Research on the treatment of sulfide-containing wastewater from oilwell production using segmented progressive sulfide removal process

Abstract

In response to the challenge of sulfide removal from oilwell produced wastewater, a segmented progressive sulfide removal process was adopted to treat the oilwell produced wastewater through UASB bioreactor and biomimetic reactor for segmented progressive reflux treatment. The experimental results showed that under the conditions of adopting the segmented progressive sulfide removal process, adjusting the S/N ratio of 5.2∶2 in the produced wastewater,supplementing a certain amount of HCO3-, and setting the reflux ratio of 2.7∶1, the removal efficiency of sulfide (S2-) in the produced wastewater arrived to 95.8%, and the maximum sulfide volumetric load was 6.46 kg/(m3·d). The removal efficiency of nitrate (NO3--N) reached 99.6%, with the maximum nitrate volumetric load of 1.13 kg/(m3·d). The key metabolite of sulfide metabolism was elemental sulfur, with a recovery rate of 83.8%, which was verified by SEM and XRD simultaneously, and followed by SO42- and S2O32-. While the key metabolite of nitrate metabolism was N2, with a yield of 72.4%, and followed by NO2-. The new process not only solved the problem of efficient removal of sulfide and nitrate from the produced wastewater, but also realized resource recovery(S0) and non-pollution emission of metabolic end products(such as N2).

Keywords

• oilwell produced wastewater
• sulfide
• segmented progressive sulfide removal process
• volumetric load
• recovery of elemental sulfur