EP3405436A1

EP3405436A1 - Ballast water ozone and hydrogen peroxide treatment method and apparatus for ships

Info

Publication number: EP3405436A1
Application number: EP16716704.8A
Authority: EP
Inventors: Salvatore Teti; Marco Nava
Original assignee: Biomarine SRL
Current assignee: Biomarine SRL
Priority date: 2016-01-19
Filing date: 2016-01-19
Publication date: 2018-11-28
Also published as: WO2017125956A1

Abstract

A method and apparatus for the purification of ballast water through ozonation for ships provides to insert in the ballast water system of ships mixing members that permit the mixing of ballast water with a process water which is sea water, preferably drawn from the cooling water of the engine room, ozonized through the injection of ozone gas and added with hydrogen peroxide. The method and the apparatus of the invention greatly improve the effectiveness of the ozonation treatment of ballast water by eliminating the risk of having not solubilized gaseous ozone in ballast water.

Description

TITLE

BALLAST WATER OZONE AND HYDROGEN PEROXIDE TREATMENT METHOD AND

APPARATUS FOR SHIPS TECHNICAL SECTOR

The present invention relates to a method for the purification of the ballast water of ships by means of ozonation treatment, in which the ballast water is treated in the system of ballast water piping between an outlet to the sea and a ballast water tank.

The present invention also relates to an apparatus for the purification of the ballast water of ships by means of ozonation treatment, of the type in which a ballast water system comprises at least one outlet to the sea and at least one ballast water tank connected by pipes along which it is disposed at least one ballast pump and means for ozonation of the ballast water.

STATE OF THE ART

The discharge of ballast water from ships can have a very negative impact on the marine environment.

Cruise ships, large oil tankers and cargo ships use a large amount of ballast water, which is often loaded in coastal waters in a certain region after the ship has discharged wastewater or goods, and is then discharged at the next port of call. When the ballast water is discharged it usually contains a variety of biological materials, including plants, animals, viruses and bacteria. These often include non-native harmful biological material, alien species which can cause serious ecological and economic damage to aquatic ecosystems, also with human health problems.

The treatment of ballast water is therefore of increasing importance and, recently have been proposed apparatuses for the ozone treatment of large ships' ballast water. In fact, ozone is used as a disinfectant since the end of the nineteenth century. Ozone is a naturally occurring allotrope of oxygen and has the highest oxidation potential among all commercially available oxidants. The ozone is an oxidizing agent and a biocide and is unstable in water.

A method and apparatus for water ozonation treatment for ships is proposed with the international application published under n.WO2010013903 in the name of NK CO LTD. In this, are described a polyvalent method and related for ozonation treatment for a ship, which are able to perform different treatments such as purification of water used in ship, the purification of waste water generated during the journey, the purification of harmful gases generated during operation of the engine of the ship or generated from the internal space of the vessel, the treatment and sterilization of water ballast, all using the sterilizing potential of ozone gas generated by an ozone generator present on board. The concentration of the ozone gas generated by the ozone generator can be controlled so that it can be provided at different concentrations for the various uses mentioned above. In the said international application, the treatment of ballast water is carried out by blowing ozone gas directly into the ballast water piping. The proposed method and apparatus allow to optimize the use of the ozone generator which is exploited for various purposes, however, it has big limitations in the ballast water treatment quality.

In fact, the chemistry of ozone in seawater is more complex than in fresh water as it leads to the formation of secondary disinfectant products. The biggest difference is due to the presence of bromide ions in sea water. This implies that the ballast water ozonation causes the formation of bromate ions and bromoform. In addition, ozone can also react with the so-called NOM (natural organic matter), whose presence in the ballast water reduces the formation of bromates as it reduces the amount of oxidant free to react with the bromide ion.

For the above reasons, in order to obtain an optimal treatment of ballast water through ozonation it is necessary to study specific processes and apparatuses that allow to increase the effectiveness of the treatment and thus to reduce as much as possible the presence of harmful products in ballast water treated.

SUMMARY OF THE INVENTION

The object of the present invention is to propose a method and a related apparatus for the purification of the ballast water of ships by means of ozonation treatment able to optimize the effectiveness of ballast water treatment.

Another object of the present invention is to propose a method and related apparatus that combines a high efficacy of treatment of ballast water with low plant costs.

According to one aspect of the present invention, the above objects and still others are achieved by means of a method as expressed in the independent claim 1.

