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OILY SLUDGE DISPOSAL

OILY SLUDGE DISPOSAL. IN THE CONTEXT OF THE MARINE POLLUTION AGREEMENT. INTRODUCTION. MARPOL – (Marine Pollution Agreement) International convention signed by 137 countries around the world, including the UAE in October 2006

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OILY SLUDGE DISPOSAL

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  1. OILY SLUDGE DISPOSAL IN THE CONTEXT OF THE MARINE POLLUTION AGREEMENT

  2. INTRODUCTION • MARPOL – (Marine Pollution Agreement) • International convention signed by 137 countries around the world, including the UAE in October 2006 • Introduced to reduce, and reduce the risk of, pollution at sea from shipping • To prevent the disposal of wastes at sea • Requires Port Authorities to control waste disposal by ensuring all vessels have Certificates of Safe Disposal for all waste streams, namely solids, sewage and oily waste before leaving port • In particular the disposal of oily slops and sludges

  3. SOURCE • The sources of oily effluents generated by shipping are mainly from: • Impurities removed from bunker fuel oil • Tank cleanings (bunker and cargo) • Oily effluent water • Lubricants and greases

  4. CHARACTERISATION These streams can be characterised into two groups as follows: Slops:Sludge: Pumpable Un-pumpable Solids < 1,5% m/m Solids > 35% m/m Water 30% - 60% v/v Water 10% - 20% Specific Gravity <1 Specific Gravity >1 The importance of this distinction is in the handling, processing and disposal costs.

  5. SLOPS: Pumped overboard Either into a barge or a road tanker on the wharf side The quantity of oil generated is typically 0,5% of vessel’s fuel used The typical recoverable oil in slops is >95% The cost per tonne of oil recovered is relatively low SLUDGE: Shoveled by hand into small plastic bags Placed in skips Removed overboard by crane The quantity is much less than slops and dependent on the period between tank cleanings The typical recoverable oil in sludge is <66% The cost per tonne of oil recovered is relatively high RECOVERY The method of recovery of these waste streams varies significantly:

  6. DISPOSAL • The principles of disposal should always be to: • MAXIMISE the UTILISATION of the energy source through recovery and recycling • MINIMISE the quantity of waste requiring DISPOSAL with regard to: • Environmental considerations/circumstances • Best Available Practical Technology (BAPT) • Facilities and infrastructure • Cost

  7. UTILISATION • SLOPS: Has a high usable oil content, and recovery and dewatering can be practically and economically carried out. The recovered oil can be either: • Returned to BUNKER FUEL OIL by blending • Currently no practical technology available to render slops into bunker fuel oil specification • However as most refineries produce bunker fuel that is well within the quality specification, judicious blending is possible, although this is not necessarily to the liking of ship owners and engineers • INDUSTRIAL FUEL OIL • Requires a different and often lower quality specification • Can be practically achieved with current technology • Requires a local industrial base using heating fuel

  8. UTILISATION • SLUDGE: The sludge can be utilised as is, in: • Cement manufacture (Fe & Al content beneficial) • Clay brick manufacture (replaces coal) • And not much else! • However some useful oil can generally be recovered from the sludge. This has the advantage of reducing the volume of waste and renders the sludge more acceptable for disposal • But at considerable cost

  9. DISPOSAL • SLOPS: • SOLIDS (sludge): • The removal of the inorganic solids from slops produces a sludge as there is usually some associated oil remaining. • This sludge can be less than 60% oil by mass • And would typically account for less than 5% by mass of the oil in the slops received. • WATER: • The water can be • Easily removed to below 1% remaining in the oil • Pre-treated to remove the bulk of the oil (<200 ppm) • Disposed to a biological water treatment facility

  10. DISPOSAL • SLUDGE: • The removal of the free oil in sludge results in a sludge requiring disposal with around 50% oil content by mass and accounts for around 40% by mass of the sludge received. • Further processing can reduce the oil content even further but at a cost • There are various available technologies: • Centrifugation, solvent wash, steam stripping • Incineration, pyrolisation or thermal desorption

  11. DISPOSAL • The choice of approved disposal options needs to consider: • The ENVIRONMENTAL IMPACT of each alternative in respect of the: • Available practical technology • Type and quantity of pollution produced • The local circumstances • The acceptable cost-benefit ratio • Sustainability • Monitoring and control required

  12. PROCESS SLOPS WATER TREATMENT SLUDGE WATER DISPOSAL SLOPS PROCESSING SLUDGE PROCESSING OIL PRODUCT SLUDGE TREATMENT SOLIDS DISPOSAL

  13. SYSTEM REQUIREMENTS • Policy (port authority) detailing requirements, standards, procedures, system, authorisations, measurement, monitoring etc • Vessel disposal control system • Infrastructure: • Barges and/or road tankers • Wharf side tankage for slops/ballast water • Sludge handling (skips and trucks) • Processing facilities • Slops • Sludge • Effluent oily water • Disposal Facilities • Landfill for sludge/solids/plastic • Bio-treatment for effluent water • Compliance monitoring

  14. LOW SPEED HORIZONTAL SPINDLE CENTRIFUGE HIGH SPEED VERTICAL SPINDLE CENTRIFUGE

  15. FORCED FEED EVAPORATOR FOR WATER REMOVAL

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