Biological treatment of produced water: A comprehensive review and metadata analysis

A metadata analysis was conducted to analyze the impact of several operating conditions on the biological removal of chemical oxygen demand (COD) from produced water (PW). Operating conditions including temperature, salinity, oxygen availability, treatment technology, microorganism type, and treatment scale were investigated. No limiting maximum COD elimination capacity was reported in the literature, signaling the need to experiment with higher COD concentrations at reduced retention times to identify if such a limit exists. The maximum recorded COD elimination capacity of PW was achieved under low salinity and aerobic conditions in a membrane bioreactor using oil-degradation bacteria on a laboratory scale. Suspended growth exhibited maximum COD removal efficiency, and membrane bioreactors were the most studied technique and achieved the highest performance. Superior COD removal efficiency was realized under hypersaline conditions; however, the COD removal efficiency under freshwater conditions was higher than that under hypersaline conditions.

Automated summary

The study found that using oil-degradation bacteria under low salinity and aerobic conditions in a membrane bioreactor can achieve the highest COD removal efficiency in produced water. Suspended growth showed the best performance in terms of COD removal efficiency, and membrane bioreactors were the most studied and yielded the highest performance.