2013 survey of effluent quality and water use at European refineries

Report no. 12/18: Since 1969, Concawe has been gathering and compiling data on aqueous effluents from European oil refinery installations. Surveys have been completed at 3-5 yearly intervals and the survey design has been updated over time to address various scientific and legislative developments. Since 2010, for example, the data collection also focused on water uses within the installations. This report presents the findings of the survey completed in 2014 for the 2013 reporting year of European refinery effluent quality and water use. A total of 79 refineries participated in the survey from the EU-28 countries, Norway and Switzerland. Of the 79 questionnaires returned, 79 yielded data on effluent quality and 70 provided data on site water use. A statistical assessment of site water use is presented, including aggregated data on intake and effluent volumes, water treatment processes, and costs associated with water use. In addition, annual average concentration and discharge mass for a number substances and parameters regulated at EU level are compared with survey data from previous years.

The data returned from the surveys provides perspective on historic trends in refinery water use and effluent discharge and insight into the recent refinery sector performance. The data also allows Concawe to assess the potential impact of proposed changes to existing European legislation. A total of 3.5 billion m3 of water was withdrawn in 2013 by the 70 refineries that returned data on site water use (vs 4.5 billion m3 in 2010 for 100 refineries). Approximately 3.0 billion m3 or 86 % of the total abstracted water was brackish or saline and used for once-through cooling. The total freshwater withdrawal was 493 million m3 (average 7.0 million m3 per refinery), with 371 million m3 (average 5.3 million m3 per refinery) used for purposes other than once-through cooling. By way of comparison, the 2010 survey of 100 refineries indicated a total freshwater withdrawal (for purposes other than once-through cooling) of 4.2 million m3 per refinery on average.

Using the IPIECA definition for freshwater consumption (indicator E6; IPIECA, API and IOGP, 2015), refineries consumed a total of 271 million m3 of fresh water in 2013 vs 282 million m3 in 2010. The average relative freshwater consumption was apparently higher in 2013 at 621 m3/kilotonne throughput vs 467 m3/kilotonne throughput in 2010. All comparison with 2010 water use data could, however, reflect the different population of refineries reported under the 2010 and 2013 surveys, or differences in the way that the surveys were designed (the 2013 survey captured more detailed information on water uses). An average of 0.48 m3 of process water was discharged from the reporting refineries per tonne of annual feedstock throughput, which was lower than reported in the previous two Concawe surveys (0.82 in 2008; 0.67 in 2010). With regard to effluent quality, the results of the 2013 survey are consistent with the long-term trend towards reduced discharge of oil (reported as Oil in Water (OiW) or Total Petroleum Hydrocarbons (TPH)).

While total and relative oil discharge (i.e. normalised to throughput) are lower relative to the 2010 and 2008 survey years at 354 tonnes and 0.71 g/tonne throughput, respectively, fewer refineries participated in the 2013 survey and so the discharge data are not directly comparable. For the 59 refineries that reported under both the 2010 and 2013 survey average relative TPH discharge decreased by 28% from 2010 to 2013. From 1993 to 2013 the survey data indicate a large decrease in total and relative discharge of ammonia and phenols, and a smaller decrease in total nitrogen. For Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Total Organic Carbon (TOC) survey data from 2000-2013 indicate an overall decrease in relative load.