 9.0 bars generates acceleration up to 15 000g. Acceleration of > 7000 g, is labeled with light grey, generated acceleration of > 10000 g is labeled with grey colour and generated acceleration of > 15000 g is labeled with black colour. Figure 6 shows test phytoplankton species

Tetraselmis sp. and Isochrysis sp. that are used to test the efficiency of the plant.

Figure 7 is a graphical overview of population densities in a course of 5 days monitoring, a graphical display of average concentrations in a given time after the treatment.

Figure 9 shows cracked cysts photographed after hydrocyclone treatment

Figure 10 shows nauplii photographed after hydrocyclone treatment: a) live; b) dead (without viscera); c) lacerated

Figure 11, 11a and lib shows a blueprint of ship's pilot plant.

Figure 12 represents a graphical overview of experimental results with average values of individuals separated by hydrocyclone, at the experimental site Sibenik bay.

Figure 13 represents graphical overview of experimental results with average values of unviable individuals in respect to the total number of individuals, at the experimental site Omisljaj bay.

DESCRIPTION OF THE INVENTION

The present invention encompasses the method and ship plant for inactivation of planktonic organisms in water ballast, using hydrodinamic forces. The present invention describes a method that consists of pumping water into ballast tanks through upgradeable system of hydrocyclones connected in a parallel. Using a ship's centrifugal pump with capacity up to 3500 m³/h and incoming pressure of > 6.0 bars, great acceleration and degree of decompression are achieved, which in turn, generate the effect of mechanical inactivation of planktonic organisms by hydrodynamic forces (separation is achieved to a lesser degree, and this content is returned back to where it is pumped from) .

A ship' s plant according to present invention relates to use of the above processed water that is transferred into a smaller tank, specially designed for this equipment (measuring, for example, 600 m³) . From here, water is pumped with a centrifugal pump (incoming pressure of up to - 3.5 bars, and capacity equal to the above mentioned pump) into a UV reactor, which is an advisable secondary component of a plant. Additional application of an advanced oxidation system - AOP is also possible. The processed water is then transferred into individual tanks through a network of pipes, thereby achieving the proposed goal.

A method and a plant, in accordance with the present invention comprise of plant construction and installation on a ship, which inactivates organisms contained in the ballast during process of manipulation with the same, and thereby prevents distribution of organisms in coastal areas where pumped out .

The present invention describes the use of a special type of hydrocyclone capable of achieving acceleration and pressure values that are lethal for organisms contained within the ballast . A method used in the present invention provides effective inactivation of introduced planktonic organisms, provided that they are in the extending zone, which is submitted to acceleration not less than 5000 g, and a degree of decompression not less than 65.0 bar/s.

A method in accordance with the present invention has advantages with respect to other solutions described in prior art as it represents a new technology that enables economically feasible, corrosively neutral, as well as an ecologically sound method for inactivation of planktonic organisms during uptake of ballast water into tanks. Furthermore, hydrocyclones are easily installed, do not have movable parts, practically require no or little maintenance, do not take up much space and they are relatively inexpensive.

APPLICATION EXAMPLE

To carry out the process of the invention, that is, to implement and maintain the plant for inactivation of planktonic organisms, the following steps or stages were performed:

course of research:

a. blueprint and construction of laboratory pilot plant;

b. testing hydrocyclone characteristics;

c. experiments conducted in laboratory pilot plant;

d. blueprint, construction of pilot plant to be incorporated on a ship and experiments while ship is underway. Each step in the course of the method and plant concept experiments is described in the following text, which connotes that every obvious change pertains to the scope of invention of concern .

In step (a) , portable laboratory blue print and construction is performed to meet the requirements for invention of concern (schematic overview is shown in figure 2) .

Multimedia filter (5) and sieve-filter (6) according to figure 2, were bypassed and therefore excluded from treatment process during the course of all experiments.

In this step UV reactor is designed and constructed to meet experiment requirements, and is shown with components description in figures 3, 3a and 3b. UV reactor is equipped with an axially located agitator (3 propellers), with regulator for revolutions, from 0 to 500, and four lamps, 55 W each, wavelength 254 nm. All components are specially designed and produced in domestic companies.