Conventionally, a method for the purification of the ballast water of ships by means of ozonation treatment provides that the ballast water is treated in the system of ballast water piping between an outlet to the sea and a ballast water tanks, in particular via direct blowing ozone into the ballast water piping.

According to a peculiar aspect of the present invention, the treatment of ballast water includes steps of:

injection of ozone produced by an ozone generator into process water consisting of sea water,

- addition of hydrogen peroxide to the process water;

promotion of ozonation of the process water to which ozone and hydrogen peroxide have been added by letting it pass through contact reactors; mixing of the ozonated process water with the ballast water.

The above outlined method provides that the ozone gas is previously injected in sea water, which constitutes the auxiliary process water which can be drawn from the outside or from other internal use, that this is added with hydrogen peroxide, whose presence improves the reactions of ozonation, and that, after having given to the mixture the reaction time required, the auxiliary ozonated water is mixed with the ballast water so that, thanks to the better liquid-liquid solubility, the ozonation treatment of the ballast water takes place in an optimized manner.

Further advantages and characteristics of a method according to the present invention are expressed in the dependent method claims.

According to another aspect of the present invention the above objects are achieved by an apparatus according to what is expressed in the independent claim 5.

Conventionally, an apparatus for the purification of ballast water of ships by means of ozonation treatment provides the presence of a ballast water system in which there is at least an outlet to the sea and at least one ballast water tank connected by pipes along which is disposed at least one ballast pump and means for ballast water ozonation which are usually constituted by nozzles able to blow in the ballast water piping the ozone produced by an ozone generator.

According to a peculiar aspect of the invention the apparatus provides an ozonation system suitable for supplying the above-mentioned means for ballast water ozonation, the ozonation system comprising:

at least one ozone generator,

at least an hydrogen peroxide tank,

a piping system suitable to carry process water consisting of sea water to the means for ballast water ozonation,

ozone injection means of injecting ozone produced by said ozone generator in said piping system where said process water flows,

hydrogen peroxide adduction means, for entering hydrogen peroxide taken from the hydrogen peroxide tank in the piping system, for adding hydrogen peroxide to the process water. An apparatus as outlined above allows the ozonation of process water and adding it with hydrogen peroxide, which then is properly mixed to the ballast water in the ballast water system, to effectively treat the ballast water.

Further characteristics and advantages of an apparatus according to the present invention are expressed in the dependent claims of apparatus.

BRIEF DESCRIPTION OF DRAWINGS

The characteristics and advantages of the invention, however, will be more easily understood from the following description of an embodiment thereof, given as non- limiting example, with reference to the accompanying figures in which:

- Figure 1 shows a block diagram of an apparatus according to the present invention;

Figure 2 shows a schematic perspective view of the main components of an apparatus according to the invention;

Figure 3 shows a schematic perspective view of an ozonation plant included in the apparatus of Fig.1 ;

Figure 4 shows a perspective view of a portion of a ballast water system in an apparatus according to Fig.l;

Figure 5 shows in detail a part of Fig.4;

Figure 6 shows a perspective view similar to that of Fig. 4 of a ballast water plant for ships of conventional type.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to Figures 1 and 2 it is indicated as a whole with 100 an apparatus for ozone treatment of ballast water for ships according to the present invention.

The apparatus 100, arranged on several levels, LI, L2, L3 inside of a ship, includes means for production of compressed air, 110, means for production of oxygen, 120, an ozone generator, 130, cooling means, 140, for the ozone generator, a system for ozonation of process water, 150, and a ballast water system, 160.

A first portion of the apparatus consists in the production of compressed air, and from this in the production of oxygen which is used by the ozone generator 130. These portions of the apparatus comprise an air compressor, 111, a filter (not shown) for the filtration of air between the compressor 111 and a compressed air tank, 112, filters (not shown) between the compressed air tank 112 and an oxygen generator, 121, in two stages, a process oxygen tank, 122, and an oxygen tank, 123, for the containment of pure oxygen at 96%.

