#54 Essential Considerations for Operating Oily Water Separators on Ships 20 Key Factors

In this article, we delve into the critical operational factors that influence the performance of an Oily Water Separator (OWS). A proper understanding of these factors is vital for the efficient functioning of the OWS, an essential component on-board ships. Marine engineers encounter various types of Oily Water Separators throughout their careers, each with its unique features. While equipment-specific knowledge can be obtained from on-board operational manuals, a fundamental understanding of OWS operation remains consistent across types.

Operational Factors Affecting Oily Water Separator Performance on Ships:

1. Avoid Emulsions: Emulsions occur when the interfacial tension between two liquids decreases sufficiently, allowing droplets of one liquid to disperse in another. Mechanical agitation, shearing forces, solvents, chemicals, surfactants, and particulate matter can reduce interfacial tension and lead to emulsion formation.

2. Avoid Chemical Emulsions: Chemical emulsions result from the addition of certain chemicals to water, acting as surfactants that hold oil droplets in an emulsified state. These chemicals may include detergents used for cleaning and alkaline substances used for boiler maintenance.

3. Avoid Secondary Dispersion: Emulsions can be primary or secondary. Primary emulsions consist of larger oil droplets that generally separate within 24 hours. Secondary emulsions, composed of fine oil droplets that do not naturally separate, are caused by turbulent conditions.

4. Avoid Suspended Solids: Suspended solids, such as mud, boiler soot, and cargo residues, can stabilize emulsions, complicating oil-water separation. Neutrally buoyant solids are particularly challenging to remove and can trigger high ppm alarms.

5. Avoid Turbulence: OWS systems operate optimally under laminar flow conditions. Avoid using OWS during heavy rolling, ensure all line valves are fully open to prevent turbulence, and be cautious of retrofitting on old pipelines, as inadequate suction line valve opening can lead to turbulent flow and emulsion formation.

6. Avoid Particulate Matter: Fine particulate matter, like soot, rust, and microbial contamination, can act as emulsifying agents. Proper filtration is essential to prevent fouling of filter media.

7. Optimal Chemical Use: When necessary, use emulsion breakers as recommended to separate oil from water and release free oil. Avoid using more than the recommended amount, as it can exacerbate the problem.

8. Restrict Drainage of Chemicals: Properly collect and dispose of chemicals used in engine room operations to prevent them from entering bilges. Extreme pH levels can also cause chemical emulsification.

9. Detergent Disposal: Dispose of mop water separately, or use quick-break detergents for cleaning, as regular detergents can act as surfactants and cause oil-water emulsification.

10. Avoid Prolonged Storage: Minimize the retention of bilge water, as prolonged storage can alter the properties of free oil, making it difficult to remove due to oxidation and microbial action.

11. Proper Filtration: Remove large solid particles and floating media from bilge water to prevent filter media fouling.

12. Collect Leakages: Ensure minimal oil enters bilge wells, and store significant oil-water mixtures separately. Remember that the Oily Water Separator is not a purifier.

13. Heat the Influent: Heating the influent reduces the viscosity of the continuous media, facilitating better separation.

14. Segregation of Wastes: Avoid mixing sludge and bilge water, as even a small amount of sludge can contaminate a significant volume of bilge water.

15. Fill Up OWS Prior to Use: Ensure the OWS is filled with clean water and all air pockets are removed before allowing bilge water to enter to prevent sensor confusion.

16. Back Flush: Perform back flushing of the OWS as recommended by the manufacturer to extend filter media life.

17. Clean Sensors: Frequent cleaning of electronic interface sensors ensures proper oil removal and sharp cut-off, reducing water discharge to the separated oil tank.

18. Remove Accumulated Oil: Regularly remove any accumulated oil from the OWS chambers, in addition to automated oil removal.

19. Follow Proper Operating Procedures: Adhere to the step-by-step and systematic operating procedures outlined for the OWS.

20. Proper OWS Maintenance: Consistently maintain the OWS according to the manufacturer's instructions to ensure its optimal performance.

Improving the performance of the Oily Water Separator involves careful consideration of these operational factors. By addressing these aspects, we can enhance the efficiency and reliability of the OWS, contributing to a cleaner and more environmentally responsible maritime industry.