Laboratory pilot plant is installed in TIBO container to enable the possibility of moving it to a ship or shipyard.

In step (b) , testing of hydrocyclone characteristics is performed. Since the market offers exclusively hydrocyclones of industrial type (for purpose of separation, with small acceleration up to 20 g) , extensive research in the area of the specific application market (other than water treatment area) was conducted. Hydrocyclones of small capacity and great acceleration (up to 7500 g) were found. Prior to this discovery, hydrocyclones of capacities 2000 1/hr and 4500 1/hr were progressively used to meet the needs of the experiment. They were named «small» cyclone and «large» cyclone. During the hydrocyclone- testing course, inbound pressure was varied from 2.0 to 5.0 bars, and computer simulations checked motions occurring inside the hydrocyclone (pressure, speed, acceleration) . It was found that when raising inbound pressure, both cyclones achieved increase in flow rate, while outflow at the lower opening (loss of liquid in course of separation) stayed unchanged («large» cyclone 2%, «small» cyclone 3%)

Pressures were chosen according to the following criteria: 2.0 bar, a first step under nominal hydrocyclone pressure (which is 2.5 bar) and 5.0 bar because it is adequate pressure for ship's ballast pump of large capacity (in laboratory pilot plant, lesser values of pressure were achieved during experiment) .

It was shown, during the course of testing the hydrocyclone in line with invention of concern, through simulation of sea water flow in «large» cyclone with inbound pressure of 3,0 bar, that great values of acceleration (2000 g and more) are achieved in a very limited zone, accompanied by a degree of decompression of 10.7 bar/s.

Simulation of flow in «large» cyclone with inbound pressure of 5.0 bar, indicates values of acceleration up to 5000 g and more, in a slightly extending zone, accompanied by a degree of decompression of 19.6 bar/s.

Simulation of flow in «small» cyclone with inbound pressure of 3.0 bar, indicates values of acceleration up to 5000 g and more, achieved in zone of significant extension, accompanied by a degree of decompression of 20.6 bar/s. Simulation of flow in «small» cyclone with inbound pressure of 5.0 bar, indicates values of acceleration up to 5000 g and more, in predominant extension, accompanied by a degree of decompression of 65.0 bar/s.

With regards to the above-mentioned experimental results, from the hydrocyclone test experiment, it can be concluded that «small» cyclone with inbound pressure of 5.0 bar, is the most suitable for achieving the desired results, which is inactivation of organisms with hydrocyclone. The experiment first tested the correlation between flow rate and inbound pressure, as well as the amount of precipitate that is returned back to the sea.

In step (b) , according to present invention, the hydrocyclone flow rate is examined using a stream of computer simulations with the help of Computation Fluid Dynamics (CFD) (Figure 4) .

Based on simulation results, inbound pressure of 5.0 bar is chosen, because the acceleration values that are generated measure > 5000 g in predominant extension are accompanied by a degree of decompression of 65.0 bar/s. Such pressure could be reached with centrifugal pump with a big capacity (~ 3500 m³/h) , which is common on large ships today.

Simulation results for inbound pressures of 3.0, 5.0 and 9.0 bars are shown in figures 5, 5a, 5b.

There is no doubt that with increased inbound pressure, acceleration and decompression values produced would be doubled (acceleration > 10000 g; degree of decompression 130,0 bar/s), which would result in greater effectiveness in inactivation of planktonic organisms, if such is required. Volume of lost liquid in the process of separation (returned back to the sea) is not in any correlation with inbound pressure and measures ~ 3%, which is an acceptable loss in capacity of a ballast pump.

In step (c) the experiments are conducted in a laboratory- pilot plant. In the period from March 2006 through June 2007, the experiment, in line with invention of concern, used test phytoplankton species Tetraselmis sp. and Isochrysis sp. as well as zooplankton species Artemia salina. Artemia salina testing was conducted on permanent stages, cysts and early developmental stages, which are nauplii (24 hours after hatching) . For development of nauplii, 2 g/1 of cysts were used, which were hydrated 1 hour prior to use. The cysts were cultured in jars for 24 hours, under conditions of illumination and temperature of 25°C. After 24 hours, hatched nauplii were transferred into clean jars, counted and set at a concentration of 2000 individuals/1.

