Challenges and Considerations in the Selection and Installation of Ballast Water Treatment Systems

Dr. John Kokarakis

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The quadric-modal process

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The selection of BWTS

►Ship owners have to identify the most suitable BWTS for their specific vessel(s).

► This choice is challenging due to the limited availability of operational experience with BWTS and the rapid development of the BWTS market.

►Various criteria related to the individual vessel, its area of operation, the characteristics of BWTS vendors and the BWTS itself have to be taken into consideration.

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Selection Questionnaire

TECHNICAL

1Is there any risk of corrosion due to the active substance in your system if applicable? In case of negative answer, how long have relevant tests been applied? Do you possess a non objection letter from paint makers?

2 Is the system approved by any Classification Society and which one(s)?

3 Is the system approved by USCG?4 Is the system approved by any Flag Administration?

5Does the system include mechanical filter? If not how are you going to tackle large organisms or potential future sediment requirements?

6How does your system perform on a biological level compared to the required standard? Is the performance above the required standard?

7Can the system be up-rated through increased treatment intensity and modularity to meet possible future stricter standards?

HEALTH & SAFETY1 Is there any toxic effect in your system?

2 Are there any means to ensure safety against toxic effects, if yes are they redundant?

3 What is the exposure to toxic substances on a daily basis if any?

4 How safe is the handling of the active substances? Is personnel involved in this handling?

5 Are there any chemicals/gases produced by your system?6 Are there any chemicals/gases added to your system?

7 What is the Total Residual Oxidant (TRO) produced by your system if any?

FINANCIAL QUESTIONS1 What is the acquisition cost of the system for the capacity

required for our vessel?

2 What is the cost of peripherals associated with your system if any?

3 What is the Lead time for your system?4 What is the cost per service call for your system?

5 How many service calls are typically required per annum in a five year period?

COMPARATIVE ANALYSIS

TODIM AND THOR

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Selection Questionnaire

OPERATION1 What is the required Electric power?

2 What is the estimated pressure drop at the nominal ballasting rate?

3 On the scale of 1 to 5 with 1 pertinent to the less complex system, how would you rate your system?

4 Is there any redundancy in your system?

5Is it necessary to treat Ballast water during de-ballasting process, considering: a) Ballast voyage duration 3 days, b) Ballast voyage duration 6 days, c) Ballast voyage duration 9 days?

6In case Ballast water does not need to be treated during de-ballasting, can it be directly discharged overboard (for example using side shell gravity overboard valves), or is it required to monitor Ballast water before de-ballasting?

7In some vessels ballasting & de-ballasting of the Aft Peak tank is via the Bilge Fire & GS pump. Is there a way your system to treat ballast water for Aft Peak tank in this case, or the tank needs to be connected to the Ballast piping?

8 What is the required time for treatment to accomplish elimination of harmful micro-organisms?

9 Is the system affected by low salinity and to what degree?

10 Is the system affected by low water temperature? If yes what is that temperature range?

11 Under what conditions has the system been tested?

12Further to the above, are there instances of filter clogging due to sediment/suspended solids in the ballast water (during testing or actual operation)? Is there a need for backflushing and at what frequency?

13 What kind of works are required to be carried out by the crew during system's operation?

14Is there any effect of turbidity in your system and to what extent?

15Is there any active ingredient involved in your system and which?

16In case active ingredient is produced or added in your or by your system, is there any specific requirement by Class to install the system in isolated/segregated space? What are the relevant ventilation requirements?

17 Are there any gas detectors in your system?If yes, for which gases are these for?

18 What kind of control & automation does your system use (e.g. probes, sensors, etc)?

19What are the system's alarms, what is their function and set limits?

20 Is your system capable of operating effectively at the minimum de-ballasting rate dictated by the stripping system?

21Can your system work when ballasting/de-ballasting by gravity?

22What kind of byproducts (gases,chemicals, etc) are discharged to the atmosphere or marine environment during operation? In case of chemicals, are these approved not to be Harmful to the Marine Environment?

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Selection Questionnaire

INSTALLATION1 What is the required system footprint based on vessel's

ballasting rate?2 Is it required to install one BWTS per pump?

3 Is the system modular in nature so it can be up-rated in case of up-rating Ballasting rate?

4How many systems have been ordered and installed up to date?

MAINTENANCE

1What is the required annual cost of all consumables, basis vessel's Ballast capacity and above required ballasting/de-ballasting operations per year

2 What are the required maintenance intervals of your system? What are the required inspection intervals?

3 Can the aforementioned maintenance be performed by the crew or does it require specialized personnel?

4 What is the required inspection space (for access)? Has this been included in above footprint?

5 How many service stations do you have worldwide?

6 In case of systems using consumables (chemicals, etc) please specify the ports of supply. Is it possible to transfer consumables by air or are these considered dangerous goods?

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Installation questions: WHERE, HOW, WHAT

► Find a suitable location (minimize pipe and electrical runs)

► Integrate electrically into vessel system

►Engineer system for Class approval

► Integrate with existing pumps & ejectors (include crossovers)

► Isometric piping drawings (prefab)

►Organization & logistics to avoid off-hire

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What needs to be checked/submitted to Class

► P&ID of the ballast system including any connections to othersystems (bilge, fire etc.)

► Arrangement of all units and auxiliary systems with criticalimportance for the functioning of the treatment system.

► Drawings of the Main Switchboard modification

► Updated electric load balance

► Evaluation if new short circuit calculations are necessary.VFD will not for instance affect the short circuit currents.

