2016 Survey of Effluent Quality and Water Use at European Refineries

12 Jun 2020

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 for the 2016 reporting year of European refineries’ effluent quality and water use. Compared to previous surveys, the 2016 survey design had improved Quality Assurance and Quality Control (QA/QC) and data integrity.

A total of 72 refineries from the EU-28 countries, Norway and Switzerland participated in the survey from 98 potential respondents (73% response rate). 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 discharged mass for a number of chemical substances and parameters regulated at EU level are compared with survey data from previous years. The data returned from these 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.

All 72 refineries were included in the 2016 record of water intake, showing a total of 2.9 billion m3 of water being withdrawn in 2016 (vs 3.5 billion m3 for 78 refineries included in the 2013 survey analysis). Out of the total water withdrawn, 80% represented by once-through cooling water, which was primarily salt/brackish surface water (97%). The water withdrawn excluding once-through cooling water and pass-through waters (non-harvested rainwater) was 475 million m3, out of which 352 million m3 was fresh water (average 4.8 million m3 fresh water withdrawn per refinery).

Of the total intake used for site purposes, most was used for recirculating cooling purpose (44%), followed by use in demineralised water production and/or steam/boiler (25%), and use in flue gas scrubbers (7%). Water losses by use type was reported to be dominated by losses in recirculating cooling use (76%), followed by steam/boiler use (10%) and demineralised water production (7%).

An average of 0.65 m3 of treated effluent water was discharged from the reporting refineries per tonne of annual feedstock throughput, which is lower than that reported in the previous two Concawe surveys (0.90 in 2013; 0.94 in 2010). With regard to process effluents, over 90% of the reporting refineries in 2016 applied three-stage biological waste water treatment, or transferred their process water effluent to an external facility applying three-stage biological waste water treatment. This clearly illustrates that the vast majority of the reporting refineries utilised the provisions of the Best Available Techniques (BAT) Reference document (BREF) for the Refining of Mineral Oil and Gas (REF BREF)1 and its BAT Conclusions (2014/738/EU2) for treatment of effluents.

With regard to effluent quality, the results of the 2016 survey are consistent with the long-term trend towards reduced discharge loads of oil (reported as Oil in Water (OiW) or Total Petroleum Hydrocarbons (TPH)). Moreover, the total and relative load (i.e. normalised to throughput) are lower relative to the 2013 and 2010 survey years, being at 262 tonnes and 0.51 g/tonne throughput, respectively, for 2016. The decrease was confirmed by looking at the median relative TPH load for only the 46 refineries that reported under all surveys form 2010 to 2016.

For other effluent quality parameters, taking 2010-2016 data into account, reductions in relative load was observed for 12 of the analysed quality elements (various organics and heavy metals such as Chemical Oxygen Demand (COD), Total Suspended Solids (TSS) and cadmium) in 2016. Whereas three were kept at constant levels (total nitrogen, phenols and total phosphorus) and two increasing (mercury and vanadium) in 2016.