In accordance with present invention, the experiments were divided into three groups:

1. phytoplankton species treatment;

2. Artemia salina, cysts and nauplii treatment

3. subsequent hydrocyclone nauplii treatment (species Artemia salina) with inbound pressure of 5,0 bar, and coloration with Neutral Red, following treatment for verification of counting method reliability.

1. Phytoplankton treatment In accordance with present invention, test species Tetraselmis sp. and Isochrysis sp. were selected for research on effectiveness of plant on phytoplankton (figure 7) .

All experiments were conducted in triplicates. Filtered and sterilized sea water used in the experiment, as well as phytoplankton species came from Research and Development Center for Mariculture (RIC) , in Bistrina.

In the treatment, seawater passed through the hydrocyclone with inbound pressure of 2,4 bar (declared optimal inbound pressure), and 4,8 bar (maximal pressure achieved in the pilot plant in line with invention of concern) as well as combined; hydrocyclone (4,8 bar) and UV reactor.

Phytoplankton was injected through an aircompressed chamber into the system, in order to avoid possible damage the pump can inflict on the organisms.

The plant was calibrated injecting clean seawater, thereafter, volume and concentration of phytoplankton was determined for the compressed chamber, which was diluted in the 200 1 seawater system.

The total treated volume was calculated from flow rate values (~ 1,9 m³/h) and duration of the experiment (~ 5 min) , and it was ~ 200 1. Under pressure condition of 5.0 bar, 10 1 of concentrated phytoplankton was added (10⁸ cell/1) to make a final concentration in the treatment process one order in magnitude smaller (10⁷ cell./l). This particular concentration was chosen because it is greater than the values that are noted for algal blooms (10⁶ cell/1), and therefore testing the effectiveness of the plant in the worst-case scenario, as if the ballast was taken in an area of algal bloom. The samples were taken at the beginning, in the middle and at the end of the experiment, 10 1 of treated sea water. The experimental samples along with control and purge samples were subsequently cultured in RIC, under ideal conditions with addition of feeding medium. The density of phytoplankton population was determined daily in the course of 5 days, using the Utermόl method. Samples were than analyzed under Olympus® 1X71 inversion microscope.

Experiment results are show in the table below.

Table 1: Review of phytoplankton treatment results in the course of first 5 days

Table 1. shows that the population density of species Tetraselmis sp. was increasing in the first two days, while third, fourth and fifth day it was decreasing. Population density of species Isochrysis sp . was decreasing the first and second day, following a slight trend of growth. Graphical overview was modulated and it is shown in figure 8.

The conditions in which the organisms were held (transparent plastic bags with 24 hour illumination, aeration and feeding) are ideal conditions for growth; however, these are not the conditions in ballast tanks. On the contrary, the tanks are devoid of light, with no aeration or feeding medium. Accordingly, the achieved results lead to a conclusion that the last phase of inactivation, in tanks, would be very effective.

2. Cyst and nauplii treatment of species Artemia salina

For the purposes of this invention, research was conducted using 200 1 volume of sterilized seawater to which cysts and nauplii were added in concentration of 2000 individuals/1 (Sutherland et al . , 2001). Seawater containing cysts, and subsequently nauplii, passed through hydrocyclone with inbound pressures of 2,4 bar and 4,8 bar. The experiment was also done in combination with UV reactor, under both above mentioned pressure conditions.

Samples of 1000 1 were taken for analysis. Three control samples were taken prior to the beginning of the experiment, while five samples were taken in regular intervals during the course of experiment, and at the system exit after the treatment .

The samples containing cysts were analyzed immediately after treatment, by counting, and were cultured subsequently in aerated chambers with ideal conditions for 24 hours. They were then counted to check for hatched nauplii.