With reference also to FIG. 3, the oxygen of the oxygen tank 123 feeds the ozone generator 130 which is of conventional type in which ozone is produced by chemical reaction of oxygen atoms with oxygen molecules. In these conventional ozone generators the production of ozone requires the presence of a gas container where there are two electrodes separated by a dielectric material. The power supply with a high frequency voltage to the electrodes causes an endothermic process in which 95% of the energy involved is released in the form of heat that must be dissipated. The dissipation of heat takes place thanks to the cooling means 140. The cooling means 140 are constituted by a water cooling system. A closed-loop water circulation system supplies cooling water to the ozone generator 130 through plate heat exchangers. The temperature and the flow rate of the cooling water at the outlet of the cooling means 140 are constantly monitored through a control panel 180, so that the ozone generator 130 is always effectively cooled.

The ozone produced by the ozone generator 130 is fed to the system for ozonation of process water 150 represented in Figures 1 and 3. The process water circulating in the ozonation system 150 is preferably cooling water coming from the ship's engine room. The treatment water is passed through a series of filters, 151, with 200 micron mesh. In the embodiment shown in FIG. 3, once the process water has been filtered it is distributed to three parallel plumbing to feed three separate ballast water systems 160. Once filtered the treatment water is pushed towards a contact reactor, 152, by a booster pump, 153. In the section between the booster pump 153 and the contact reactor 152, an ozone injector, 154, enter in the ozonation system 150 ozone produced by the ozone generator 130. Among the ozone injector 154 and the contact reactor 152 are interposed means for feeding hydrogen peroxide, 155, intended to enter in the ozonation system 150 hydrogen peroxide taken from a hydrogen peroxide tank, 156. Some of the above-mentioned components, shown in the schematic view of FIG. 1, are not illustrated in FIG. 3 for simplicity of representation. In addition, the ozonation system 150 includes additional conventional components, not shown, used in ways that are known by the experts of the field, such as isolation valves, pressure switches, flow meters, metering valves, drain valves and others.

The contact reactors favor the mixing of ozone at a high concentration and hydrogen peroxide with the process water. The process water outgoing from the contact reactor is fed to the ballast water system 160.

Furthermore, a ozone destruction system, 157, which is provided to eliminate the ozone gas not solubilized in the process water, is associated to the contact reactor 152. Ozone not solubilized is collected at the exit from any contact reactor 152 and introduced into the ozone destruction system 157.

With reference to FIGS. 1 and 4, the water ballast system 160 comprises a sea chest, 161, from which the sea water is taken with which are fed the ballast tanks, 162 (not shown in FIG.4). Between the sea chest 161 and the ballast tank 162 is interposed a ballast pump, 163, intended to circulate the ballast water in the piping of the ballast system 160. A bypass duct, 164, is arranged at the ballast pump 163, and together with respective bypass valves, 165, is suitable to allow the passage of the ballast water without that the same pass through the ballast pump 163. Between the ballast pump 163 and the outlet 161 to the sea cest, in the vicinity of the latter it is disposed a sludge separator, 166, suitable to retain the coarsest impurities which precipitate in its interior. Between the sludge separator 166 and ballast pump 163 is provided also an underwater self-cleaning filter, 167, suitable to perform further filtering of ballast water. Between the ballast pump 163 and the ballast tanks 162 a branch of the ballast water system 160, provided with a suitable drain valve, 168, leads to a discharge to the sea chest, 169, suitable to allow the expulsion outside of the ballast water.

Between the ballast pump 163 and the ballast tanks 162 are provided ballast water ozonation means 170. The above ballast water ozonation means 170 are constituted by a static mixer suitable for mixing the treatment water coming from the ozonation system 150 with the water of the ballast water system 160. The static mixer is advantageously constituted by a flash pipeline reactor, shown in greater detail in FIG. 5, suitable to furnish the ozonated process water coming from the ozonization system 160 in the ballast water stream. The use of a PFR (flash pipeline reactor) for mixing has considerable advantages in that it allows a particularly fast and efficient mixing with minimal pressure losses in the ballast water stream. In addition, the PFR is installed in line with minimum dimensions compared to the contact reactors or other types of mixing members.

As can be seen by comparing Figure 4 with Figure 6 in which is shown a conventional ballast water system, the plant differences are minimal for which an apparatus according to the present invention can also be installed in existing ships by making few changes to the existing ballast water system. In fact, in a conventional ballast water system it is sufficient to insert in line, along the pipe between the ballast pump and ballast tanks, the ballast water ozonation means 170 which allow the mixing of the process water with the ballast water. Advantageously it is also provided the bypass duct 164 and the underwater self-cleaning filter 167. A method for ballast water treatment according to the present invention is immediately deducible from the mode of operation of an apparatus 100 as described above. In fact, the ballast water taken from the sea chest 161 is sent to the ballast tank 162 by means of the ballast pump 163. Between the ballast pump 163 and the ballast tank 162 the ballast water is ozonated by mixing it with process water taken from an ozonation system 150. The ballast water is mixed with the process water by pumping the process water in the ballast water stream without interrupting or altering the flow of the latter, preferably by using a PFR, 170.

