Hotel Service Unit 18 Q4

With reference to the use of Oily Water Bilge Separators, the type of pump that should be used is a positive displacement pump.

Reasons:

1. Self-Priming Capability: Bilges often contain air pockets and varying levels of liquid. Positive displacement pumps are self-priming, meaning they can create a vacuum and start pumping even when the suction line isn’t fully filled with liquid. Centrifugal pumps, on the other hand, require priming and may struggle to operate efficiently in such conditions.
2. Handling Variable Flow and Viscosity: Bilge water composition can change, containing varying amounts of oil, debris, and even solids. Positive displacement pumps can handle these fluctuations in viscosity and flow rate better than centrifugal pumps. Centrifugal pumps tend to lose efficiency or even stall at lower flow rates or higher viscosities.
3. Tolerance to Dry Running: The bilge pump might occasionally run dry as the bilge level drops. Positive displacement pumps are designed to handle short periods of dry running without significant damage. Centrifugal pumps can quickly overheat and suffer damage if they run dry due to the lack of cooling and lubrication from the pumped liquid.
4. High Suction Lift Capability: Positive displacement pumps can generally lift fluids from greater depths or distances compared to centrifugal pumps. This is important in larger vessels or when the pump is located far from the bilge wells.
5. Ability to Handle Debris: Although both pump types can be affected by debris, certain positive displacement pumps (like diaphragm or progressing cavity pumps) are more tolerant of solids and debris often found in bilge water.

Specific Types of Positive Displacement Pumps Suitable for OWS:

• Screw Pumps: Robust and efficient, they handle varying viscosities and moderate solids content well.
• Diaphragm Pumps: Excellent for handling viscous fluids, solids, and even air, making them ideal for bilge applications.
• Gear Pumps: Simple and reliable, they offer good self-priming and can handle some debris, but might be less efficient with varying viscosities.
• Progressive Cavity Pumps: Gentle pumping action minimizes emulsification of oil and water, crucial for effective separation in the OWS.

Conclusion:

The choice of a positive displacement pump for OWS ensures reliable bilge pumping even under challenging conditions, with varying fluid levels, viscosities, and occasional dry running. Their self-priming capability, ability to handle debris, and tolerance to variable flow rates contribute to the effective operation of the OWS and help maintain compliance with environmental regulations.

The bilge water feed rate significantly impacts the performance of an Oily Water Separator (OWS).

Optimal Flow Rate:

• Each OWS has a designed maximum flow rate specified by the manufacturer. Operating within this range ensures that the separator has enough time to effectively separate the oil from the water.

Effects of Exceeding the Flow Rate:

1. Reduced Separation Efficiency:

• The primary consequence of exceeding the flow rate is incomplete separation of oil and water.
• The OWS relies on gravity and coalescence to achieve separation, and these processes need sufficient time to occur.
• If the flow rate is too high, the water passes through the system too quickly, carrying oil droplets with it and exceeding the permissible discharge limit of 15 ppm.

2. Alarm Activation and Shutdown:

• The Oil Content Monitor (OCM) constantly measures the oil content in the discharged water. If the oil concentration exceeds the 15 ppm limit due to incomplete separation, the OCM triggers an alarm.
• In many systems, this alarm will automatically shut down the discharge pump or activate a recirculation mode, preventing the discharge of non-compliant effluent. This leads to operational disruptions and delays in bilge pumping.

3. Potential Equipment Damage:

• Mechanical Stress: Excessively high flow rates can put undue stress on the OWS components, such as pumps, valves, and filters, potentially leading to premature wear, damage, or even failure.
• Filter Clogging: The increased flow can push more debris and solids into the filters, causing them to clog more quickly and requiring more frequent cleaning or replacement.

4. Environmental Pollution:

• Non-compliant Discharge: The primary concern is the risk of discharging oily water with an oil content exceeding the 15 ppm limit, leading to marine pollution and violating MARPOL regulations.
• Harmful Effects: Oil pollution can have devastating effects on marine life, ecosystems, and coastal areas.