The samples containing nauplii were analyzed immediately after the treatment, by counting living, damaged and unviable individuals. Analysis was performed on Olympus® SZ4060 binocular loupe.

The results are show as number of individuals (cysts and nauplii) in volume of one liter (ind./l) .

Table 2. Cyst and nauplii of species Artemia salina after hydrocyclone treatment, conducted in the laboratory pilot plant (expressed in percentages)

According to results as shown on Table 2., passage of 15 % cysts and 26 % nauplii indicates that the effectiveness of separation is very high. Of this portion, only 14,7 % cysts hatched (in ideal culture conditions that are in contrast to conditions that are in water ballast tanks) , which indicates a positive result. Of 26% of which passed through, only 4% viable nauplii were recorded, which also indicates a positive result.

Achieved results in accordance with the present invention prove that inactivation of planctonic organisms is possible with hydrodynamic forces alone, which are present in hydrocyclone during seawater flow. Not only is it possible, however, it is realistic and very effective.

The state in which inactivated nauplii were recorded, following their passage through the hydrocyclone, points to a conclusion that the achieved effect is a consequence of decompression and shearing of water layers under whirl and great acceleration conditions (figure 12) .

In the case of cysts, the cracking (figure 11.) also seems to be a consequence of shearing of water layers in a whirl and acceleration conditions.

Table 3. Cyst and nauplii of species Artemia salina after UV radiation and combination of hydrocyclone and UV radiation treatment conducted in the laboratory pilot plant A. expressed in percentages

B. Average numerical values, number of individuals in 10 ml volume (average values of all three experiments)

The results of UV radiation after hydrocyclone treatment do not show remarkable effect on cysts, while the viability of nauplii is halved (4 % hydrocyclone alone, 2 % hydrocyclone + UV) .

3. Construction of ship's pilot plant and test of effectiveness on ship while underway

In step (d) pilot plant was designed and constructed for incorporation into a ship system. In order to achieve plant capacity applicable for experiments on a ship while underway, a cluster of hydrocyclones, working in parallel, was designed and constructed with a built-in induction flow meter. The UV reactor is added which was priorly used in a portable laboratory. Taking into account the expert advice given by WGBOSV {Working Group on Ballast and Other Ship Vectors) , minimal volume of sample for experiments in marine environment was 1 m³. Special storage tanks were designed and installed along with concentrators (plankton sieve, 53 μm net) .

The ship that was used for conduction of experiments in accordance with the present invention, did not provide conditions for determination or count of viable and unviable phytoplanktonic organisms, therefore the results obtained were for zooplanktonic organisms only. The results obtained in the laboratory pilot plant were used for test phytoplanktonic organisms . i) Testing in the experimental site Dubrovnik

Experimenting started on a berthed vessel in Sustjepan (outer edge of port Gruz) . Since it was not possible to count zooplanktonic organisms treated in such large volume, over a course of 24 hours, the method chosen for reference counting was coloring with «Neutral red» liquid, the method often used for these types of experiments (Fleming and Coughlan, 1978; Tanga et al., 2006). This liquid colors viable organisms in a red hue, while unviable organisms stay uncolored. The sample was then conserved in a 4 % formaldehyde solution which allows examination for an unlimited amount of time.

While examining the control samples, it was deduced that the surrounding sea is poor with zooplankton (~ 4000 organisms / m³) and, that it would not be possible to conduct a reliable statistical experiment. Therefore, it was decided to repeat the experiments in alternative site, Elafiti Islands. It was concluded however, that the density of zooplanktonic organisms was very similar to Gruz bay.

The treated samples showed uncertain effectiveness of chosen count method. Almost all organisms were colored red, which would indicate that they all survived the treatment. These results are in contrast with the results conducted in the laboratory pilot plant (4 %, that is 2 % viable) . Due to contrasting results, a series of experiments on species Artemia salina, were repeated in the laboratory pilot plant. The results indicated that «Neutral red» colors the organisms that are lacerated as well. At this point it was concluded that the method does not registers death of an organisms, but death of cells, which occurs at a later time.

