Environment Report 2013

ENVIRONMENT REPORT 2013

6.10 Disposal of Operational Waste Operational waste disposal routes are divided into five categories: reuse and recycle, landfill, incineration, waste to energy and ‘other’. The last category includes any treatment methods not captured within the other groups such as composting or the treatment of aqueous wastes. In 2012, 26 per cent (34,258 tonnes) of waste was reused or recycled; this includes scrap metal, oils and sludge. Around 28 per cent (36,453 tonnes) of operational wastes were sent to landfill, comprising general accommodation wastes, treated slops (solid residues) and other wastes. The largest volumes of special wastes returned to shore for recycling and/or disposal are drilling derived oily sludge. The treatment varies among the different effluent treatment plants but generally includes gravity settlement, flocculation, filtration and heat to facilitate the separation of oil, water and solids. In some cases, the solids are subject to further thermal treatment to bring the oil content under the special waste classification threshold of one per cent hydrocarbons. The cleaned solids are then sent to landfill for final disposal. The separated water is treated to enable discharge to sewer. The recovered oil is usually reused as a fuel after further treatment offsite by specialist contractors.

Figure 13: Operational Waste by Disposal Route

Landfill

Reuse and Recycle

Other

Incineration

Waste to Energy

60,000

50,000

40,000

30,000

20,000

Tonnes

10,000

0

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Source: EEMS August 2013

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