Conclusion:

• It’s essential to operate the OWS within its designed flow rate to ensure efficient oil-water separation, comply with environmental regulations, and protect the marine environment.
• Operators should monitor the flow rate during bilge pumping and adjust it as needed.
• Regular maintenance and inspections are crucial to ensure the OWS remains in optimal working condition.

Remember, efficient operation of the OWS is not only crucial for compliance but also for environmental stewardship and responsible maritime practices.

A bilge holding tank is a crucial component of a ship’s pollution prevention system. Its primary purpose is to collect and temporarily store bilge water before it undergoes treatment or is discharged overboard.  

1. Bilge water – Wärtsilä

Let’s break down the key purposes in more detail:

1. Regulatory Compliance:

• MARPOL Annex I restricts the direct discharge of oily mixtures, including bilge water, into the sea. It sets a limit of 15 parts per million (ppm) for oil content in discharged water.   1. Marpol Annex I Part A – The Master Mariner www.themastermariner.com
• The bilge holding tank allows the ship to store bilge water when it cannot meet these discharge criteria, such as when the ship is in port, near shore, or the oily-water separator (OWS) is not operational.

2. Facilitating Treatment:

• The holding tank provides a space to accumulate bilge water, enabling batch processing through the OWS.
• This is often more efficient than continuous treatment of small volumes of bilge water, especially when the OWS has a minimum flow rate requirement.

3. Emergency Storage:

• In the event of OWS malfunctions, power outages, or other unforeseen circumstances, the bilge holding tank serves as an emergency storage for bilge water. This prevents uncontrolled discharge into the sea, minimizing the risk of pollution incidents.

4. Operational Flexibility:

• Having a holding tank allows the crew to manage bilge water more flexibly. They can choose the optimal time for treatment and discharge, taking into account factors like weather conditions, proximity to sensitive areas, and the availability of port reception facilities.

5. Additional Benefits:

• The holding tank can also act as a settling tank, allowing some of the oil and solids to separate naturally from the water, making the subsequent treatment in the OWS more efficient.
• It can also provide a buffer to accommodate sudden increases in bilge water generation, such as during heavy weather or equipment leaks.

In summary, a bilge holding tank serves as a crucial intermediary between the bilge wells and the overboard discharge, ensuring compliance with MARPOL regulations, enabling efficient treatment, and providing a safety buffer to prevent accidental pollution.

An

Oil Content Discharge Monitor (OCM), also known as an Oil Content Meter, is a crucial device used on ships to continuously monitor and measure the concentration of oil in the discharged water from an Oily-Water Separator (OWS).

1. Understanding Oil in Water Monitoring – Rivertrace

Key Function:

• Real-time Monitoring: The OCM continuously analyzes the effluent (treated water) from the OWS to determine its oil content in real-time.   1. How Oil-in-Water Monitors Revolutionize Municipal Wastewater Management! arjayeng.com
• Regulatory Compliance: Its main purpose is to ensure that the oil content in the discharged water remains within the permissible limit set by MARPOL Annex I, which is 15 parts per million (ppm).   1. How does an oil in water monitor work? – Rivertrace rivertrace.com
• Alarm and Control: If the oil content exceeds the limit, the OCM triggers an alarm and can automatically stop the discharge or activate a recirculation mode to prevent pollution.   1. Understanding Oil in Water Monitoring – Rivertrace rivertrace.com

Importance of OCM:

• Environmental Protection: It plays a crucial role in preventing marine pollution by ensuring that only adequately treated water with low oil content is discharged into the sea.   1. How does an oil in water monitor work? – Rivertrace rivertrace.com
• Regulatory Compliance: The OCM helps ships comply with MARPOL Annex I regulations on oil discharges, avoiding potential penalties or detentions.   1. Understanding Oil in Water Monitoring – Rivertrace rivertrace.com
• Operational Efficiency: By monitoring oil content in real-time, it allows for immediate corrective action in case of OWS malfunctions or excessive oil discharges, minimizing operational disruptions.   1. Oil content meter – Wikipedia en.wikipedia.org

In summary, the Oil Content Discharge Monitor is a vital component of a ship’s pollution prevention system, enabling continuous monitoring and control of oil discharges in compliance with MARPOL regulations. It helps protect the marine environment and ensures responsible ship operations.