Based on this experience, it was decided that experiments aboard a ship be conducted in the conditions of middle and northern Adriatic, that is, in Sibenik and Kvarner bays, which are rich in zooplankton.

It was also concluded, that volume of sea water treated needs to be increased to 10 m³. A new concentrator (plankton sieve) was designed and constructed to meet the needs of experiments in line with the invention of concern.

As far as count method is concerned, it was decided not to color the samples immediately, however, some time after sampling. In the meantime the organisms were aerated.

H) Testing in experimental site Sibenik bay

The experiment in line with the invention of concern, was conducted on September 13th, (2007) at the location N 43°44'23'', E 15°52'53' and above depth of 34,8 meters.

The sea was pumped and treated with a small hydrocyclones in 3 consecutive cycles, with inbound pressure of 5,0 bar. In each cycle 10 m³ of sea volume was treated. The precipitate of all three cycles was comprised into one sample, and was named purge. The entire process is repeated under continuous hydrocyclonic and UV radiation treatments. Following each cycle, the treated 10 m³ volume of sea water was concentrated using plankton sieve into a 5 1 canister. The samples obtained were: control "K"; one for each of 3 hydrocyclonic treatments "HCl" (1, 2 and 3) ; combined purge sample (3 hydrocyclone cycles) "HC2G"; samples for each of three hydrocyclone and UV cycles "HCUV" (1, 2, 3) and combined purge sample (3 hydrocyclone + UV cycles) "HC2UVG" . All samples were colored 24 hours following the treatment, in the meantime they were aerated.

The average parameters during the experiments were: temperature 20,31⁰C, salinity 32,49 psu and conductivity 50,1 μs/cm.

Density of zooplankton population during the experiment measured on average, 31872 organisms in m³. On average, 62,69% organisms were separated, out of which 74,55 % were unviable. This fact is not relevant for the inactivation process, because the entire separated content was returned back to the surrounding sea. The organisms that passed through measured on average to be 37,31 %, out of which 95,3 % were unviable. In the ship's tanks, 1,75% organisms, from the surrounding sea populations, were viable after 24 hours.

Hi) Testing in experimental site Omisalj bay

The experiment was conducted on September 15th, (2007) at the location N 45°15'04^{1 1}, E 14°31M0,6', and above depth of 34,8 meters. The sea was pumped and treated with a small hydrocyclones in 3 consecutive cycles, with inbound pressure of 5,0 bar. In each cycle 10 m³ of sea volume was treated. The precipitate of all three cycles was comprised into one sample, and was named purge. The entire process is repeated under continuous hydrocyclonic and UV radiation treatments.

Following each cycle, the treated 10 m³ volume of sea water was concentrated using plankton sieve into a 5 1 canister. The samples obtained were: control "K"; one for each of 3 hydrocyclonic treatments u "HCl" (1, 2 and 3); combined purge sample (3 hydrocyclone cycles) "HC2G"; samples for each of three hydrocyclone and UV cycles "HCUV" (1, 2, 3) and combined purge sample (3 hydrocyclone + UV cycles) "HC2UVG" . All samples were colored 8 hours following the treatment and in the meantime they were aerated.

The average parameters during the experiments were: temperature 20,97°C, salinity 37,44 psu and conductivity 56,64 μs/cm (figure 14) .

Density of zooplankton population during the experiment measured on average, 21425 organisms in m³. On average, 54,50 % organisms were separated, out of which 38,89 % was unviable. The organisms that passed through measured on average to be 45,50 %, out of which 67,21 % were unviable. In the ship's tanks, 14,92 % organisms, from the surrounding sea populations, were viable after 8 hours.

Copepods were a dominant group which made up to 98,70 % of overall population, which was in accordance with published scientific data. Since the copepods are predominantly an abundant group within zooplankton, they are generally considered as an indicator of zooplankton population.