► Control system block diagram and power supply arrangement

► List of controlled and monitored points/sensors

► Description of interface towards the ship’s existing systems

► New stability calculations may be required Total weightadded must be reported.

► Reinforcements needed due to the added elements.

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3-D Laser Scanning/ Digital Capture of the Shape of Objects

► It is not magic- there is need for a lot of know-how and experience

► 750,000 to 1,000,000 points per second = A cloud of points

► Merging-processing of point clouds

► Valuable tool for retrofits-sister vessels

► Slash time for site surveys (~5 hours)

► 3-D scan of the engine room to ascertain installation

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The temporal/commercial aspect

► It is estimated that the whole process can take aslittle as 9 but up to 18 months. The aim is tostreamline the process learning from experience.The duration relies on many factors includingavailability of equipment, dockyards and workforcewith relevant skills; not only for machineryinstallation but also all the verification andcertification processes.

► Fleet operators with many vessels could well beable to negotiate deals for multi-ship installationsbut factors such as ship type and ballast capacitiesmay mean that a single manufacturer does not havesuitable systems for all vessels in a fleet.

► Can we afford not to fit a BWT system?

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Chick’s Law

► The (k)(t) value(concentration x time),thus the level ofmicroorganisminactivation achieved,can be increased byapplying greaterdoses of thedisinfectant or byincreasing the timethat the water is incontact with thedisinfectant (Chick’sLaw)

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The limitations

► Treatment process is limited by watertemperature and salinity to achieve optimumperformance. A heat exchanger might be usedto raise the water temperature.

► Large tankers and bulk carriers take ballast at rates inexcess of 6,000 m3/hr. Only a few approved systemscan meet this requirement.

► Space on board ships is at a premium. It could be agreat problem in retrofit situations. Explosion proofversions provides extra flexibility.

► Ballast can become contaminated by theresidue/sediment in the tank. This maynecessitate the treatment during de-ballasting.

► Management of dangerous gases is animportant parameter to consider when installingBWTS.

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Hydraulic constraints

► Instructions must be included in the BallastWater Management Plan stating if only onepump or two must be run at a given time.An orifice might be utilized to limit flowthrough the BWT system.

►Assess the suitability of existingpiping/flanges to tackle the higher pressurein the system.

►Systems which treat ballast water duringintake only, can utilize gravity discharge withprovision for neutralization.

► Utilize the original ballast pumps to save some ofthe cost but if they can maintain the flow ratedemanded by the new system

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Filtering

► Screen & disc types

► Hydro-cyclones

► Ice slush might be a challenge for filters

► The size and location (height) of thebackwash pipe as well as whether abackwash pump is installed are alsocrucial parameters for the goodoperation of filters.

► Filters use the same ballast water tobackwash, reducing the flow rateup to 30%. Backwash pumpsincrease the loss in ballastingcapacity.

25μm to 50μm

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What to avoid in filters

►Clogging

►Mechanical failure

►Restriction in piping

►Corrosion

►Water hammer

►Damage due to foreign particles

► Lack of spares for moving parts

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Installation in Oil & Chemical Tankers

► For oil and chemical tankersthe system must be installedin the hazardous area zonesince ballast water is adjacentto cargo tanks.

►Some systems might beinstalled in separatecompartments in the engineroom or cargo pump room.

►Ensure ballast tank gaugingwill not be affected by theBWT.

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Tankers - Hazardous Areas

►Equipment with moving parts that can cause staticelectricity are not allowed to be installed in hazardousareas.

► There are standards for the apparatus group and thetemperature. Apparatus group: IIA, IIB, IIC.Temperature group: T1, T2, T3, … T6.

►Systems installed in cargo area need to be explosionproof.

►A system installed in the E/R of a tanker would pumpballast water through the treatment system, up to theopen deck and down to the ballast tanks. Ballast couldbe discharged through the cargo pump room using thenormal ballast system.

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The interface between hazardous and non-hazardous areas

►Given the need for accessibility tocarry out routine maintenance andrepair, it is preferable to installBWTS in a non-hazardous areasuch as the engine room or anauxiliary machinery space.

►Equipment placed in the engineroom does not have specialexplosion (EX) requirements.Equipment in the pump room of anoil tanker must be intrinsically safe(EX ia or EX ib).

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Tankers- BWTS on deck is acceptable

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Tankers - Acceptable Arrangement

Ballasting

De-ballasting

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Can chemical feed line be led from E/R to P/R?

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Challenge: Sampling

► Maximize the representativeness of the watersample (especially for larger mobilezooplankton).

► Sample is extracted from the pipe in a locationwhere the biological components are well mixedand uniform.

► Candidate locations in the discharge of theballast pump (where turbulence is very high).

► Isokinetic sample from a pipe located at thecenter of the main ballast pipe is preferable thanfrom a small pipe attached to the wall of thepipe.

► Inside diameter of the sampling pipe should beapproximately 10% of the diameter of theballast pipe

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Ballast water monitoring► Flow cytometry is a laser based biophysical

technology of cell counting and sorting.

► This biomarker is widely used inbiochemistry and in fresh water sampling.

► Ship can have a certificate of organism-freeballast water prior to port entry.

► No time will be lost for sampling and testing

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Are we forgetting something?

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Fight with operational measures instead…

►Minimization of ballasting during presence of target species

►Minimization of ballasting at night

►Minimization of ballasting in areas where sewer and industrial discharges occurs

►Minimization of ballasting in global hot spots

►Minimization of sediment uptake in shallow ports or dredging areas

►Remember though, that ballasting needs to be synchronized with unloading