The process water is sea water used preferably from the cooling water of the engine room which is previously ozonated through injection of gaseous ozone produced by an ozone generator 130 and then added with hydrogen peroxide taken from a hydrogen peroxide tank 156.

Further, the process water to which gaseous ozone and hydrogen peroxide have been added passes into contact reactors 152 before being mixed to the ballast water. In this way, ozone not-solubilized process water is eliminated so that gaseous ozone can not reach the ballast water.

From the description given above of a preferred embodiment, the advantages of the method and apparatus of the invention, in particular in relation to the effectiveness of the treatment compared to conventional ozonation treatments of ballast water.

As is obvious to people skilled in this industry, modifications and changes of technical nature can certainly be envisaged without departing from the inventive concept of the invention described, and in accordance with the scope of protection defined by the following claims.

Claims

1. Method for the purification of the ballast water of ships by means of ozonation treatment, in which the ballast water is treated in the ballast water piping system between a sea chest and a ballast water tank characterized in that it comprises steps of:

addition of hydrogen peroxide to the process water,

promotion of ozonation of the process water to which ozone and hydrogen peroxide have been added by passage in contact reactors,

mixing of ozonated process water with the ballast water.

2. Method according to claim 1 characterized in that said step of mixing process water with the ballast water is carried out by pumping the process water in the ballast water stream without interrupting or altering the flow of the latter.

3. Method according to the previous claim characterized in that said step of mixing the process water with the ballast water occurs in a Pipeline Flash Reactor disposed between a ballast pump and a ballast tank.

4. Method according to claim 1 characterized in that said process water is drawn from the cooling water of the engine room.

5. Apparatus for the purification of the ballast water of ships by means of ozonation treatment, of the type in which a ballast water system comprises at least one outlet to a sea chest and at least one ballast water tank connected by pipes along which is arranged at least one ballast pump, and means for ozonation of the ballast water, characterized in that it comprises an ozonation system suitable to feed said means for ozonation of the ballast water, said ozonation system comprising:

at least one ozone generator, at least a hydrogen peroxide tank,

a piping system suitable to carry process water consisting of sea water to said means for ballast water ozonation,

ozone injection means for injecting ozone produced by said ozone generator in said piping system where said process water flows,

hydrogen peroxide adduction means, for entering hydrogen peroxide taken from said hydrogen peroxide tank in said piping system, for adding hydrogen peroxide to said process water.

6. Apparatus according to the previous claim characterized in that said ballast water ozonation means consist of a Pipeline Flash Reactor suitable to mix said ozonated process water to the flow of said ballast water.

7. Apparatus according to claim 5 or 6 characterized in that said ozonization system comprises at least a contact reactor arranged to receive the process water in which ozone was blown and hydrogen peroxide was added, suitable to promote the ozonation of said process water.

8. Apparatus according to claim 5 or followings, characterized in that said ozonization system is arranged for picking up said process water from the cooling water of the engine room, upstream of said ozone injection means being arranged at least one filter and at least one booster pump .

9. Apparatus according to claim 5 or followings characterized in that said ballast water system comprises at least a bypass duct arranged in correspondence of said ballast pump, and respective valves, which facilitate the passage of said ballast water without the same passing through said ballast pump.

10. Apparatus according to claim 5 or followings characterized in that said ballast water system comprises at least an underwater self-cleaning filter disposed between said sea chest and said ballast pump.

11. Apparatus according to claim 5 or followings characterized in that it comprises a water cooling system capable of cooling said ozone generator.

12. Apparatus according to claim 5 or followings characterized in that it comprises a plant for the production of oxygen intended to supply oxygen tanks, said tanks of oxygen being arranged for feeding said ozone generator.

13. Apparatus according to claim 5 or followings characterized by comprising at least a compressor for producing compressed air and compressed air tanks fed by said compressor and designed to feed said tank for the production of oxygen.