Claims

PATENT CLAIMS

1. A method for inactivation of planktonic organisms in water ballast, by hydrodinamic forces, wherein said method comprises: a. - running seawater through a series of hydrocyclones working in a parallel by using the ship's centrifugal ballast pump, with capacity up to 3500 m3/h and supplied pressure > 6.0 bars, b. - inbound water mass achieves very high values of acceleration and degree of decompression in the hydrocyclone, which in turn, results in mechanical inactivation of planktonic organisms by hydrodynamic forces, c. - separation is used to a lesser degree, and this content is returned back to surrounding sea, where it is pumped from.

2. A ship's plant for inactivation of planktonic organisms in water ballast by hydrodynamic forces, wherein said plant comprises :

a. - upgradeable hydrocyclone clusters (1), UV reactor as an advisable secondary component of the plant (which can be supplemented by advanced oxidation system - AOP) (2), b. - ballast centrifugal pump of > 6.0 bars (depending on desired parameters and a position of cluster) which sucks surrounding sea water and presses it through a hydrocyclon cluster (3) , c. - a tank for cascading seawater that has been treated in the hydrocyclone cluster (4), d. - conventional centrifugal pump of ~ 3.5 bars, which sucks seawater from the cascade tank, presses it through UV reactor and transmits it through ballast piping into ballast tanks (5) .

3. A ship's plant, according to Claim 2, wherein said plant is incorporated in ship's system and enables activation in conditions when vessel is making way.

4. A ship's plant, according to Claims 2 and 3, wherein said plant comprises of a hydrocyclon cluster for operation in a parallel, with built-in induction flow meter, UV reactor, storage tank as well as concentrators, plankton sieves with 53 μm netting.

5. UV reactor according to Claim 2, wherein said UV reactor is equipped with an axial agitator with 3 propellers, revolution regulation possibility, from 0 to 500, and with four lamps, 55 W each, wavelength 254 nm.

6. A method and ship's plant according to Claims 1 and 2, wherein said method and the plant enable operation of ship' s system such that treated sea water is transmitted into a smaller ballast tank (measuring 600 m³) , from where the water is sucked by a centrifugal pump (incoming pressure of up to - 3.5 bars, and the capacity equal to the above mentioned pump) into a UV reactor, which is an advisable secondary component of the plant.

7. A method and a ship's plant according to Claims 1, 2 and 6, wherein additional application of advanced oxidation system - AOP is also possible where the treated water is then transmitted into individual tanks through a network of ballast piping.

8. A method and a ship's plant according to Claims 1 and 2, wherein preferred use is the use of a hydrocyclone of small capacity.

9. A method and a ship's plant according to Claims 1, 2 and 8, wherein the preferred use is the use of hydrocyclone with high acceleration, preferably up to 7500 g.

10. A method and ship's plant according to Claims 1 and 2, wherein preferred hydrocyclone is a small hydrocyclone with inbound pressure of 5.0 bars.

11. A method and ship's plant according to Claims 1 and 2, wherein the circulation in «small» hydrocyclone with inbound pressure of 5.0 bars, achieves values of acceleration up to 5000 g and more, in predominant extension, accompanied by a degree of decompression of 65.0 bar/s.

12. A method and ship's plant for inactivation of planktonic organisms by hydrodynamic forces, according to Claims 1 and 2, wherein increased inbound pressure, acceleration and decompression values produced are doubled (acceleration > 10000 g; degree of decompression 130.0 bar/s).

13. A method and ship's plant according to Claims 1 and 2, wherein said method and a ship's plant is economically feasible.

14. A method and ship's plant according to Claims 1 and 2, wherein said method and a ship's plant is corrosively neutral.

15. A method and ship's plant according to Claims 1 and 2, wherein said method and a ship's plant is an ecologically sound method for inactivation of planktonic organisms during uptake of ballast water into tanks.

16. Use of a method and a shop's plant according to Claims 1 and 2, for inactivation of planktonic organisms.

17. Use of a method and a plant according to Claims 1 and 2, for inactivation of phytoplanktonic species Tetraselmis sp .

18. Use of a method and a plant according to Claims 1 and 2, for inactivation of phytoplankton species Isochrysis sp.

19. Use of a method and a plant according to Claims 1 and 2, for inactivation of zooplanktonic organisms Artemia salina sp.