Modern Wastewater Treatment at a Shell Refinery

Processing of lower-quality crude oil, in particular due to higher loads of nitrogen and sulfur compounds, together with changing product requirements led to an increased burden of the process wastewater. Therefore, Shell decided to expand the existing ARA with H+E.

Processing of lower-quality crude oil, in particular due to higher loads of nitrogen and sulfur compounds, together with changing product requirements led to an increased burden of the process wastewater at the German Shell refinery in Hamburg-Harburg. In particular, the sour water strippers ran up against their limits and were no longer able to cope with the high contents of nitrogen compounds, essentially ammonium, and further toxic substances present in the wastewater. This caused problems in both processing and stability and therefore led to operating restrictions. As a result, and also in order to meet the stricter compliance criteria to be implemented in the foreseeable future, Shell decided to expand its existing wastewater treatment plant (WWTP).

Developed Solution

The aim of the new wastewater treatment plant was modifying and expanding the nitrogen processing capacity of the biological stage, in order to ensure the stability of the nitrification process and to meet the new regulatory environmental requirements in the long term. Additional aspects included the separation of free and suspended oils, operational safety by removal of H₂S, reducing toxic load impacts, and plant extension without shut-down during operation.

Applied Process Combination

The waste water treatment plant comprises a physico-chemical pretreatment section (CPI, sulfide treatment, flotation) with downstream biological sulfide extraction (accelator), a two-stage moving-bed bio reactor, a multiple-stage nitrification with an upstream denitrification, a downstream denitrification for the removal of the remaining nitrate, a sedimentation, and an outlet polisher (both biofilter and sand filter), a new sludge dewatering unit, as well as a thermal incineration for waste air.

Facts & Figures

Ensuring stability of the nitrification processes
Compliance with environmental requirements
Conversion in ongoing operation